Physiology- Renal III Flashcards Preview

Physiology > Physiology- Renal III > Flashcards

Flashcards in Physiology- Renal III Deck (74):
0

Osmolarity determined by

Amt of solute/vol ECF

1

Extracellular fluid Na conc and osmolarity are regulated by

Amt of extracellular water

2

Total body water controlled by

Fluid intake
Renal excretion of water

3

As water levels in body increase, what happens to osmolarity

Decreases

4

Antidiuretic hormone AKA

Vasopressin

5

Role of antidiuretic hormone

Regulates plasma osmolarity and sodium conc by altering renal excretion of water independently of rate of solute excretion

6

Antidiuretic hormone feedback loop

Increased osmolarity sensed by osmoreceptors in hypothalamus--> posterior pituitary secretes ADH--> increases permeability of distal tubule and collecting ducts to water

7

What parts of the kidney does ADH act on?

Distal tubule
collecting duct

8

Tonicity of glomerular filtrate compared to plasma

Isotonic (same osmolarity)

9

Proportion of solutes and water absorbed in proximal tubule

Equal proportions---> little change in osmolarity

10

How is water absorbed in descending loop of henle

Osmosis

11

Obligatory urine volume

Amount of urine necessary to be excreted per day to to rid body of metabolic waste products
In normal person = .5 L/day

12

What is obligatory urine volume dictated by?

Maximal concentrating ability of kidney

13

Why you shouldn't drink sea water

1 L sea water in = 1.5 L water excreted
Leads to dehydration

14

Requirements to excrete a concentrated urine

High level of ADH
high osmolarity of renal medullary interstitial fluid
-countercurrent mechanism

15

Major factors contributing to hyperosmotic renal medullary interstitium

1. Active transport of Na ions and co-transport of K Cl and other ions out of thick ascending loop of henle into medullary interstitium
2. Active transport of ions from collecting ducts into medullary interstitium
3. Facilitated diffusion of urea from inner medullary collecting ducts into medullary interstitium
4. Diffusion of less water than reabsorption of solutes from medullary interstitium

16

Countercurrent multiplier

Repetitive reabsorption of NaCl by thick ascending limb of loop of henle and continued inflow of new NaCl from proximal tubules into loop of henle

17

How cortical collecting ducts play a role in concentrating urine

If ADH levels are high, cortical collecting ducts become permeable to water
-large amts of water get reabsorbed from tubule into cortex interstitium, where it is swept away by capillaries

18

Why is water reabsorbed into cortex from collecting ducts instead of renal medulla?

To preserve high medullary interstitial osmolarity

19

Role medullary collecting ducts play in concentration of urine

Wen ADH present, water gets further reabsorbed in interstitium and carried away from vasa recta
-urea is reabsorbed from medullary collecting duct into medullary interstitium and is "recycled"

20

2 features of renal medullary blood flow that contribute to preservation of hyperosmolarity of renal medulla

Low medullary blood flow
Vasa recta serve as countercurrent exchangers

21

Level plasma osmolarity is maintained at

280-295

22

What level is plasma osmolarity at when thirst is sensed

294 mOsm/L

23

What level does osmolarity have to raise by for ADH release to be stimulated

1%

24

Disturbances in osmolarity are reflected by

Alterations in serum Na concentrations; hyper/hyponatremia

25

ADH secretion is stimulated by

Hyperosmolarity
Volume depletion

26

What is hyperosmolarity sensed by

Hypothalamic osmoreceptors

27

What is volume depletion sensed by

Carotid sinus baroreceptors

28

Extracellular fluid volume determined mainly by

Balance between intake and output of water and NaCl

29

If ingestion of NaCl is greater than excretion of NaCl, what will happen to ECF volume?

Will increase

30

If excretion of NaCl is greater than ingestion of NaCl, what happens to ECF volume?

Decreases

31

Sensors that control ECF volume

Vascular low pressure volume sensors*
Vascular high pressure volume sensors*
CNS
hepatic system

32

Where vascular low pressure volume sensors are located

Walls of cardiac atria
Right ventricle
Pulmonary vessels

33

How much of a change in blood volume is required to evoke a response from vascular low pressure volume sensors

5-10% change in blood volume and pressure

34

What happens in response to vascular low pressure volume sensors sending signals to brainstem

Modulation of sympathetic nerve outflow and ADH secretion
-decrease in filling increases sympathetic nerve activity and stimulates ADH
-dissension of structures decreases sympathetic nerve activity

35

Where are vascular high pressure volume sensors located

Arterial side of circularity system
Wall of aortic arch
Carotid sinus
Afferent arterioles in kidney

36

How much of a change in blood pressure is required for vascular high pressure volume receptors in aortic arch and carotid sinus to send signals to brainstem

5-10%

37

Decrease in BP sensed by vascular high pressure volume sensors causes what?

Increases sympathetic nerve activity and ADH secretion

38

Increase in BP sensed by vascular high pressure volume sensors causes

Decrease in sympathetic nerve activity

39

When vascular high pressure volume sensors sense a change in volume at afferent arteriole of kidney, what structure responds to these changes

Juxtaglomerular apparatus

40

Juxtaglomerular apparatus response to reduced perfusion pressure in afferent arteriole

Release of renin

41

Juxtaglomerular apparatus response when an increased perfusion pressure is sensed

Suppression of renin release

42

Volume sensor signals

Sympathetic nerves
Renin-angiotensin-aldosterone system
Natriuretic peptides
Antidiuretic hormone

43

With ECF depletion, stimulation of renal sympathetic nerve activity leads to

Constriction of afferent and efferent arterioles
Renin secretion stimulated by granular cells
NaCl reabsorption along nephron stimulated directly

44

What is the net effect of renal sympathetic activity

Decrease excretion of NaCl
Restore ECF volume to normal

45

Renin secretion stimulated by

Reduced perfusion pressure
Sympathetic nerve activity
Reduced delivery of NaCl to macula densa

46

Functions of angiotensin II

Stimulation of aldosterone secretion by adrenal cortex
Arteriolar vasoconstriction, increasing BP
stimulation of ADH secretion and thirst
Increase NaCl reabsorption by proximal tubule, thick ascending loop of henle, distal tubule, and collecting duct
Stimulates secretion of aldosterone

47

Natriuretic peptides

ANP and BNP are secreted when heart dilates to relax vascular smooth muscle and promote excretion of NaCl and water by kidneys

48

Hi and low pressure volume sensors send signals to kidneys to increase excretion of NaCl and water by:

Decreasing sympathetic nerve activity
Releasing natriuretic peptides
Inhibit ADH secretion
Decrease renin secretion
Decrease aldosterone secretion

49

General responses of nephrons to the need for volume sensors to want to get rid of sodium and water

GFR increases
Reabsorption decreases in proximal tubule and loop of henle
Sodium reabsorption decreases in distal tubule and collecting duct

50

Extracellular volume depletion cause kidneys to

Reduce excretion of NaCl and water

51

Reduced excretion of NaCl and water is done by

Increasing sympathetic nerve activity
Increased secretion of renin
Decreasing natriuretic peptides
Increased secretion of ADH

52

The kidneys effort to reduce excretion of NaCl and water results in

Decreased GFR
Increased Na reabsorption by proximal tubule and loop of henle
Increased Na reabsorption by distal tubule and collecting duct

53

Acidemia

Fall in pH (more acidic)

54

Alkalemia

Rise in pH (more basic)

55

Most metabolic processes in the body result in the production of

Acid

56

Largest source of acid from within the body

Catabolism and oxidation of glucose and fatty acids...ultimately CO2+H2O= carbonic acid

57

What gets rid of volatile acid production

Pulmonary ventilation

58

Nonvolatile acids formed primarily from

Metabolism of sulfur-containing amino acids

59

What gets rid of nonvolatile acids

Excretion of H ions thru kidney

60

H ion conc determined by

Ratio of PCO2 and bicarbonate concentration

61

3 primary systems to prevent acidosis or alkalosis

1. Chemical acid-base buffer systems of body fluids
2. Respiratory center
3. Kidneys

62

Chemical acid-base buffer systems of body fluids

Bicarbonate and phosphate buffer systems
Proteins as infra cellular buffers

63

How respiratory center prevents acidosis/alkalosis

Removal of CO2 and therefore bicarbonate from ECF

64

How kidneys prevent acidosis/alkalosis

Excrete either acidic or alkaline urine

65

Body produces how much nonvolatile acid/day?

~80 mEq

66

Reabsorption of bicarbonate and secretion of H are accomplished through process of

H secretion by tubules
-bicarbonate must combine with H to form H2CO3 before it can be reabsorbed

67

3 mechanisms used by kidneys to regulate ECF H conc

Secretion of H
Reabsorption of filtered bicarbonate
Production of new bicarbonate

68

H ion secretion and bicarbonate reabsorption occur in all parts of tubules except

Descending ans ascending thin limbs of loop of henle

69

What must happen for each bicarbonate to be absorbed

One H must be secreted

70

How H is secreted in proximal tubules, thick segment of ascending loop of henle, and early distal tubule

Secondary active secretion of H is coupled with Na transport

71

How intercalated cells of late distal and collecting tubules secrete H

Active transport

72

Phosphate buffer system

Phosphates are ultimately responsible for holding H+'s in urine so that H+'s can be expelled from the body in urine. This also allows HCO3- to be reabsorbed from the kidney back into the body, without H+ following the HCO3- back into the body.

73

Ammonia buffer system

.