ECF And ICF Fluid Compartments Flashcards
Water makes up what % of body weight
60 males
50 females
The exchange of water between ICF ECF takes place a crosse plasma membrane by
Osmosis
Diffusion
Carrier mediated transport
Largest subdivision of ECF
Are the interstitial fluid of peripheral tissue and
Plasma of circulating blood
Minor components of ECF Include
Lymph CSF Synovial fluid Serous fluids Aqueous humor Perilymph Endolymph
The greatest variation is in the ICF, between sexes because
Differences in the intracellulae water content of fat versus muscle
In clinical situations it’s customary to estimate that 2/3 of total body weight is—
And 1/3 is—
ICF
ECF
Exchange among the subdivisions of the ECF occurs primarily across —
The endothelial lining of capillaries;
Or
Travel from interstitial spaces to plasma through lymphatic vessels
The ECF ICF are called fluid compartments because
They commonly have separate sections
The principal ions in the ECF are
Sodium
Chloride
Bicarbonate HCO3-
The ICF has an abundance of
Potassium
Magnesium
Phosphate ions HPO4 2-
Large amount of negatively charged proteins
Ions can enter and leave the cell how?
Specific membrane channels and/or carrier mechanisms
The regulation of fluid balance and electrolyte balance are intertwined because
Changes in solute concentration lead to immediate changes in water distribution
4 basic principles in fluid and electrolyte balance
- All the homeostatic mechanisms that monitor and adjust the composition of body fluids respond to changes in the ECF,not in the ICF
- No receptors directly monitor fluid or electrolyte balance.
- Cells cannot move water molecules by active transport
- The body’s content of water or electrolytes will increase if dietary gains exceed losses to the environment, and will decrease if losses exceed gains
Receptors can monitor
Plasma volume and osmotic concentration
All movement of water across plasma membrane and epithelium takes place
Passively
In response to osmotic gradients
3 hormones mediate physiological adjustments to fluid balance and electrolyte balance
Antidiuretic hormone ADH
Aldosterone
Natriuretic peptides ANP and BNP
Osmoreceptors
Special cells in the hypothalamus
Monitor the osmotic concentration of the ECF
Secrete ADH; anti diuretic hormone
How much change in osmotic concentration is enough to alter osmoreceptor activity
2%
6 mOsm/L
As osmotic concentration increase
Increase of ADH secretion
2 important effects of increase of released ADH
Stimulates water conservation by kidneys, reducing urinary water loss and concentration of the urine.
It stimulates the hypothalamus thirst center, promoting the intake of fluids.
Restores plasma osmotic concentration.
Aldosterone is secreted by
Adrenal cortex
What is the major role of the aldosterone secretion
In determining the rate of Na+ absorption and K+ loss along the DCT and collecting system of the kidneys.
Higher plasma concentration of aldosterone results in
Kidneys conserve Na+ and water retention.
Then: Na, Cl, and water leave the tubular fluid.
Increases sensitivity of salt receptors in the tongue.
Aldosterone is secreted in response to
Increasing K or decreasing Na levels in blood
Or
In response to the activation of renin-angiotensin-aldosterone system
Renin release occurs in response to any of these:
A decrease in plasma volume or blood pressure at the juxtaglomerular complex of the nephron;
A decrease in the osmotic concentration of tubular fluid at the DCT;
Decreasing Na or increasing K concentrations in the renal circulation.
Natriuretic peptides
Atrial natriuretic peptides ANP
Brain natriuretic peptides BNP
Are released
By cardiac muscle cells in response to abnormal stretching of the heart walls (from increased blood pressure or blood volume)
Natriuretic peptides effect
Reduce thirst
Block release of ADH and aldosterone
The resulting diuretics decreases blood pressure and plasma volume, eliminating stretching
Fluid movement in minor components of the ECF
Back and forth across the mesothelial surfaces that line the peritoneal, pleural, and pericardial cavities, and through the synovial membranes that line joint capsules.
Water moves between blood and CSF, between the aqueous humor and vitreous humor of the eye, and between the perilymph and endolymph of the internal ear.
Water movement can take place between the ICF but under normal circumstances
the two are in osmotic equilibrium.
Exchange between plasma and the interstitial fluids is due to the relationship between
Net hydrostatic pressure and the net colloid osmotic pressure
Net hydrostatic pressure
Pushes water out of plasma and into interstitial fluid
Net colloid pressure
Tends to draw water out of the interstitial fluid and into plasma
