Histo Block C

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dfusel2
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182860
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Histo Block C
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2012-12-11 23:17:38
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Histology Block C
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  1. layers of the GI
    • mucosa: lamina propria (CT underlying the epithelium) + muscularis mucosa (smooth muscle)
    • submucosa: dense irregular CT
    • muscularis externa: inner circular & outer longitudinal layers of smooth muscle
    • serosa: serous membrane
  2. mucosa
    • varies by location
    • epithelium
    • lamina propria - CT layer that contains glands, vessels & components of the immune system
    • muscularis mucosa - smooth muscle cells in two layers
  3. functions of mucosa
    • protection: from antigens, pathogens & other substances (esophagus)
    • absorption: allows movement of digested nutrients, water & electrolytes into the blood and lymph (small intestine)
    • secretion: provides lubrication & delivers enzymes, hormones and antibodies
  4. mucosa of esophagus
    • epithelium is protective
    • stratified squamous nonkeratinized
    • lamina propria is unspecialized
    • muscularis mucosa consists of scattered bundles of longitudinal muscle fibers
  5. mucosa of stomach
    • gastric mucosa specialized to produce digestive enzymes & acids
    • simple columnar epithelium
    • mucus-secreting cells protect against self-digestion
  6. mucosa of small intestine
    • specialized for absorption
    • simple columnar epithelium
    • absorptive cells (enterocytes) w/ scattered goblet cells
    • surface area vastly increased via evaginating villi
  7. mucosa of appendix
    mucosa similar to colon (absorptive & secretory simple columnar epithelium) w/ more lymphoid tissue
  8. mucosa of colon
    • absorptive & secretory epithelium
    • simple columnar epithelium
    • shaped into crypts (NO villi)
  9. mucosa of anal canal
    • epithelium is protective
    • nonkeratinized stratified squamous
    • transitions to epidermis (keratinized)
  10. lamina propria
    • contains most of the elements of ordinary CT
    • generally not as fibrous as the deeper CT of submucosa
    • has a relatively high proportion of lymphocytes & other immune cells
    • has practically no fat cells
    • includes a rich bed of capillaries
  11. submucosa
    • consists of dense irregular CT
    • contains blood vessels, lymphatic vessels & nerves (enteric nervous system)
  12. muscularis externa
    • two layers of smooth muscle - inner circular & outer longitudinal
    • myenteric plexus: Auerbach's plexus (postganglionic parasympathetic neurons) between the layers of smooth muscles
  13. function of inner circular smooth muscle layer
    • forms sphincters
    • pharyngoesophageal sphincter
    • pyloric sphincter
    • ileocecal valve
    • internal anal sphincter
  14. retroperistalsis
    vomiting
  15. function of muscularis externa
    contractions of the muscularis mix & propel the contents of the digestive tract - peristalsis
  16. serosa/adventitia
    • serous membrane + small amount of CT
    • large amound of adipose can develop here
  17. parts of the GI without serosa
    thoracic portion of the esophagus, duodenum, ascending & descending colon, rectum & anal canal
  18. auerbach's plexus
    • exists between the circular & longitudinal layers of muscularis externa
    • provides motor innervation to both layers
    • provides secretomotor innervation to the mucosa (postganglionic parasympathetic neurons)
  19. meissner's plexus
    • lies in the submucous coat of the intestine
    • contains ganglia from which nerve fibers pass to the muscularis mucosa & the mucous membrane
  20. GI: enteric nervous system
    • Auerbach's plexus
    • Meissner's plexus
  21. esophagus
    • connects the pharynx to the stomach
    • epithelium: nonkeratinized stratified squamous epithelium
    • lamina propria: lymphatic nodules
    • submucosa: dense irregular CT; large blood & lymphatic vessels; Meissner's plexus & glands
    • muscularis externa: upper 1/3 - striated muscle; middle 1/3 - mixed muscle; lower 1/3 - smooth muscle
  22. esophageal glands
    • esophageal glands proper: occur in submucosa; secrete mucus
    • esophageal cardiac glands: terminal portion of esophagus; neutral secretion
  23. esophageal glands proper
    • occur in submucosa
    • secrete mucus
    • secretion is slightly acidic; functions to lubricate luminal wall
    • small, compound tubuloalveolar glands
    • scattered along length of esophagus, slightly more concentrated in upper 1/2
  24. esophageal cardiac glands
    • similar to cardiac glands
    • found in the terminal portion of the esophagus
    • secretion is neutral & designed to protect the esophagus from acid reflux from the stomach
  25. Barrett's esophagus
    • a condition in which the lining of the esophagus changes from squamous to columnar epithelium
    • result of chronic acid reflux into the esophagus
    • pre-cancerous
  26. stomach/esophagus junction
    abrupt change from stratified squamous epithelium to simple columnar epithelium
  27. characteristics of stomach
    • rugae: longitudinal folds or ridges
    • gastric pits: numerous openings in the mucosal surface
    • mucous surface cells: secrete mucus & provide mechanical protection from components of chyme & stomach acid
    • mucosa: simple columnar epithelium
  28. regions of the stomach
    • cardiac
    • fundus
    • pylorus
  29. gastric glands
    • simple branched tubular glands
    • produce gastric juice (~2L/day)
    • consists of a neck & the fundus (body)
  30. contents of gastric juice
    • hydrochloric acid (parietal cells)
    • pepsin (chief cells)
    • mucus (mucus cells)
    • intrinsic factor (enteroendocrine cells/parietal cells)
  31. hydrochloric acid
    • pH 1.0-2.0
    • produced by parietal cells
    • initiates digestion of dietary proteins
    • converts inactive pepsinogen to pepsin
    • bacteriostatic
  32. pepsin
    • proteolytic enzyme
    • converted from pepsinogen (produced by chief cells) by HCl
    • hydrolyzes proteins into peptides
  33. mucus of gastric glands
    • provides an acid protective coating
    • provides a physical barrier between stomach cells & ingested material
    • neutral pH
    • secreted by mucous neck cells
  34. intrinsic factor
    • glycoprotein that binds to vitamin B12
    • essential for absorption of B12 in ileum
    • produced byparietal cells in humans
  35. pyloric portion of the stomach
    • pyloric glands - branched, coiled tubular glands
    • mucous secreting cells
    • enteroendocrine cells
    • DEEP gastric pits
  36. cardiac portion of the stomach
    • mucous secreting cells - protect the epithelium of the esophagus
    • shallow gastric pits
  37. fundic portion of the stomach
    • fundic glands produce gastric juice
    • fundic glands: simple branched tubular glands
    • gastric juice contents: HCl, pepsin, mucus, intrinsic factor
  38. fundic gland cell types
    • mucous neck cells
    • chief cells
    • parietal cells
    • enteroendocrine cells
  39. parietal cells
    • located within the gastric glands
    • have an extensive intracellular canalicular system
    • produces hydrogen ions
    • transports K and Cl ions
    • forms HCl
    • secretes intrinsic factor
  40. pernicious anemia
    • lack of intrinsic factor (can be autoimmune)
    • intrinsic factor: glycoprotein secreted by the parietal cells; binds vitamin B12 allowing it to be absorbed in the ileum
    • can be caused by gastritis, gastretomy
    • symptoms: fatigue, shortness of breath, tingling sensations, difficulty walking and diarrhea, red tongue, abnormally large, misshapen RBCs
  41. stomach ulcers
    • most common site in cardiac region of stomaach
    • caused by acid damaging the epithelium or by a Heliobacter pylori infection
  42. small intestine
    • principal site for digestion & absorption
    • duodenum, jejunem & ileum
    • contains plicae circulares, villi with lacteals, crypts of Lieberkuhn, GALT, paneth cells
  43. villi
    • fingerlike projections covered with simple columnar epithelium & goblet cells
    • absorptive cells have microvilli on apical surfaces
    • in small intestine
    • increased surface area to maximize absorption of nutrients
  44. crypts of Lieberkuhn
    • intestinal glands: simple tubular glands
    • occur between the villi
    • extend from the muscularis mucosa through to the lumen
  45. paneth cells
    • found in the base of the crypts
    • produce antibacterial enzymes
    • regulate normal bacterial flora of the small intestine
    • have intensely pink staining granules
  46. enterocytes
    break up molecules & transport them into the tissues
  47. characteristics of duodenum
    • plicae circulares
    • villi - leaflike
    • crypts of Lieerkuhn between the villi
    • Brunner's glands: found in the submucosa; secrete alkaline mucus that neutralizes acids from the stomach
  48. jejunum
    • principal site of nutrient absorption
    • villi are fingerlike
    • intestinal glands (Paneth cells)
    • NO brunner's glands
  49. ileum
    • site of water & electrolyte resorption
    • similar histology to the jejunum
    • contains Peyer's patches
    • fingerlike villi
  50. Peyer's patches
    located on the side of the ileum opposite the mesentery
  51. large intestine
    • function: resorption of electrolytes & water; elimination of undigested food
    • NO plicae
    • NO villi
    • LOTS of goblet cells
    • teniae coli
  52. colon
    • NO villi
    • submucosa
    • mucosa + TONS of goblet cells (increasing toward the distal end of the colon)
    • taenia coli
    • crypts of Lieberkuhn are deeper than those in the small intestine
    • site of most water & mineral resorption
  53. diarrhea
    • increaase in volume of stool OR frequency of defecation
    • one of the most common clinical signs of gastrointestinal disease
    • may reflect primary disorders outside of the digestive system
    • caused by viruses, bacteria, parasites or drugs
  54. Hirschsprung disease
    • developmental disorder of the enteric nervous system
    • both myenteric (Auerbach) and submucosal (Meissner) plexi are absent
    • sometimes called "mega-colon"
    • results in functional obstruction of the bowel
  55. appendix
    • numerous lymphatic nodules around the entire structure
    • mucosa similar to the colon
  56. appendicitis
    • symptoms
    • low-grade fever accompanies rigor, nausea & vomiting
    • tenderness & firm swelling can be felt on palpation over right lower abdomen
    • pain is aggravated w/ touch, pressure, moving, cough, sneeze, deep breath, straining, etc.
    • loss of appetite with diarrhea or constipation
    • elevated WBC count due to inflammation
  57. anal canal
    • transition from simple columnar epithelium (intestinal mucosa) to keratinized stratified squamous epithelium
    • muscularis externa thickens to form the internal anal sphincter
    • external anal sphincter is striated muscle
  58. liver
    • largest internal organ
    • divided into two lobes
    • within lobes are lobules
    • produces most of the body's plasma proteins (albumins, lipoproteins, glycoproteins, prothrombin)
    • stores & converts vitamins & iron (A,D,K)
    • degrades drugs & toxins
    • produces bile
  59. vitamins stored in liver
    • Vitamin A: precursor of retinal
    • Vitamin D: important for Ca & K metabolism
    • Vitamin K: important for prothrombin synthesis
  60. plasma proteins
    • albumins: regulates plasma volume & colloid osmotic pressure
    • lipoproteins: VDLs (transport triglycerides)
    • glycoproteins: proteins involved in iron transport (haptoglobin, transferrin, etc.)
    • prothrombin & fibrinogen: blood clotting
  61. structure of liver tissue
    • parenchyma
    • connective tissue stroma (reticular fibers)
    • sinusoidal capillaries
    • perisinusoidal spaces (space of Disse)
  62. blood supply to liver
    • dual blood supply
    • venous (portal) system via the hepatic portal vein
    • arterial supply via the hepatic artery
  63. blood flow through the liver
    • hepatic artery & portal vein dump into sinusoids then central vein
    • central vein empties into the sublobular veins then the inferior vena cava
  64. liver lobule
    • functional unit drained by a central vein
    • six-sided prism with each corner being a portal triad
    • afferent blood supply & bile drainage
  65. liver sinusoids
    • hepatic artery & portal vein supply the sinusoidal capillaries
    • lined with simple squamous epithelium
    • sinusoidal blood "bathes" the hepatocytes
    • intimate contact with hepatocytes
    • provide exchange of substances between blood & hepatocytes
    • empty into central vein
  66. hepatocytes
    • large polygonal liver cells
    • about 80% of cells in the liver
    • make up the cell plates of the parenchyma
    • many are binucleate
    • capable of division & regeneration
    • store glycogen & lipids
    • numerous peroxisomes (involved in detoxifying, particularly alcohol)
    • metabolic, endocrine & secretory function
  67. Kupffer cells
    • arise from monocytes
    • form part of lining of the sinusoids
    • tissue macrophages
    • phagocytic
    • involved in the breakdown of old or damaged RBCs
  68. bile duct
    composed of simple cuboidal or columnar epithelium
  69. bile canaliculi
    • thin tubes that collect bile secreted by hepatocytes
    • merge to form bile ductules which eventually become common hepatic duct
  70. portal triad
    • branch of hepatic artery
    • branch of portal vein
    • branch of bile duct
  71. pathophysiology of excessive alcohol
    • excessive alcohol consumption causes a variety of digestive system disorders
    • alcoholic liver disease, fatty liver, liver fibrosis, liver cirrhosis, alcoholic hepatitis, pancreatitis
  72. effect of alchol on the liver
    • decrease in detoxification & hepatocyte function, barrier dysfunction & permeability
    • increase in Kupffer cell activation, LPS sensitization, bacterial overgrowth & microbial translocation
  73. functions of gallbladder
    • STORAGE OF BILE DUCT
    • bile exits liver through common hepatic duct
    • bile is shunted through cystic duct into gallbladder
    • storage capacity of 40-70mL
    • expulsion of bile upon relaxation of sphincter of Oddi
    • smooth muscle cells in wall of gallbladder contract to expel bile through the cystic & common hepatic duct into duodenum
  74. Rokitansky-Aschoff sinuses
    invaginations of the mucosa extending into the muscularis externa
  75. bile
    • emulsifies lipids
    • aids in digestion & absorption of lipids from gut
    • contains organic components (lecithin, cholesterol, bilirubin)
    • contains inorganic components (bile salts)
  76. cholelithiasis
    • gall stones
    • cholesterol stones: usually yellow-green & made primarily of hardened cholesterol
    • pigment stones: small, dark stones made of bilirubin
  77. symptoms of gall stones
    • pain in right upper or middle upper abdomen
    • pain may be constant, sharp, cramping or dull
    • pain may spread to the back or below the right shoulder blade
    • fever
    • yellowing of skin & whites of eyes (jaundice)
    • clay-colored stools
    • nausea & vomiting
  78. liver physiology
    • during cephalic & gastric phases, stimulation by vagal nerve fibers causes release of pancreatic juices
    • acidic chyme entering duodenum causes the enteroendocrine cells of the duodenal wall to release secretin
    • fatty protein rich chyme induces release of cholecystokinin
    • CCK & secretin enter bloodstream
    • upon reaching the pancreas, CCK induces the secretion of enzyme-rich pancreatic juice
    • secretin causes copious secretion of bicarbonate-rich pancreatic juice
  79. cell types of exocrine pancreas
    • centroacinar: secrete biocarbonate ions
    • acinar: secrete pancreatic amylase, pancreatic lipase, trypsinogen, chymotrypsinogen, etc.
  80. exocrine pancreas
    • acini comprise 80% of pancrease
    • composed of columnar to pyramidal epithelial cells with minimal stroma
    • centroacinar cells: in center of acini; occasionally in clusters; pale cytoplasm & oval nuclei
    • intercalated duct: drains acini via interlobular ducts (cuboidal epithelium) to interlobular ducts lined by mucin secreting columnar cells
  81. exocrine pancreatic secretions
    • secretin: stimulates water & bicarbonate secretion by duct cells; is stimulated by acid from stomach and luminal fatty acids
    • cholecystokinin: promotes discharge of digestive enzymes by acinar cells; released from duodenum in response to fatty acids, peptides & amino acids
    • pancreatic enzymes: trypsin, chymotrypsin, aminopeptidases, elastase, amylases, lipase, phospholipases, nucleases
  82. pancreatic self digestion prevention
    packaging of most proteins as inactive proenzymes
  83. secretin
    • stimulates water & bicarbonate secretion by duct cells
    • stimulated by acid from stomach & luminal fatty acids
  84. cholecystokinin
    • promotes discharge of digestive enzymes by acinar cells
    • released from duodenum in response to fatty acids, peptides & amino acids
  85. pancreatic enzymes
    • trypsin
    • chymotrypsin
    • aminopeptidases
    • elastase
    • amylases
    • lipase
    • phospholipases
    • nucleases
  86. ducts of exocrine pancreas
    • acini
    • intercalated ducts: extends into acinus
    • intralobular ducts: form a complex branching network; striated ducts
    • interlobular ducts: lined with low columnar epithelium
    • main pancreatic duct
  87. components of the urinary system
    • paired kidneys - left slightly higher than right
    • paired ureters - exit hilum; insert into trigone (posterior aspect of urinary bladder)
    • single urinary bladder
    • single urethra
  88. functions of the urinary system
    • waste excretion/ water conservation
    • acid/base regulation
    • endocrine function - erythropoietin & renin
    • hydroxylation of vitamin D
  89. kidney capsule components
    • outer layer of capsule: collagen & associated fibroblasts
    • inner layer of capsule: mostly myofibroblasts, few collagen fibers
  90. medullary rays
    straight tubules (striations) in the cortex, some of which are continuous with collecting tubules of the medulla
  91. kidney lobule
    • medullary ray at center
    • one half adjacent cortical labyrinth
    • duct of Bellini: single medullary duct
    • all nephrons associated with the duct
  92. types of nephrons
    • juxtamedullary nephron: long loops of Henle
    • midcortical nephron: short loops of Henle
  93. layers of medulla
    • outer stipe: only thick tubular segments, outer medullary collecting ducts
    • inner stripe: thick & thin tubular segments; outer medullary collecting ducts
    • inner medulla: thin segments; inner medullary collecting ducts
  94. components of nephron
    • renal corpuscle: glomerulus + Bowman's capsule
    • proximal convoluted tubule
    • proximal straight tubule
    • descending thin limb of loop of Henle
    • ascending thin limb of loop of Henle
    • ascending thick limb of loop of Henle (Distal staight tubule)
    • macula densa
    • distal convoluted tubule
  95. components of uriniferous tubule
    • renal corpuscle: glomerulus + Bowman's capsule
    • proximal convoluted tubule
    • proximal straight tubule
    • descending thin limb of loop of Henle
    • ascending thin limb of loop of Henle
    • ascending thick limb of loop of Henle (Distal staight tubule)
    • macula densa
    • distal convoluted tubule
    • connecting/collecting tubule
    • outer medullary collecting duct
    • inner medullary collecting duct
    • papillary ducts of Bellini
  96. renal corpuscle components
    • glomerular capullary tuft
    • visceral layer of Bowman's capsule
    • parietal layer of Bowman's capsule
  97. vascular pole of renal corpuscle
    • afferent arteriole
    • juxtaglomerular cells
    • glomerular capillaries
    • efferent arteriole
    • distal staight tubule w/ macula densa
    • extraglomerular mesangial cells
    • mesangial cells
  98. urinary pole of renal corpuscle
    • proximal convoluted tubule
    • parietal layer of Bowman's capsule
    • podocytes
    • basal lamina/basement membrane
    • urinary space
  99. layers of glomerular basement membrane
    • lamina rara externa - associated with podocyte layer
    • lamina densa
    • lamina rara interna - associated with capillary layer
  100. glomerular filtration barrier components
    • podocyte pedicels
    • glomerular basement membrane - lamina rara externa, lamina densa, lamina rara interna
    • capillary endothelium
  101. function of glomerular filtration barrier
    • endothelium pores: retain formed elements of the blood & repel anionic molecules
    • GBM: physical & charge dependent repulsion of molecules
    • pedicels: limit molecular passage by slit size & anionic charge
  102. components of glomerular basement membrane
    • type IV collagen
    • laminin
    • fibronectin
    • heparan sulfate
  103. function of glomerular filtration membrane
    limits protein loss: mechanical barrier & anionic charge
  104. nephrin
    cell adhesion molecule that links adjacent pedicels & forms diaphragm of filtration slit
  105. glomerular filtration barrier diaphragm components
    • nephrin: cell adhesion molecule, links adjacent pedicels, forms the diaphragm
    • neph1 & 2: linking proteins supporting the nephrin sheet
    • FAT1,2 & P-cadherin: cell adhesion molecules
  106. mesangium
    • mesangial cells (pericytes)
    • mesangial matrix
  107. mesangial cell characteristics
    • contractile
    • phagocytic
    • proliferate
    • synthesize matrix collagen
    • secrete prostoglandins & endothelins (very potent vasoconstrictors)
  108. function of mesangial cells
    • provide mechanical support
    • control glomerular barrier membrane material turnover
    • regulate blood flow
    • secrete vasoactive substances
    • respond to angiotensin II
  109. function of proximal convoluted tubules
    • major site of reabsorption (80% of ultrafiltrate)
    • glycocalyx: ATPases, peptidases
    • transcellular pathway: ATP dependent transport of glucose, peptides, proteins & water
    • paracellular pathway: for small ions (calcium, potassium, water)
  110. descending limb of loop of Henle
    • exclusively water reabsorption due to osmotic gradient
    • cell types I, II, III (mostly squamous cells)
  111. ascending limb of loop of Henle
    • Na, K ATPase pump drives creation of gradient due to impermeability of ascending limb to water
    • type IV cells
  112. loop of Henle: counter-current multiplier
    • purpose: produce a hypertonic medullary interstitium
    • method: descending & ascending loops of Henle differ in their respective permeability to water and ions; Na/K ATPase pump in thick ascending & distal tubule drives creation of gradient
    • descending: thin descending is freely permeable to water; limited permeability to Na, Cl, urea
    • ascending: thin ascending impermeable to water; freely permeable to Na, K, Cl
    • long loops: greatest medullary hypertonicity
  113. distal tubules
    • low cuboidal cells
    • reduced short microvilli
    • no prominent brush border
    • basal plasma membrane infoldings/mitochondria
  114. distal tubule in juxtaglomerulus apparatus
    contains Na sensitive macula densa cells at vascular pole
  115. function of distal tubules
    • distal tubule: reabsorption of about 7% of filtered water
    • proximal pars recta: sensitive to aldosterone (Na reabsorption from urine)
    • distal portion: sensitive to antidiuretic hormone (ADH/vasopressin = water reabsorption)
    • basal infoldings: Na/K ATPase, mitochondria
  116. characteristics of medullary collecting ducts
    • low cuboidal epithelium
    • central nuclei
    • lateral cell boundaries
    • intercalated (dark) & principal (light) cells
  117. intercalated cells
    • dark cells
    • secrete either H+ or HCO3-
    • reabsorb K+
    • buffering system
  118. principal cells
    • light cells
    • respond to aldosterone from adrenal cortex
    • resorb Na+ and water
    • secrete K+
  119. characteristics of papillary collecting ducts
    • columnar cells
    • clear cytoplasm
    • lateral cell boundaries
  120. function of ducts of Bellini
    • serve as osmotic equilibrating device
    • depends on ADH-dependent water channels (AQP-2)
  121. requirements to produce concentrated urine
    • loop of Henle: thick descending, thin descending, thin ascending, thick ascending
    • vasa recta: descending & ascending segments, both freely permeable to water & ions (passive exchange)
    • hypertonic medullary interstitium: serves as osmotic equilibrating device; depends on ADH-dependent water channels (AQP-2)
    • antidiuretic hormone: ADH dependent distal portion of distal tubule & water channels in ducts of Bellini (AQP-2)
  122. epithelium of renal papilla
    simple columnar on surface
  123. epithelium of minor calyx
    transitional epithelium
  124. blood supply of urinary system
    • G1 & G2 glomeruli: efferent arterioles give rise to peritubular capillaries
    • G3 glomeruli: efferent arterioles give rise to vasa recta capillaries
    • arcuate aa & vv: boundary between cortex & medulla
    • interlobular aa & vv: give rise to stellate arteries & veins (afferent arterioles)
  125. vasa recta: countercurrent exchange system
    • purpose: restores isotonic plasma; maintains hypertonic medullary interstitium
    • method: descending & ascending loops of vasa recta are freely permeable to water & ions (passive exchange); Na/K ATPase pump in thick ascending loop of Henle and distal tubule drives creation of gradient
    • descending: plasma is in equilibrium with medullary hyperosmotic interstitium at bottom of loop
    • ascending: hyperosmotic blood looses salt & gains water from interstitium
  126. components of the juxtaglomerular apparatus
    • juxtaglomerular cells of the afferent arteriole
    • macula densa cells of the distal tubule
    • extraglomerular mesangial cells (lacis cells)
  127. function of the JGA
    • juxtaglomerular cells: secrete renin; react to decrease in stretch
    • extraglomerular mesangial cells: modify activity of JG cells
    • macula densa cells: sense changes in Na and regular JG cells
  128. characteristics of ureters
    • length: ~25 cm
    • lining: transitional epithelium
    • muscular tunics: inner longitudinal, middle circular, outer longitudinal
  129. divisions of male urethra
    • prostatisc urethra: transitional epithelium
    • membranous urethra: stratified or pseudostratified columnar epithelium
    • penile (spongy) urethra: pseudostratified columnar epithelium; navicular fossa lined by stratified squamous
  130. divisions of female urethra
    • proximal: transitional epithelium
    • terminal: stratified squamous epithelium
  131. endocrine system
    • glands: system of ductless glands
    • hormones: blood borne - distant cells; paracrine secretion - adjacent cells; autocrine - producing cell
    • function: physiological coordination, slow acting compared to rapidly acting nervous system
  132. organization of endocrine system
    • discrete glands: have CT capsule & vascular supply; pituitary, thyroid, parathyroid, pineal, adrenal
    • glands of mixed function: kidney, liver, pancreas, placenta, atrium
    • diffuse endocrine tissue: diffuse neuroendocrine system; APUD - amine precursor uptake decarboxylation; GEP - gastroenterohepatic (gut & pancreas)
  133. classes of hormones
    • steroid & fatty acid derivatives: originate from mesenchymal cells; often act intranuclearly (ovaries, testes, adrenal cortex)
    • proteins & polypeptides: originate from endoderm (except anterior pituitary); cells often act on cell surface receptors (pituitary, thyroid, parathyroid, pancreas, gut, lung APUD cells)
    • amino acid analogues: originate from neuroectoderm; often associated with neurotransmitters (thyroid parafollicular cells, adrenal medulla)
  134. release of hormones: humoral stimulus
    • body measures baseline levels & detects variations
    • stimulus: low Ca+ ions
    • response: parathyroid glands secrete PTH to increase blood calcium
  135. release of hormones: neural stimulus
    • fast acting response to "flight or fright" stimulus
    • response: pre-ganglionic sympathetic stimulation elicits release of epinephrine & norepinephrine via adrenal medulla
  136. release of hormones: hormonal stimulus
    • slower response to certain developmental cues
    • stimulus: homeostasis & growth
    • response: pituitary gland stimulates other glands to release hormones
  137. cellular targeting
    • systemic: into bloodstream; adrenal medulla - epinephrine
    • paracrine: affect neighboring cells; Leydig cells of testes - testosterone (maturation of sperm)
    • autocrine: cell that secretes hormone is affected by same hormone; supraoptic nucleus of thalamus - oxytocin
  138. receptor-ligand complex
    ligand/NT/hormone/drug + receptor/enzyme/protein
  139. hormone action: cell surface receptors
    • ligand: usually peptide hormones or amino acid analogues
    • physiological effects: second messengers, increase metabolism, cellular division, excretion/secretion, vasoconstriction/dilation, increased contractility
  140. hormone action: intracellular receptors
    • ligand: usually lipid or protein bounded hormones
    • physiological effects: changing the function of the cell by targeting DNA transcription & mRNA translation
    • slow & lasting effects
  141. regulation of hormone secretion
    • negative feedback: the response or product of the initial stimulus diminishes further stimulation (ex - thyroxine)
    • positive feedback: the response or product of the initial stimulus enhances further stimuluation; magnifies response (ex - oxytocin)
  142. hypothalamus
    • part of CNS
    • the "general" in charge of maintaining homeostasis in the body
    • controls most endocrine functions & the autonomic nervous system
    • close association with the pituitary gland
  143. adenohypophysis
    • anterior pituitary
    • pars distalis
    • pars intermedia
    • pars tuberalis
  144. neurohypophysis
    • posterior pituitary
    • infundibulum
    • pars nervosa
    • median eminence
  145. development of pituitary gland
    • oral ectoderm (Rathke's pouch): pars distalis, pars intermedia, pars tuberals (anterior pituitary)
    • neuroectoderm: infundibulum, pars nervosa (posterior pituitary)
  146. innervation of pituitary gland
    • pars distalis: largely vasomotor
    • pars nervosa: neurohumoral
  147. blood supply of pituitary gland
    • inferior hypophyseal artery: pars nervosa
    • superior hypophyseal artery: infundibulum, median eminence
    • primary capillary plexus: infundibulum, median eminence
    • secondary plexus: pars distalis
  148. hypothalamo-hypophyseal portal tract
    proximal end: site where hypothalamic releasing factors enter blood to influence pituitary gland hormone release
  149. cell types of pars distalis
    • basophils: corticotropes (ACTH cells), gonadotropes (FSH & LH cells), thyrotropes (TSH cells)
    • acidophils: somatotropes (GH cells), lactotropes (PRL cells, mammotropes)
    • chromophobes: acidophil or basophil that has released its hormones
  150. cell types of pars intermedia
    • basophils: alpha & beta-endorphin cells that secrete MSH (melanocyte stimulating hormone)
    • chromophobes
    • colloid
    • folliculostellate cells: cells that border colloid
  151. cell types of pars nervosa
    • pituicytes: support cells
    • Herring bodies: swelled axon terminals from the supraoptic & paraventricular nuclei of the hypothalamus (oxytocin & ADH secreting cells)
  152. hormones of Herring bodies
    • oxytocin: targets uterus, mammary glands & CNS
    • ADH: antidiuretic hormone stimulates aquaporin insertion into the apical & basolateral domains of cells in the DCT & CD
  153. pituitary renal axis
    • Detection of low blood pressure
    • Response: secretion of ADH (gets into bloodstream quickly)
    • Two targets: DCT & collecting ducts in kidney - increased water absorption (aquaporin proteins) & Vasoconstriction
    • Effect: RAISE BP (increasing amount of fluid in vessels)
    • Feedback (negative) to inhibitADH secretion
  154. pineal gland development
    • downward projection of the diencephalon
    • epiphysis cerebri
    • meninges invade, create connective tissue septa
  155. pineal gland anatomy
    • triangular (pine cone) shaped
    • located at the anatomical midline of the brain
    • postganglionic fibers from the superior cervical ganglion (SCG) supply innervation
    • corpora arenacea: accumulation of calcium deposits
    • pineal recess: continuation of third ventricle
    • gland consists of anastomosing cords of cells, separated by CT septa
  156. pineal gland cell types
    • pinealocytes: small neuronal-like cells, short processes which terminate on blood vessels; secrete melatonin
    • neural glial cells: small nuclei, many slender processes; filled with intermediate filaments & resemble astrocytes
  157. function of pinealocytes
    • secrete melatonin in response to decreased light via retinohypothalamic pathway
    • melatonin may regulate circadian cycle, sleep induction, inhibit gonadal development & mood
  158. retinohypothalamic pathway
    light - retina - suprachiasmatic nucleus - intermediolateral cell column - superior cervical ganglion - postganglionic fibers - pineal gland
  159. adrenal gland development
    • neural crest: adrenal medulla
    • intermediate mesoderm: adrenal cortex
  160. adrenal gland anatomy
    • capsule: zona glomerulosa, zona fasciculata, zona reticularis
    • medulla
  161. blood supply of adrenal gland
    • superior, middle & inferior suprarenal arteries
    • capsular arteriole
    • fenestrated cortical sinusoidal capillaries: supply cortex, drain into fenestrated medullary sinusoidal capillaries
    • medullary arterioles: direct blood supply from the capsular artery to the medullary capillary sinusoids
    • fenestrated medullary capillary sinusoids: drain hormone rich blood into adrenomedullary collecting veins
    • central adrenomedullary vein (left & right suprarenal vein): drains either into the IVC (right) or left renal vein (left)
  162. adrenal gland hormones
    • zona glomerulosa: mineralocorticoids (aldosterone)
    • zona fasciculata: glucocorticoids (cortisol)
    • zona reticularis: gonadocorticoids (cortisol, weak androgens)
    • medulla: epinephrine & norepinephrine
  163. function of adrenal glands
    • short term: neural control stimulates release of catecholamines (epinephrine & norepinephrine)
    • long term: stimulation of hypothalamic-pituitary-adrenal axis allows release of glucocorticoids & androgens
  164. function of zona glomerulosa
    • secrete mineralocorticoids (aldosterone & deoxycorticosterone)
    • effects water and electrolyte balance in renal tubules
    • controlled by renin-angiontensin-aldosterone system
  165. zona glomerulosa histology
    • columnar cells, ovoid groups
    • sER, modest amount of lipids
  166. zona fasciculata histology
    • broadest zone
    • 1-2 cell thick radial cords
    • lots of lipids
  167. function of zona fasciculata
    • secrete glucocorticoids (cortisol & corticosterone)
    • influences carbohydrate metabolism
    • suppresses immune system
    • elevated in stress
    • controlled by ACTH
  168. zona reticularis histology
    • small cells
    • anastomosing cords of cells
    • sources of cells for all zones of adrenal cortex
  169. function zona reticularis
    • secrete weak androgens - DHEA (dehydroepiandrosterone)
    • controlled by CRH-ACTH (adrendocorticotropic releasing hormone)
  170. adrenal medulla histology
    • large cells
    • anastomosing cords of cells
    • secretes into venules
  171. function of adrenal medulla
    • secretes catecholamines (epinephrine & norepinephrine)
    • functions as modified sympathetic ganglion
    • innervated by preganglionic sympathetic fibers
    • functions in "fight or flight"
  172. conversion of norepinephrine to epinephrine
    • Enzymatic activity induced by glucocorticoids
    • Medullary capillary percolated cortisol down from cortex to medulla
    • PNMT (phenylethanolamine N-methyltransferase) converts NE to E
    • Preganglionic sympathetic neuron stimulated cells to release hormones
  173. renin-angiotensin-aldosterone axis
    • Macula densa detects low sodium; send signals to JG cells
    • JG cells detect low pressure (decreased stretch)
    • JG cells secrete renin
    • Renin converts angiotensinogen to angiotensin I
    • ACE (from lungs) converts angiotensin I to angiotensin II
    • Angiotensin II stimulates zona glomerulosa to secrete aldosterone
    • Aldosterone helps increase BP through reabsorbing salts & water at collecting ducts
    • Increase in BP inhibits JG cells from releasing renin
  174. Hypothalamic-Pituitary-Adrenal axis
    • Long term stress to system causes hypothalmus to release CRH
    • Corticotropes in anterior pituitary release ACTH
    • Adrenal cortex (z. fasciculata & z. reticularis) release glucocorticoids & androgens
    • Glucocorticoids & androgens inhibit release of CRH & ACTH
  175. devt. derivative of thyroid gland
    pharyngeal endoderm
  176. cell types of thyroid follicle
    • follicular cells/ "P" cells
    • parafollicular cells/ "C" cells
  177. follicular cells/P cells
    • make up the follicular epithelium; line follicles
    • range from simple squamous (inactive) to columnar (active) depending on functional state of gland
    • apex of cells are joined by junctional complexes and project toward lumen of the follicle
    • base of cells rest on basal lamina
    • follicle is filled with colloid consisting of thyroglobulin & surrounded by fenestrated capillaries
    • synthesize, store & release thyroid hormones
  178. parafollicular cells/ C cells
    • lightly staining large cells ("clear cells")
    • between the plasma membrane & basal lamina of the follicular cells
    • apical border does NOT reach the follicular lumen
    • secrete calcitonin into pericapillary space surrounded by fenestrated capillaries
  179. thyroglobulin
    • inactive glycoprotein secreted by follicular cells
    • stored as colloid in follicular lumen
  180. thyroid hormones
    • triiodothyronine: T3, most active form
    • tetraiodothyronin: T4, most prevalent form in circulation
  181. function of thyroid hormones
    • regulate growth & development
    • regulate activity of the nervous system, alertness
    • controls basal metabolic rate, regulating carbohydrate metabolism
  182. thyroid hormone disorders
    • hypothyroidism: in children, leads to cretinism; in adults, myxedema
    • hyperthryoidism: leads to hyperactivity, weight loss, agitation (ex. Graves disease)
    • goiters: develop in both hypo- & hyperthryoidism
  183. synthesis & storage of thyroid hormones
    • thyroid stimulating hormone binds to receptor, stimulates second messenger system
    • thyroglobulin synthesized in rER, stored as colloid in the follicle lumen
    • thyroid peroxidase also stored in vesicle & lumen (helps to iodize thyroglobulin)
    • ATP dependent pump sends iodide from blood to cell
    • Iodide diffuses into lumen
    • Iodide oxidized to iodine by thyroid peroxidase in lumen
    • thyroglobulin is iodinated in lumen
  184. release of thyroid hormones
    • lysosomal pathway
    • iodothyroglobin is endocytosed when thyroid stimulating hormone binds
    • lysosomes fuse with colloid vesicle
    • proteolysis of TG-I yields T3 & T4
    • T3&T4 are secreted basolaterally and enter circulation
  185. Graves disease
    • excessive, unregulated synthesis of iodothyroglobulin
    • principal cause: autoimmune thyroid-stimulating antibodies
    • clinical characteristics: elevated T4, increased uptake of radioiodine, suppressed serum TSH levels, palpitations & tachycardia, exophthalmia, increased appetite, weight loss, increased sympathetic nerve tone
  186. exophthalmia
    • protruding globes associated with retracted eyelids
    • retrobulbar edema & increased CT matrix; leads to diplopia
    • symptom of Graves disease (hyperthyroidism)
  187. calcitonin
    • suppresses bone resorption (inhibits osteoclast activity)
    • lowers blood calcium level
    • NOT essential for life
    • regulated by blood calcium levels
    • rapid, acute homeostatic effect
    • opposes PTH secreted by chief cells of parathyroid gland
  188. devt. derivative of parathyroid glands
    • 3rd pharyngeal pouches: inferior parathyroid glands
    • 4th pharyngeal pouches: superior parathyroid glands
  189. parathyroid gland cell types
    • anastomosing cords of cells
    • chief/principal cells: small pale cells, contain secretory granules (PTH)
    • oxyphil cells: large cells/cytoplasm, no granules, rich in mitochondria, very eosinophilic
  190. function of PTH
    • increases blood calcium level
    • bone resorption: induces osteoblasts to release M-CSF (binds to monocytes, converst into osteoclasts); anabolic effect increased bone density
    • increased reabsorption of calcium by the kidney: phosphate is excreted
    • increased absorption of calcium by the gut
  191. PTH
    • essential for live
    • slow, long-term homeostatic action
    • raises blood calcium level
  192. PTH disorders
    • osteitis fibrosa cystica: over-activity of PTH results in osteoporosis & fractures
    • tetany: under-activity can lead to death
  193. islets of Langerhans
    • cuboidal cells in endocrine pancreas containing a number of cell specific secretory granules
    • beta cells: 70%; found in core; secrete insulin (lower blood glucose)
    • alpha cell: 15%; secrete glucagon (raise blood glucose)
    • delta cells: 10%; secrete somatostatin & gastrin
    • PP/F cells: 5%; synthesize pancreatic polypeptide
    • D1 cells: secrete vasoactive intestinal peptide (VIP)
    • EC cells: release secretin, motilin (opposite effects of F cells)
    • Epsilon cells: secrete ghrelin (stimulates appetite)
  194. beta cells
    • synthesize insulin
    • insulin decreases blood glucose by increasing glyconeogenesis (glycogen formation in liver), storage (fat in adipocytes) & utilization (skeletal muscle)
  195. alpha cells
    • synthesize glucagon
    • glucagon increases blood glucose by increasing gluconeogenesis, glycogenolysis, proteolysis, hepatic lipase & fat mobilization
  196. delta cells
    • synthesize somatostatin & gastrin
    • somatostatin inhibits secretion of: insulin (paracrine), glucagon (paracrine) & HCl (parietal cells)
  197. F cells/ PP cells
    • synthesize pancreatic polypeptide
    • stimulates gastric chief cells
    • inhibits release of somatostatin
    • decreases bile secretion, gut motility, acinar pancreas bicarbonate secretion
  198. insulin synthesis
    • preproinsulin: synthesized in rER; signal sequence removed
    • proinsulin: transferred to Golgi apparatus; C peptide bound to A and B chains held together by disulfide bonds
    • mature insulin: produced after cleavage of C peptide from proinsulin in secretory vesicle
  199. insulin release
    energy & calcium dependent fusion of secretory vesicle (containing mature insulin & C peptide fragments) with plasma membrane allows release of insulin into bloodstream
  200. effects of hyperglycemia
    • increase in blood glucose above 120 mg/dl
    • causes release of insulin from beta cells
    • increase glucose storage in liver, skeletal muscle & gate
    • decreases blood glucose
    • inhibits further insulin release
  201. effects of hypoglycemia
    • decrease in blood glucose below 70 mg/dl
    • stimulates release of glucagon from alpha cells
    • mobilize glucose stores in liver, skeletal muscle & fat
    • increases blood glucose
    • inhibits further glucagon release
  202. mechanism of insulin target cells
    • insulin binds to alpha subunit of insulin receptor to activate autophosphorylation of beta subunit of receptor
    • activated insulin receptor recruits GLUT-4  (insulin dependent glucose transporter protein) to plasma membrane
    • GLUT-4 translocation facilitates uptake of glucose into tissue, out of blood
  203. type I diabetes
    • insulin dependent diabetes mellitus (IDDM)
    • lack of insulin due to destruction of beta cells: viruses, autoimmune, toxins
    • generally found in children
    • individuals require exogenous insulin to maintain life (no pancreatic insulin production)
  204. type II diabetes
    • non-insulin dependent diabetes mellitus (NIDDM)
    • insufficient insulin secretion relative to glucose levels
    • fewer numbers of insulin receptors: decreased tissue response to insulin
  205. effects of diabetes
    • Cerebral infarcts (strokes), hemorrhages
    • Myocardial infarcts
    • Loss of beta cells
    • Urinary bladder neuropathy
    • Blindness (due to retinopathy, glaucoma, cataract)
    • Glomerulosclerosis, pyelonephritis (due to thick basal lamina, proliferation of mesangial cells)
    • Gangrene (due to arterosclerosis)
    • Polydipsia: increased thirst
    • Polyphagia: increased hunger
    • Polyuria: increased urination
  206. female reproductive system
    • ovaries, fallopian tubes, uterus, cervix & vagina
    • undergoes regular cyclic changes from puberty to menopause
    • primarily respondes to changes in levels of estrogens & progestogens
  207. ovaries
    • produce gametes & steroid hormones
    • medulla: central portion of ovary; contains loose CT and mass of large contorted blood vessels
    • cortex: in periphery; contains the ovarian follicles (at different stages of development)
    • blood-follicle barrier: to protect developing eggs; size & charge selective
    • surrounded by tunica albuginea (dense CT layer between germinal epithelium & cortex)
  208. germinal epithelium
    • single layer of cuboidal epithelium covering surface of ovary
    • originally though to be the site of germ cell formation
    • continuous with the mesovarium
  209. follicle development
    • primordial follicle: appear in ovary during 3rd month of fetal life
    • primary follicle
    • secondary follicle
    • mature Graafian follicle
    • corpus luteum: empty follicle after ovulation
    • corpus albicans: regression of corpus luteum
  210. ovarian cycle
    • primordial follicle: has unilamellar structure; contains primary oocyte
    • primary follicle: has multilamellar structure; zona pellucida; contains primary oocyte
    • secondary follicle: has antrum; contains primary oocyte
    • mature Graafian follicle: contains primary oocyte until hours before ovulation when meiosis I is completed; presence of first polar body indicates secondary oocyte
  211. hormonal regulation of follicular phase
    • FSH & LH stimulate the development of several primary follicles
    • FSH stimulates granulose & thecal cells - begin to secrete estrogens
    • later, progesterone levels begin to rise (LH peak) stimulating further development & growth of follicles
    • ovulation occurs
  212. hormonal regulation of luteal phase
    • granulosa & thecal cells of the ruptured follicle form the corpus luteum
    • corpus luteum secretes estrogens & progesterone
    • no fertilization: corpus luteum degenerates
    • fertilization: corpus luteum maintained by hCG; secretes estrogen & progesterone
  213. corpus luteum
    • collapse follicle (after ovulation) becomes the corpus luteum
    • secretes estrogen & progesterone
    • these hormones stimulate growth of the lining of the uterus
    • if fertlization does not occur, the corpus luteum degenerates into the corpus albicans
  214. polycystic ovary syndrome
    • normal ovary: one or two follicles at a time ready to ovulate
    • polycystic ovary: endocrine imbalance leads to MANY follicles just below surface of ovary
  215. symptoms of polycystic ovary syndrome
    • infertility
    • infrequent, absent and/or irregular menstrual periods
    • hirsutism - increased hair growth
    • acne, oily skin, dandruff
    • weight gain or obesity (due to excess insulin)
    • skin tags
    • pelvic pain
    • anxiety or depression
    • sleep apnea
  216. ovarian cysts
    • Graafian follicle cysts: most common; develop when an egg does not release properly during ovulation; will generally be reabsorbed
    • corpus luteum cysts: egg fails to release; thin wall containing fluid (antrum) may rupture; will reabsorb
    • hemorrhagic cysts: small ruptures in one of the blood vessels in the cyst wall
  217. ovarian cyst complications
    • ovarian torsion: ovary moves out of its usual position in pelvis; painful twisting of the ovary
    • rupture: severe pain & internal bleeding
  218. fallopian tube components
    • infundibulum: funnel shaped segment adjacent to ovary
    • ampulla: longest segment of the tube; site of fertilization
    • isthmus: narrow segment adjacent to the uterus; mucosal folds are less complex than ampulla; muscularis is thickened
  219. mucosa of oviduct
    • ciliated simple columnar cells
    • nonciliated secretory peg cells
  220. muscularis of the oviduct
    • inner circular muscular layer
    • outer longitudinal muscular layer
  221. movements within the oviducts
    • transport is bidirectional (cilia & peristaltic contractions)
    • fertilization occurs at the ampulla
    • ovum stays in the fallopian tubes for 3 days
    • estrogen stimulates ciliogenesis & progesterone increases the number of peg cells
  222. components of the uterus
    • endometrium: mucosa of the uterus; proliferates & degenerates during the menstrual cycle
    • myometrium: thick muscular layer; nondistinct muscular orientation
    • perimetrium: visceral peritoneal covering of the uterus
  223. phases of the uterus
    • estrogenic/proliferative phase
    • progestational/secretory phase
    • menstrual phase
  224. secretory phase of uterus
    • begins after ovulation
    • extends until the onset of the next menses
    • under the influence of progesterone
    • glands assume a corkscrew shape & have large irregular lumens
  225. leiomyomas
    • uterine fibroids: thickening of uterine muscle
    • occur in up to 50% of all women
    • more common in African American women & obese women
    • grow in response to estrogens
  226. Rx for leiomyomas
    • birth control pills & IUDs stop growth by lowering estrogen levels
    • gonadotropin-releasing hormone agonists shrink fibroids but cause menopause
    • Rx: hysterectomy
  227. vagina
    • inner mucosa has numerous rugae
    • lined with nonkeratinized stratified squamous epithelium
    • muscular layer is 2 indistinct smooth layer muscles
    • NO glands in walls (mucus is from cervical glands)
  228. cervix
    • endometrium contains large branched glands
    • amount & thickness of cervical mucus changes throughout menstrual cycle
    • mid-cycle: mucus is increased 10X and thinner (facilitates sperm travel)
  229. cervical glands
    • secrete mucus
    • secretion changes during menstrual cycle
  230. Pap smears
    • used to diagnose infectious diseases (Candida albicans, Trichomonas vaginalis, Cornebacterium vaginale) and early cervical cancer & endometrial cancer
    • effective & inexpensive screening tool
  231. HPV
    • human papillomavirus
    • over 100 subtypes - 14 cause cervical cancer
    • vaccines: Gardasil & Cervarix
  232. mammary gland
    • modified apocrine sweat glands
    • 15-20 lobes of branched tubuloalveolar glands
    • lobes are subdivided into lobules
    • initial development caused by estrogens/progesterones of puberty
    • during pregnancy - estrogen & progesterone produced by the corpus luteum cause proliferation of ducts & growth of alveoli
    • after delivery - estrogen & progesterone decrease, allowing prolactin to be released
    • oxytocin is also released & stimulates contraction of myoepithelial cells (ejecting milk into ducts)
  233. placenta
    • consists of three parts - amnion, chorion, decidual tissue
    • chorionic villi are of fetal origin
    • decidual tissue is of maternal origin
  234. syncytiotrophoblast
    • produces hCG for the first 2 months of pregnancy until the placenta can produce sufficient estrogen & progesterone to maintain itself & the uterine lining
    • pituitary LH is shut down by high progesterone & estrogen from the corpus luteum
  235. male reproductive system
    • testes
    • seminal vesicles
    • bulbourethral (Cowper's) glands
    • prostate gland
    • epididymis & vas deferens (system of ducts & conduits)
  236. morphology of mature spermatozoa
    • head: nucleus & acrosomal cap
    • neck: where flagellum connects to nucleus
    • tail: middle, principle & end pieces
    • middle piece - mitochondrial sheath (energy for motility)
  237. mitosis
    • cell division that results in two daughter cells that are identical to parent cell
    • before division, chromosomes duplication (2n to 4n)
    • prophase - metaphase - anaphase - telophase
  238. meiosis
    • series of two consective divisions in which chromosome number & DNA content is halved to form gametes
    • unique to germ cells
    • female: produce one ovum
    • male: produce 4 spermatozoa
  239. meiosis I
    • reductional division (2n,4d to 1n,2d)
    • S phase duplicates chromosomes
    • prophase I: leptonene - zygotene - pachytene - diplotene - diakenesis
    • metaphase I: homologous chromosomes line up on metaphase plate randomly (independent assortment ensures genetic diversity)
    • anaphase I: chromosomes separate towards opposite poles of cell
    • telophase I: cytokinesis occurs creating 2 genetically unique daughter cells
  240. phases of prophase I
    • leptotene: chromosome are straight & separate
    • zygotene: homologous chromosomes pair up (tetrads)
    • pachytene: "crossing over" occurs
    • diplotene: chromosomes uncoil & separate a little
    • diakinesis: nucleoli disappear; nuclear membrane disintegrate into vesicles
  241. meiosis II
    equatorial division; no replication (1n,2d to 1n,1d)
  242. phases of spermatogenesis
    • spermatogonial phase: spermatogonia divide mitotically to increase in number; divide into primary spermatocytes
    • spermocyte phase: primary spermatocytes undergo meiosis I to become secondary spermatocytes; crossing over & independent assortment occur
    • spermatid phase: secondary spermatocytes undergo meiosis II to become spermatids
  243. spermiogenesis
    • golgi phase: coalescence of proacrosomal granules unti the acrosomal vesicle; centrioles initiate axoneme assembly
    • cap phase: acrosomal vesicle spreads over anterior of nucleus (acrosomal cap)
    • acrosome phase: nucleus flattens, elongates & moves next to cell membrane; cytoplasm displaced posterior; manchette forms; flagellum grows; mitochondrial wraps around axoneme
    • maturation phase: reduction of excess cytoplasm around flagellum; sperm no longer attached to each other - released from Sertoli cells
  244. Charcot-Boettcher inclusions
    crystalloid inclusion bodies of Sertoli cell
  245. Sertoli cell
    • supporting non-germinal cell
    • secretes nutrients & provides support for developing sperm cells
    • extend from lumen of seminiferous tubule to basement membrane
    • tight junctions between cells divide compartments of seminiferous tubule
    • contribute to formation of blood-testis barrier
    • contain Chorcot-Boettcher crystalloid inclusion bodies
  246. blood-testis barrier
    • protects developinig sperm cells in the lumen from antibodies & antigens in the blood
    • primary spermatocytes are genetically unique cells - immune system would recognize them as foreign cells
    • blood vessels are NOT in seminiferous tubules, but within interstitial spaces between seminiferous tuubules
  247. cells types of seminiferous tubule
    • peritubular myoid cells
    • sertoli cells
    • leydig cells
    • developing sperm cells
  248. Leydig cells
    • stereogenic cells in interstitial spaces between seminiferous tubule
    • secrete testosterone in response to LH from pituitary gland
  249. pathway of sperm
    seminiferous tubule - straight tubule - rete testis - efferent ductules - epididymis - vas deferens - ejaculatory duct - prostatic urethra - membranous urethra - penile spongy urethra
  250. capacitation
    modifications of plasma membrane proteins of sperm due to exposure within female reproductive tract (allows fertilization)
  251. prostate gland
    • largest accessory gland; unpaired; epithelial lining variable (testosterone dependent)
    • fibromuscular: contractions propell secretions into urethra
    • concentric layers of mucosal & submucosal & main prostatic glands
    • peripheral zone: most susceptible to prostate cancer
    • transitional zone: susceptible to benign prostatic hyperplasia (BPH)
  252. secretions of prostate gland
    • prostatic acid phosphatase (PAP): can be detected in blood
    • prostate-specific antigen (PSA): also produced in liver; high levels indicate prostate cancer (prostatic carcinoma)
    • fibrinolysin & citric acid
  253. seminal vesicles
    • multifolded mucosa - pseudostratified columnar epithelium
    • thin smooth muscle layer
    • fibrous coat
    • secretions - fructose, simple sugars, amino aacids, ascorbic acid, prostaglandins
  254. bulbourethral glands
    • paired glands found in urogenital diaphragm
    • compound tubuloalveolar glands with simple columnar epithelium
    • secretes galactose, galactosamine, galacturonic acid, sialic acid & methylpentose
    • preseminal fluid lubricates penile urethra - alkaline to neutralize environment of urethra & vagina
  255. functions of testosterone
    • supports sperm cell development
    • responsible for maintaining duct & accessory glands
    • promotes development of male secondary sex characteristics
    • negative feedback inhibition of pituitary LH secretion
  256. mechanism of hormonal control of male reproductive system
    • pituitary secretes FSH - stimulating sertoli cells to secrete ABP
    • pituitary secretes LH - stimulating Leydig cells to secrete testosterone
    • sertoli cells secrete androgen binding protein into lumen of seminiferous tubules
    • androgens (testosterone from Leydig cells) bind to androgen binding proteins, keeping testosterone levels high in the seminiferous tubule
    • androgen binding protein signals pituitary to stop secreting FSH
    • testosterone signals pituitary to stop secreting LH
    • inhibin (from Sertoli cells) shuts off hypothalmus & pituitary stimulation

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