What are the four major cations found in the body?
- Sodium (Na+)
- Potassium (K+)
- Calcium (Ca++)
- Magnesium (Mg+++)
What are the three major anions found in the body?
- Chloride (Cl-)
- Bicarbonate (NCO---)
- Phosphate (PO4---)
Where can you find extracellular fluid (ECF) in the body?
- Spinal fluid
- Interstitial fluid
- Cerebral fluid
What substance moves freely in order to equalize solutes across a semi-permeable membrane?
(Solutes MAY move through a permeable membrane, but water moves through a semi-permeable one. This is why cells will shrink or swell when equalizing solutes on either side of the cell membrane.)
What hormonal factors affect thirst?
- Pituitary gland (secretes ADH into bloodstream)
- Adrenal glands (secretes aldosterone, cortisol, epinepherine, norepinephrine)
- Kidneys (RAA system)
- Hypothalamus (produces ADH)
- Thyroid (produces T3 and T3 which affect cardiac output)
- Heart (produces ANP - atrial natriuretic peptides)
How is the pituitary gland involved in fluid balance?
It secretes ADH (anti-diuretic hormone). This conserves water in the bloodstream. ADH causes renal cells to reabsorb water from the renal tubules, and back into the bloodstream.
How are the adrenal glands involved in fluid balance?
- They secrete:
- aldosterone - (affects kidneys) causes resorption of Sodium and water from renal tubes
What releases aldosterone, what triggers it, and what is its function on fluid balance?
- The adrenal glands release aldosterone
- It is triggered by the presence of angiotensin II
- and it causes the kidneys to resorb Sodium (and water follows) into the bloodstream
(Increases blood volume/ increases blood pressure)
What releases ANP, what triggers it, and what is its function in fluid balance?
- ANP comes from the atrial valve in the heart (atrial natriuretic peptide)
- High blood pressure/volume triggers its release
- it affects the kidneys by dilating the afferent artierioles, which increases the filtration rate, causing a loss of fluid in the urine
- it also blocks the release of resin, providing a negative feedback to the RAAS system
(overall effect is to REDUCE blood volume and blood pressure)
What releases ACE, what triggers it, and what is its function in fluid balance?
- ACE is released by the lungs and also the kidneys (but mostly the lungs)
- It is released as a matter of course
- It converts available Angiotensin I to Angiotensin II
(which then causes an increase in blood volume)
What releases renin, what triggers it, and what is its function in fluid balance?
- Renin is released by the kidneys
- When the kidneys detect a decrease in perfusion (low blood volume or pressure)
- It starts the chain reaction of converting angioteninogen (free floating from liver) to angiotensin I
(which eventually will increase blood volume/pressure)