Exam 4: Regulation of Na, Osmolarity, and ECF

Question 1

What does unregulated or insensible fluid loss come from?

Answer 1

Sweat
Stool
Respiratory

Question 2

What does regulated fluid loss come from?

Answer 2

Renal (urine)

Question 3

What does unregulated or insensible electrolyte loss come from?

Answer 3

Sweat

Stool

Question 4

What does regulated electrolyte loss come from?

Answer 4

Renal

Question 5

When does water diuresis in a normally hydrated person occur?

Answer 5

After ingestion of 1 L H2O

Question 6

What does excessive water consumption have a little change in?

Answer 6

Plasma mOsm

Urine electrolyte concentration

Question 7

What does excessive water consumption have a big change in?

Answer 7

Urine mOsm

Urine production

Question 8

What is water consumption primarily regulated by?

Answer 8

ADH

Question 9

What is very efficient at absorbing water?

Answer 9

GI tract

Question 10

What is the formation of dilute urine?

Answer 10

Ingest a large amount of electrolyte free water in excess of needs
Continue to reabsorb electrolytes
Decrease reabsorption of H2O
Decrease ADH release

Question 11

What is the ability to form concentrated urine dependent on?

Answer 11

Antidiuretic hormone

Renal medullary hypertonicity

Question 12

What is the formation of concentrated urine?

Answer 12

Continue to reabsorb electrolytes
Increase reabsorption of H2O
Increase ADH release

Question 13

How is the renal medullary tonicity created and maintained?

Answer 13

The counter-current multiplier mechanism

Question 14

Describe parallel current flow transfer

Answer 14

Diffusion constant
Time/flow ratio
Once equilibrium established–no further exchange
Less transfer that counter current flow

Question 15

Describe counter current flow transfer

Answer 15

Diffusion constant
Time/flow ratio
But overall greater transfer than parallel flow–utilizes the whole contract area

Question 16

What is involved in the regulation of ADH?

Answer 16

Na
Blood pressure
Thirst control
Alcohol
α2-agonist

Question 17

Which has a greater impact on ADH secretion and thirst stimulation, osmolarity or pressure/volume?

Answer 17

Osmolarity

Question 18

What does blood loss result in?

Answer 18

Loss of fluid and Na equally

Question 19

What kind of fluid is horse sweat?

Answer 19

Isotonic

Question 20

What are local renal mechanisms of ECF volume regulation?

Answer 20

Changes in GFR
Changes in tubular reabsorption
Changes in tubular secretion
Changes in hormones

Question 21

What are systemic mechanisms of ECF volume regulation?

Answer 21

Changes in hormones
Changes in sympathetic activity
Changes in blood pressure
Changes in blood composition

Question 22

What does angiotensin do?

Answer 22

Stimulates aldosterone
Constricts efferent arterioles
Directly increases sodium reabsorption
Increases systemic BP

Question 23

What does aldosterone do?

Answer 23

Stimulate Na reabsorption
H2O tends to follow
Complete lack of results in relying only on pressure natriuresis, requires close management

Question 24

What does ADH do?

Answer 24

Promotes water retention

Question 25

What does ANP do?

Answer 25

It blocks angiotensin, aldosterone, and ADH