Compartments & Volume

Question 1

Explain the changes that occur during isotonic overhydration.

Answer 1

1. Increase in ECF
2. No change in ICF
3. No change in osmolarity

Question 2

Explain the changes that occur during hypotonic overhydration.

Answer 2

1. Increased ECF
2. Increased ICF
3. Decreased osmolarity

Question 3

Explain the changes that occur during hypertonic overhydration.

Answer 3

1. Increased ECF
2. Decreased ICF
3. Increased osmolarity

Question 4

Explain the changes that occur with isotonic dehydration.

Answer 4

1. Decrease in ECF.
2. No change in ICF.
3. No change in osmolarity.

Question 5

Explain the changes that occur with hypotonic dehydration.

Answer 5

1. Decreased ECF
2. Increased ICF
3. Decreased osmolarity

Question 6

Explain the changes that occur with hypertonic dehydration.

Answer 6

1. Decreased ECF
2. Decreased ICF
3. Increased osmolarity

Question 7

Where does free water formation occur?

Answer 7

In the ascending limb, because salt is able to be reabsorbed while water is trapped in the tubule.

Question 8

Where does free water reabsorption occur?

Answer 8

In the collecting duct, because while salt is trapped in the tubule, water is free to flow out.

Question 9

Is most of our water body weight intracellular or extracellular?

Answer 9

Intracellular (40%)

Extracellular (20%)

Question 10

About what percentage of our total body weight is water?

Answer 10

50-70%

Question 11

Explain what happens when you sweat lightly vs. sweating profusely.

Answer 11

When you sweat lightly, there is time for reabsorption of salt, so your sweat will be more hypotonic. When you sweat profusely, there is less time for reabsorption, so sweat will be more hypertonic.

Question 12

How does excess Na+ consumption lead to an increase in ECF volume?

Answer 12

Increased plasma osmolarity, increased ADH, increased water reabsorption, increased ECF

Question 13

It the receptor for aldosterone intracellular or extracellular?

Answer 13

Intracellular! Aldosterone binds to its receptor and makes more Na+ channels to increase Na+ conductance. It also stimulates the mitochondria to make more ATP which can export Na+ back into the body.

Question 14

2 primary controls of aldosterone release

Answer 14

1. Angiotensin II

2. Increased extracellular K+

Question 15

3 actions of aldosterone

Answer 15

1. Increase Na+ reabsorption
2. Increase K+ excretion
3. Increase H+ excretion

Question 16

3 effects of hypoaldosteronemia (Addison’s disease)

Answer 16

1. Loss of salt (hypotensin)
2. Hyperkalemia
3. Acidosis

Question 17

3 effects of hyperaldosteronemia

Answer 17

1. Hypertension
2. Hypokalemia
3. alkalosis

Question 18

2 types of hyperaldosteronemia

Answer 18

Primary

Secondary

Question 19

In primary hyperaldosteronemia, what occurs? What happens to the levels of renin?

Answer 19

The adrenal glands produce too much aldosterone, which leads to hypertension, so renin release decreases.

Question 20

In secondary hyperaldosteronemia, what occurs? What happens to the levels of renin?

Answer 20

Kind of like renal artery stenosis, body senses decreased pressure in the afferent arteriole, and renin is increased.

Question 21

This is considered the anti-aldosterone, because it has the opposite effect.

Answer 21

Atrial natriuretic factor

Question 22

What does ANP do?

Answer 22

Decreases Na+ reabsorption in the collecting duct

Question 23

2 things that angiotensin II does

Answer 23

1. stimulates aldosterone release

2. directly increases Na+ reabsorption in the proximal tubule

Question 24

How does Na+ consumption and excretion remain in balance even with loss of nephrons?

Answer 24

Increase fractional excretion

Question 25

How do creatinine and urea formation and excretion remain in balance even with loss of nephrons?

Answer 25

Increase plasma concentration of creatinine

Question 26

Reduced tissue oxygenation leads to the release of this

Answer 26

erythropoietin

Question 27

Blood volume equation

Answer 27

Blood volume = plasma volume/(1-hct)

Question 28

Interstitial fluid volume equation

Answer 28

IFV = EFV - PV

Question 29

Why would injection of ANP increase GFR?

Answer 29

In a condition in which ANP is administered, the blood volume is likely high. So, this protein acts to enhance sodium excretion. One way ANP does this is by relaxing the afferent arteriole and contracting the efferent leading to an increase in GFR. An increase in GFR also tends to enhance sodium excretion.

Question 30

In Addison’s disease, there is a low circulating level of (blank) which leads to (blank) Na+ levels, and (blank) K+ levels.

Answer 30

Aldosterone
Low
High

Question 31

Would high aldosterone levels lead to pitting edema?

Answer 31

No! It will tend to increase blood pressure, but there are compensatory mechanisms in place to avoid edema, such as ANP release

Question 32

Increased Na+ plasma concentration ALONG with decreased urine osmolarity (hypotonic urine) could be indicative of what disease?

Answer 32

Diabetes insipidus. Lack of ADH, so water is being trapped in the tubule, creating a dilute urine. Plasma osmolarity will increase if the water is not being replaced by drinking.

Question 33

SIADH is associated with REDUCED or ENHANCED Na+ reabsorption?

Answer 33

Too much ADH, so reduced Na+ reabsorption.

Question 34

If the urine to plasma concentration ratio is 2/1 is the urine hypotonic or hypertonic?

Answer 34

Hypertonic

Question 35

Equation for intracellular fluid volume

Answer 35

IFV = Total body water - EFV