Endocrine Control of Body Fluid Volume Flashcards Preview

Human Epithelial Biology > Endocrine Control of Body Fluid Volume > Flashcards

Flashcards in Endocrine Control of Body Fluid Volume Deck (49)
1

Where does the distal tubule end?

the collecting ducts

2

How much of the ion loads are reabsorbed?

95%

3

what is the estimated residual load of NaCl?

700-1000mmol NaCl/day

4

What are the hormones that regulate ion and water balance?

ADH
Aldosterone
ANP
PTH

5

What is the effect of ADH?

increased water absorption

6

What is the effect of Aldosterone?

increase Na absorption
increase K/H secretion

7

What is the effect of ANP?

decrease Na absorption

8

What is the effect of PTH?

increase Ca absorption
decrease PO4

9

What does the distal tubule have a low permeability to?

water and urea

10

What does urea concentrated in the tubular fluid do?

establishes the osmotic gradient within the medulla

11

What are the two segments to the distal tubule?

early and late

12

What happens in the early distal tubule?

NKCC transport - Na Cl reabsorption

13

What happens in the late distal tubule?

Ca reabsorption
H secretion
Na reabsorption
K reabsorption

14

What is the collecting duct split into?

early and late

15

What is the early duct similar to?

the late distal tubule

16

What happens in late collecting duct?

a low ion permeability
permeability to water influenced by ADH

17

When in ADH released?

when APs lead to Ca dependent exocytosis

18

What is the half life of ADH?

10-15mins

19

Where is ADH produced?

paraventricular nuclei in hypothalamus

20

What does ADH do in the distal tubular cell?

increases permeability of the collecting duct by inserting aquaporins

21

What is the effect of ADH on urine?

high water permeability = hypertonic urine 1400mosmol/l

22

How does the tubular fluid equilibrate with the interstitium?

aquaporins

23

What is true in the collecting duct?

impermeable to water so no water reabsorption in presence of minimal ADH

24

What does ADH do to urine osmolarity, volume and total solute excretion?

increase osmolarity
decrease volume

25

What happens in water deficit?

hypothalamic osmoreceptors detect increase in osmolarity and decreased Arterial blood pressure

26

What is diabetes insipidus or nephrogenic diabetes insipidus?

hereditary disease with large volumes of dilute urine and constant thirst

27

What is the treatment for diabetes insipidus?

ADH replacement

28

What are some stimulants and inhibitory influences of ADH?

nicotine stimulates
alcohol, stretch receptors in upper GI inhibits

29

When is aldosterone secreted?

in response to rising K or falling Na in blood
activation of the renin-angiotensin system

30

What does Aldosterone do?

Na reabsorption and K secretion

31

Where is most K reabsorbed?

early regions of the nephron

32

What happens to K when aldosterone is absent?

rest is reabsorbed in distal tubule

33

What does an increase in K directly stimulate?

adrenal cortex

34

How does a decrease in plasma Na promote indirect secretion of aldosterone?

the juxtaglomerular apparatus

35

What does a decrease in NaCl, ECF and BP do?

stimulates release of renin from kidney which converts angiotensinogen to angiotensin I

36

What converts Angiotensin I to angiotensin II?

angiotensin converting enzyme

37

What does angiotensin II do?

stimulates adrenal cortex to produce aldosterone
stimulates thirst, ADH and arteriolar vasoconstriction
Na and Cl reabsorption

38

What are the steps in renin release from granular cells in JGA?

reduced pressure in afferent arterioles - more renin
macula densa cells sense the amount of NaCl in distal tubule - if reduced NaCl then renin released
increased sympathetic activity as a result of reduced BP - causes renin release

39

What can abnormal increases in RAA system?

hypertension

40

What are abnormal increased in RAA responsible for in congestive heart failure?

fluid retention
failing heart causes decreased CO and BP -> low BP stimulates RAA -> increases salt and water retention -> failing heart

41

What is the treatment for abnormal RAAS?

low salt diet, diuretics, ACE inhibitors

42

What is ANP?

a hormone from atrial muscle cells that is released when the cells are mechanically stretched due to increase in plasma volume

43

What does ANP promote?

excretion of Na and diuresis

44

What is micturation?

urination

45

What is urination governed by?

micturation reflex
voluntary control

46

How much can the bladder store?

250-400ml before the stretch receptors activate the micturation reflex

47

What does the micturation reflex do?

involuntary emptying of the bladder by simultaneous bladder contraction and opening of the internal and external urethral sphincters

48

How can micturation be voluntarily prevented?

by deliberate tightening of external sphincter and surrounding pelvic diaphragm

49

What stimulation causes the bladder to contract?

parasympathetic