Compartments & Volume Flashcards
Explain the changes that occur during isotonic overhydration.
- Increase in ECF
- No change in ICF
- No change in osmolarity
Explain the changes that occur during hypotonic overhydration.
- Increased ECF
- Increased ICF
- Decreased osmolarity
Explain the changes that occur during hypertonic overhydration.
- Increased ECF
- Decreased ICF
- Increased osmolarity
Explain the changes that occur with isotonic dehydration.
- Decrease in ECF.
- No change in ICF.
- No change in osmolarity.
Explain the changes that occur with hypotonic dehydration.
- Decreased ECF
- Increased ICF
- Decreased osmolarity
Explain the changes that occur with hypertonic dehydration.
- Decreased ECF
- Decreased ICF
- Increased osmolarity
Where does free water formation occur?
In the ascending limb, because salt is able to be reabsorbed while water is trapped in the tubule.
Where does free water reabsorption occur?
In the collecting duct, because while salt is trapped in the tubule, water is free to flow out.
Is most of our water body weight intracellular or extracellular?
Intracellular (40%)
Extracellular (20%)
About what percentage of our total body weight is water?
50-70%
Explain what happens when you sweat lightly vs. sweating profusely.
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.
How does excess Na+ consumption lead to an increase in ECF volume?
Increased plasma osmolarity, increased ADH, increased water reabsorption, increased ECF
It the receptor for aldosterone intracellular or extracellular?
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.
2 primary controls of aldosterone release
- Angiotensin II
2. Increased extracellular K+
3 actions of aldosterone
- Increase Na+ reabsorption
- Increase K+ excretion
- Increase H+ excretion
3 effects of hypoaldosteronemia (Addison’s disease)
- Loss of salt (hypotensin)
- Hyperkalemia
- Acidosis
3 effects of hyperaldosteronemia
- Hypertension
- Hypokalemia
- alkalosis
2 types of hyperaldosteronemia
Primary
Secondary
In primary hyperaldosteronemia, what occurs? What happens to the levels of renin?
The adrenal glands produce too much aldosterone, which leads to hypertension, so renin release decreases.
In secondary hyperaldosteronemia, what occurs? What happens to the levels of renin?
Kind of like renal artery stenosis, body senses decreased pressure in the afferent arteriole, and renin is increased.
This is considered the anti-aldosterone, because it has the opposite effect.
Atrial natriuretic factor
What does ANP do?
Decreases Na+ reabsorption in the collecting duct
2 things that angiotensin II does
- stimulates aldosterone release
2. directly increases Na+ reabsorption in the proximal tubule
How does Na+ consumption and excretion remain in balance even with loss of nephrons?
Increase fractional excretion
How do creatinine and urea formation and excretion remain in balance even with loss of nephrons?
Increase plasma concentration of creatinine
Reduced tissue oxygenation leads to the release of this
erythropoietin
Blood volume equation
Blood volume = plasma volume/(1-hct)
Interstitial fluid volume equation
IFV = EFV - PV
Why would injection of ANP increase GFR?
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.
In Addison’s disease, there is a low circulating level of (blank) which leads to (blank) Na+ levels, and (blank) K+ levels.
Aldosterone
Low
High
Would high aldosterone levels lead to pitting edema?
No! It will tend to increase blood pressure, but there are compensatory mechanisms in place to avoid edema, such as ANP release
Increased Na+ plasma concentration ALONG with decreased urine osmolarity (hypotonic urine) could be indicative of what disease?
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.
SIADH is associated with REDUCED or ENHANCED Na+ reabsorption?
Too much ADH, so reduced Na+ reabsorption.
If the urine to plasma concentration ratio is 2/1 is the urine hypotonic or hypertonic?
Hypertonic
Equation for intracellular fluid volume
IFV = Total body water - EFV
