Ch 40.1 Fluids Flashcards
Intracellular fluid (ICF)
Fluids within cells
60% of total body fluids
Extracellular fluid (ECF)
Fluid outside of cells
Interstitial
fluid between cells in the tissue
Intravascular
blood and plasma
Transcellular
fluid separated by epithelium
Electrolyte
An element or compound or that, when dissolved or dissociated in water or solvent, separates into ions
Cations
positively charged ion
SODIUM (NA+)
POTASSIUM (K+)
CALCIUM (CA2+)
MAGNESIUM (MG2+)
Anions
negatively charged ion
CHLORIDE (CL–)
BICARBONATE (HCO3–)
PHOSPHATE (PO43–)
Osmosis
Movement of water from an area of lesser solute concentration to one of greater concentration
Osmotic pressure
Pressure needed to counter the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high concentration
A solution with a high solute concentration: high osmotic pressure; draws water into itself
osmolality of a fluid
is the number of dissolved particles in 1 kg of water
osmotic laxatives.
These laxative salts are poorly absorbed through the intestinal lining and thus draw water into the intestinal lumen, causing an accumulation of water and softened stool. The swelling also stretches the intestine, stimulating peristalsis,
Diffusion
Movement of a solute through a semipermeable membrane from areas of higher to lower concentration; may be assisted by a channel or carrier
Active transport
Movement of ions across a concentration gradient, by means of adenosine triphosphate (ATP)
Filtration
- Movement across a membrane, under pressure, from areas of higher to lower pressure
- passive process where water moves in and out of capillaries
Hydrostatic pressure
- Force exerted by fluids within a compartment
- “fluid pressure”
- higher at arterial (35mm Hg) than venous (15mm Hg)
Edema
an accumulation of fluid in the interstitial space. Can be caused with increase of venous pressure. preventing the normal movement of water from the interstitial space into the intravascular space
Obligatory water loss
the minimum amount of fluid loss that can occur of approximately 500 mL is essential, regardless of intake. It is the amount of fluid necessary to maintain balance. This is why a person with no fluid intake will die of dehydration within a matter of days.
Sensible water loss
• refer to typical routes of excretion such as urination and defecatio
• includes water loss through typical routes of excretion such as urine and feces
-kidneys
Insensible water loss
is difficult to measure. Increases in response to changes in respiratory rate and depth. Water loss from the skin is regulated by the sympathetic nervous system, which activates sweat glands. Fever may increase insensible water loss.
GI tract is also vital in fluid regulation. . Every day, approximately 9 L of fluid is ingested or secreted into the small intestine, but only 100 mL is lost through the feces, under normal conditions.
Diarrhea can cause GI tract to become the site of a large amount of fluid loss which may impact maintaining normal fluid homeostasis.
-skin/lungs
Osmoreceptors
monitor serum blood osmotic pressure and are very sensitive to changes.
Aldosterone
- released by adrenal cortex
- with an increase in potassium, a decrease in sodium or to counteract hypovolemia as part of the renin-angiotensin-aldosterone system or RAAS
- Increases reabsorption of sodium, chloride and water. (Na, Cl, H2O)
- Aldosterone also secretion and excretion of potassium and hydrogen (K, H)
Natriuretic peptides
- ⬇blood volume.
- released from cardiac muscle when there is an increase in circulating blood volume.
- facilitate diureses by increasing sodium excretion and fluid loss.
- reduce thirst and block ADH and aldosterone release to reduce blood volume.
