Mod 19 Urinary system

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Mod 19 Urinary system
2014-04-14 19:54:06

urinary system
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  1. Urinary system: what it does & organs involved
    aside from waste-removal, plays vital role in maintaining homeostasis

    Consists of kidneys, ureters, bladder and urethra
  2. kidneys: location
    • in abdominal cavity btwn posterior ab wall and peritoneum; in area of inferior thoracic vertebrae & superior to lumbar vertebrae
    • Since only anterior aspect is covered by peritoneum, said to be retroperitoneal
    • Cause liver on right side takes up so much space, right kidney slightly lower than left
    • partially protected by floating ribs

  3. ureter
    • transports urine from kidneys to bladder
    • one extending from each kidney
    • is also retroperitoneal
  4. bladder
    • a hollow, distensible organ in pelvic cavity
    • holds an average of 700 - 800 ml of urine
  5. urinary system functions
    • Regulation of Electrolytes
    • Regulation of blood pH
    • Maintain blood concentration (osmolarity)
    • Regulate blood volume
    • Regulate BP
    • Excretion of wastes
    • Production and release of hormones
    • ** Everyone's pH on vacation was horribly puky
  6. Describe regulation of electrolytes
    Controls levels of various anions and cations
  7. Describe regulation of pH
    Control of pH by secreting H+ into the urine and return of HCO3- back to the blood
  8. Describe regulation of Blood Volume
    Adjusts blood volume by conserving or eliminating urine
  9. Describe maintenance of blood osmolarity
    control of blood concentration
  10. Describe the urinary systems's production of hormones
    • Calcitriol (active Vit D) to increase calcium levels
    • erythropoietin to increase red blood cell production
    • Renin - angiotensin system
    • **Everyone's Riding that Cock - Think of horny hormones
  11. Describe regulation of blood glucose level
    • release of glucose, produced by gluconeogenesis, into the blood
    • * gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of kidneys. Production of glucose
  12. Describe excretion of wastes
    Excretion of ammonia, urea, bilirubin, creatinine, uric acid, & other wastes
  13. External structure of the kidney
    • covered by 3 layers of tissue (from deep to superficial):
    • Renal capsule - protects and maintains kidney's shape
    • Adipose capsule - maintains position of kidney in abdominal cavity, also protects
    • Renal fascia - anchors kidney to abdominal wall & neighboring structures
  14. Internal structure of kidney
    has two distinct regions: renal cortex and medulla
  15. medulla
    • Internal part, kinda look like slices of pie or pyramids
    • make up renal pyramids  
  16. renal cortex
    • outer most region of cortex
    • extends btwn the renal pyramids in medullary region to form the renal columns
  17. renal pyramids
    • triangular structures of medulla that appear striated due to presence of renal tubules and ducts
    • renal papillae (at apex) drain into calyces
  18. renal papillae
    • the apices of the pyramids
    • where urine produced by nephrons drains into and taken to minor calyces (calyx)
    • *Remember, urine comes from filtering the blood.
  19. Renal calyces
    • sing: calyx
    • basically "plumbing" or channels to drain the urine out of kidney
    • Each kidney has: 
    • 8 - 18 Minor
    • 2 - 3 Major
    • Major calyces empty into renal pelvis
  20. renal pelvis
    • one large cavity (in each kidney) which the major calyx drain into
    • basically one large catch basin for urine before it goes to ureters
  21. path of urine drainage:
    • made from nephron:
    • Collecting duct
    • Papillary duct in renal pyramid
    • minor calyx
    • major calyx
    • renal pelvis
    • ureter
    • urinary bladder
  22. Trace renal blood flow from aorta to where it enters venous flow
    • Abdominal aorta
    • Renal artery
    • Segmental arteries ("branching off w/in kidney)
    • Interlobar arteries (btwn lobes or pyramids) 
    • Arcuate arteries ("arch"- arching over pyramids)
    • Interlobular arteries (tiny, feed into nephron)
    • Afferent arterioles
    • Glomerular capillaries - filters by pressure
    • Efferent arterioles- w remaining blood
    • Peritubular capillaries
    • *Always Remember Sex Is Amazing If A Giant Erect Penis Volunteers.
  23. Trace venous renal blood flow
    • begins venous after peritubular capillaries
    • interlobular veins
    • Arcuate veins
    • Interlobar veins
    • Renal vein
    • Inferior vena cava
    • *Notice with venous flow, segmental is skipped
    • **I Acknowledge I'm Really Incredible
  24. peritubular capillaries
    • where blood goes after efferent arterioles
    • crazy circular patterned capillaries that surround the nephron, where stuff is exchanged w nephron
    • Includes the vasa recta

    After these capillaries, THEN we can enter venous system
  25. vasa recta
    • type of peritubular capillaries which go straight down one side of nephron and straight up the other side
    • found in juxtamedullary nephrons
    • "recta" means straight
  26. How is kidney's blood flow unique
    • Afferent arterioles feed into glomerular capillaries
    • in glomerular capillaries, blood is filtered, by pressure
    • the filtered blood then goes into efferent arterioles

    *Notice, usually after blood flows through capillaries, it enters a venule. Not here, it again enters an arteriole
  27. nephron
    • the main functional unit of the kidney - where urine is made
    • each kidney contains approx 1 million
    • 2 types: Cortical and juxtamedullary nephrons
    • also includes 2 structures: renal corpuscle & renal tubules
  28. renal tubules
    • part of nephron
    • role is to modify the filtrate (product of filtration) to facilitate the final product of urine formation
    • 3 total, named based on shape and/or position related to glomerulus:
  29. Names & location of renal tubules
    Proximal convoluted tubule - tightly-coiled & attached directly to glomerulus

    • loop of Henle - forms hair-pin turn by connecting two lengths, or limbs or the tubule, the ascending and descending
    • Distal convoluted tubule - similar to proximal tubule as it is tightly coiled, but further away from glomerulus

    *convoluted meaning twists and turns, like the mouse trap ride
  30. Explain flow of "urine" through renal tubules
    • products leave glomerulus via proximal convoluted tubule 
    • Flows into/through loop of Henle
    • Then into distal convoluted tubule
    • From here, several distal convoluted tubules (from other nephrons) combine to form a single collecting duct (or tube)
    • Again, many collecting ducts combine to form a papillary duct, which then empties into a minor calyx
  31. Good way to imagine the renal corpuscle
    • Picture a fist pushed against a partially deflated balloon:
    • The fist would be the glomerulus
    • The balloon would be the double-layered capsule
  32. renal corpuscle
    • Is the filtering structure of the nephron
    • located in cortex
    • consists of 2 compartments: the glomerulus (glomerular capillaries) and glomerular capsule
  33. glomerulus
    • part of renal corpuscle
    • is the filtering structure made up of the glomerular capillaries
  34. glomerular capsule
    • receives glomerular filtrate from the filtration process and is like the receptacle
    • Also called Bowmans capsule
  35. glomerular filtrate
    • Fluid in transition?
    • refers to the fluid in the glomerular capsule
    • Because it isn't blood anymore, but isn't urine yet
    • Therefore, fluid entering the nephron is blood, within the nephron is glomerular filtrate, and exiting nephron it's urine
  36. Cortical vs Juxtamedullary nephrons:
    • difference is simply the length of the loops of Henle
    • 80-85% of nephrons are cortical & their loop only extends short distance into medulla
    • Remaining nephrons' loops extend into deepest regions of renal pyramids. 
    • These long loops play a role in ability to concentrate the urine
  37. juxtaglomerular apparatus
    • refers to both the macula densa and juxtaglomerular cells
    • Together, they control the blood pressure within the kidneys
  38. macula densa
    • densely-packed columnar cells in the ascending loop of Henle
    • Arranged next to the afferent arteriole
  39. juxtaglomerular cells
    • specialized smooth muscle cells of the afferent arteriole, control diameter or arteriole
    • Important in controlling rate of filtration
    • Named because of their position
  40. Renal tubule functions
    • Glomerular filtration
    • Tubular reabsorption
    • Tubular secretion
  41. glomerular filtration
    • The renal corpuscle facilitates this process
    • First step of urine production, water & most solutes in blood plasma move across wall of glomerular capillaries (filter) into the glomerular capsule and then into the renal tubule
  42. tubular reabsorption
    • Process of returning important substances from the glomerular filtrate back to the bloodstream
    • As filtered fluid flows along the renal tubule & through collecting duct, tubule cells reabsorb approx 99% of filtered water & many useful solutes, which return to the blood as it flows through the peritubular capillaries and vasa recta
  43. tubular secretion
    • As fluid flows along the renal tubule and through collecting duct, the tubule & duct cells secrete other material, such as wastes, drugs, and excess ions, into the fluid to be excreted as urine
    • Occurs throughout the nephron
  44. Describe glomerular membrane
    • 3 layers of tissue that form the filtration membrane (deep to superficial):
    • Capillary endothelium
    • Basal lamina
    • Podocytes
    • *Less than 1% of even smallest proteins can pass
    • **Everyone Believes I Possess a filter.
  45. Capillary endothelium (of glomerular membrane)
    • These capillaries are fenestrated, so they are much more permeable than the vascular system
    • Allows the passage of all blood solutes into the glomerular capsule but limits passage of the formed elements
    • (Recall formed elements are RBC, WBC, etc)
  46. Basal lamina (of the glomerular membrane)
    • a layer of connective tissue sandwiched btwn the endothelium and podocytes
    • Limits passage of large proteins
  47. Podocytes
    • unique cells which form the visceral layer of the glomerular capsule
    • Have numerous foot-processes (pedicels) that extend from the podocytes
    • These pedicels have small spaces btwn them
    • Permeability of the membrane can be controlled by amount of space provided by pedicels
  48. filtration slits
    • refers to the small spaces btwn the pedicels
    • Prevents filtration of medium-sized proteins
  49. So what can get through the glomerular membrane
    • Everything BUT:
    • cells
    • Large & medium sized proteins
  50. Describe process of filtration
    • The use of pressure to force fluids, including solutes through a semipermeable membrane
    • The filtration membrane works cause glomerular capillaries provide large surface area, membrane is thin and porous, & capillary blood pressure is high
  51. GFR
    • glomerular filtration rate
    • the amount of glomerular filtrate formed in all the renal corpuscles of both kidneys each minute
    • Body averages about 115 ml/min; men slightly higher
    • Results in approx. 180 L produced per day
  52. 3 pressures which contribute to glomerular filtration
    • One encourages filtration: GBHP
    • 2 Oppose filtration: CHP & BCOP
  53. GBHP
    • Glomerular Blood (capillary) Hydrostatic Pressure
    • Favors filtration - 55 mmHg
    • Caused by blood pressure in capillaries; so blood coming into the renal corpuscle from the afferent arteriole
    • Promotes filtration by forcing water and solutes in plasma through filtration membrane
  54. CHP
    • Capsular hydrostatic pressure
    • Opposes filtration - 15 mmHg
    • Is the hydrostatic pressure exerted against the filtration membrane by fluid already in the capsular space and renal tubule
    • Therefore presents a "back pressure"
    • *Recall capsule also called Bowman's capsule
  55. BCOP
    • Blood colloid osmotic pressure
    • Opposes filtration - 30 mmHg
    • Caused by osmotic pressure from proteins remaining in the plasma
    • The proteins draw water back toward them 
    • *Recall osmotic pressure is simply water going from areas of high concentration (many water molecules) to areas of low concentration (less water molecules). 
    • Since there is less water molecules where the large proteins are, water is drawn there by osmosis
  56. NFP
    • (glomerular) net-filtration pressure
    • the "net" result of 3 pressures
    • what determines whether or not urine formation takes place
    • The lower the filtration pressure, the less urine is formed
    • If net pressure is zero or neg., termed as renal failure
    • GBHP (55 mmHg) - CHP (15 mmHg) - BCOP (30 mmHg) = 10 mmHg
    • Therefore, on average, GBHP wins by 10
  57. Importance of regulating GFR
    • Glomerular filtration rate - needs to be held fairly constant
    • If too low, nearly all filtrate may be reabsorbed & certain waste products may not adequately be excreted; there is buildup of waste products in blood
    • If too high, needed substances may pass to quickly through renal tubules that some are not reabsorbed, n would be lost in urine
  58. Body's mechanisms to control GFR
    • Renal autoregulation
    • Neural regulation
    • Hormonal regulation
  59. Explain renal autoregulation of GFR
    • 2 ways kidneys can auto-control: myogenic mechanism & tubuloglomerular feedback
    • *If positive net-filtration was mostly influenced by renal BP, the GFR would fluctuate throughout the day w sleep, exercise, anxiety, etc.
  60. myogenic mechanism
    • One type of renal autoregulation:
    • The process by which the kidney's can adjust the blood pressure in and out of the glomerulus by constricting or dilating the afferent and efferent arterioles
    • If BP is high, the afferent arteriole can constrict to reduce blood flow to the glomerulus
    • This will reduce the GFR
  61. tubuloglomerular feedback
    • One type of renal autoregulation:
    • controlled by JGA (juxtaglomerular apparatus)
    • Macula densa detect increased electrolytes (Na+, Cl-, and water) showing up in distal tubules
    • If these are present in increased amounts, may be due to increased GFR, so not enuf time to reabsorb
    • Therefore, JGA inhibits the release of NO (nitric oxide), resulting in vasoconstriction
  62. Explain why inhibiting NO would cause vasoconstriction
    • NO (nitric oxide) is a potent vasodilator
    • With less present, the arterioles will constrict and decrease the GFR
    • This will give time to reabsorb the electrolytes
  63. Explain Neural regulation of GFR
    • Renal blood vessels are controlled primarily by sympathetic nervous system
    • Norepinephrine causes constriction of afferent and efferent arterioles and decreased GFR
    • By inhibiting sympathetic control & decreasing norepinephrine, will result in dilation of afferent arteriole = increasing GFR
  64. Explain hormonal regulation of GFR
    • Two main hormones contribute to GFR, and have opposite effects:
    • Angiotensin II  decreases GFR
    • ANP (atrial natriuretic peptide): increases GFR
  65. Angiotensin II
    is potent vasoconstrictor of the renin-angiotensin-aldosterone system, so increased amounts will decrease GFR
  66. ANP
    • atrial natriuretic peptide
    • produced by cells in atria.
    • If there is an increase in blood volume, cells in atria stretch and sense increase, signals heart to secrete ANP
    • Causes cells in glomerulus to to become more porous, letting more blood get through Thus increasing GFR
  67. What's in glomerular filtrate?
    • blood minus the formed elements ( and the majority of the plasma proteins
    • Through filtration, 16-20% of plasma in afferent arterioles becomes part of filtrate
  68. How can substances be reabsorbed via tubular reabsorption?
    • By one of two routes:
    • paracellular reabsorption - btwn renal tubule cells
    • transcellular reabsorption - through the renal tubule cells
    • *This is necessary since things are filtered simply by size, whether we need it or not. The things we need must be reabsorbed
  69. What must take place for transcellular reabsorption?
    The substance must cross the apical membrane of the tubule cell, pass through the cytoplasm, and enter into the interstitial fluid by crossing the basolateral membrane
  70. Where is the majority of solute and water reabsorbed & in what %'s?
    • In the proximal convoluted tubule 
    • To maximize reabsorption capacity, the cells here are cuboidal epithelium w microvilli
    • Reabsorbs:
    • 65% of water, sodium & potassium
    • 100% of glucose and amino acids
    • 50% of the urea
  71. Transport proteins
    • Proteins present on the surfaces of cells to actively reabsorb many of the solutes
    • Each type of transporter has a limit to how fast it can reabsorb a particular solute, kinda like a speed limit
  72. Tm
    • transport maximum
    • A transport proteins "speed limit" to how fast it can reabsorb a particular solute
    • If the level of a solute exceeds the transport maximum, any excess will be excreted into the urine
  73. Filtered and reabsorption amounts for water
    • Amount in filtrate per day: 180 L
    • Reabsorbed: 178-179 L
    • Amount in urine per day: 1-2 L
  74. Filtered and reabsorption amounts for Protein
    • Amount in filtrate per day: 2.0 g
    • Reabsorbed: 1.9 g
    • Amount in urine per day: 0.1 g
  75. Filtered and reabsorption amounts for Glucose
    • Amount in filtrate per day: 162 g
    • Reabsorbed: 162 g
    • Amount in urine per day: 0 g
    • *We want ALL our glucose
  76. Filtered and reabsorption amounts for Sodium
    • Amount in filtrate per day: 579 g
    • Reabsorbed: 575 g
    • Amount in urine per day: 4 g
  77. Filtered and reabsorption amount for urea
    • Amount in filtrate per day: 54 g
    • Reabsorbed: 24 g
    • Amount in urine per day: 30 g
    • *Is a waste product
  78. Filtered and reabsorption amounts for Creatinine
    • Amount in filtrate per day: 1.6 g
    • Reabsorbed: 0 g
    • Amount in urine per day: 1.6 g
    • *Want to get rid of it all, is a waste product
  79. Extra thoughts on glucose in blood & diabetics
    • Why polyuria (excessive urination): Glucose is a big substance &  it pulls fluid out of tissues. 
    • But in urine, if there's excessive glucose in filtrate, water follows leading to excessive urination
    • So with large substances, if we're not reabsorbing them, they pull more water out with them in the urine
  80. glucosuria
    • a condition in which glucose is lost into the urine
    • Happens when diabetics don't keep blood glucose under 200 & exceeds the renal transport max for glucose
  81. How is the reabsorption of water controlled
    • All water reabsorption in the kidneys is controlled by osmosis
    • Two different ways: 
    • Obligatory reabsorption
    • Facultative reabsorption
  82. obligatory reabsorption
    • Occurs as water follows solutes because of osmosis
    • So as solutes are reabsorbed, water is "obliged" to follow
    • Where solids go, water follows; concentration gradient set up
    • Since most of nephron is permeable to water, this can occur anywhere in tubules, but most takes place in proximal convoluted tubule
    • Accounts for 90% of water reabsorption
  83. facultative reabsorption
    • Occurs because body is trying to "facilitate" a specific need
    • Again, due to osmosis, but under influence of ADH (antidiuretic hormone) , which influences cells in the distal convoluted tubule & collecting ducts
    • Accounts for 10% of total water reabsorption
  84. Two main functions of tubular secretion & secreted substances
    • Secretion of H+ controls pH
    • Hydrogen and ammonium ions are secreted and bicarbonate conserved to maintain physiological pH
    • Secreted substances: H+, K+, NH4+ (ammonia waste products) , creatinine (waste), and some drugs
  85. Summarize influence of Renin-Angiotensin-Aldosterone system ~ to the point of change from angiotensin I to angiotensin II
    • Stimulated by decrease in renal BP
    • Juxtaglomerular cells secrete the hormone renin
    • Renin converts angiotensinogen to angiotensin I
    • Angiotensin converting enzyme then converts angiotensin I to angiotensin II
    • Among other things, angiotensin II stimulates the release of aldosterone
  86. What does Angiotensin II do?
    • causes vasoconstriction of the afferent arterioles, enhances sodium chloride, and water reabsorption
    • also stimulates the adrenal cortex to secrete aldosterone
  87. What does aldosterone do?
    signals cells in the collecting ducts to reabsorb more sodium, chloride, and water and secrete more potassium
  88. What influence does ADH have on tubular reabsorption and secretion?
    • Osmoreceptors in the hypothalamus detect an increase in blood concentration
    • The posterior pituitary secretes ADH (antidiuretic hormone)
    • ADH stimulates the insertion of water-channel proteins (aquaporin-2) in cells of the collecting duct
    • Increases water permeability and reabsorption of water
  89. Production of dilute urine
    • When fluid is in excess, the body can form very dilute urine
    • It does this by decreasing the release of ADH (antidiuretic hormone) from the posterior pituitary
    • The low level of ADH causes the cells of the distal convoluted tubule & collecting duct to be less permeable to water
    • Results in less water reabsorbed
  90. Production of concentrated urine
    • more complex than dilute urine
    • Involves making a concentration in the interstitial fluid of the renal medulla by 2 mechanisms:
    • Countercurrent multiplication
    • Countercurrent exchange

    Takes place primarily in the loop of henle & vasa recta of the juxtamedullary nephrons
  91. What is meant by "countercurrent" in the mechanisms for making concentrated urine
    • refers to the fact that 2 fluids involved are flowing in opposite directions
    • refers to filtrate flowing down the descending limb of the loop of Henle and up the ascending limb
    • So fluids moving in 2 directions
  92. Why are countercurrent mechanisms facilitated in the production of concentrated urine
    • A persons intake and use of water can vary throughout the day
    • But the total volume of fluid in the body must remain fairly constant
    • Via the two mechanisms (countercurrent multiplier and exchange) able to control total fluid volume during times of dehydration
  93. What's the goal of the countercurrent multiplier?
    • Uses the loop of Henle to create an interstitial concentration gradient  in the medulla
    • In order to reabsorb water, Na& Cl-
  94. What's the importance of creating & maintaining a concentration gradient?
    • By doing this, the body can alter the permeability of cells of the collecting ducts under the influence of ADH to reabsorb or excrete urine based on need
    • When water intake is low, or water loss is high, the kidneys must conserve water to maintain adequate fluid volumes but still eliminate wastes
  95. How does countercurrent multiplier work
    • One mechanism to concentrate the urine
    • Facilitated by loop of Henle
    • The goal is to create an interstitial concentration gradient in the medulla
    • To concentrate the urine, osmosis must take place
    • ~As filtrate flows down the descending limb it becomes more concentrated (from the reabsorption of water back into the body)
    • ~As filtrate flows up the ascending limb it becomes less concentrated via the reabsorption of Naand Cl- (by active transport). The limb is not permeable to water
    • The reabsorption of salt helps establish the concentration gradient
  96. Whats the purpose of concentrating the filtrate going down the descending
    • On the descending loop, water is pumped out. This concentrates the NaCl
    • This way, we have lots of salt to pump out on the ascending side
    • The salt helps establish the concentration in the interstitial fluid
  97. What happens once the interstitial concentration gradient is created via the countercurrent mechanism?
    • ADH can increase the permeability of water in the collecting duct by creating water channels
    • Large amounts of water can be reabsorbed by facultative reabsorption, back into the interstitial area
    • Water flows out cause of the high concentration of NaCl. Water wants to go to it's low concentration area
    • Allows body to secrete very concentrated urine on an as-needed basis
  98. Where does the water go that is drawn out of the collecting ducts, into the interstitial fluid (cause of the high concentration of NaCl)
    It is reabsorbed back into the blood stream via the vasa recta
  99. So what happens if we don't have any ADH
    • There will be no water channels, therefore we will make a very dilute urine
    • Can also have just a few ADH = few water channels
  100. What's the goal of the countercurrent exchange mechanism?
    • To provide oxygen and nutrients, via the vasa recta, w/o disrupting the interstitial concentration gradient
    • Basicly a recycling thing
    • Going down the loop, water goes out and sodium comes in
    • Going back up, sodium goes out and water comes back in.
    • This enables them to leave and come back to the vasa recta w/o messing up the concentration gradient in the interstitial fluid
  101. Urea recycling
    • Water and urea are permeable in lower part of collecting duct, which allows them to diffuse into interstitial fluid
    • Urea is permeable the lower portions of the loop of Henle, so it diffuses back in at the hairpin turn n a little up the ascending side
    • Urea simply repeats this circle, recycling itself
    • This helps keep/maintain deep concentration gradient in lower parts of medulla

    The water simply gets reabsorbed at the vasa recta
  102. What what all is used to keep/maintain the concentration gradient in the interstitial fluid within the medulla
    • Na+
    • Cl-
    • Urea
  103. Describe the Volume and Color of normal urine
    • Volume = 1 - 2 liters per day
    • Color = Variable shades of yellow, duh
    • Obviously color will reflect concentration, but diseases and conditions can cause urine to be red, brown, orange, etc
  104. Describe the turbidity and odor of normal urine
    • Turbidity = Fresh urine is typically clear, but can be cloudy, due to contamination or urinary disease/conditions
    • Odor = Mild ammonia-like odor, but other odors can be apparent w various diseases/conditions
    • *Turbidity is the cloudiness or haziness of a fluid caused by individual particles (total suspended or dissolved solids) that are generally invisible to the naked eye
  105. Describe the pH of normal urine
    • Variable, 4.5 - 8.0
    • Average is 5.0 - 6.5
  106. Describe specific gravity of normal urine
    • 1.005 - 1.025
    • Specific gravity (density) is the weight of the urine, compared to the equivalent volume of water
  107. Blood tests that can be done to evaluate renal function
    • BUN - blood urea nitrogen
    • Plasma creatinine
    • Specifically tests glomerular filtration
    • Urea and creatinine are both waste products; increased amounts in blood commonly represent a decreased glomerular filtration rate
  108. BUN
    • Blood urea nitrogen; a test for renal function (specifically glomerular filtration)
    • The nitrogen in the blood that is part of the urea molecule comes from the catabolism of amino acids
    • If glomerular filtration decreases, amount of urea in blood will dramatically increase
  109. Creatinine
    • is a waste product from muscle tissue
    • to provide an extra energy reserve in muscle, the body uses creatine

    • Once released from muscle, enzymes in blood convert it to creatinine
    • In the kidneys, it passes the glomerular membrane and 100% is excreted in urine
  110. Plasma Creatinine
    • Laboratory blood test which evaluates renal function, specifically glomerular filtration
    • If the amount of creatinine in blood increases, it's due to decreased glomerular filtration rate
  111. Describe a complete UA test
    • Urinalysis
    • Involves a group of biochemical test as well as a microscopic examination of the urine
  112. Describe biochemical urinalysis tests
    • Determined by using test strips (dipsticks)
    • On each strip, can contain anywhere from 1 - 10 absorbent pads, each detecting a different chemical:
    • Albumin, glucose, bilirubin, blood, WBC and bacteria, etc
  113. Describe microscopic urinalysis test
    • Sample of urine is poured into tube and put in centrifuge
    • This causes insoluble material to be pulled to bottom
    • Liquid is then poured out and sediment is examined
    • Normal urine sample will have very little sediment
    • Looking for white blood cells, red blood cells, yeast, bacteria, etc
  114. Describe the structure of the ureters
    • 10-12 inches long
    • Each attach obliquely to the base of the bladder
    • Isn't a valve present at connection to bladder, but as bladder fills the opening closes to prevent backflow
    • Lined w mucus membrane containing transitional epithelium, which allows for stretch
    • Mucus protects epithelium from urine contact
  115. Describe how urine flow is not just gravity feed
    Although gravity does play a part in urine flow through ureters, hydrostatic pressure and peristaltic contractions of smooth muscle in ureter walls push urine towards the bladder
  116. What provides the bladders distensibility
    • Rugae (folds) in the mucous membrane lining
    • Also has transitional epithelium
  117. Trigone
    • A triangular-shaped area at the base of the bladder
    • The 3 apices of the triangle are the openings of the two ureters and the urethra
  118. detrusor muscle
    • muscle which surrounds the mucosal layer of the bladder, assists w the emptying
    • consists of 3 layers of muscle fibers:
    • inner-longitudinal
    • middle-circular
    • outer-longitudinal
  119. Name the superficial layers of the bladder
    • Adventitia - a layer of areolar connective tissue located on posterior and inferior surfaces, continuous w ureters
    • Serosa - a layer of visceral peritoneum on the superior surface
  120. Describe the sphincters of the bladder
    • Internal urethral sphincter - made up of circular fibers around the opening of the urethra. Is involuntary
    • External urethral sphincter - made up of deep skeletal muscles of the perineum; once learned is voluntarily controlled
  121. Micturition
    • also called urination or voiding
    • the process of releasing urine from the bladder
    • is both voluntary and involuntary
  122. Describe the micturition reflex
    • Stretch receptors are stimulated when the bladder contains 200-300 ml
    • parasympathetic response stimulates contraction of the detrusor muscle and relation of the internal urethral sphincter (involuntary)
    • Conscious sensation of bladder fullness
    • Inhibition of somatic neurons to external urethral sphincter (voluntary)
    • voiding
  123. urethra
    • the end of the urinary system
    • a small tube leading from the urinary bladder to the exterior of the body
  124. male urethra
    • is about 8 inches long
    • divided into 3 regions:
    • prostatic - by prostate
    • membranous - "tant" area
    • spongy urethra - w/in penis
    • also functions to transport semen, fomred by testes and accessory sex glands
  125. female urethra
    • only about 1.5 inches
    • located btwn clitoris and vaginal opening
    • Shourter length contributes to high incidence of bladder infections in females
  126. Describe "body fluids"
    • Consists of the water and solutes in the body's fluid compartments
    • 60% of body mass
    • Many compartments, or rather "containers"
  127. State the relative volumes for intra and extracellular compartments
    • 2/3's of body fluids are intracellular
    • 1/3 is extracellular
    • *The extracellular environment can be divided into a number of compartments, but the main space if the interstitial compartment
  128. Daily water gain
    • Approx 2500 ml
    • most comes from one source: ingestion of food (700 ml) and liquid (1600 ml)
    • small amount comes from metabolic water (200 ml)
  129. metabolic water
    a small volume of water which is gained through ATP synthesis
  130. Daily water loss
    • Approx 2500 ml water lost daily:
    • Kidneys (1500 ml)
    • skin (600 ml)
    • Lungs (300 ml)
    • GI tract (100 ml)
  131. Daily water gained vs lost
    To maintain normal fluid proportions, water gained should be qual to water lost and vise versa
  132. Describe mechanism to regulate daily water gain
    • Controlled by bodies thirst center in hypothalamus
    • detects the increase in blood osmolarity (concentration) and triggers thirst response
  133. Dehydration
    • a condition where water loss exceeds gain
    • results in decreased BP and increased blood osmolarity
  134. Other receptors for dehydration
    the kidneys, baroreceptors in the arteries, and neurons in the mouth that detect dryness
  135. Describe water movement in body
    • Recall the volumes of fluid in intracellular and interstitial compartments are not the same
    • For cells not to shrink or swell, osmolarity of both fluids must stay the same
    • Changes in osmolarity will cause water to move from one compartment to another
    • Can be compensated as long as it's not sudden or excessive
    • Kidneys can excrete water at 15 ml/minute
  136. What happens with excessive water consumption
    • A decrease in plasma and interstitial osmolarity causes water to move into the intracellular environment, resulting in cellular swelling
    • If severe enough, can cause cellular death (water intoxication)
    • This is why there isn't a pure water IV solution
  137. Water intoxication
    • When water intake is so much that osmolarity in plasma & interstitial causes water to go straight into cells (lower concentration)
    • Causing cells to swell
    • symptoms include severe headache, light-headedness
    • Can lead to convulsions, coma, and death
  138. Recall anions and cations
    • if a neutral atom loses one or more electrons, it has a net positive charge and is known as a cation. (Yay, I hit a cat)
    • If an atom gains electrons, it has a net negative charge and is known as an anion (When I'm mad, I'm an asshole)
  139. Anions/Cations that are found in higher concentrations extracellularly
    • Na+
    • Cl-
    • Bicarbonate
    • Calcium
    • (Major ones are Na & Cl... salt water)
  140. Anions/Cations that are found in higher concentrations intracellularly
    • Protein anions
    • K+ (major one)
    • Mg2+
    • phosphate
    • sulfate
  141. mEq/L
    • milliequivalents/Liter
    • Is the unit used to express electrolyte levels
    • It reflects the concentration of anions or cations in a given volume of solution
    • One equivalent is the + or - charges equal to the amount of charges in 1 mole of H+ ions
    • -- 1 mole = 6.022 x 1023
    • So a milliequivalent is simply one-thousandth of an equivalent
  142. What would the levels be in plasma for sodium and potassium?
    • Sodium = 136 - 146 mEq/L
    • Potassium - 3.2 - 5.0 mEq/L
  143. What is the pH of a solution if it contains a large number of free H+
    • It's very acidic
    • This doesn't mean it simply contains the element hydrogen, it contains FREE hydrogen ions
    • This is were buffers are useful, they help regulate
    • *Recall H+ are byproducts of metabolism. Need buffers so we don't get too acidic
  144. buffer
    • helps regulate pH
    • a molecule that has the ability to bind H+, and therefore temporarily reduce the acidity in a solution
    • thus reducing the pH of the solution
    • It doesn't remove the H ions but simply binds to them
  145. Common buffer systems:
    • Protein buffering system
    • Carbonic acid-bicarbonate buffering system
    • Phosphate buffering system
  146. Protein buffering system
    • Most abundant buffering system in the plasma and intracellular fluid
    • The carboxyl functional group can bind H+
    • Side chains on 7 of 20 amino acids can bind H
  147. Recall carbonic acid-bicarbonate buffering system
    If we have excess H+, they can combine w bicarb to form carbonic acid, which dissociates into water and carbon dioxide

    H+ HCO3- ⇔ H2CO3 ⇔ H2O + CO2
  148. What systems help regulate pH
    Respiratory and Renal
  149. How should you remember CO2, H+, and HCO3-
    • CO2 can combine w water to form carbonic acid, which dissociates into bicarb and H+
    • Therefore, a buildup of carbon dioxide will be ACIDIC

    • H= acid
    • bicarb = HCO3- = base
  150. respiratory control of pH
    • An increase in Carbon dioxide results in an increase in H+, so any condition causing the accumulation of CO2 will result in the lower pH
    • Changes in rate and depth of ventilation can alter the blood pH, and takes place in minutes
    • Therefore, alter rate and depth of vents to exhale or retain CO2
  151. hyperventilation
    • doubling the ventilation rate
    • Will increase the pH about .23 units
  152. hypoventilation
    • Reducing the ventilation rate by 75%
    • Can decrease the pH by about 0.4 units
  153. Explain the renal control of pH... how is it able to help
    • Metabolic reactions produce large amounts of acids
    • The kidneys can secrete large amounts of H+: H+ are exchanged for Na+ in the proximal convoluted tubule; also via proton pumps in collecting duct - getting rid of H+
    • The collecting ducts can secrete H+ when pH is low and HCO3- when pH is high
    • Recall a proton is a H+
  154. Summarize what systems control: H+, CO2, and HCO3-
    • Kidneys regulates H+ & HCO3-
    • Respiratory regulates CO2
  155. Explain Acidosis and Alkalosis
    • Recall normal pH is 7.35 - 7.45
    • Acidosis = blood pH below 7.35
    • Alkalosis = blood pH above 7.45
  156. Respiratory acidosis
    Any condition that results in inadequate exhalation, thus accumulation of CO2

    • Can be caused by:
    • Hypoventilation
    • Emphysema
    • Overdose of respiratory-suppressive drugs
  157. Respiratory alkalosis
    • Results from exhalation of too much CO2
    • hyperventilating 

    • Can be caused by:
    • Severe anxiety 
    • Oxygen deficiency
  158. What happens in metabolic Acidosis
    • Decrease in plasma HCO3- (can be caused from diarrhea) 
    • Non-respiratory acid accumulation (ketosis, lactic acidosis, etc.)
    • Failure of kidneys to excrete H+ (cause of renal dysfunction)

    Ketones = byproduct of fat metabolism, seen in diabetes
  159. What happens in metabolic alkalosis
    • Too basic from either:
    • Non-respiratory acid loss (ex: vomiting)
    • OR
    • Excessive HCO3- due to alkaline drugs (antacids)