Fluid and Electrolyte Imbalance

Question 1

Hydrostatic Pressure

Answer 1

arterial end of capillary
- Hydrostatic pressure higher than oncotic pressure —> fluid pushed into interstitial space
- Interstitial hydrostatic pressure has small negative value = fluid moving from capillary to tissue

Question 2

Oncotic Pressure

Answer 2

venous end of capillary
- More fluid in interstitial space = plasma proteins left behind = higher capillary osmotic pressure that pulls fluid from interstitial space back into vessel
- Some particles (glucose and electrolytes) move from vessel into interstitial space = interstitial colloidal osmotic pressure
- Pulls small amount of fluid into interstitial space

Question 3

Increased Capillary Hydrostatic Pressure

Answer 3

Cause higher amount of fluid leaving capillary
- Hydrostatic pressure remains high in venous end = fluid continuing leaving capillary

Causative Factors: Increased fluid pressure - hypertensions, increased in fluid volume (i.e sodium and water retention)
- Back up of blood flow - DVT, thromboembolism

Question 4

Decreased Capillary Colloidal Osmotic Pressure

Answer 4

lacking pull of fluids back into capillaries at venous end

Causative Factors: Albumin: most prevalent colloid or solid in plasma —> any decrease albumin = decrease COP
- Liver disease, burns, malnutrition, excessive wound drainage

Question 5

Increased Interstitial Colloidal Osmotic Pressure

Answer 5

solutes escape vessel into interstitial fluid = fluid taken with that will be held in interstitial space

Causative Factors: Leaky capillaries —> cap permeability increases w/ chemical mediators of inflammation and some medications

Question 6

Increased Tissue Hydrostatic Pressure

Answer 6

lymphatic obstructed = excess fluid not being removed
- Complicated by increased tissue oncotic pressure = continuous pull from vessel

Causative Factors: lymphedema, Liver disease or physical obstruction due to surgery

Question 7

Third Spacing

Answer 7

fluid trapped in transcellular compartments

Transcellular Compartments: small subdivision of extra-cellular fluid compartment
- Joint spaces, pericardial and pleural cavities, peritoneum, ocular fluid

Question 8

Fluid Balancing Receptors

Answer 8

baroreceptors and osmoreceptors

Question 8

Baroreceptors

Answer 8

sensors in blood vessels walls and kidneys
Measure stretch in vessel walls produced by blood volume and pressure

Question 9

Osmotic Receptors

Answer 9

in hypothalamus
- Keep track of osmolality (concentration) of blood
- Sodium is active particle in blood

Question 10

Mechanisms of fluid balance

Answer 10

thirst, ADH, sympathetic nervous system, RAAS, natriuretic peptide

Question 11

Those at risk of fluid imbalance

Answer 11

infants, elderly, obese, immunocompromised