Body fluid compartments (intra and extracellular fluids) Flashcards
Most important means by which body maintains a balance between intake and output is by ……..
controlling the rates at which the kidneys excrete these substances.
plasma and interstitial (extracellular) composition
Highly permeable capillary membrane
Protein level > in plasma because of low membrane permeability
Na+, Cl- and HCO3-
Intracellular fluid composition
Separated by cell membrane
Highly permeable to water not electrolytes (semi-permeable)
K+, Mg+, proteins, and PO4+
Gibbs Donnan Equilibrium
2 solutions containing ions are separated by membrane that is permeable to some of the ions but not to others –> electrochemical equilibrium is established
The principle of conservation of mass:
total mass of a substance after dispersion in the fluid compartment will be the same as the total mass injected into the compartment.
Distribution of fluid between intracellular & extracellular compartments determined by……
osmotic effect of small solutes.
Electrolytes or small ions (i.e.: sodium & chloride) determine distribution of…..
fluids across the semi-permeable cell membrane
______ ______ cause fluids to shift between compartments
Osmotic factors
Rate of diffusion of water is called _____.
Osmosis
_______ refers to the # of particles in solution rather than molar concentration
Osmole
1 mole of NaCl –> dissolve into solvent (1 L) –> Concentration of ……
2 osm/L solution (Na <—> Cl)
Osmolality:
Osmoles / kg of water
Osmolarity
Osmoles / liter of solution
_______ _______ refers to the amount of pressure required to prevent osmosis.
Pressure applied in ______ direction of osmosis
osmotic pressure
opposite
Osmotic pressure of a solution is ________ to the concentration of osmotically active particles
proportional
1 mOsm gradient change = ________ mmHg. osmotic pressure
19.3mmHg
Interstitial Fluid & Plasma: _____% due to ____ and ____ ions.
80% due to sodium and chloride
Intracellular Fluid: ____% due to ______ ions
50% due to potassium
Total osmolarity of each compartment:
300 mOsm/L
Conditions of HYPONATREMIA:
Diarrhea & Vomiting
Diuretic abuse
Addison’s Disease
Excess water retention (ADH)
Conditions of HYPERNATREMIA:
Lack of ADH
Diabetes insipidus
Dehydration
Aldosterone secretion
If plasma sodium concentration rapidly falls below ____ to _____ mmol/L, brain swelling may lead to seizures, coma, permanent brain damage, and death.
115 to 120 mmol/L
Because the skull is rigid, the brain cannot increase its volume by more than about ___percent without it being forced down the neck(herniation),which can lead to permanent brain injury and death.
10
Primary loss of water from the extracellular fluid results in_______ and _______/
hypernatremia and dehydration
DI
Excessive secretion of the sodium-retaining hormone ________can cause a mild degree of hypernatremia and overhydration.
aldosterone
Intracellular edema can occur in certain conditions:
Inflammation has a direct effect on increasing cell membrane permeability
Depression of cellular metabolic function
Lack of nutrition to the cells
Decreased blood flow: reduced oxygen & nutrient supply
Ionic pumps of cell membrane require oxidative metabolism (ATP) to remove intracellular sodium
Two general causes of extracellular edema:
- Abnormal leakage from plasma
- Lymphatic failure to return fluids to blood
Abnormal leakage from plasma: (3)
Excessive capillary filtration rate
Filtration dependant on permeability & surface area of capillary
Starling factors: hydrostatic pressure & colloid osmotic pressure
Abnormal leakage from plasma: 3 Causes
Increased capillary filtration coefficient
Increased capillary hydrostatic pressure
Decreased plasma colloid osmotic pressure
Lymphatic failure to return fluids to blood: (3)
Lymphatic blockage preventing return of proteins to plasma
Increased interstitial colloid osmotic pressure
Cancer, surgery, infection (filaria nematodes)
Causes of Extracellular Edema:
- Increased capillary pressure
- Decreased plasma protein
- Increased capillary permeability
- Blockage of lymph return
Edema caused by HF:
_____ _____ to the kidneys is reduced and this reduced blood flow stimulates secretion of_____, causing increased formation of _______ and increased secretion of ________ both of which cause additional salt and water retention by the kidneys.
Blood flow
Renin
angiotensin II
aldosterone
Safety Factors That Prevent Edema:
- The safety factor caused by low tissue compliance in the negative pressure range is about 3 mm Hg.
- The safety factor caused by increased lymph flow is about 7 mm Hg.
- Wash down” of interstitial fluid proteins (as lymphatic flow increases proteins are washed away)
Renal Blood flow =
22% of cardiac output (1100ml/min
Renal blood flow in order =
Renal artery —-> segmental arteries —-> interlobar arteries —–> arcuate arteries interlobular arteries —-> afferent arterioles ——> glomerular capillaries
“RSI AIA”
Highest metabolism is in the Renal ______.
Cortex
Describe Cortical Nephrons:
Short loops of Henle, extend to outer medulla
Outnumber juxtamedullary nephrons ~7:1
Describe Juxtamedullary Nephrons:
Extend deep into medulla with long loops of Henle
Play a big role in concentrating urine
Just a few, deeper and into medulla
