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physiology (Woods) > lecture 15 (T3): micturition and glomerular filtration > Flashcards

lecture 15 (T3): micturition and glomerular filtration Flashcards

1
Q

how are sensory signals from bladder stretch receptors conduction to sacral region of spinal cord

A

via pelvic nerves

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2
Q

how are sensory signals from bladder stretch receptor conducted reflexively back to bladder

A

via parasympathetic nerves

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3
Q

what are the major functions of nephrons

A

get rid of waste materials (urea, creatinine, uric acid, bilirubin
regulate water, electrolyte balance, body fluid osmolarity
regulate arterial pressure
regulate acid-base balance
secretion, metabolism and excretion of hormones, gluconeogenesis

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4
Q

how is arterial pressure regulated long term in nephrons

A

excrete variable amounts of sodium ions and water

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5
Q

how is arterial pressure regulated short term in nephrons

A

secrete hormones and vasoactive factors such as renin

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6
Q

what hormones are secreted, metabolized, and excreted from nephrons

A

erythropoietin

active form of vitamin D

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7
Q

what are the 3 processes that determine the rates at which different substances are excrete in urine

A

filtration, reabsorption and secretion

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8
Q

what is the mathematical expression of the urinary excretion rate

A

fitration rate-reabsorption rate+ secretion rate

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9
Q

what is the first step in urine formation

A

filtration

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10
Q

what are the components of the glomerular filtrate

A

water, ions, glucose, urea

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11
Q

what is the equation for the filtration fraction

A

GFR/renal plasma flow

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12
Q

what is the fraction of renal plasma flow that is filtered

A

20%

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13
Q

why are some low-molecular weight substances not freely filtered

A

they are partially bound to proteins

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14
Q

what are the 3 layers of the filtration barrier

A 
endothelium (with fenestrae and negative charge)
basement membrane (with collagen and proteoglycan fibers and strong negative charges)
podocytes (with negative charges)
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15
Q

what is GFR determined by

A

balance of hydrostatic and colloid osmotic forces acting across capillary membrane
capillary filtration coefficient

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16
Q

what is the filterability of water

A

1.0

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17
Q

what are some diseases that lower glomerular capillary filtration coefficient

A

chronic uncontrolled hypertension and diabetes mellitus

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18
Q

define minimal change nephropathy

A

loss of negative charges on the basement membrane

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19
Q

define hydronephrosis

A

distension and dilation of renal pelvis and calyces

20
Q

what is the numerical value for glomerular hydrostatic pressure

A

60 mm Hg

21
Q

what is the numerical value for bowman’s capsule hydrostatic pressure

A

18 mm Hg

22
Q

what is the numerical value for glomerular capillary colloid osmotic pressure

A

32 mm hg

23
Q

what is the numerical value for colloid osmotic pressure of bowman’s capsule

A

zero

24
Q

what is K1

A

capillary filtration coefficient= product of permeability and filtering surface area of capillaries

25
Q

what happens to GFR if K1 is increased

A

it increases

26
Q

what factors influence glomerular capillary colloid osmotic pressure

A

arterial plasma colloid osmotic pressure

filtration fraction

27
Q

what factors increase glomerular colloid osmotic pressure

A

increasing filtration fraction

28
Q

what variables determine GFR

A

arterial pressure (proportional)
afferent arterial resistance (as it increases, GFR decreases)
efferent arteriole resistance (proportional)

29
Q

what is the equation for renal blood flow

A

(renal artery pressure-renal vein pressure)/ (total vascular resistance)

30
Q

all blood vessels of the kidneys are richly innervated by _______________

A

sympathetic system

31
Q

what are strong activations of renal sympathetic nerves

A

constrict renal arterioles

decrease renal blood flow and GFR

32
Q

what is endothelia released by

A

damaged vascular endothelial cells of kidneys and other tissues

33
Q

what disease states lead to an increase in plasma level associated with vascular injury

A

toxemia of pregnancy
acute renal failure
chronic uremia

34
Q

what does endothelia contribute to

A

renal vasoconstriction leading to reduced GFR

hemostasis when a blood vessel is severed

35
Q

what does angiotensin II do in controlling GFR

A

constricts efferent arterioles

formed in situations associated with decreased arterial pressure or volume depletion

36
Q

why do afferent arterioles seem be protected against the effects of angiotensin II

A

due to release of prostaglandins and nitric oxide which are vasodilators

37
Q

what is the role of nitric oxide in controlling GFR

A

derived from endothelial cells

basic peel helps maintain renal vasodilation

38
Q

what do prostaglandins and bradykinin do in controlling GFR

A

they are vasodilators that may offset effects of sympathetic and angiotensin II vasoconstrictor effects

39
Q

define autoregulation

A

relative constancy of GFR and renal blood flow

40
Q

what is the primary function of autoregulation

A

maintain relatively constant GFR
allow precise control of renal excretion of water and solutes
prevent relatively large changes in GFR and renal excretion that would otherwise occur with changes in blood pressure

41
Q

what is normal GFR

A

180L/day

42
Q

what are the 2 components of the tubuloglomerular feedback mechanism for autoregulation

A

an afferent arteriolar feedback mechanism

an efferent arteriolar feedback mechanism

43
Q

where is the macula densa located

A

distal tubule

44
Q

where are juxaglomerular cells located

A

in afferent and efferent arterioles

45
Q

what happens to flow rate in loop of henle when GFR decreases

A

it slows
increased reabsorption of sodium and chloride ions in ascending limb
decrease in sodium chloride in macula densa

46
Q

what does a decrease in [NaCl] result in (signal from macula dense)

A

decrease resistance to blood in afferent arterioles

increase renin release from JG cells, angiotensin II and efferent arteriolar resistance

47
Q

what is the major storage site of renin

A

JG cells

physiology (Woods) (18 decks)

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