M1 Physio: Regulation Of Body Fluids: Na+ And Water

Front 1

True or False:
Sodium body concentration is a major determinant of ECF volume.

Back 1

FALSE. Sodium body CONTENT, not concentration!!
p. 506

Front 2

Body water content is the major determinant of body fluid ________.

Back 2

osmolarity
p. 506

Front 3

Why does the sodium content of the body determine ECF volume?

Back 3

1. sodium and accompanying ions are major solutes of ECF and most of the sodium in the body is in the ECF
2. When solute moves, water follows.
THUS, the amount of sodium in ECF determines the amount of water in ECF which is the ECF volume.
p. 506

Front 4

What is "positive sodium balance"?

Back 4

Plasma volume is part of ECF volume. Thus, ECF Na+ content determines ECF volume, which determines plasma volume and blood volume, which determines arterial pressure. Positive sodium balance is an INCREASE in Na+ content that causes an increase in ECF volume, blood volume and usually increase in arterial pressure. p. 506

Front 5

What is "negative sodium balance"?

Back 5

Plasma volume is part of ECF volume. Thus, ECF Na+ content determines ECF volume, which determines plasma volume and blood volume, which determines arterial pressure. Negative sodium balance is an DECREASE in Na+ content that causes a decrease in ECF volume, blood volume and usually decrease in arterial pressure. p. 506

Front 6

If a person abruptly increases their Na+ and water intake, initially, Na+ intake > Na+ excretion by kidneys, thus the person is in:
A. negative sodium balance
B. positive sodium balance
C. sodium balance

Back 6

B. positive sodium balance

After several days, the kidneys detect the increased ECF volme and initiates mechanism that cause excretion of the extra sodium. During this compensatory period, the kidneys excrete more sodium than is being ingested and the person loses weight, reflecting hte decrease in ECF volume.
p. 507

Front 7

A person having diarrhea will exhibit __________.
A. negative sodium balance
B. positive sodium balance
C. sodium balance

Back 7

A. negative sodium balance
After several days, the kidneys detect the decrease in ECF volume and initiate mechs to decrease Na+ excretion by kidneys until Na+ balance is restored.
p. 507-8

Front 8

True or False:
The body detects changes in sodium content by detecting changes in ECF volume and then makes appropriate adjustments in sodium excretion to bring sodium content back to normal.

Back 8

TRUE. (Think of positive/negative sodium balance!) p. 508

Front 9

The body detects changes in sodium content by....

Back 9

detecting changes in ECF volume! Think of positive/ negative sodium balance! p. 508

Front 10

What is EABV?

Back 10

Effective arterial blood volume, or the "functional" arterial blood volume which determines tissue perfusion. Usually changes in EABV coincide with parallel changes in ECF volume but there are important situations where ECF volume is drastically INCREASED and EABV is decreased- as in congestive heart failure where excess ECF volume is located in the ISF (edema) and not in circulation. p. 508

Front 11

List the four mechanisms for regulating sodium balance (and thus ECF volume).

Back 11

1. Renin-AngiotensinII-Aldosterone system (RAA)
2. Sympathetic nervous system
3. Naturiuretic peptides (ANP, BNP, Urodilatin)
4. ADH p. 508

Front 12

Diagram the RAA system.

Back 12

Front 13

What does Renin do?
A. Angiotensinogen --> Angiotensin I
B. Angiotensin I --> Angiotensin II
C. Angiotensin II --> Aldosterone

Back 13

A. Angiotensinogen --> Angiotensin I
p. 509

Front 14

What causes renin to be released?

Back 14

decreased: ECF volume, EABV, arterial pressure, and renal perfusion pressure
p. 509

Front 15

What does angiotensin II do? (2)

Back 15

1) Increases production and secretion of aldosterone (which increases sodium reabsorption, which increases BV which increase arterial pressure towards normal
2) vasoconstriction, which increases TPR which increases arterial pressure towards normal
p. 509

Front 16

Where does angiotensin converting enzyme (ACE) act?

Back 16

Primarily in the lung
p. 509

Front 17

What does aldosterone do?

Back 17

Aldosterone increases sodium reabosorption and thus increases blood volume and increases arterial pressure towards normal.
p. 509

Front 18

______ is the major sodium regulating hormone. It acts on the principal cells of late distal tubule and collecting duct to induce synthesis of sodium channels thereby increasing sodium reabsorption , ECF volume, BV and arterial pressure.
A. ADH
B. Aldosterone
C. Angiotensin II
D. Renin

Back 18

B. Aldosterone

p. 509

Front 19

Which of the following does not belong regarding renin secretion?
A. Decreased perfusion pressure
B. Increased distal delivery of sodium
C. Increased sympathetics
D. Prostaglandins

Back 19

A. Decreased perfusion pressure
C. Increased sympathetics
D. Prostaglandins ALL stimulate renin secretion but B. Increased distal delivery of sodium inhibits it! p. 510

Front 20

True or False:
ANP inhibits renin secretion.

Back 20

True. Renin ultimately increase sodium reabsorption. ANP works to ultimately excrete MORE sodium!
p. 510

Front 21

_____ has the opposite effect to the RAA system and activated sympathetic system with regards to regulation of sodium content in the body.
A. ADH
B. ANP

Back 21

B. ANP
p. 510

Front 22

Name one thing that stimulates angiotensin II secretion and one thing that inhibits angiotensin II secretion.

Back 22

Stimulates: Increased renin
Inhibits: ACE inhibitors
p. 510

Front 23

What do the following do to renin secretion (stimulate/ inhibit)?
A. decreased perfusion pressure
B. decreased sympathetics
C. decreased distal delivery of sodium
D. ANP
E. prostaglandins

Back 23

A, C, E = stimulate
B, D = inhibit
p. 510

Front 24

What do the following do to angiotensin II secretion (stimulate/inhibit)?
A. increased renin
B. ACE inhibitors

Back 24

A. increased renin = stimulation
B. ACE inhibitors = inhibition
p. 510

Front 25

What do the following do to Aldosterone secretion (stimulate / inhibit)?
A. Increased angiotensin II
B. Decreased arterial pressure via RAA
C. hyperkalemia

Back 25

all stimulate
p. 510

Front 26

Regarding the sympathetic nervous system response to sodium content regulation, what happens when the carotid sinus baroreceptors sense a decreased body sodium content, ECF volume and arterial pressure?

Back 26

Sympathetic activation. Has two effects: 1. constriction of afferent arterioles (thus decreasing GFR), 2. stimulation of Na+ reabsorption in proximal tubule
Together these cause decreased sodium excretion and help restore body sodium content, ECF volume, and arterial pressure back to normal. p. 511

Front 27

Regarding the sympathetic nervous system response to sodium content regulation, what happens when the carotid sinus baroreceptors sense an increased body sodium content, ECF volume and arterial pressure?

Back 27

There is inhibition of sympathetics leading to dilation of the afferent arterioles (increased GFR) and also decreased sodium reabsorption leading to increased sodium excretion thus decreasing body sodium content , ECF volume, and arterial pressure back towards normal. p. 511

Front 28

List the natriuretic hormones and what do they do?
A. Increase sodium reabsorption
B. Increase water reabsorption
C. Increase sodium excretion
D. Increase water excretion

Back 28

Natriuretic hormones: ANP, BNP, urodilatin. All of them C. Increase sodium excretion
p. 511

Front 29

How are natriuretic hormones different from the RAA system and activated sympathetics system? (2)

Back 29

RAA and activated sympathetics system works to reabsorb sodium but natriuretic hormones work to excrete sodium. Also, natriuretic hormones (or at least ANP) responds to changes in blood volume pressure on the VENOUS side as supposed to the arterial side like the other two. p. 511

Front 30

What do the following do to ANP secretion (stimulate/ inhibit)?
A. increased ECF volume
B. Increased atrial pressure

Back 30

Both: stimulate
p. 511

Front 31

What do the following do to ANP secretion (stimulate / inhibit)?
A. Decreased ECF volume
B. decreased atrial pressure

Back 31

Both : inhibit
p. 511

Front 32

Where is each natriuretic hormone released?
A. ANP
B. BNP
C. Urodilatin

Back 32

A. ANP = atria, in response to stretch
B. BNP = ventricles, in response to stretch
C. Urodilatin = distal nephron p. 511

Front 33

True or False:
BNP is structurally related to ANP and its actions are the same but stronger.

Back 33

TRUE. BNP is used clinically to produce a large increase in sodium excretion in order to reduce ECF volume in heart failure cases!
p. 511

Front 34

Urodilatin is structurally related to ______ and is secreted by the distal nephron. What does it cause?

Back 34

ANP, causes local inhibition of sodium reabsorption leading to increased sodium excretion.
p. 511

Front 35

What does antidiuretic hormone (ADH) do?
A. Increases sodium reabsorption
B. Increases water reabsorption
C. Decreases sodium reabsorption
D. Decreases water reabsorption

Back 35

B. Increases water reabsorption
p. 511

Front 36

True or False:
One stimulus for ADH secretion is hypovolemia.

Back 36

TRUE. Hypovolemia is low blood volume. ADH, water reabsorption, kicks in!
p. 511

Front 37

True or False:
Hypovolemia turns on both the RAA and ADH secretion pathways.

Back 37

TRUE. The activated RAA leads to increased sodium reabsorption and increased ECF sodium content and eventual increase in BV, etc. etc. The increased ADH leads to increased water reabsorption and increased body water.
p. 511

Front 38

What is the normal body fluid osmolartiy value?

Back 38

~ 290 mOsm / L
p. 512

Front 39

In order to estimate plasma osmolarity...
A. what is the "quick n dirty" way
B. what is the calculating way

Back 39

A. quick= 2 * [Na+]
B. accurate = 2 * [Na+] + glucose/18 + BUN / 2.8
p. 512

Front 40

The body fluid osmolarity is kept constant by adjusting body _____ content rather than by adjusting body _____ content.

Back 40

adjusting body water content rather than adjusting body solute content
p. 512

Front 41

When body fluid osmolarity rises by ___% there is immediate stimulation of thirst and drinking behavior due to osmoreceptors in the [ hypothalamus / pituitary ] that detect the increase in osmolarity.

Back 41

1%, hypothalamus
p. 513

Front 42

ADH is also called _________.

Back 42

vasopressin
p. 513

Front 43

Where is ADH synthesized and stored?

Back 43

synthesized in hypothalamus neurons; stored and released from posterior pituitary
p. 513

Front 44

What are stimuli for ADH secretion (both osmotic and non-osmotic)?

Back 44

osmotic: increase in plasma osmolarity of as little as 1%
non-osmotic: blood volume decrease by 10%, pain, nausea, angiotensin II, hypoglycemia, nicotine, optiates. Inhibitors of ADH secretion are ethanol and ANP. p. 513-4

Front 45

True or False:
The response of ADH to hypovolemia is more sensitive than the response to increased osmolarity and when evoked, it is more powerful and will override the response to osmolarity.

Back 45

FALSE. Hypovolemia response is LESS SENSITIVE (10%) in comparison to osmolarity (1%). But it is true that the response to hypovolemia , if evoked, is more powerful and will override the osmolarity response. p. 514

Front 46

What would the following do to ADH secretion (stimulate / inhibit)?
A. Increased plasma osmolarity
B. Hypovolemia
C. ANP
D. Ethanol
E. Nausea

Back 46

A. Increased plasma osmolarity
B. Hypovolemia
E. Nausea
ALL stimulate

C. ANP
D. Ethanol both inhibit
p. 514

Front 47

What do the following do to ADH secretion (stimulate / inhibit)?
A. Increased plasma osmolarity
B. Hypervolemia
C. ANP
D. pain

Back 47

A. Increased plasma osmolarity
D. pain
both STIMULATE

B. Hypervolemia
C. ANP
both INHIBIT
p. 514

Front 48

ADH has two major actions. Name em.

Back 48

1. Increased water permeability in principle cells of late distal tubule and collecting ducts via insertion of water channels in the luminal membrane. V2 receptor, cAMP. Leads to increase in water permeability and reabsorption.
2. contraction of vascular smooth muscle. blood vessel receptor, V1, IP3/Ca2+ mechanism. Leads to increased TPR and arterial pressure. p. 515