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Flashcards in Physiology- Renal II Deck (47):
0

3 basic process involving formation of urine

Ultrafiltration of plasma by glomerulus
Reabsorption of water and solutes from ultrafiltrate
Secretion of of selected solutes into tubular fluid

1

Major function of nephrons

Reabsorption of NaCl and water

2

What gets reabsorbed in proximal tubule

65% of filtered:
Na
Cl
K
Water
Urea
90% of filtered:
Bicarbonate
Almost all of filtered:
Glucose
Amino acids
Phosphate

3

What gets secreted at proximal tubule

Hydrogen ions
Drug toxins
Organic acids and bases
-bile salts
-oxalates
-irate
-catecholamines

4

How much NaCl is reabsorbed in loop of henle?

25%

5

How much water is reabsorbed in loop of henle

15%

6

What is loop of henle responsible for

Urinary concentrating ability
-generation of hypertonic medullary interstitium=countercurrent multiplication

7

What gets reabsorbed in loop of henle

NaCl
Water
Calcium
Magnesium

8

Major segments of loop of henle

Descending thin limb

9

Descending thin limb highly permeable to

Water

10

Descending thin limb impermeable to

NaCl

11

Ascending thin limb does reabsorption of

NaCl

12

Ascending thin limb impermeable to

Water

13

Ascending thick limb does reabsorption of

NaCl
Na
K
2Cl

14

Ascending thick limb impermeable to

Water

15

Which part of loop of henle is the primary target of loop diuretics

Ascending thick limb

16

How does loop of henle contribute to urine concentrating ability

By establishing hypertonic medullary interstitium

17

How is hypertonic medullary interstitium created

Reabsorption without water dilutes tubular fluid and increases osmolality of interstitial fluid surrounding thick ascending loop of henle

18

What is reabsorbed at distal tubule

5% NaCl
Ca

19

What works to reabsorbe NaCl at distal tubule

Thiazides

20

What is ca reabsorption stimulated by in distal tubule

Parathyroid hormone

21

Major divisions of collecting duct

Cortical collecting duct
Medullary collecting duct

22

Role of collecting duct

Regulates final composition of urine
Reabsorbs 4-5% of filtered Na
Important for regulation of salt and water balance

23

2 cell types in cortical collecting duct

Principal
Intercalated

24

Principal cells are site of action of

Aldosterone

25

What is reabsorbed in principal cells

Na
Cl

26

What is secreted in principal cells

K

27

What is permeability of water in principal cells dependent on

ADH

28

Intercalated cells responsible for regulation of

Acid base balance

29

What is reabsorbed at intercalated cells

K
Bicarbonate

30

What is secreted at intercalated cells

H

31

What is reabsorbed at medullary collecting duct

NaCl
Water (controlled by ADH)
Urea

32

What is secreted at medullary collecting duct

H

33

Mechanisms that control tubular reabsorption

Glomerular balance
Peritubular capillary and renal interstitial fluid physical forces
Pressure naturesis/diuresis
Hormonal control
Sympathetic nervous system

34

Glomerular balance

Intrinsic ability of tubules to increase their absorption rate in response to increased tubular load (increased tubular inflow)
-total rate of absorption increases as filtered load increases

35

Peritubular capillary and renal interstitial fluid physical forces

Hydrostatic and colloid osmotic forces govern rate of reabsorption across peritubular capillaries

36

Aldosterone secreted by

Adrenal cortex

37

What is aldosterone's site of action

Principal cells of cortical collecting tubule

38

Effects of aldosterone

Increases Na and K reabsorption

39

Secretion of aldosterone stimulated by

Increased extracellular K concentration
Increased angiotensin II levels
-typically occur in conditions associated with Na and volume depletion or low BP

40

3 main effects of angiotensin II

Stimulates aldosterone secretion
Constricts efferent arterioles
Directly stimulates reabsorption in proximal tubules, loop of henle, distal tubules, and collecting ducts

41

Antidiuretic hormone

Increases water permeability of distal tubule, collecting tubule, and collecting duct
-helps body conserve water in times of ECF volume depletion

42

Atrial natriuretic peptide secreted by

Cells in cardiac atria

43

What stimulates release of atrial natriuretic peptide

Distension by increased plasma volume

44

What does atrial natriuretic peptide do?

Directly inhibits reabsorption of Na and water by renal tubules, especially collecting ducts
Inhibits renin (thus, aldosterone), which indirectly inhibits Na and water reabsorption

45

What does activation of sympathetic nervous system decrease excretion of?

Na
Water
(By constricting renal arterioles, reducing GFR)

46

Sympathetic nervous system increases

Renin release
Na reabsorption (low levels of stimulation) in proximal tubule, thick ascending loop of henle
-does this by activating adrenergic receptors in renal tubular epithelial cells