Renal 7

Question 1

What is secretion of K+ for

Answer 1

Acts directly on adrenal cortex protecting body from hyperkalemia

Question 2

What are 4 causes of aldosterone release

Answer 2

1. Decreased BP
2. Increased osmolarity
3. Large drops in plasma Na
4. Increases in K

Question 3

How does decreased BP release aldosterone

Answer 3

Initiate a pathway that results in production of angiotensin which triggers aldosterone release

Question 4

How does increased osmolarity trigger release of aldosterone

Answer 4

Acts directly on adrenal cortex during dehydration

Question 5

Renin angiotensin system (RAS)

Answer 5

Multi step pathway for maintaining BP
- day to day aldosterone secretion

Question 6

What is the multi step pathway of the renin angiotensin system

Answer 6

• Decrease BP causes release of renin from granular cells
• renin cleaves angiotensin to ANG I then converted to ANGII by ACE
• ANG II travels to adrenal cortex and stimulates production of aldosterone

Question 7

What does the renin-angiotensin pathway begin with

Answer 7

Renin secretion (enzyme)

Question 8

What secretes renin

Answer 8

Granular cells

Question 9

How is renin secretion indirectly stimulate

Answer 9

Sense when GFR decreases:
2. Sympathetic neurons activated by CVCC when BP decreased terminated on granular cells
3. Paracrine feedback (prostaglandins) from macula densa cells signal granular cells to secrete

Question 10

What is the direct stimuli that cause renin secretion

Answer 10

Low BP in renal arterioles cause granular cells to secrete in response to less stretch

Question 11

What are granular cells also known as

Answer 11

Juxtaglomerular cells

Question 12

What is renin’s main role

Answer 12

Convert an inactive angiotensin, into angiotensin I

Question 13

What is angiotensin

Answer 13

Plasma protein constantly circulating in blood

Question 14

What is ACE

Answer 14

Angiotensin converting enzyme
- enzyme produced in blood vessel endothelium

Question 15

What are angiotensin II receptors

Answer 15

G protein coupled receptors

Question 16

Effects of ANG II

Answer 16

1. Increased sympathetic (increased CO + BP, vasoconstriction)
2. Proximal tubule Na reabsorption
3. Thirst
4. AVP secretion, increased H20 absorption

Question 17

How does ANG II increase proximal tubule Na reabsorption

Answer 17

Stimulates an apical Na/H+ exchanger

Question 18

What do pharmaceutical companies use ACE inhibitors for

Answer 18

Treatment of hypertension

Question 19

What does natriuretic peptide (ANP) promote

Answer 19

Na+ and water excretion
Less vasopressin

Question 20

Peptide produced and secreted by specialized myocardial cells in atria

Answer 20

Atrial natriuretic peptide

Question 21

What caused release of ANP

Answer 21

Increased blood volume causes increased stretch of atria causing myocardial cells to release

Question 22

What is the ANP receptor

Answer 22

Enzymatic membrane bound receptor acting through cGMP second messenger system

Question 23

Affects of ANP in kidney

Answer 23

Relaxes afferent arterioles to increase GFR
Reduce renin release from granular cells, reduce aldosterone and ANG II
Reduce Na reabsorption

Question 24

Affects of ANP at hypothalamus

Answer 24

Reduces AVP release
Inhibit thirst

Question 25

Affects of ANP at adrenal cortex

Answer 25

Inhibits aldosterone release

Question 26

Affects of ANP at medulla

Answer 26

Acts on CVCC to decrease BP

Question 27

Why is potassium balance complicated

Answer 27

Reabsorbed and secreted

Question 28

Where is K+ reabsorbed

Answer 28

Proximal tubule and ascending limb of loop

Question 29

Where is K+ secreted

Answer 29

Distal tubule and cortical collecting duct

Question 30

At normal K+ excretion

Answer 30

Reabsorption is less than filtered

Question 31

Low K+ does what to aldosterone

Answer 31

Decreases aldosterone Reducing secretion which reduces excretion

Question 32

High K+ stimulates what

Answer 32

Aldosterone release Increases secretion and excretion

Question 33

Alterations in body K levels affects what

Answer 33

The resting membrane potential of all cells

Question 34

Increased K+ in ECF

Answer 34

Hyperkalemia Reduced efflux from cell, more K+ retained Causes hyper excitation

Question 35

Low K+ around cell

Answer 35

Hypokalemia Increased K+ leakage Hyperpolarizes cell causing larger stimulus to reach threshold

Question 36

Where is potassium balance especially important

Answer 36

Excitable tissues such as heart and skeletal muscles

Question 37

What does hypokalemia cause

Answer 37

Muscle weakness because more difficult for hyperpolarized motor neurons and muscles to fire APs

Question 38

What is effects of hyperkalemia

Answer 38

More dangerous, initially leads to hyperexcitability Eventually cells unable to repolarize and become less excitable Arythmias in heart

Question 39

What can disturbances in K+ balance result from

Answer 39

Kidney dysfunction, eating disorders, diarrhea, diuretics

Question 40

Behavioural responses are critical for

Answer 40

Restoring to normal state, when ECF volume decreases or osmolarity deviates

Question 41

What are only way to replace los water and increase Na+ content

Answer 41

Drinking water and eating salt

Question 42

What causes relief of thirst

Answer 42

Act of drinking water, water does not have to be absorbed Receptors in mouth/pharynx respond and decrease thirst and AVP release

Question 43

What stimulates thirst center in hypothalamus

Answer 43

Increase blood osmolarity, decreased blood volume, decreased blood pressure, dry mouth