lecture 15 (T3): micturition and glomerular filtration Flashcards Preview

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Flashcards in lecture 15 (T3): micturition and glomerular filtration Deck (47):
1

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

via pelvic nerves

2

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

via parasympathetic nerves

3

what are the major functions of nephrons

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

4

how is arterial pressure regulated long term in nephrons

excrete variable amounts of sodium ions and water

5

how is arterial pressure regulated short term in nephrons

secrete hormones and vasoactive factors such as renin

6

what hormones are secreted, metabolized, and excreted from nephrons

erythropoietin
active form of vitamin D

7

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

filtration, reabsorption and secretion

8

what is the mathematical expression of the urinary excretion rate

fitration rate-reabsorption rate+ secretion rate

9

what is the first step in urine formation

filtration

10

what are the components of the glomerular filtrate

water, ions, glucose, urea

11

what is the equation for the filtration fraction

GFR/renal plasma flow

12

what is the fraction of renal plasma flow that is filtered

20%

13

why are some low-molecular weight substances not freely filtered

they are partially bound to proteins

14

what are the 3 layers of the filtration barrier

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

15

what is GFR determined by

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

16

what is the filterability of water

1.0

17

what are some diseases that lower glomerular capillary filtration coefficient

chronic uncontrolled hypertension and diabetes mellitus

18

define minimal change nephropathy

loss of negative charges on the basement membrane

19

define hydronephrosis

distension and dilation of renal pelvis and calyces

20

what is the numerical value for glomerular hydrostatic pressure

60 mm Hg

21

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

18 mm Hg

22

what is the numerical value for glomerular capillary colloid osmotic pressure

32 mm hg

23

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

zero

24

what is K1

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

25

what happens to GFR if K1 is increased

it increases

26

what factors influence glomerular capillary colloid osmotic pressure

arterial plasma colloid osmotic pressure
filtration fraction

27

what factors increase glomerular colloid osmotic pressure

increasing filtration fraction

28

what variables determine GFR

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

29

what is the equation for renal blood flow

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

30

all blood vessels of the kidneys are richly innervated by _______________

sympathetic system

31

what are strong activations of renal sympathetic nerves

constrict renal arterioles
decrease renal blood flow and GFR

32

what is endothelia released by

damaged vascular endothelial cells of kidneys and other tissues

33

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

toxemia of pregnancy
acute renal failure
chronic uremia

34

what does endothelia contribute to

renal vasoconstriction leading to reduced GFR
hemostasis when a blood vessel is severed

35

what does angiotensin II do in controlling GFR

constricts efferent arterioles
formed in situations associated with decreased arterial pressure or volume depletion

36

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

due to release of prostaglandins and nitric oxide which are vasodilators

37

what is the role of nitric oxide in controlling GFR

derived from endothelial cells
basic peel helps maintain renal vasodilation

38

what do prostaglandins and bradykinin do in controlling GFR

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

39

define autoregulation

relative constancy of GFR and renal blood flow

40

what is the primary function of autoregulation

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

what is normal GFR

180L/day

42

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

an afferent arteriolar feedback mechanism
an efferent arteriolar feedback mechanism

43

where is the macula densa located

distal tubule

44

where are juxaglomerular cells located

in afferent and efferent arterioles

45

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

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

46

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

decrease resistance to blood in afferent arterioles
increase renin release from JG cells, angiotensin II and efferent arteriolar resistance

47

what is the major storage site of renin

JG cells