Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Renal > Lecture 12: Regulation Of Na Excretion > Flashcards

Lecture 12: Regulation Of Na Excretion Flashcards

1
Q

List the components of sodium regulation

A

ECV

Sensors:
Arterial + renal BRs
cardiopulmonary receptors

Effectors:
Urinary excretion
Nerves/hormones = sympathetic division, RAAS, ADH, ANP, vasodilator PGs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is total body sodium sensed by?

A

Surrogate =

ECV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define effective circulating volume (ECV; arterial filling)

Explain how it differs from ECF

A

ECV = the part of the ECF that can activate mechanisms to bring changes in sodium excretion

It’s the part of the ECF that is in the arterial system and can be sensed by regulatory mechanisms involved in sodium homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Identify two diseases in which ECF and ECV are dissociated, explaining why total body sodium is increased in these diseases

A

HF
Nephrotic syndrome

Sensors detect decreased ECV (even though the ECF is actually increased) - sodium- retaining mechanisms get activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe effects of volume depletion on ECF, ECV and CO

A 
ECF = dec.
ECV = dec.

CO = dec.
(Loss of vol. = dec. PL)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe effect of HF on ECF, ECV and CO

A

ECF = inc.

ECV = dec.
(Less vol/stretch sensed leading to water/salt retention that will inc. ECF)

CO = dec.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are effects of nephrotic syndrome on ECF, ECV and CO

A

ECF = inc.

ECV = dec.

CO = no change or dec.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define pressure natriuresis, briefly describing the proposed mechanisms for this effect

A

Phenomenon of BP’s direct effect on sodium excretion

Mediated mainly by dec. Na reabsorption

When there is inc. Na intake (and more total body sodium), ECV inc. = inc. BP = inc. renal perfusion pressure = dec. Na reabsorption and inc. GFR = inc. sodium excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the effect of increased nerve traffic on kidney function/sodium excretion

A

Nerves and hormones speed up sodium balance and decrease impact of dietary salt on total body sodium

Dec. ECV = dec. stretch of arterial BRs = inc. symp. Tone to kidneys
+ inc. sodium reabsorption
+ inc. renin secretion
+ as a last resort: dec. GFR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe innervation of kidney

A

EXCLUSIVELY sympathetic

3 main innervated:
+ AA
+ granular cells
+ tubular epithelium

Receptor subtypes:
alpha1, alpha2, beta1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe effect of low levels of sympathetic stimulation

A

Alpha2 receptors on PT + beta on DCT get stimulated

Inc. NHE in PT
=
Inc. Na reabsorption in PT and inc. Na reabsorption in DCT via NCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe effect of intermediate levels of sympathetic stimulation

A

Beta1 receptors on granular cells stimulated

Inc. renin secretion
=
Activation of RAAS
=
Inc. Na reabsorption AND renovascular effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe effect of high levels of sympathetic stimulation

“Last resort of neural regulation”

A 
Alpha1 on AA stimulated
=
Vasoconstriction
=
Dec. RBF and GFR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe indirect/direct relationships amongst effectors of sodium homeostasis

A

ECV + arterial BRs = direct

arterial BRs + symp. Tone = indirect

Symp. Tone + sodium excretion = indirect

Symp. Tone + RAAS = direct

RAAS + sodium excretion = indirect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are hormonal regulators of Na balance and ECV?

A

Vasoconstrictors + anti-natriuretic hormones:
+ AngII
+ Aldosterone
+ Vasopressin (ADH)

Vasodilators + natriuretic hormones:
+ ANP/BNP
+ PGs
+ NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe effects of AngII on systemic circulation, renovascular, and tubules

A

Systemic circulation:
Vasoconstriction = Inc. SVR = inc. BP

Renovascular:
More vasoconstriction on EA than AA = dec. RPF & inc. GC hydraulic pressure = inc. FF & ____ effect on GFR

PT: inc. Na reabsorption via NHE

DCT/CNT/CD:
Inc. aldo and direct stimulation of NCC and ENaC = inc. Na reabsorption

17
Q

For volume depletion, what are pattern of RAAS components in the plasma?

A 
Dec. stretch on arterial and intracranial BRs from depletion
=
Inc. renin secretion
=
Inc. AngII
=
inc. aldosterone
18
Q

What are effects of PGs on kidney function?

Systemic circulation
Renovascular
Tubules

A

Counteract neurohormonal vasoconstriction

systemic circulation:
Local vasodilation = dec. SVR = dec. cardiac AF and BP

Renovascular:
Vasodilation @AA = inc. RPF + GFR

Thick AL and CD:
Dec. Na reabsorption (in humans?)

19
Q

What increases PG synthesis?

A

Neurohormonal activation:

AngII
ADH
Sympathetic stimulation

20
Q

What effect do PGs have on renin?

A

Inc. renin secretion

21
Q

What effect can NSAIDs have when there is nerurohormonal activation?

A

Dec. renal perfusion and GFR

Little effect on renal fxn under normal conditions

22
Q

Describe effect of ACEI on glomerular hemodynamics

A

ACEI = dec. synthesis of AngII = AA and EA vasodilation (EA&raquo_space; AA = dec. GC hydraulic pressure) = dec. RVR = inc. RPF

23
Q

What does vasopressin do?

A

Allows reabsorption of water in CNT/CD

24
Q

What regulates ADH secretion?

A

P(osm) and ECV

Inc. P(osm) = inc. ADH

Dec. ECV = inc. ADH

25
Q

What are non-osmotic stimuli ?

A

High levels of AngII

Severe vomiting, pain + major stress (post-op)

Significant decrease in ECF or ECV

26
Q

Describe relationship between osmotic and non-osmotic stimuli

A

Osmotic stimulus more potent vs. non-osmotic

Strong non-osmotic can OVERRIDE osmotic

27
Q

Describe effects of high levels and any levels of ADH

A

High levels = systemic circulation:
ADH = V1 vasoconstrictor = inc. SVR = inc. BP

any level = CNT/CD:
Binding to V2 receptor on principal cells = insertion of AQP2 channels on apical side = inc. water reabsorption = dec. water excretion

28
Q

What do osmoregulation and volume regulation sense?

What do they affect?

A

Osmoregulation
Sense: plasma osmolality
Effects: water excretion (via ADH) + water intake (via thirst)

Volume regulation
Sense: ECV
Effects: sodium excretion

29
Q

Describe effects of ANP/BNP on systemic circulation, renovascular effects, and tubules

A

Systemic circulation:
Vasodilation = dec. SVR = dec. cardiac AL

Renovascular:
Dilate AA + constrict EA = inc. GC hydraulic pressure, inc. RPF = inc. GFR = dec. renin secretion

CD (IMCD):
Oppose actions of aldosterone = dec. Na reabsorption

30
Q

What are NO actions in the kidneY?

A

Vasodilation and inc. GFR

Inc. Na excretion

31
Q

Describe circumstances in which it is dangerous to administer an NSAID

A

True volume depletion or low ECV

Examples: HF or cirrhosis

32
Q

What is TGF?

A

Tubuloglomerular feedback

Negative feedback system in kidney

Macula densa senses salt delivered to alter GFR in the same nephron

33
Q

Describe proposed mechanisms for TGF

A

Sense:
Macula densa cells sense NaCl via NKCC2 while cilia sense flow

Effects:
Paracrine mediators constrict/dilate AA to induce change in GFR

34
Q

What are effects on GFR of inc. NaCl delivery to macula densa?

A

Release of paracrine mediators (inc. adenosine) =
AA constriction
=
Dec. GFR

35
Q

What are effects of dec. NaCl delivery to macula densa?

A 
Release of paracrine mediators 
(Dec. Adenosine, inc. PGE2)
=
AA dilation 
=
Inc. GFR
36
Q

Explain why TGF stabilizes the function of the nephron but does not stabilize TB sodium

A

TGF autoregulates GFR in single nephrons!!!

Will affect distal nephron that shares same macula densa

37
Q

Describe glomerulotubular balance (GTB) and the proposed mechanism for it

A

Describes positive relationship between tubular fluid flow rate and reabsorption

Inc. in GFR + filtered load = inc. reabsorption of solutes (mainly PT) so that fraction of solute reabsorbed remains constant

38
Q

What is GTB mediated by?

A

Physical factors

Flow-mediated changes by microvilli on apical surface of PT

Renal (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions