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NPB 101L > Lab 7 Prelab > Flashcards

Lab 7 Prelab Flashcards

1
Q

List the functions of the kidney.

A
  • Regulation of water concentration and fluid volume
  • Regulation of inorganic ion concentrations
  • Regulation of acid-base balance
  • Some gluconeogenesis & synthesis of hormones
  • Excretion of metabolic waste products and xenobiotics
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2
Q

List the 4 essential renal processes in the nephron.

A
  • Filtration
  • Reabsorption
  • Secretion
  • Excretion
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3
Q

Define renal filtration.

A

Water and small solutes are forced under pressure to flow from the glomerulus into the Bowman’s space

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4
Q

Define renal reabsorption.

A

Substances reclaimed from lumen to blood

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5
Q

Define renal secretion.

A

Substances move from peritubular capillary to lumen

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6
Q

Define renal excretion.

A

Substances are removed in the urine

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7
Q

How many kidneys do humans have? Location?

A

2 kidneys located at either side of the vertebral column at posterior/dorsal wall outside main visceral cavity (retroperitoneal)

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8
Q

Define retroperitoneal.

A

Outside main visceral cavity

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9
Q

How many ureters do we have? Function?

A
  • 2 ureters connecting each kidney to the urinary bladder

- Collects major calices

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10
Q

How many urethras do we have? Function?

A

1 urethra connecting the bladder to the exterior for excretion

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11
Q

What is the function of the fibrous capsule of the kidney? What tissue does it work with?

A

Works w/ adipose layer to protect outside of each kidney

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12
Q

What 2 major layers is kidney tissue organized into?

A

Cortex and medulla

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13
Q

What are the pyramids of the kidney? Appearance? Characteristics?

A
  • Cone-shaped

- Arranged w/ tips (papilla) pointing inward

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14
Q

Describe the diff calices of the kidneys. Function, location of each?

A
  • Minor calices collect each pyramid

- Major calices collect groups of minor calices

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15
Q

What is the significance of the hilum of the kidney?

A

Vessels and ureter enter the kidney here

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16
Q

What is a nephron? How many do we have? Location?

A
  • Functional unit of the kidney
  • 1 million total
  • Extends through both cortex and medulla
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17
Q

What is the function of juxtamedullary nephrons? What % of nephrons do these make up?

A
  • Contribute to medullary osmotic gradient

- 15%

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18
Q

What type of nephrons make up 85% of the total amount of nephrons in the kidneys?

A

Cortical nephrons

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19
Q

What does the renal corpuscle include?

A
  • Glomerulus

- Bowman’s capsule

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20
Q

What is the glomerulus?

A

Capillary filtration unit

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21
Q

What is Bowman’s capsule? Location?

A
  • Site where filtrate passes from the vascular system into the tubule system
  • Surrounds glomerulus
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22
Q

What are the functions of the renal corpuscle?

A
  • Connects to proximal convoluted tubule to pass on filtrate

- Creates a filtrate similar to plasma, free of blood cells and proteins

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23
Q

What is the input and output of the renal corpuscle?

A
  • Input = afferent arteriole

- Output = efferent arteriole

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24
Q

What does it mean to be fenestrated? Which cells are fenestrated?

A

Endothelial cells have holes in them

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25
Q

What comprises the basement membrane of the glomerulus? Function?

A
  • Composed of gel-like acellular network of collagen and glycoproteins
  • Surrounds endothelial cells
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26
Q

What are podocytes? Function? Location?

A

Interdigitate around the basement membrane, leaving gaps for flow-thru

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27
Q

What kinds of molecules pass through the basement membrane? Which are repelled?

A
  • Large, negatively charged proteins are repelled

- Small solutes pass through

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28
Q

What drives glomerular filtration of plasma?

A

Pressure differences

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29
Q

What is the equation for net filtration? Define each component and give typical values.

A

P (NFP) = [P(gc) + π(bc)] -
[P(bc) + π(gc)]
-P(gc): hydrostatic pressure in glomerular capillaries (~50 mmHg)
-π(gc): oncotic pressure in Bowman’s capsule (very small, negligible)
-P(bc): hydrostatic pressure in Bowman’s capsule caused by the fluid collecting there (~10 mmHg)
-π(bc): oncotic pressure in glomerular capillaries since there are proteins in the blood, but not in the filtrate (~25 mmHg)

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30
Q

What are the characteristics of tubules?

A
  • Lined w/ epithelial cells

- Have differing channels and pumps all along the length of the tubule

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31
Q

What are peritubular capillaries?

A

Second capillary bed that comes off the efferent arteriole and surrounds the tubule system

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32
Q

What happens to substances that are not filtered at the glomerulus? What is this process called?

A

Tubular secretion: substances secreted into the tubule by the peritubular capillary

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33
Q

What substances are secreted vis tubular secretion?

A

K+, H+, NH4+, urea, some creatinine, some hormones, some drugs

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34
Q

What is the mechanism by which tubular secretion occurs?

A

Active transport across epithelial cell membranes

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35
Q

What is tubular reabsorption?

A

Tubular epithelial cells transport certain substances back across into the peritubular capillary

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36
Q

What are the mechanisms by which tubular reabsorption occurs?

A
  • Can be passive (using flux down gradients)

- Active transport (using pumps or exchangers)

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37
Q

Where does potassium secretion occur? What does it depend on?

A
  • In cortical and medullary collecting ducts

- Depends on balance

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38
Q

What does potassium secretion require?

A
  • H-K-ATPase channel in Type A intercalated cells

- H+ secretion to reabsorb K+

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39
Q

What stimulates potassium secretion?

A

Aldosterone, hypernatremia, volume depletion, ACTH

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40
Q

What substances reduce potassium secretion?

A

Dopamine, ANP

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41
Q

Where does sodium reabsorption occur? What % of reabsorption occurs there? Mechanism of each?

A
  • Proximal convoluted tubule reabsorbs ~65% via uncontrolled active transport
  • Loop of Henle reabsorbs ~25% via uncontrolled passive transport
  • Distal tubules and collecting ducts reabsorb the remainder
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42
Q

What factors increase sodium reabsorption?

A
  • Aldosterone

- Antidiuretic hormone

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43
Q

What inhibits reabsorption? How?

A

ANP inhiits reabsorption by increasing sodium excretion

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44
Q

What kind of drugs affect sodium reabsorption?

A

Diuretics

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45
Q

Where does water reabsorption occur? What % of reabsorption occurs there?

A
  • Proximal tubule reabsorbs ~65%
  • Loop of Henle reabsorbs ~10%
  • Distal tubules and collecting ducts reabsorb ~5-25% depending on fluid need
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46
Q

What molecule follow sodium and water?

A

Chloride

47
Q

What follows sodium reabsorption? Why?

A

Water follows to keep osmotic balance

48
Q

Where is bicarbonate reabsorbed? What % does each location account for?

A
  • Proximal tubule reabsorbs 80%

- Loop of henle reabsorbs 10-20%

49
Q

What is the equation for glomerular filtration rate?

A 
GFR = Kf x Pnet
Kf = filtration coefficient
Pnet = net filtration pressure
50
Q

What is the typical adult GFR?

A

125 mL/min

51
Q

Why is there no way to directly measure GFR?

A

Due to small size of the renal corpuscle

52
Q

Define clearance.

A

Volume of plasma that is completely “cleaned” of a substance

53
Q

Does clearance every equal GFR?

A

No natural substance in the body where Cx = GFR

54
Q

Equation for clearance.

A

Cx = (Ux x Vurine) / Px
Ux: [x] in urine
V(urine) = urine flow rate
Px: [x] in plasma

55
Q

What does it mean if clearance is equal to GFR? Greater than? Less than?

A
  • Cx = GFR –> substance is only filtered
  • Cx > GFR –> net secretion of substance
  • Cx net absorption of substance
56
Q

By how much does creatinine overestimate GFR?

A

Overestimates GFR by 10-20%

57
Q

Why is creatinine easily monitored?

A

B/c produced at a relatively constant rate

58
Q

What is GFR proportional to?

A
  • Creatinine clearance

- Urine creatinine

59
Q

What is GFR inversely proportional to?

A

Plasma creatine

60
Q

What is specific gravity? Equation?

A
  • Ratio of density of a material to the density of water

- P(material) / P(water)

61
Q

What is specific gravity used as an index for?

A

Total solute w/in the urine (osmolarity)

62
Q

What is the juxtaglomerular apparatus?

A

Area where the distal convoluted tubule comes up b/t the afferent and efferent arterioles

63
Q

What make up the juxtaglomerular apparatus?

A
  • Extraglomerular matrix cells
  • Macula densa cells
  • Granular cells
64
Q

What is the function of macula densa cells?

A
  • Sense [NaCl] in arterioles and signal granular cells to low conc
  • Secrete vasodilator/vasoconstrictor chemicals onto arterioles
65
Q

What is the function of granular cells?

A

Secrete renin in response to macula densa cells

66
Q

What does renin do?

A

Activates angiotensinogen (in liver) to produce angiotensin I

67
Q

What does angiotensin I stimulate?

A
  • Adrenals to produce aldosterone
  • Hypothalamus to produce arginine vasopressin
  • Hypothalamic thirst drive
  • Arteriolar vasoconstriction
68
Q

What does aldosterone stimulate?

A

Na+ reabsorption by the renal distal tubule

69
Q

What is arginine vasopressin also known as?

A

Antidiuretic hormone

70
Q

Where is ADP made? Stored?

A
  • Made in the hypothalamus

- Stored in the posterior pituitary

71
Q

What is ADP release controlled by?

A
  • BP
  • Plasma osmolarity
  • Angiotensin II
72
Q

What inhibits the release of antidiuretic hormone? What happens consequently?

A
  • Ethanol (alcohol)

- You’ll pee more –> get dehydrated –> contributes to hangover

73
Q

What synthesizes and secretes atrial natriuretic peptide?

A

Cardiac atria

74
Q

When is atrial natriuretic peptide released?

A

When pressure or stretch in the atrium gets too high (high BP)

75
Q

What does atrial natriuretic peptide cause?

A

Relaxation of afferent arterioles into the renal corpuscle

76
Q

What does atrial natriuretic peptide inhibit?

A

Release of renin

77
Q

What is the RAAS system? Function?

A

Renin-Angiotensin-Aldosterone system stimulates Na+ reabsorption by the distal and collecting tubules

78
Q

What is ANP? Function?

A

Atrial Natriuretic Peptide inhibits Na+ absorption at the distal nephron –> allows Na+ and water retention in the urine –> causes increased excretion of Na+ and water by the kidney –> reduces blood volume

79
Q

What does ADH do?

A

Tubule and ductal cells become more permeable to water –> increase Na+ absorption

80
Q

Define hypotonic.

A

Soln has a lower solute concentration than the cell –> water moves out of soln into cell

81
Q

Why did creatinine clearance greatly increase in the hypotonic subject (water)?

A

Increased flow rate

82
Q

Why did the sodium clearance greatly decrease in the hypotonic subject (water)?

A

Increased flow rate

83
Q

What is the expected result for specific gravity of the hypotonic subject (water)?

A

Decreased from normal

84
Q

What did creatinine clearance increase in the isotonic subject (saline)?

A

Increased flow rate

85
Q

Why did the sodium clearance increase in the isotonic subject (saline)?

A

Increased flow rate

86
Q

Why did the sodium clearance decrease in the hypertonic subject (bicarbonate)?

A

Decreased flow rate

87
Q

Why did the creatinine clearance decrease in the hypertonic subject (bicarbonate)?

A

Decreased flow rate

88
Q

Why did the pH increase in the hypertonic subject (bicarbonate)?

A

Bicarbonate raises the pH of water

89
Q

Define isotonic.

A

Solute concentration is equal inside and outside of cell –> water moves equally in both directions

90
Q

Define hypertonic.

A

Solute concentration is higher in soln than cell –> water moves out of cell into soln

91
Q

What changes in flow rate, Cr clearance, pH, specific gravity, [Na+], and Na+ clearance occurred in the hypotonic subject?

A
  • Increase in flow rate
  • Increase in Cr clearance
  • Increase/? in pH
  • Decrease in specific gravity
  • Decrease in [Na+]
  • Decrease in Na+ clearance
92
Q

What changes in flow rate, Cr clearance, pH, specific gravity, [Na+], and Na+ clearance occurred in the isotonic subject?

A
  • Increase in flow rate
  • Increase in Cr clearance
  • Increase/? in pH
  • No change in specific gravity
  • No change/increase in [Na+] & Na+ clearance
93
Q

What changes in flow rate, Cr clearance, pH, specific gravity, [Na+], and Na+ clearance occurred in the hypertonic subject?

A
  • Huge increase in pH
  • Increase in specific gravity
  • Increase in [Na+]
  • Increase in Na+ clearance
94
Q

What is the role of osmoreceptors in water balance and ADH release?

A

Osmoreceptors are particularly sensitive to decreases in extracellular fluid osmolarity –> stimulate the pituitary to secrete ADH

95
Q

If the room had been very hot during the exercise tests in the respiratory or cardiovascular labs, how might water balance and osmoreceptors have been effected?

A

Hot room would induce increased sweating –> increased water and Na+ loss –> osmoreceptors would stimulate ADH secretion

96
Q

How does the kidney regulate plasma bicarbonate or hydrogen concentrations?

A

pH is controlled by the active secretion of H+ and bicarb ions by the intercalated cells in the proximal, distal, and collecting tubules

97
Q

What is water diuresis? What pathologic states/diseases induce diuresis? How?

A
  • Increased urinary output of water w/ little/no increase in excretion of solutes
  • Normally a response to excess water ingestion, but can occur in response to an inappropriate vasopressin secretion
98
Q

What hormone combats diuresis, and what are its pathways of function?

A

Vasopressin

99
Q

What does angiotensin II do?

A
  • Stimulates the synthesis and secretion of aldosterone by the adrenal cortex
  • Increases the Na+-H+ exchange in the proximal convoluted tubule
  • Increases thirst
  • Causes vasoconstriction of the arterioles –> increases TPR and arterial pressure
100
Q

What changes in GFR occurred in response to hypotonic (water) drinks? Mechanism?

A

Increase in GFR b/c decrease in plasma osmolarity and increase in plasma volume trigger ANP system

101
Q

What changes in GFR occurred in response to isotonic (saline) drinks? Mechanism?

A

Increase in GFR b/c isotonic increase in plasma volume activates ANP system

102
Q

What changes in GFR occurred in response to alkalytic (bicarb) drinks? Mechanism?

A

Decrease in GFR b/c increase in plasma osmolarity and minimal effect on volume activates RAAS system

103
Q

What changes in Na+ clearance occurred in response to isotonic drinks?

A

Higher than normal

104
Q

What changes in Na+ clearance occurred in response to hypotonic drinks?

A

Same or lower than normal

105
Q

What changes in Na+ clearance occurred in response to alkalytic drinks?

A

Same as normal

106
Q

What are the mechanisms controlling Na+ balance? How does each contribute?

A
  • RAAS system compensates for reduced Na+

- ANP compensates for elevated body Na+

107
Q

What are the major components of gastric secretions?

A

Water and HCl (protons)

108
Q

If we know the plasma concentration of a certain molecule or substance, which properties would that substance need to accurately estimate GFR?

A
  • Freely filtered at a constant rate

- No secretion or reabsorption

109
Q

What is the function of the ascending loop of Henle?

A

Drives osmotic gradient in kidney

110
Q

What is the function of the distal convoluted tubule?

A

Reabsorbs additional sodium due to aldosterone

111
Q

What is the function of the proximal convoluted tubule?

A

A majority of essential ions and glucose are reabsorbed

112
Q

What is the function of the descending loop of henle?

A

Mainly permeable to H2O

113
Q

What is the function of the collecting duct?

A

Location of AQP2 channels

114
Q

Constriction of the ____ arteriole and the dilation of the ____ arteriole will lead to increased filtration at the glomerulus.

A
  • Efferent

- Afferent

NPB 101L (13 decks)

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