Physiology Renal Exam 4 (IP2): Control of Na+ and H2O Excretion I Lecture

Aldosterone is a mineralocorticoid produced in the (medulla/cortex) of the ________ gland to (increase/decrease) renal (K+/Na+/Cl-) reabsorption

cortex, adrenal, increase, Na+

aldosterone (increases/decreases) sodium reabsorption

increases

the physiological regulation of Na+ is essential for what two things?

electrolyte balance, control of blood volume

T/F: sodium is filtered, reabsorbed, and secreted

false, it is not secreted

the amount of sodium excretion is regulated by what two things

GFR, reabsorption

sodium homeostasis is potentially disturbed by changes to what two factors?

hint:

1. exercise, stress will change this factor

2. this factor can either be high or low

GFR, sodium intake

changes in GFR are compensated for by altering filtration via ________ ___________ and altering sodium reabsorption via ________ __________

tubuloglomerular feedback, glomerulotubular balance

tubuloglomerular feedback (TGF) is responsible for altering (filtration/Na+ reabsorption)

filtration

glomerulotubular balance is responsible for altering (filtration/Na+ reabsorption)

Na+ reabsorption

changes in sodium intake are compensated by altering sodium reabsorption via what hormone

aldosterone

with tubuloglomerular feedback, a reduction in GFR will (increase/decrease) sodium in the (proximal/distal) tubule which will then activate the juxtaglomerular apparatus

decrease, distal

A decrease in arterial pressure will initially (increase/decrease) GFR

decrease

A decrease in GFR will (increase/decrease) sodium in the distal tubule

decrease

a decrease in sodium within the distal tubule will be sensed by what cells present in the distal tubule

macula densa

in response to a decrease in arterial blood pressure, the macula densa cells stimulate __________ cells to (increase/decrease) the secretion of renin which causes a (increase/decrease) in (afferent/efferent) resistance

juxtaglomerular, increase, increase, efferent

An increase in renin secretion will cause an (increase/decrease) in GFR

increase

an increase in efferent resistance will (increase/decrease) GFR

increase

In response to a drop in arterial blood pressure, Macula densa cells stimulate the adrenal glad to (increase/decrease) adenosine secretion which (increases/decreases) (afferent/efferent) resistance

decrease, decreases, afferent

decreasing afferent resistance and increasing efferent resistance will (increase/decrease) GFR

increase

glomerulotubular balance occurs in the (proximal/distal) tubule

proximal

If filtered sodium increases due to increased GFR, then the amount of sodium reabsorbed (increases/decreases)

increases

T/F: glomerulotubular balance is not a self-regulated process

false, it is

glomerulotubular balance is a self regulated process driven by what two things?

GFR, starling forces

(tubuloglomerular feedback/glomerulotubular balance) has a negative feedback effect when sodium excretion is increased

glomerulotubular balance

(tubuloglomerular feedback/glomerulotubular balance) has a negative feedback effect when GFR is increased

tubuloglomerular feedback

the quantity of sodium reabsorbed is regulated by what hormone

aldosterone

maximal aldosterone = (2-3%/no) sodium is excreted

no

minimal aldosterone = (2-3%/no) sodium is excreted

2-3%

In the distal tubule, how is sodium reabsorbed on both the apical and basolateral membranes?

Hint: what kind of transporters?

basolateral: Na+/K+ ATPase

apical: Co-transport with Cl- ions (NCC)

In the late distal tubule and collecting tubule, how is sodium reabsorbed on both the apical and basolateral membranes?

Hint: what kind of transporters?

basolateral: Na+/K+ ATPase

apical: epithelial sodium channels (ENaC)

how does aldosterone increase sodium reabsorption in the late distal and collecting tubules on the basolateral membrane?

increases number and activity of Na+/K+ ATPase

how does aldosterone increase sodium reabsorption in the late distal and collecting tubules on the apical membrane?

increase number, open time, and inhibits degradation of ENaC channels

what is the name of the kinase that inhibits degradation of ENaC?

serum & glucocorticoid regulated kinase 1 (SGK1)

how does aldosterone increase the activity and number of Na+/K+ ATPase and ENaC channels?

drives gene expression by entering into the nucleus

a (increase/decrease) in plasma potassium levels will stimulate the adrenal cortex to increase aldosterone secretion

increase

why would an increase in plasma potassium levels stimulate the adrenal cortex to increase aldosterone secretion

increasing aldosterone will increase number and activity of N+/K+ ATPase on the basolateral membrane which will pump potassium out of the cell faster to lower the plasma potassium levels

a (increase/decrease) in plasma sodium levels will stimulate the adrenal cortex to increase aldosterone secretion

decrease

why would a decrease in plasma sodium levels stimulate the adrenal cortex to increase aldosterone secretion

increasing aldosterone will increase number and activity of N+/K+ ATPase on the basolateral membrane which will pump sodium out of the tubule and to the peritubular capillaries. It will also increase the activity, number, and open time for ENaC channels

a (increase/decrease) in plasma adrenocorticotropic hormone levels will stimulate the adrenal cortex to increase aldosterone secretion

increase

why would an increase in plasma adrenocorticotropic hormone levels stimulate the adrenal cortex to increase aldosterone secretion

the part of the adrenal cortex that secretes aldosterone has ACTH receptors so it will inevitably respond to ACTH by secreting aldosterone

a (increase/decrease) in plasma angiotensin II levels will stimulate the adrenal cortex to increase aldosterone secretion

increase

why would an increase in plasma angiotensin II levels stimulate the adrenal cortex to increase aldosterone secretion

angiotensin II is what stimulates the adrenal cortex to release aldosterone. it triggers the RAAS

what is considered to be the "gas pedal" for sodium reabsorption

aldosterone

A decrease in sodium intake will decrease plasma sodium levels which will (increase/decrease) aldosterone secretion causing sodium reabsorption to (increase/decrease) and sodium excretion to (increase/decrease)

increase, increase, decrease

An increase in sodium intake will increase plasma sodium levels which will (increase/decrease) aldosterone secretion causing sodium reabsorption to (increase/decrease) and sodium excretion to (increase/decrease)

decrease, decrease, increase

in a case of hemorrhage, what does aldosterone contribute?

increase sodium reabsorption and therefore water reabsorption as well