Medic 14 A&P Chapter 18

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Medic 14 A&P Chapter 18
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Chapter 18
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  1. Vocab
  2. Caylx
    a cup of flowers; minor calyx
  3. detrudere
    to push down; detrusor muscle
  4. fenestra
    a window; fenestrated capillaries
  5. glomus
    a ball; glomerulus
  6. gonion
    angle;trigone
  7. juxta
    near; juxtaglomerular aparatus
  8. micturition
    to urinate;micurition
  9. nephros
    kidney;nepron
  10. papillae
    small, nipple-shaped projections; renal papillae
  11. podon
    foot;podocyte
  12. recus
    straight;vasa recta
  13. ren
    kidney;renal artery
  14. retro-
    behind;retroperitoneal
  15. vasa
    vessels;vasa recta
  16. Objective:
    Identify the components of the urinary system and list their functions (pp.659-660)
  17. Urinary system performs the vital function of
    removing the organic waste products generate by cells throughout the body.
  18. Functions of the urinary system
    • Regulate blood volume and blood pressure
    • Regulate plasma concentration of ions
    • Help stabilize blood pH
    • Conserve valuable nutrients
  19. Regulate blood volume and Bp
    • Adjusting the volume of water lost in urine
    • releasing EPO
    • releasing renin
  20. Regulate plasma concentration of ions
    • Na+, K+, Cl-, and other ions are regulated by controlling the quantities lost in the urine.
    • Plasma concentration of calcium ions is regulated by synthesis of calcitriol.
  21. Help stabilize blood pH
    pH is stabilized by controlling the loss of H+ ions and HCO3-(bicarb) in urine.
  22. Conserve valuable nutrients
    Glucose and amino acids are conserved by preventing their excretion in urine while organic waste products are eliminated
  23. Organization of urinary system
    • Two kidneys, produce urine
    • Urine travels through paired ureters
    • to the urinary bladder for temp storage
    • urination occurs, contraction of muscular bladder forces the urine through the urethra and out of the body
  24. Objective:
    Describe the structural features of the kidneys(pp.660-661)
  25. Kidneys are located
    • on either side of the vertebral column between the last thoracic and third lumbar vertebrae.
    • The right kidney often sits lower then the left.
    • Both lie between the muscles of the doral body wall and the peritoneal lining
  26. Retroperitoneal refers to
    behind the peritoneum
  27. Position of the kidneys are maintained by
    • overlying peritoneum
    • contact with adjacent organs
    • supporting connective tissue
  28. Each kidney is covered by
    a dense fibrous renal capsule and its packed in a soft cushion of adipose tissue
  29. Floating kidney
    • Damage to the suspensory fibers may cause the kidney to be displaced.
    • Dangerous because ureters or renal blood vessels may become twisted of kinked during movement.
  30. Typical kidney is
    reddish brown and about 10 cm long, 5.5 cm wide and 3 cm thick in adults and weighs about 150 g
  31. Hilum
    • indentation that is the site of exit for the ureter
    • site which the renal artery and renal never enter and where the renal vein exits
  32. Renal capsule
    covers the surface of the kidney and lines the renal sinus
  33. Renal sinus
    internal cavity within the kidney
  34. Kidney is divided into
    • the renal cotex
    • renal medulla
  35. Renal medulla contains
    18 conical renal pyramids, that projects into the renal sinus
  36. Renal papilla
    tip of each renal pyramid
  37. Renal columns extend toward the
    renal sinus between adjacent renal pyramids
  38. Urine production occurs in the
    renal pyramids and overlying areas of the renal cortex
  39. Ducts within each renal papilla dischare urine into a cup shaped drain called
    minor calyx
  40. Four or five minor calyx merge to form
    major calyx
  41. Renal pelvis
    funnel shaped chamber formed by the calyxs
  42. Renal pelvis is connects to
    the ureter through which urine drains out of the kidney
  43. Urine production begins in the renal cortex, in microscopic tubular structures called
    nephrons
  44. Each kidney has roughly ___ million nephrons
    1.25
  45. Objective:
    Trace the path of blood flow through a kidney
    (PP.662-63)
  46. Each minute how many mL of blood flows through the kidneys
    1200 mL
  47. Kidney receives blood from a
    renal artery that originates from the abdominal aorta
  48. As the renal artery enters the renal sinus, it divides into branches that supply a series of _________ _______ that radiate outward between the renal pyramids.
    interlobar arteries
  49. Acruate arteries
    arch along the boundary lines between the cortex and medulla
  50. interloBUlar arteries
    supply the cortex given rise from arcuate arteries
  51. Afferent arterioles
    branch from each interlobular artery deliver blood to the capillaties that supply individual nephrons
  52. Efferent arteriole
    Leaves each nephron
  53. Peritubular capillaries
    • recieves blood from efferent arterioles,surround the proximal and distal convoluted tubules 
    • provide route fro pickup or delivery of substances that are reabsorbed or secreted by these portions of the nephron
  54. Cortical nephrons
    located mostly within the cortex
  55. Juxtamedullary nephrons
    located near the renal medulla
  56. Blood flow from efferent arterioles differ in
    • cortical nephrons 
    • juxtamedullary nephrons
  57. In juxtamedullary nephrons, peritubular capillaries are connected to the
    vasa recta, long straight capillaries that parallel the loop of henle deep into the medulla
  58. Juxtamedullary nephrons enable the kidneys to produce
    concentrated urine
  59. blood flow from the peritubular capillaries and vasa recta enters a network of venules and small veins that converge on the
    interlobular veins
  60. Mirror image of arterial supply blood from interlobular veins converge and then empty into the
    arcuate , interlobar, and renal veins
  61. Describe the structure of the nephron and processes involved in urine formation (pp.663-666)
  62. Nephron
    Basic functional unit of the kidney
  63. Nephron conisists of two main parts
    • a renal corpuscle
    • Renal tubule composed of two convoluted segments separated by a single U-shaped tube
    • Convuluted segments are in the cortex and U shaped tube extends partially or completely into the medulla
  64. Renal corpuscle
    nephron begins here,round structure that consists of a cup shaped chamber (bowman's capsule) that contains a capillary network, or Glomerulus
  65. Blood arrives at the glommerulus by way of?
    Afferent and Efferent arterioles
  66. In renal corpuscle, blood pressure forces fluid and dissolved solutes out of the glomular capillaries and into tthe surrounding capsular space. this is called
    filtration
  67. Filtrate
    Product of filtration, a protein free solution
  68. From renal corpuscle,filtrate enters the renal tubule. Major segments of the renal tubule are
    • Proximal convoluted tubule (PCT)
    • Loop of henle
    • Distal convoluted tubule(DCT)
  69. As filtrate travels along the tubule its compositon changesm and then is called
    tubular fluid
  70. Collecting system
    • Each nephron empties into a collecting duct
    • collecting duct leaves the cortex and descentds into the medulla, and carries  tubular fluid from many nephrons toward a papillary duct that delivers the fluid now called urine, into the calyces and on to the renal pelvis
  71. Renal corpuscle
    is the site of filtration
  72. Filtrate leaves the renal corpuscle and enters the renal tubule. Renal tubule is responsible for
    • reabsorbing all of the useful organic molecules from the filtrate
    • reabsorbing over 90% of water in the filtrate
    • secreting into the tubular fluid any waste products that were missed by the filtration process
  73. Renal corpuscle consists of
    • capillary network of the glomerulus
    • structure known as bowmans capsule
  74. Bowmans capsule
    forms the outer wall of the renal corpusvle and encapsulates the glomerular capillaries
  75. Capsular epithelium makes up the wall of
    the capsule and is continious with a specialized epithelium that covers glomerular capillaries
  76. Capsular space
    separates the two epithelia, which revieves the filtrate and empties into the renal tubule.
  77. Podocytes
    epithelium that covers that capillaries consists of sites called podocytes
  78. Characteristics of podocytes
    • long cellular processes called pedicels that wrap around invidual capillaries 
    • thick basemnet membrane separates cappillaries and podocytes
  79. Glomeular capillaries are said to be
    fenestrated, they contain pores
  80. To enter the capsular space, a solute must be small enough to pass through
    • the pores of endothelial cells
    • fibers of basement membrane
    • filtration slits between the slender process of the podocytes
  81. Filtration membrane is composed of
    • fenestrated capillary, basement membrane, and filtration slits
    • that prevents the passage of blood cells and most plasma proteins but permits water,metabolic wastes,ionsmglucose,fatty acids, vitamens and other solutes into the capsular space.
  82. Most vaulable solutes will be reabsorbed by the
    PCT proximal convoluted tubule
  83. Filtrate moves from the renal corpuscle to the first segment of the renal tubule called
    PCT proximal convoluted tubule
  84. Cells of the PCT absorb
    organic nutrients,plasma proteins and ions from the tubular fluid and release them into the intersitital fluid the surrounds the renal tubule
  85. As a result of the PCT, solute concentration of the intersitial fluid increases while that of the tubular fluid decreses, water then moves out of the tubular fluid by
    osmosis
  86. Last portion of the PCT sharply bends toward the medulla and connects to the
    loop of henle
  87. Loop is comprised of
    descending limb that travels toward the renal pelvis and ascending limb that returns to the cortex
  88. Ascending limb
    • is not permeable to water and solutes actives transports sodium and chloride ions of of the tubular fluid
    • as result intersitial fluid of the medulla will contain unusually high solute concentrations
  89. Descending limb
    • permeable to water
    • as it descends into the medulla waters moves out of the tubular fluid by osmosis
  90. Ascending loop of henle ends where it bends and comes in close contact with the glomerulus and its vessels , the ___ begins
    DCT begins and its passes immediately adjacent to the afferent and efferent arterioles
  91. DCT is an important site for
    • active secretions of ions,acids,drugs, and toxins
    • selective reabsorption of sodium ions from tubular fluid
  92. In final portions of the DCT osmotic flow of water may assist in concentrationg the
    tubular fluid
  93. Macula Densa
    Epithelial cells of the DCT are closest to the glomerulus
  94. Juxtaglomercular apparatus
    • macula densa and juxtaglomerular cells (in the wall of the afferent arteriole)
    • endocrine structure secretes hormone EPO and enzyme Renin
  95. DCT which is the last segment of the nephron, opens up to the
    collecting system
  96. Colleting duct merge to form
    a a papallary duct which delivers urine to the minor calyx
  97. Collecting system makes final adjustments to
    composition of urine by reabsorbing water and reabsorbing  or secreting sodium,potassium,hydrogen, and bicarbonate ions
  98. Functions of the nephron and collecting system in the kidney
    Renal corpuscle
    Filtration of plasma to initiate urine formation
  99. Functions of the nephron and collecting system in the kidney
    Proximal convoluted tube (PCT)
    Reabsorbtion of ions,organic molecules, vitamens,water
  100. Functions of the nephron and collecting system in the kidney
    Loop of henle
    • descending limb: reabsorption of water from tubular fluid
    • ascending limb: reabsorption of ions; creates concentration gradient in the medulla, which enables the kidney to produce concentrated urine
  101. Functions of the nephron and collecting system in the kidney
    Distal convoluted duct DCT
    reabsorption of sodium ions;secretiomn of acids, ammonia, drugs
  102. Functions of the nephron and collecting system in the kidney
    Collecting duct
    Reabsorption of water and of sodium, and bicarbonate ions
  103. Functions of the nephron and collecting system in the kidney
    Papillary duct
    conduction of urine to minor calyx
  104. Objective: 
    List and describe the factors that influence filtration pressure and the rate of filtrate formation. (pp.666-668)
  105. Primary function of urine production is to
    maintain homeostasis by regulating volume and composition of the blood
  106. Homeostatic process of urine production involves secretion of dissolved solutes especially the following three metabolic wastes
    • Urea
    • Creatinine
    • Uric Acid
  107. urea
    • most abundent organic waste
    • generate about 21 grams of urea daily
    • most of it during breakdown of amino acids
  108. Creatinine
    • generated in skeletal muscle tissue through the breakdown of creatine phosphate. 
    • Body generates roughly 1.8 g daily
  109. Uric acid
    • Produced during the breakdown and recycling of RNA
    • you generate about 480 mg of uric acid daily
  110. Kidneys minimize water loss by producing urine that is
    4 to 5 times more concentrated then normal body fluids.
  111. To maintain homeostasis kidneys perform 3 processes
    • Filtration
    • reabsorption
    • secretion
  112. Filtration
    Bp forces water across the filtration membrane in the renal corpuscle
  113. Reabsorption
    • removal of water and soulute molecules from the filtrate and their re entry into the circulation at the peritubular capillaries 
    • Filtrate occurs after filtrate enters the renal tubule.
    • passive through osmosis
  114. Secretion
    is the transport of solutes out of the peritubular epithelium and into the filtrate.
  115. Kidneys can continue to work efficiently only so long as
    • filtration
    • reabsorption
    • secretion proceed in proper balance
  116. Filtration occurs exclusively in the
    renal corpuscle, across the capillary walls of the glomerulus
  117. Reabsorption of nutrients occurs primarily at the
    PCT
  118. Active secretion occurs primarily at the
    DCT
  119. Regulation of the amount of water, sodium ions and potassium ions lost in the urine results from interactions between the
    loop of henle and collecting system
  120. Blood pressure at the glomerulus tends to foce water and solutes out of the bloodstream and into the
    capsular space
  121. For filtration to occur
    the outward force must exceed any opposing pressures such as osmotic pressure of the blood.
  122. Filtration pressure is
    the net foce that promotes filtration
  123. Filtration pressure at the glomerulus is higher than cappillary blood pressure elsewhere in the body because
    • of the slight difference in the diameters of the afferent and efferent arterioles.
    • Efferent are slighly smaller in diameter
    • result creates backup that increases BP in glomerular capillaries
  124. Filtration pressure is very low around
    10 mmHg
  125. If glomerulur pressure falls signifigantly...
    kidney function will stop
  126. Reflexive changes in the diameters of the afferent, efferent arterioles or glomerular capillaries can compensate for
    minor variations in blood pressure
  127. Reninangiotension system is a mechanism that
    is one of the mechanims that responsible for regulating BP and blood volume
  128. Glomerular filtration
    process of filtrate production at the glomerulus
  129. Glomerular Filtration Rate (GFR)
    • The ammount of filtrate produced in the kidneys each minute. 
    • 6 square meters of filtration surface
    • GFR averages around 125 mL per min
  130. Tubular reabsorption is an
    extremely important process
  131. Inability to reclaim watter that enters filtrate is known as
    Diabetes insipidus(caused by inadequate ADH secretion)
  132. Objective:
    Describe the changes that occur in the tubular fluid as it moves through the nephron and exits as urine(pp.668-671)
  133. Reabsorption and secretion in the kidney involve a combination of
    diffusion,osmosis, and carrier mediated transport.
  134. Cells at the PCT actively reabsorb organic nutrients,plasma proteins, and ions from filtrate and then transport them into
    intersititial fluid that surrounds the renal tubule
  135. Osmotic forces pull water from the wall of the PCT into the surrounding intersitial fluid. TJe reabsorbed materials and water diffuse into
    peritubular capillaries
  136. PCT reclaoms what % of the volume of filtrate produced at the glomerulus, along with virtually all of the glucose, amino acidsm and other organic nutrients.
    60-70%
  137. PCT also actively reabsorbs
    ions, including sodium,calcium,bicarb,magnesium,phosphate amd sulfate ions
  138. Ion pumps of the PCT are  individually
    regulated and may be influenced by circulating ion or hormone levels
  139. Active secretions into the tubular fluid (like hydrogen) play important role in
    regulation of pH,
  140. What compounds are ignored by the PCT and other segments of the renal tubule
    Uric acid and urea
  141. From the PCT, the loop of henle reabsorbs more then % of remaining water as well as % of sodium and chloride ions that remain in the tubular fluid
    half and 2/3
  142. Descending limb
    is permeable to water but not other solutes
  143. Ascending limb is impermeable to both
    water and solutes
  144. the ascending limb actively pumps
    sodiumand chloride ions out of the tubular fluid and into the interstitial fluid of the renal medulla
  145. concentration gradient at  the bend of the descnding limb
  146. roughly half of the volume of filtrate that enters the loop of henle is reabsorbed in the
    descending limb
  147. Most of the sodium and chloride ions are removed in the
    ascending limb
  148. the filtrate declines to around
    1/3  of the concentration of plasma
  149. By the time filtrate reaches the DCT roughly % of solutes and water have been reabsorbed
    • 80 water
    • 85 solute
  150. DCT is connected to a collecting duct that
    drains into the renal pelvis
  151. As filtrate passes through the DCT and collecting duct final adjustments are made in its
    compostion and concentration, composition depends on the types of solutes present, concentration depends on volume of water in which the soultes are dissolved
  152. DCT and collecting duct are impermeable to solutes, changes in composition can only occur through
    • active reabsorption or secretion
    • Primary function of DCT is active secretion
  153. Throughout most of the DCT , tubular cells actively transport sodium ions out of the tubular fluid in exchange for
    potassium or hydrogen ions
  154. DCT and collecting ducts contain ion pumps that respond to the hormone
    Aldosterone, produced in the adrenal cortex
  155. Aldosterone secretion occurs in response to lowered
    sodium ion concentraions or elevated potassium ion concentraions in the blood
  156. Higher the aldosterone levels the
    more sodium ions reclaimed and more potassium ions are lost
  157. The ammount of water reabsorbed along the DCT and collecting duct is controlled by circulating levels of
    ADH
  158. In absense of ADH the DCT and collecting duct are
    impermeable to water
  159. Higher the ADH, the greater the water permeability and the more
    concentraited the urine
  160. Overview of kidney function and urine formation
    step 1
    • Glomerular filtration produces a filtrate that resembles blood plasma byt contains few plasma proteins
    • filtrate has same osmotic concentration as plasma or intersitial fluid
  161. Overview of kidney function and urine formation
    Step 2
    • PCT, 60-70% of water is reabsorbed and almost all of the dissolved nutrients are reabsorbed.
    • osmotic concentration of tubular fluid remains unchanged
  162. Overview of kidney function and urine formation
    Step 3
    PCT and descending limb of the loop of henle, water moves into the surrounding intersititial fluid and leaves a small fluid volume of highly concentrated tubular fluid (20% of origional flitrate)
  163. Overview of kidney function and urine formation
    Step 4
    • Ascending limb of henle, impermeable to water and solutes
    • tubular cells actively pump Na+ and Cl-  out of tubular fluid
    • because Na+ and Cl- are removed urea accounts for a greater proportion of the solutes in the tubular fluid
  164. Overview of kidney function and urine formation
    Step 5
    • DCT and collecting duct determine final composition and concentration
    • these segments are impermeable to solutes but ions may be actively transported into or out of the filtrate under the control of hormones such as aldosterone
  165. Overview of kidney function and urine formation
    Step 6
    • Concentration of urine controlled by variations in water permeability of the DCT and collecting ducts
    • Segments are impermeable to water unless exposed to ADH
    • absence of ADH= no water reabsorption occur, produces diluted urine
    • High concentrations of ADH= collecting ducts become freely permeable to water and produces small volume of conentraited urine.
  166. Clinical note: Acute renal failure
  167. Acute renal failure (ARF)
    is a deteriroation in renal function over hours or days that causes the accumulation of toxic wastes and causes the loss of internal homeostasis
  168. ARF usually results from
    a decline in blood flow
  169. Prerenal failure
    result from lack of bloodflow to the kidney
  170. intrinsic renal failure
    Problem with the kidney itself
  171. Postrenal failure
    problem in urine flow
  172. Depressed renal blow flow and substances that are toxic to the kidney cause
    renal cell ischemia and death
  173. recovery depends upon
    restoration of renal blood flow
  174. Objective:
    Discuss the process of urination and how it is controlled (pp.672-674)
  175. Normal kidney function depends on adequate
    glomerular filtration rate (GFR)
  176. GFR is regulated three ways
    • By local automatic adjustments in glomerular pressure
    • through activities of the sympathic devision of the ANS
    • throught the effects of various hormones (hormonal mechanisms result in long term adjustments)
  177. Local, automatic changes in the diameters of the afferent arterioles,efferent arteroles and the glomerular capillaries can compensate for
    • minor variations in blood pressure
    • for example reducation in blood flow and decline in glomerular filtration pressure trigger dialtion of afferent arteriole and glomerular capillaries and constrict efferent arteriole
  178. Autonomic regulation of kidney function occurs primarily through the
    sympathetic division of the ANS
  179. Sympathetic activation has what types of effects
    direct and indirect
  180. direct effects of the sympathetic division
    • is powerful constriciton of afferent arterioles ,which decreases the GFR and slow production of filtrate
    • Triggered by crisis such as acute reduction in BP or a AMI
    • Sympathetic activation can overide the local regulatory mechanism that act to stabilize GFR
    • as crisis passes, GFR will return to normal
  181. Major hormones involved in kidney function control
    • Angiotension II
    • ADH
    • aldosterone
    • ANP
  182. Hormones regulated by the renin-angiotension system are
    • angiotension II
    • Aldosterone
    • ADH
  183. Renin-angiotension system- renin
    • If GFR remains low the juxtaglomerular apparatus releases the enzyme reninin into circuation
    • Renin converts angiotensiogen to angiotension I
    • ACE concerts Angiotension I to II
  184. Effects of angiotensions II
    • Brief powerful constriction in peripheral capillary beds, that elevates Bp in renal arteries
    • triggers constriction of efferent arterioles awhich elevates glomular pressure and filtration rates
    • Trigers release of ADH in the CNS which stimulates reabsorption of water and soium ions and induces senation of thirst
    • at the adrenal gland, stimulates secretion of aldosterone by the adrenal cortex and E and NE by the adrenal medullae, sudden dramatic increase in BP
    • at the kidneys aldoserone stimulates sodium reaborption along the DCT and collecting system
  185. ADH
    • inceases the water permeability of the DCT and collecting duct which stimulates the reabsorption of water from the tubular fluid
    • induces sensation of thirst
  186. ADH release occurs
    • under angiotension II stimulation
    • and independently when hypothamic neurons are stimulated by a reducation in bp or incease in solulte concentration of circulating blood
    • specialized hypothalmic neurons are called osmoreceptors
  187. Aldosterone
    • stimulates reabsorption of sodium ions and secretion of potassium ions along the DCT and collecting duct
    • occurs primarily under angiotension II stimulation and inresponse to a rise in potassium ion concentration of the blood
  188. ANP artial natriuretic peptide
    • opposes those of the renin angiontension system
    • released by atrical cardiac muscle cells when blood volume and bp are too high
    • ANP affects the kidney by a decreasein the rate of sodium ion reabsorption in the DCT,leads to increased sodium loss in the urine
    • dilation of the glomerular capillaries which resulse in increased flomerular filtration and urinary water loss
    • inactivation of the renin angiotension sysmtem through the inhibition of renin,aldosterone, and ADH secretion
    • net loss of sodimm ions 
    • lowers bp and blood volume
  189. Objective:
    Describe the structures and function of the ureters ,urinary bladder,and urethra(pp.675-680)
  190. Structures of the urinary tract are responsible for the
    transport,storage,and elimination of urine
  191. Ureters
    pair of muscular tubes that conduct urine from the kidneys
  192. Ureteral openings within the urinary bladder are slit like ,which
    is a shape that prevents backflow of urine when the bladder contracts
  193. Wall of bladder contains
    transitional epithelium , middle later of longitudal and circular bands of smooth muscle and outer connective tissue layer continues with renal capsule
  194. Every 30 sec a _______ contraction begins at the renal pelvis and sweeps across the ureter and forces urine towards the bladder
    peristaltic
  195. Cannuli
    kidney stones,presence is known as nephrolithiasis
  196. Urinary bladder
    hollow muscular organ that sotres urine prior to urination. demensions depends on destention
  197. trigone
    triangular area that the urinary bladder is bounded by the ureteral openings and enternce to the uretha
  198. Neck of the urinary bladder
    contains the internal uretharl sphincter, surrounds the urethral entrance
  199. internal urethral sphinter
    provides involuntary control over dischage of urine from the bladder

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