UR3 (pt. 2)

series of events if I have LOW Na

1. Detected by baroreceptors, macula dense cells, aff. art

2. renin released (jG cells/granular cells)

3. renin: angiotensinogen → angiotensin 1

4. ACE: angiotensin 1 → angiotensin 2

5. AT PCT - increase Na reabsorption

at PCT, how does Na reabsorption get increased via what transporters?

1. Na/H antiporter

2. Na/K ATPase

where is angiotensin 2 produced?

PCT

What does RAAS do to GFR?

decreases GFR

Because RAAS decreases GFR, what’s result of eff. aff. arts and mesengial cells being contracted?

• BOTH aff and eff arts contract: more time to reabsorb Na in tubule

• Mesangial cells contract: decreased SA for glom to filter

What contracts to decrease GFR?

• aff art

• mesengial cells

What is aldosterone formed by?

adrenal cortex (in adrenal gland)

What is aldosterone stimmed by, and what’s the result?

stimmed:

• angiotensin 2

• increased K lvls

• ACTH (adrenal corticotropin hormone)

causes:

• increased Na absorption

• increased K secretion

What does adrenal corticotropin hormone (ACTH) stimulate?

Release of aldosterone

What type of hormone is aldosterone?

Steroid hormone

Can aldosterone enter cell?

YES - steroid hormone. receptors inside cell

Why can excessive aldosterone secretion be an issue?

• it promotes increased K, which makes resting membrane potential not as ‘-’ and can cause Na channels not to work

What does aldosterone promote?

Reabsorb Na and secrete K

If my kidneys are failing to reabsorb Na, what part of kidney has been disrupted?

(hint: hormone)

Adrenal cortex failed (aldosterone)

What part of nephron does aldosterone work at?

DCT and CD

T or F: aldosterone can enter cell

TRUE! it is a steroid hormone

on there DCT and CD, what transporters does aldosterone increase activity of?

• Na and K channels in luminal membrane

• Na/K ATPase

Where does aldosterone open channels?

on luminal membrane; Na reabsorbed, K excreted

What does ANP stand for?

Atrial Natriuretic Peptide

What is ANP formed by, what causes release? what’s result?

formed by: cardiac atrial cells

release cause: high BP from high Na lvls

result: atrial stretch receptors sense high BP,

• decrease Na reabsorption

If atrial stretch receptors sense ___, they decrease __ reabsorption

if sense high BP, decrease Na reabsorption

ANP: 2 funcs:

1. Inhibits:

• aldosterone secretion

• Na channels in CD

2. Dilates aff. art.

what inhibits aldosterone secretion?

ANP

what ions does ANP inhibit from being absorbed?

Na. It also inhibits secretion of K (bc aldosterone)

Where on nephron does ANP inhibit Na channels?

CD