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A-BIOL 1191 LECTURE > CH 26 > Flashcards

CH 26 Flashcards

1
Q

what are general functions of the urinary system?

A
  1. removes wastes from blood
  2. regulates composition, pH, volume, osmolarity, pressure of blood
  3. produces hormones
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2
Q

what is blood osmolarity?

A

total concentration of dissolved solutes present in blood

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3
Q

what are wastes that the kidneys can excrete?

A

nitrogenous wastes:
- urea
- uric acid
- creatinine
- urobilin
- ammonia

  • drugs
  • toxins
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4
Q

which ions can the kidneys control the amount present in blood?

A
  • Na+
  • Cl-
  • Ca2+
  • HPO4 2-
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5
Q

how do the kidneys regulate blood pH?

A
  • control H+ excreted into urine
  • conserve HCO3 -
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6
Q

what are some hormones the kidneys can produce

A
  • calcitriol
  • erythropoietin
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7
Q

how do the kidneys regulate blood glucose levels?

A

through gluconeogenesis:
kidneys convert glutamine into glucose

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8
Q

why is right kidney more inferior than left kidney?

A

liver displaces it

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9
Q

what is the hilum of the kidney?

A

notch containing attachment to ureters, and blood, lymphatic, and nerve supply

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10
Q

what are the three layers of the kidneys? from deep to superficial

A
  1. fibrous capsule
  2. perirenal fat capsule
  3. renal fascia
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11
Q

what is fibrous capsule?

A

collagen-rich sheet
- maintains kidney shape
- protects kidneys from mechanical injury

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12
Q

what is perirenal fat capsule?

A

fatty tissues
- protect kidney from trauma
- anchors kidney within retroperitoneal cavity

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13
Q

what is renal fascia?

A

collagen + elastin rich CT
- anchors kidneys to surrounding organs and abdominal wall

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14
Q

what is the parenchyma?

A

functional portion of kidneys, consisting of renal cortex + pyramids
- contains nephrons

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15
Q

what is urine inside collecting ducts and papillary ducts called?

A

filtrate; further reabsorption can still occur

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16
Q

what is fluid inside the major and minor calices called?

A

urine; no further reabsorption occurs

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17
Q

describe pathway of urine through kidneys to ureters

A

Collecting ducts → Papillary Ducts → Minor calices → Major calices → Renal pelvis → Ureter

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18
Q

what is the renal sinus?

A

depression in the side of the kidney
- where hilum of kidney is nestled into

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19
Q

what is cardiac output?

A

total amount of blood pumping out of ventricles per unit time (L/min)

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20
Q

Describe arterial blood pathway in kidney

A

Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Cortical Radiate artery → afferent glomerular arteriole → glomerulus → efferent glomerular arteriole → peritubular capillaries

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21
Q

Describe venous blood pathway in kidney

A

peritubular capillaries → cortical radiate vein → arcuate vein → interlobar vein → renal vein

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22
Q

what is a kidney lobe?

A

a renal pyramid
- associated renal column on either side
- associated renal cortex

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23
Q

how are glomerular capillaries different from other capillaries?

A

they lie between two sets of arterioles, no venule

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24
Q

which division of the ANS innervates the kidneys?

A

the sympathetic division

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25
Q

Describe innervation of kidneys:

A

lateral grey horn of SC → lumbar splanchnic nerve → renal ganglion → renal plexus

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26
Q

what do vasomotor nerves that innervate kidneys do?

A

constrict the arteriole smooth muscle

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27
Q

what is the renal corpuscle?

A

filters blood plasma

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28
Q

what is the glomerular capsule

A

double-walled epithelial sheath around glomerulus that keeps filtrate inside nephron and sends it to the PCT

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29
Q

what is glomerulus

A

capillary network where blood is filtered

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30
Q

what is the renal tubule

A

where fluid filtered through glomerulus flows into and may be reabsorbed back into the body

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31
Q

what are cortical nephrons?

A

short nephron loops in renal cortex and outer renal medulla

  • blood supply is by peritubular capillaries
  • 80-85% of nephrons
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32
Q

what are juxtamedullary nephrons?

A

long nephron loops that reach deepest regions of the renal medulla
- blood supplied by peritubular capillaries + vasa recta
- 15-20% of nephrons

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33
Q

why are the walls of a nephron thin?

A
  • single epithelial cell layer
  • facilitates exchange btwn blood and filtrate
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34
Q

what cells compose the visceral layer of the glomerular capsule?

A

podocytes- simple squamous e.

  • pedicels wrap around endothelial cells of the glomeruli
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35
Q

what cells compose the parietal layer of the glomerular capsule?

A

-simple squamous e.

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36
Q

what is histology of the PCT

A

simple cuboidal e.
- microvilli on apical surface

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37
Q

what is histology of nephron loop’s thin ascending limb

A

simple squamous e.

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38
Q

what is histology of the nephron loop’s descending limb

A

simple squamous e.

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39
Q

what is the histology of nephron loop’s thick ascending limb

A

simple cuboidal/low columnar

  • more cytoplasm needed b/c they fxn in secretion
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40
Q

what is histology of DCT

A

simple cuboidal e.

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41
Q

what is histology of last DCT and CD

A

simple cuboidal e.

  • principal cells
  • microvillous intercalated cells
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42
Q

what are macula densa

A

columnar cells part of ascending limb of nephron loop

  • contains chemoreceptors that detect increased [Na+] in blood
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43
Q

what are juxtaglomerular cells

A

modified smooth muscle cells on walls of afferent glomerular arteriole
- detect low blood pressure and secrete renin

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44
Q

what are principal cells

A

simple cuboidal e. cells in collecting ducts
- express receptors for ADH and Aldosterone

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45
Q

what are intercalated cells

A

microvillous simple cuboidal e. cells in DCT and CD that regulate blood pH by secreting H+ and reabsorbing HCO3-

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46
Q

why are injured nephrons not replaced

A

you are born w/ all nephrons you will ever have

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47
Q

how do kidneys grow if you are born w/ all nephrons you will ever have

A

nephrons grow by increasing size and capacity

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48
Q

what is a hypertrophic kidney?

A

an increased size kidney
- more susceptible to renal failure

a hypertrophic kidney usually develops when an individual loses one kidney, so the remaining one increases capacity and size to make up for the loss, but it becomes more susceptible to renal failure

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49
Q

what is glomerular filtration

A

blood plasma and small enough dissolved substances get filtered into the glomerular capsule

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50
Q

what is tubular reabsorption

A

water, ions, and other substances get reabsorbed from renal tubule lumen into peritubular capillaries and ultimately into systemic circulation

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51
Q

what is tubular secretion

A

wastes, drugs, excess ions secreted from peritubular capillaries into renal tubule, ultimately making their way into urine

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52
Q

what is the filtration fraction

A

portion of blood plasma that filters out of afferent glomerular arterioles (16-20% in healthy adults)

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53
Q

what are the three barriers filtered substances cross during glomerular filtration?

A
  1. glomerular endothelial cells
  2. basal lamina of glomerulus
  3. pedicel’s slit membrane
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54
Q

how do glomerular endothelial cells fxn in glomerular filtration

A

large fenestrations permit all (except RBCs) to exit capillaries
- regulated by mesangial cells

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55
Q

what are mesangial cells

A

cells btwn efferent and afferent arterioles that contract to regulate filtration

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56
Q

how does basal lamina of glomerulus fxn in glomerular filtration

A

collagen + ANIONIC glycoproteins permit water + small solutes out of capillaries but REPEL negatively-charged plasma proteins

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57
Q

what are pedicels

A

foot-like processes of podocytes

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58
Q

what is a flitration slit

A

spaces btwn pedicels

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59
Q

how does slit membrane fxn in glomerular filtration

A

only very small molecules can pass through, prevents filtration of medium-sized proteins

  • water
  • ions
  • glucose
  • vitamins
  • amino acids
  • ammonia
  • urea
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60
Q

why does filtration at renal corpuscle occur in larger volumes than at systemic capillaries?

A
  • glomerular capillaries have large SA for exchange
  • very permeable, leaky filtration membrane
  • glomerular capillary blood pressure is high
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61
Q

why are efferent glomerular arterioles smaller in diameter than afferent glomerular arterioles

A
  • to increase vascular resistance in efferent glomerular arterioles, leading to high blood pressure in the capillaries
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62
Q

how do mesangial cells regulate surface area glomerular capillaries have

A

mesangial cells contract= decreased SA

mesangial cells relaxed= increased SA

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63
Q

what is bulk flow?

A

net movement of solutes down fluid pressure gradients into out of blood, regardless of solute’s conc. gradient

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64
Q

what is capsular hydrostatic pressure

A

pressure of glomerular filtrate on basement membrane of glomerular capillaries

  • promotes reabsorption
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65
Q

what is glomerular blood hydrostatic pressure

A

pressure of blood plasma on walls of glomerular capillaries

  • promotes filtration
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66
Q

what is blood colloid osmotic pressure

A

pull of solutes in blood (especially blood proteins) on fluids outside glomerular capillaries

  • promotes reabsorption
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67
Q

what is the formula for net filtration pressure in the nephrons?

A

GBHP - (CHP+BCOP)

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68
Q

does net filtration or net reabsorption occur from glomerular capillaries?

A

net filtration, GBHP is greater than CHP and BCOP combined

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69
Q

what determines the rate of glomerular filtration?

A

anything that also determines the net filtration pressure, blood pressure, blood volume in systemic circulation

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70
Q

what happens if GFR is excessively high?

A

insufficient time for reabsorption, loss of important substances in urine

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71
Q

what happens if GFR is excessively low?

A

nearly all filtrate is reabsorbed and wastes will not be excreted

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72
Q

what will hemorrhage do to NFP?

A

Blood volume decreases, blood pressure decreases, NFP decreases because glomerular BHP also decreases

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73
Q

what will hemorrhage do to GFR?

A

systemic BHP decreases, glomerular BHP decreases, so GFR decreases

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74
Q

how can GFR be controlled?

A
  • adjusting blood volume entering glomeruli
  • altering glomerular capillary surface area
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75
Q

what are 3 mechanisms that control GFR?

A
  1. renal autoregulation
  2. neural regulation
  3. hormonal regulation
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76
Q

how is renal autoregulation carried out?

A
  • kidneys must maintain constant blood flow even if conditions are changed (e.g. during exercise) so renal autoregulation ensures systemic blood pressure remains constant
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77
Q

what are the two renal autoregulation mechanisms?

A
  1. myogenic mechanism
  2. tubuloglomerular feedback
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78
Q

what is the stimulus in myogenic mechanism?

A
  • stretching of afferent glomerular arteriole walls
  • increased blood flow through afferent glomerular arterioles
  • increased glomerular filtration
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79
Q

what are the receptors for myogenic mechanism?

A

stretching of the walls of afferent glomerular arterioles stimulates arteriolar constriction

  • less perfusion to the arterioles
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80
Q

what is the net physiological response of myogenic mechanism?

A
  • blood flow decreased
  • GBHP back to homeostatic levels
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81
Q

what is the stimulus for tubuloglomerular feedback?

A

increased GFR, rapid delivery of Na+ and Cl- to macula densa cells

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82
Q

what are the receptors for tubuloglomerular feedback?

A

the macula densa cells detect increased delivery of Na+, CL-, and water, they are chemoreceptors

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83
Q

what is the control center of the tubuloglomerular feedback?

A

juxtagomerular apparatus decreases secretion of nitric oxide

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84
Q

what are the effectors of the tubuloglomerular feedback?

A

afferent glomerular arterioles vasoconstrict (b/c less nitric oxide to vasodilate)

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85
Q

what is the net physiological response of the tubuloglomerular feedback?

A

decrease in GFR

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86
Q

which one is faster? myogenic mechanism or tubuloglomerular feedback?

A

myogenic mechanism

  • tubuloglomerular feedback involves signals sent to multiple cells in sequence
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87
Q

what is the major stimulus of neural regulation in the kidneys?

A

increase in activity level of renal sympathetic nerves that release norepinephrine

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88
Q

what type of neurotransmitter binds to what type of adrenergic receptors on target cells in neural regulation of the kidneys?

A

sympathetic fibres of renal nerves release norepinephrine that bind α-1 adrenergic receptors

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89
Q

what is the net physiological response of neural regulation of the kidneys?

A

when NE binds α-1 receptors on afferent glomerular arterioles, they vasoconstrict and GFR decreases

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90
Q

what are the effectors of neural regulation?

A

afferent glomerular arterioles

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91
Q

what does decreases renal perfusion lead to?

A

-decreased urinary output
- reallocation of blood flow to other organs

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92
Q

what are the two hormones that control glomerular filtration rate?

A
  • Angiotensin II
  • Atrial Natriuretic Peptide
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93
Q

what is major stimulus of Angiotensin II in controlling GFR?

A

decreased blood volume/pressure stimulates production of Angiotensin II

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94
Q

what are the effectors of Angiotensin II on GFR?

A

constriction of afferent and efferent glomerular arterioles

95
Q

what is the net physiological response of Angiotensin II on GFR?

A

decreased GFR

96
Q

what is the stimulus of Atrial natriuretic peptide on controlling GFR

A

stretching of atrial walls stimulates production of ANP

97
Q

what are the effectors of Atrial natriuretic peptide on controlling GFR

A

mesangial cells in glomerulus relax, increasing surface area for filtration

98
Q

what is the net physiological response of atrial natriuretic peptide on controlling GFR

A

increase of GFR

99
Q

what are the two routes for reabsorption in the tubules?

A
  1. paracellular reabsorption: between adjacent tubule cells into the peritubular capillaries
  2. transcellular reabsorption: through individual tubule cells into peritubular capillaries
100
Q

what is the apical membrane of the tubules?

A

the microvillous membrane facing the tubular lumen

101
Q

what is the basolateral membrane of the tubules?

A

the membrane that faces interstitial fluid outside of the tubules

102
Q

what cell junctions join the adjacent cells?

A

tight junctions

103
Q

where are tight junctions leaky in the tubules?

A

in the proximal convoluted tubules, where fluid is permitted to leak between tubule cells

104
Q

how do ions and fluid move across membranes?

A

thorugh transporters either at apical or basolateral membranes of the tubules

105
Q

where is Na+-K+ ATPase located on renal tubule cells?

A

on basolateral membrane

106
Q

why is there no Na+-K+ ATPase on the apical membranes?

A

to ensure unidirectional transport of Na+

  • it is constantly reabsorbed into blood
107
Q

what is the difference between a primary active transporter and a secondary active transporter?

A

Primary: directly uses ATP hydrolysis to powere movement of solutes AGAINST their conc. gradient

Secondary: uses electrochem gradients of one ion DOWN its conc gradient to power movement of another solute AGAINST its conc. gradient
- no ATP

108
Q

what is the difference between a symporter and an antiporter?

A

symporter: two things move in same direction

anitporter: two things move in opposite direction

109
Q

what are two ways water is reabsorbed into blood?

A
  1. obligatory water reabsorption
  2. facultative water reabsorption
110
Q

what is obligatory water reabsorption?

A
  • occurs in PCT + descending limb
  • osmotic movement of water following solutes
  • water moves down its conc. gradient
  • where salt goes, water follows!
111
Q

what is facultative water reabsorption?

A
  • occurs in late DCT and CD
  • controlled by ADH
  • increased permeability to water by principal cells
112
Q

where is the majority of water reabsorbed in the nephrons?

A

in the PCT via obligatory water reabsorption

113
Q

where is the major site of Na+ reabsorption?

A

in the PCT

114
Q

what proteins reabsorbed Na+ at PCT?

A

Na+-glucose symporters in apical membrane

Na+-H+ antiporters in apical membrane

115
Q

how is faciliated diffusion of HCO3- out of tubule cells into blood possible?

A

by increasing intracellular HCO3-

116
Q

how many ions of HCO3- and Na+ are reabsorbed per 1 H+ secreted?

A

1 of HCO3-
1 of Na+

117
Q

what protein allows water to be reabsorbed in PCT?

A

aquaporin-1 on both apical and basolateral membranes

118
Q

how does aquaporin-1 allow for water reabsorption at PCT

A

aquaporin-1 makes PCT highly permeable to water, allowing transcellular reabsorption to occur in addition to the paracellular reabsorption already happening in PCT

119
Q

how does Cl- being present in high concentration affect reabsorption of other ions?

A

increasing negative charge of IF by Cl- promotes diffusion of cations along same route

120
Q

how does ammonia accumulate in IF?

A

ammonia is product of deamination of amino acids

121
Q

why is there little water reabsorption in the nephron loop?

A

the cells there are impermeable to water

122
Q

what protein promotes Cl- reabsorption in the thick ascending limb?

A

Na+-K+-2Cl- symporters in apical membrane

123
Q

why is secretion of K+ back into the tubular lumen by K+ leak channels important?

A

to promote paracellular reabsorption of cations by increasing negative charge of IF

124
Q

why does K+ diffuse back into tubular lumen after Na+-K+-2Cl- symporters transport K+ into cytoplasm of tubular cells?

A

leak channels present in apical membranes allow faciliated diffusion of K+ into lumen

125
Q

what is the net reabsorption into vasa recta because of K+ leak channels?

A

1 Na+ and 2 Cl-, no K+ reabsorbed

126
Q

why does osmolarity of fluid in tubule lumen decrease as fluid flows toward ascending limb?

A

ascending limb is virtually impermeable to water so it stays in tubular lumen, but it is permeable to ions so they are reabsorbed and removed from tubular lumen

127
Q

what protein facilities sodium and chloride reabsorption in the DCT

A

Na+-Cl- symporters

128
Q

what part of the nephron does PTH affect?

A

early DCT

129
Q

how does PTH affect cells of the early DCT?

A

binds receptors on the tubular cells, stimulating reabsorption of Ca2+ when blood calcium levels are low

130
Q

what hormones do principal cells in late DCT and CD possess receptors for?

A

ADH, Aldosterone

131
Q

what do the principal cells in the late DCT and CD do?

A

reabsorb Na+, secrete K+

132
Q

why does K+ secretion vary in the principal cells?

A
  • dietary intake of K+ varies
  • blood levels of K+ varies

K+ simply follows concentration gradient

133
Q

what is the main source of K+ excreted in urine? what channel on what membrane of the principal cells?

A

apical leak K+ channels on principal cells

(basolateral leak K+ channels put K+ back into IF)

134
Q

what do intercalated cells do?

A

reabsorb HCO3- and K+, secrete H+

regulates blood PH

135
Q

what are the five hormones that regulate reabsorption and secretion?

A
  • Angiotensin II
  • Aldosterone
  • Antidiuretic Hormone
  • Atrial Natriuretic Peptide
  • Parathyroid Hormone
136
Q

how does angiotensin II regulate reabsorption and secretion?

A
  1. decrease GFR by vasoconstriction of afferent arteriole
  2. stimulate Na+-H+ antiporters in PCT
  3. stimulate aldosterone release
137
Q

what proteins does Angiotensin II affect in PCT?

A

Na+-H+ antiporters

138
Q

how does aldosterone regulate reabsorption and secretion?

A

stimulates principal cells to reabsorb more Na+, secrete more K+

  • facultative water reabsorption increases
139
Q

what is the net physiological response due to Aldosterone?

A

increased blood volume and blood pressure

140
Q

how does ADH regulate reabsorption and secretion

A
  • increased permeability of principal cells to water
  • stimulates expression of aquaporin-2 at apical membranes
  • increased facultative water reabsorption
141
Q

stimulus of ADH regulation of nephrons?

A

increased osmolarity blood plasma and IF

142
Q

receptors for ADH regulation of nephrons?

A

osmoreceptors in hypothalamus send nerve impulses to hypothalamus and post. pit

143
Q

control centre for ADH regulation of nephrons?

A

hypothalamus and post. pit.

  • increases ADH release
144
Q

effectors for ADH regulation of nephrons?

A

principal cells of collecting ducts and late DCT

  • increased water permeability, increased facultative water reabsorption
145
Q

net physiological response to ADH regulation of nephrons?

A

decrease in blood plasma osmolarity

146
Q

how does normal hydration modulate ADH levels?

A

normally hydrated = normal ADH lvls

  • 99% water reabsorbed, 1& excreted as hyperosmotic urine (1-2L/day)
147
Q

how does dehydration modulate ADH levels?

A

dehydrated = high ADH lvls

  • 99.8% water reabsorbed
  • 0.2% excreted, urinary output very low (400mL/day)
  • urine is concentrated, hyperosmotic
148
Q

what is hyperosmotic urine?

A

urine with higher concentration of solute than blood

149
Q

how does overhydration modulate ADH levels?

A

overhydrated = low ADH lvls

  • 80% reabsorbed, 20% excreted
  • dilute, hypoosmotic urine (up to 36L/day)
150
Q

what hormones does ANP suppress?

A

Aldosterone and ADH

151
Q

how does ANP affect reabsorption and secretion in the tubules?

A
  • inhibits NA+ reabsorption in PCT and CD
  • suppressed Aldosterone and ADH secretion
152
Q

what are the effects of ANP in the context of tubular secretion and reabsorption?

A
  • natriuresis
  • diuresis
  • decreased blood volume and pressure
153
Q

what is natriuresis?

A

increased Na+ excretion in urine

154
Q

what is diuresis?

A

increased urinary output

155
Q

what stimulates PTH release from dense principal parathyroid cells?

A

low blood Ca2+ levels

156
Q

what are the effectors of PTH?

A
  • tubule cells in DCT, reabsorbing more Ca2+
  • tubule cells in PCT to reabsorb less HPO4 3-, increase free Ca2+ in blood
157
Q

what does urinary output and excretion depend on?

A

fluid intake, hormone levels (like ADH)

158
Q

why do kidneys still eliminate wastes as urine even when fluid intake is low or excess fluid is lost?

A

body still produces waste, no matter the conditions

159
Q

why does IF in renal medulla have higher osmolarity than blood plasma?

A

countercurrent flow

160
Q

what is countercurrent flow?

A

fluid in a tube runs in one direction and fluid in another, nearby, parallel tube runs in opposite direction

161
Q

what are two types of countercurrent flow?

A
  • countercurrent multiplication
  • countercurrent exchange
162
Q

what mechanism establishes osmotic gradient across renal cortex into renal medulla?

A

countercurrent multiplication

163
Q

why does Na+ and CL- accumulate in the medullary IF during reabsorption?

A

Na+-K+-2Cl- symporters in thick ascending limb sets up osmotic gradient in the renal medulla

  • water is impermeable here
164
Q

what is countercurrent multiplication?

A

the opposite and parallel arrangements of the two nephron loop limbs and their difference in permeabilities MULTIPLY the concentration of ions in the medullary IF

165
Q

why is countercurrent multiplication needed when ADH levels are high?

A

ESTABLISHES the renal medullary osmotic gradient, which is crucial producing concentrated urine

166
Q

what is urea recycling?

A

urea diffuses out of medullary portion of CD, diffusing into descending and thin ascending limbs

167
Q

how does urea recycling assist countercurrent multiplication?

A

urea is recycled and increases in concentration in the renal medulla during reabsorption

168
Q

what is countercurrent exchange?

A

passive flow of water and solutes from the interstitial fluid of the renal medulla into the blood of the vasa recta

169
Q

why is countercurrent exchange needed when ADH levels are high?

A

MAINTAINS the renal medullary osmotic gradient, which is crucial producing concentrated urine

170
Q

what is the benefit of blood flowing slowly in the vasa recta?

A

allows maximal exchange of solutes, water, etc. with the surrounding interstitial fluid of the renal medulla

171
Q

what direction do solutes move as blood flows through descending portion of the vasa recta?

A

solutes move from renal medullary IF INTO blood

172
Q

what direction do solutes move as blood flows through ascending portion of the vasa recta?

A

solutes move out of blood INTO renal medullary IF

173
Q

what is the importance of countercurrent exchange in addition to maintaining the renal medullary osmotic gradient?

A

ensures that oxygen and nutrients still reach renal medullary cells without changing the osmolarity of the renal medulla IF

  • doesn’t disturb osmotic gradient in renal medulla
174
Q

what is urinalysis?

A

the collection and interpretation of urinary output volume and its physical, chemical, and microscopic characteristics

175
Q

how do blood tests allow us to analyze function of the kidneys?

A

examining composition of blood to see if kidneys are filtering properly

176
Q

what are two indicators in blood that show abnormal kindey functioning?

A
  1. blood urea nitrogen
  2. plasma creatinine
177
Q

what is blood urea nitrogen?

A

presence of urea, nitrogen in blood

  • increases when glomerular filtration fails
  • result of amino acid deamination
178
Q

how do you treat blood urea nitrogen?

A

decrease dietary protein intake

179
Q

what is plasma creatinine?

A

product of creatine phosphate catabolis by muscles

  • increases when renal function is compromised
180
Q

what is renal plasma clearance?

A

volume of blood “cleared” of a substance per unit time (mL/min)

181
Q

what does renal plasma clearance tell us?

A

the rate of excretion in urine for a particular substance

182
Q

S = (U*V)/P

A

U = [substance] in urine
P = [substance] in plasma
V = urine flow rate

183
Q

why does the renal plasma clearance of creatinine closely approximate a norma GFR?

A

creatinine is not reabsorbed

184
Q

why is para-aminohippuric acid used to measure renal plasma flow?

A

it is cleared by kidneys in one pass

185
Q

what is renal plasma flow?

A

volume of plasma passing through kidneys

186
Q

what are the ureters?

A

tubes that carry urine from renal pelvis to urinary bladder

187
Q

how do the ureters carry urine to the urinary bladder?

A
  1. peristaltic contractions
  2. gravity
  3. fluid pressure pushes urine in one way
188
Q

what allows the ureters to expand as they fill with urine?

A

the mucosa is made of urothelium

189
Q

what is the histology of the muscular layer of the ureters? from deep to superficial

A
  1. longitudinal layer
  2. circular layer

distal 1/3 of ureters have additional outer longitudinal layer

190
Q

what is the function of the adventitia of the ureters?

A
  • connects ureters to other tissues
  • anchors ureters in pelvic cavity
191
Q

what is the urinary bladder?

A

expandable organ that stores urine

192
Q

what is important about how the ureters connect to the urinary bladder obliquely?

A
  • forms a physiological valve
  • as urinary bladder fills, pressure pushes the oblique openings closed to prevent urine backflow
193
Q

what is the full volume of the urinary bladder?

A

~700-800mL but it usually doesn’t get that full

194
Q

why is the volume of the urinary bladder smaller in females?

A

the full urinary bladder pushes against the uterus

195
Q

what is the trigone?

A

inferior, triangular area inside urinary bladder containing stretch receptors

  • formed by the two ureteral openings and the internal urethral orifice
196
Q

why does the urinary bladder have rugae?

A

allows expansion of urinary bladder as it fills

197
Q

what is the function of the internal urethral sphincter?

A

involuntarily controls opening and closing of urethra, permitting passage of urine into urethra but preventing backflow of urine back into the urinary bladder

198
Q

what is the function of the external urethral sphincter?

A

voluntarily controls opening and closing of urethra

199
Q

where is the external urethral sphincter?

A

in the deep muscles of the perineum

200
Q

what is the external urethral orifice?

A

opening of urethra to outside, allows expulsion of urine

201
Q

what is the detrusor muscle?

A

muscular layer of urinary bladder consisting of:

  1. inner longitudinal layer
  2. intermediate circular layer
  3. outer longitudinal layer
202
Q

what is the function of the detrusor muscle?

A

provides tone as urinary bladder fills

203
Q

what does the circular layer of the detrusor muscle form at the inner urethral orifice?

A

the internal urethral sphincter

204
Q

what is the micturition reflex?

A

spinal reflex controlling urination

205
Q

what is the stimulus for the micturition reflex

A

volume in urinary bladder reaches 200-400mL

206
Q

what is the receptors for the micturition reflex?

A

stretch receptors in urinary bladder wall detect distension

207
Q

what is the control centre for the micturition reflex?

A

stretch receptors send nerve impulses to micturition centre in sacral spinal cord

208
Q

what is the output for the micturition reflex?

A

nerve impulses through:

  1. parasympathetic fibres to internal anal sphincter, detrusor muscle
  2. inhibitory somatic motor fibres to skeletal muscle of external urethral sphincter
209
Q

what are the effectors of the micturition reflex?

A

detrusor muscle - contracts
internal urethral sphincter - relaxes
external urethral sphincter - relaxes

210
Q

what is the net response for the micturition reflex?

A

urination

  • pressure on fluid within urinary bladder increases
  • internal urethral orifice now open
211
Q

what is the urethra?

A

terminal passage for urine from urinary bladder to exterior of body
- also discharges semen in males

212
Q

what is the histology of the urethra’s mucosa in MALES

A
  • urothelium in proximal end
  • stratified columnar / pseudostratified columnar epithelium in distal end
213
Q

what is the prostatic urethra

A

portion of urethra going through prostate in males

214
Q

what is the muscular layer of the prostatic urethra?

A

mostly circular smooth muscle, forms internal urethral sphincter

215
Q

what is the muscular layer of the membranous urethra?

A

mostly circular skeletal muscle, forms external urethral sphincter

216
Q

what is the membranous urethra?

A

portion of uretrha going through deep perineal muscles

217
Q

what is the spongy urethra?

A

portion of urethra going through corpus spongiosum penis

218
Q

what is the histology of the urethra’s mucosa in FEMALES

A
  • urothelium in proximal end
  • pseudostratified/stratified columnar in intermediate
  • nonkeratinized stratified squamous in distal end
219
Q

what is the histology of the muscular layer of the urethra in FEMALES

A
  • outer skeletal muscle
  • inner smooth muscle
220
Q

what systems does the urinary system cooperate with?

A
  • blood buffers
  • blood
  • liver
  • lungs
  • sweat glands
  • digestive system
221
Q

how does urinary system and blood buffers cooperate?

A

both blood and kidneys bind excess H+ in blood to prevent blood pH changes

222
Q

how does urinary system and blood cooperate?

A

blood transports wastes to appropriate organs for storage, processing, elimination at kidneys

223
Q

how does urinary system and liver cooperate?

A

liver detoxifies drugs to prepare wastes for excretion at kidneys

224
Q

how does urinary system and lungs cooperate?

A

both excrete CO2 waste upon exhalation

225
Q

how does urinary system and sweat glands cooperate?

A

both dissipate heat and excrete water, CO2, urea, and salts

226
Q

Imagine the discovery of a new toxin that blocks renal tubule reabsorption but does not affect filtration. Predict the short-term effects of this toxin.

A

Without reabsorption, initially 105–125 mL of filtrate would be lost per minute, assuming normal glomerular filtration rate. Fluid loss from the blood would cause a decrease in blood pressure, and therefore a decrease in GBHP. When GBHP dropped below 45 mmHg, filtration would stop (assuming normal CHP and BCOP) because NFP would be zero.

227
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (a) dark yellow urine that is turbid;

A

a. Although normally pale yellow, urine color can vary based upon concentration, diet, drugs, and disease. A dark yellow color would not necessarily indicate a problem, but further investigation may be needed. Turbidity or cloudiness can be caused by urine that has been standing for a period of time, from certain foods, or from bacterial infections. Further investigation is needed.

228
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (b) ammonia-like odor of the urine;

A

b. Ammonia-like odor occurs when the urine sample is allowed to stand.

229
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (c) presence of excessive albumin;

A

c. Albumin should not be present in urine (or be present only in very small amounts) because it is too large to pass through the filtration membranes. The presence of high levels of albumin is cause for concern as it indicates damage to the filtration membranes.

230
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (d) presence of epithelial cell casts;

A

d. Casts are hardened masses of material that are flushed out in the urine. The presence of casts is not normal and indicates a pathology.

231
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (e) pH of 5.5;.

A

e. The pH of normal urine ranges from 4.8 to 8.0. A pH of 5.5 is in normal range.

232
Q

For the following urinalysis results, indicate whether you should be concerned or not and why: (f) hematuria.

A

f. Hematuria is the presence of red blood cells in the urine. It can occur with certain pathological conditions or from kidney trauma. Hematuria may occur if the urine sample was contaminated with menstrual blood.

233
Q

Bruce is experiencing sudden, rhythmic waves of pain in his groin area. He has noticed that, although he is consuming fluids, his urine output has decreased. From what condition is Bruce suffering? How is it treated? How can he prevent future episodes?

A

Bruce has developed renal calculi (kidney stones), which are blocking his ureters and interfering with the flow of urine from the kidneys to the urinary bladder. The rhythmic pains are a result of the peristaltic contractions of the ureters as they attempt to move the stones toward the urinary bladder. Bruce can wait for the stones to pass, can have them surgically removed, or can use shock-wave lithotripsy to break apart the stones into smaller fragments that can be eliminated with urine. To prevent future episodes, Bruce needs to watch his diet (limit calcium) and drink fluids, and may need drug intervention.

A-BIOL 1191 LECTURE (12 decks)

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