ECF Regulation 1

Question 1

What are the major ECF osmoles?

Answer 1

Na+

Cl-

Question 2

What are the major ICF osmoles?

Answer 2

K+ salts

Question 3

What proportion of the body water is in ICF?

Answer 3

2/3 (28L)

Question 4

What proportion of the water is in the ECF?

Answer 4

1/3 (14L)

Question 5

What compartments make up the extracellular fluid?

Answer 5

Plasma

Interstitial fluid

Question 6

What is the renal response to decreased ECF volume due to vomiting/diarrhoea/sweating?

Answer 6

↓ Plasma volume
↓ venous pressure
↓ Venous return
↓ Atrial pressure
↓ End diastolic volume
↓ systolic volume
↓ cardiac output
↓ blood pressure
= DECREASED SINUS BARORECEPTOR INHIBITION OF SYMPATHETIC DISCHARGE

Question 7

What is the effect of increased sympathetic discharge?

Answer 7

Increased total peripheral resistance

Increased BP towards normal

Question 8

Both decreased carotid sinus baroreceptor discharge and atrial pressure do what?

Answer 8

Increased ADH

Question 9

What is the effect of decreased carotid sinus baroreceptor discharge on the kidneys?

Answer 9

Increased sympathetic vasoconstriction, which includes renal arterial constriction, this increasing renin secretion

Question 10

Increased renin increases what?

Answer 10

Angiotensin II

Question 11

What are the effects of increased angiotensin II?

Answer 11

1. Increased proximal tubule NaCl + H2O reabsorption

2. Increased aldosterone secretion

Question 12

What are the effects of increased aldosterone secretion?

Answer 12

Increased distal tubule NaCl + H2O reabsorption

Question 13

Proximal tubule

NaCl & H2O reabsorption is affected by what?

Answer 13

Angiotensin II levels

Question 14

Distal tubule

NaCl & H2O reabsorption is affected by what?

Answer 14

Aldosterone levels

Question 15

How does increased renin effect Na+ reabsorption?

Answer 15

↑Renin = ↑Angiotensin II
↑AGTII = ↓ peritubular capillary hydrostatic Pressure and ↑oncotic pressure = ↑Na+ reabsorption

Question 16

Angiotensin II is a what?

Answer 16

VASOCONSTRICTOR

Question 17

Why is oncotic pressure the driving force of reabsorption?

Answer 17

Capillaries have lost a lot of salt + water

Plasma proteins remain, oncotic pressure drives reabsorption

Question 18

What is the reabsorptive range of the proximal tubule?

Answer 18

65-75%

Question 19

How does GFR rate vary throughout volume/pressure changes?

Answer 19

Very little unless volume depletion is severe to cause ↓MBP

Question 20

What, in normovolaemia, is the pressure in the peritubular capillaries?

Answer 20

Below normal due to efferent arteriole constriction by angiotensin II

Question 21

What, in normovolaemia, is the oncotic pressure in the peritubular capillaries?

Answer 21

Greater than normal due to lost NaCl and H2O, causing a relative ↑ in plasma [protein]

Question 22

How much salt is reabsorbed in the proximal tubule in hypovolaemia?

Answer 22

75%

Question 23

What, in hypervolaemia, is the oncotic pressure in the peritubular capillaries?

Answer 23

Decreased due to increased water levels diluting the proteins

Question 24

What, in hypervolaemia, is the pressure pressure in the peritubular capillaries?

Answer 24

Increased because the efferent arteriole is less constricted

Question 25

What regulates constriction of the afferent arteriole?

Answer 25

Sympathetic VC

Question 26

What regulates constriction of the efferent arteriole?

Answer 26

Angiotensin II

Question 27

Aldosterone regulates what?

Answer 27

Regulation of distal tubule Na+ reabsorption

Question 28

Where is aldosterone produced?

Answer 28

Adrenal cortex | Zona glomerulosa

Question 29

What are Juxtaglomerular cells?

Answer 29

Specialised, granular epithelial cells on the smooth muscle of the afferent arteriole

Question 30

What is the macula densa?

Answer 30

Specialised loop of the distal tubule

Question 31

What is the Juxtaglomerular apparatus?

Answer 31

Juxtaglomerular cells and the macula densa

Question 32

Where is Renin produced?

Answer 32

Juxtaglomerular cells

Question 33

What is renin?

Answer 33

Proteolytic enzyme which acts on angiotensinogen

Question 34

ANGI --> ANGII is regulated by what?

Answer 34

ACE

Question 35

Where is ACE produced?

Answer 35

Blood vessel epithelium

Question 36

What fraction of the plasma proteins is acted on by renin?

Answer 36

alpha2-globulin

Question 37

What is the rate limiting step of the RAAS system?

Answer 37

Renin concentration

Question 38

What is the effect of increased ANGII on arterioles?

Answer 38

Vasoconstriction

Question 39

What is the effect of increased ANGII on the cardiovascular control centre of the medulla oblongata??

Answer 39

Increased cardiovascular response to increase blood pressure?

Question 40

What is the effect of increased ANGII on the hypothalamus?

Answer 40

↑ Vasopressin | ↑ Thirst

Question 41

What is the effect of increased ANGII on the adrenal cortex?

Answer 41

↑ Aldosterone = ↑ Na+ reabsorption

Question 42

What is the effect of increased ANGII on the adrenal cortex?

Answer 42

↑ Aldosterone = ↑ Na+ reabsorption

Question 43

What are the controls of renin release?

Answer 43

1. ↑ when Pressure at JG cells ↓ 2. ↑ via ↑sympathetic nerve activity via beta1 3. ↑ when NaCl to macula densa ↓ 4. Inhibited by Angiotensin II 5. Inhibited release by ADH

Question 44

What is the effect of Angiotensin II on renin?

Answer 44

Angiotensin II feeds back to inhibit renin

Question 45

What is the effect of ADH on renin?

Answer 45

Feeds back to inhibit renin

Question 46

What is the effect of increased NaCl at the macula densa on renin?

Answer 46

Decreased renin secretion

Question 47

What are the roles of Angiotensin II?

Answer 47

Stimulate aldosterone Vasoconstriction (↑ TPR) Stimulates ADH secretion Stimulates thirst/salt appetite

Question 48

What is the vasoconstrictive potency of norepinephrine compared to angiotensin II?

Answer 48

Angiotensin 4-8x more potent than norepinephrine

Question 49

How does the macula densa communicate with the arteriole?

Answer 49

Paracrine

Question 50

Increased salt flow through the macula densa has what effect?

Answer 50

Constriction of the afferent arteriole, reducing GFR

Question 51

What is the most important factor deciding the action of ADH?

Answer 51

Osmolarity in normal volume | Volume in emergency