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Physiology > Physiology- Renal III > Flashcards

Physiology- Renal III Flashcards

0
Q

Extracellular fluid Na conc and osmolarity are regulated by

A

Amt of extracellular water

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1
Q

Osmolarity determined by

A

Amt of solute/vol ECF

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2
Q

Total body water controlled by

A

Fluid intake

Renal excretion of water

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3
Q

As water levels in body increase, what happens to osmolarity

A

Decreases

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4
Q

Antidiuretic hormone AKA

A

Vasopressin

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5
Q

Role of antidiuretic hormone

A

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

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6
Q

Antidiuretic hormone feedback loop

A

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

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7
Q

What parts of the kidney does ADH act on?

A

Distal tubule

collecting duct

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8
Q

Tonicity of glomerular filtrate compared to plasma

A

Isotonic (same osmolarity)

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9
Q

Proportion of solutes and water absorbed in proximal tubule

A

Equal proportions—> little change in osmolarity

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10
Q

How is water absorbed in descending loop of henle

A

Osmosis

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11
Q

Obligatory urine volume

A

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

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12
Q

What is obligatory urine volume dictated by?

A

Maximal concentrating ability of kidney

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13
Q

Why you shouldn’t drink sea water

A

1 L sea water in = 1.5 L water excreted

Leads to dehydration

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14
Q

Requirements to excrete a concentrated urine

A

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

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15
Q

Major factors contributing to hyperosmotic renal medullary interstitium

A
  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
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16
Q

Countercurrent multiplier

A

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

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17
Q

How cortical collecting ducts play a role in concentrating urine

A

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

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18
Q

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

A

To preserve high medullary interstitial osmolarity

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19
Q

Role medullary collecting ducts play in concentration of urine

A

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”

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20
Q

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

A

Low medullary blood flow

Vasa recta serve as countercurrent exchangers

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21
Q

Level plasma osmolarity is maintained at

A

280-295

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22
Q

What level is plasma osmolarity at when thirst is sensed

A

294 mOsm/L

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23
Q

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

A

1%

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24
Q

Disturbances in osmolarity are reflected by

A

Alterations in serum Na concentrations; hyper/hyponatremia

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25
Q

ADH secretion is stimulated by

A

Hyperosmolarity

Volume depletion

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26
Q

What is hyperosmolarity sensed by

A

Hypothalamic osmoreceptors

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27
Q

What is volume depletion sensed by

A

Carotid sinus baroreceptors

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28
Q

Extracellular fluid volume determined mainly by

A

Balance between intake and output of water and NaCl

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29
Q

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

A

Will increase

30
Q

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

A

Decreases

31
Q

Sensors that control ECF volume

A

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

32
Q

Where vascular low pressure volume sensors are located

A

Walls of cardiac atria
Right ventricle
Pulmonary vessels

33
Q

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

A

5-10% change in blood volume and pressure

34
Q

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

A

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
Q

Where are vascular high pressure volume sensors located

A

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

36
Q

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

A

5-10%

37
Q

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

A

Increases sympathetic nerve activity and ADH secretion

38
Q

Increase in BP sensed by vascular high pressure volume sensors causes

A

Decrease in sympathetic nerve activity

39
Q

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

A

Juxtaglomerular apparatus

40
Q

Juxtaglomerular apparatus response to reduced perfusion pressure in afferent arteriole

A

Release of renin

41
Q

Juxtaglomerular apparatus response when an increased perfusion pressure is sensed

A

Suppression of renin release

42
Q

Volume sensor signals

A

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

43
Q

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

A

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

44
Q

What is the net effect of renal sympathetic activity

A

Decrease excretion of NaCl

Restore ECF volume to normal

45
Q

Renin secretion stimulated by

A

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

46
Q

Functions of angiotensin II

A

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
Q

Natriuretic peptides

A

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

48
Q

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

A 
Decreasing sympathetic nerve activity
Releasing natriuretic peptides
Inhibit ADH secretion
Decrease renin secretion
Decrease aldosterone secretion
49
Q

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

A

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

50
Q

Extracellular volume depletion cause kidneys to

A

Reduce excretion of NaCl and water

51
Q

Reduced excretion of NaCl and water is done by

A

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

52
Q

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

A

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

53
Q

Acidemia

A

Fall in pH (more acidic)

54
Q

Alkalemia

A

Rise in pH (more basic)

55
Q

Most metabolic processes in the body result in the production of

A

Acid

56
Q

Largest source of acid from within the body

A

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

57
Q

What gets rid of volatile acid production

A

Pulmonary ventilation

58
Q

Nonvolatile acids formed primarily from

A

Metabolism of sulfur-containing amino acids

59
Q

What gets rid of nonvolatile acids

A

Excretion of H ions thru kidney

60
Q

H ion conc determined by

A

Ratio of PCO2 and bicarbonate concentration

61
Q

3 primary systems to prevent acidosis or alkalosis

A
  1. Chemical acid-base buffer systems of body fluids
  2. Respiratory center
  3. Kidneys
62
Q

Chemical acid-base buffer systems of body fluids

A

Bicarbonate and phosphate buffer systems

Proteins as infra cellular buffers

63
Q

How respiratory center prevents acidosis/alkalosis

A

Removal of CO2 and therefore bicarbonate from ECF

64
Q

How kidneys prevent acidosis/alkalosis

A

Excrete either acidic or alkaline urine

65
Q

Body produces how much nonvolatile acid/day?

A

~80 mEq

66
Q

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

A

H secretion by tubules

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

67
Q

3 mechanisms used by kidneys to regulate ECF H conc

A

Secretion of H
Reabsorption of filtered bicarbonate
Production of new bicarbonate

68
Q

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

A

Descending ans ascending thin limbs of loop of henle

69
Q

What must happen for each bicarbonate to be absorbed

A

One H must be secreted

70
Q

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

A

Secondary active secretion of H is coupled with Na transport

71
Q

How intercalated cells of late distal and collecting tubules secrete H

A

Active transport

72
Q

Phosphate buffer system

A

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
Q

Ammonia buffer system

A

.

Physiology (17 decks)

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