Exam 4 (Fluid & Electrolyte Balance)

Question 1

ECF

Answer 1

extracellular fluid; made of interstitial fluid + plasma + other body fluids that are outside cells

Question 2

ICF

Answer 2

intracellular fluid: inside cells (cytosol)

Question 3

Difference b/w ECF & ICF

Answer 3

-ICF contains more water
-ICF has higher concentration proteins, K+, Mg 2+, sulfate, & HPO
-ECF has higher concentration of Na+, Cl-, Ca+, & HCO3-

Question 4

Basic Principles of Regulation

Answer 4

1. All regulatory mechanisms monitor ECF, not ICF
2. Receptors monitor plasma volume & osmotic concentration as indicators of fluid & electrolyte balance
3. Cells cannot move water by active transport, only passively by osmosis (*water follows salt)

Question 5

Main Sources of Water Gains & Water Losses

Answer 5

Water Gains: from food, drinks & metabolism
Water Losses: urine, feces, exhaled air, insensible perspiration (evaporation through skin) & sensible perspiration (sweating)

Question 6

Fluid Shift

Answer 6

-If low fluid/high concentration in ECF = shift is out of cells (from ICF to ECF)
-If high fluid/low concentration in ECF = shift into cells (from ECF to ICF)
*water shifts are first response, if not enough, then hormonal regulation

H2O low in ECF = high concentration in ECF, H2O leaves ICF to ECF hypoto

Question 7

ADH

Answer 7

-Secreted by posterior the pituitary upon stimulation from osmoreceptors in hypothalamus
-Released in response to increased osmotic concentration or in presence of Angiotensin II
-Effect: water reabsorption in kidney = decrease water excretion // increase thirst

Question 8

Aldosterone

Answer 8

-Secreted by adrenal cortex
-Released in response to too much K, or not enough Na or in presence of Angiotensin 22
-Effects: Na reabsorption & K loss in DCT // Water reabsorption // Increase appetite for salt

Question 9

Angiotensin II

Answer 9

-Secreted once renin is released by kidneys
-Released in response to low BP & low blood volume
-Effects: increase ADH & Aldosterone // Increase thirst // Increase water reabsorption in kidney = decrease water excretion

Question 10

ANP/BNP

Answer 10

-Secreted by cardiac muscle
-Released in response to high BP & increased blood volume
-Effects: increase water loss in kidneys // decrease thirst // decrease ADH & Aldosterone

Question 11

Dehydration !!!

Answer 11

-Causes: profuse sweating, diarrhea &/or vomiting, inadequate drinking, some endocrine conditions, & diuretic overuse
-Result in hypertonic ECF (hypernatremia)= low blood volume & BP
-Response Mechanisms: water shift out of cells (from ICF to ECF); renin-angiotensin, ADH, aldosterone cause: increase in volume (increase thirst & decrease excretion)

Question 12

Difference b/w hypovolemia & dehydration

Answer 12

-Hypovolemia caused by hemorrhage (blood loss)
-No fluid shift occurs b/c ICF & ECF are isotonic
-Hormonal regulation occurs, but not enough if sever fluid depletion

Question 13

Overhydration !!!

Answer 13

-Causes: impaired renal function, excessive IV fluids or extreme amount of water is quickly consumed
-Results: hypotonic ECF (hyponatremia), increased blood volume and BP
-Response Mechanism: water shift into cells 9from ECF to ICF); ANP causes decrease in volume (decrease in thirst & increase in excretion)

Question 14

Difference b/w hypervolemia & overhydration

Answer 14

-Hypervolemia due to Na imbalances due to congestive heart failure, kidney or liver failure. Body retains Na & water = edema
-No fluid shift occurs, b/c ICF & ECF are isotonic
-Hormonal regulation occurs but it is not very effective

Question 15

Difference b/w Total Amount & Concentration of an Ion

Answer 15

Total Amount: of all ions (osmolarity) affects water balance (drives osmotic P)
Concentration: of individual ions are important for different cellular functions

Question 16

Sodium Imbalance & Potassium Imbalance

Answer 16

sodium imbalance more common & potassium imbalance is more dangerous

Question 17

Na Gains & Losses

Answer 17

Gains: absorb from food & drinks through GI tract
Loss: excretion by kidney & perspiration
*water follows salt

Question 18

Hypernatremia

Answer 18

high Na+ concentration in ECF
Caused: fluid loss
Detected: osmoreceptors in brain
Response: same as dehydration

Question 19

Hyponatremia

Answer 19

low Na+ concentration in ECF
Caused: over hydration or rapid loss of Na (sweat)
Detected: osmoreceptors
Response: same as over hydration

Question 20

K Gains & Losses

Answer 20

Gains: absorb from food and drink though GI tract
Loss: excretion by kidney

Question 21

Hpokalemia

Answer 21

low K+ concentration in ECF
Cause: inadequate K+ intake, certain diuretic
Results: more negative resting membrane potential = excitable cells hyper polarized & less responsive to stimuli = muscle weakness & paralysis

Question 22

Hyperkalemia

Answer 22

high K+ concentration in ECF
Cause: decrease pH of ECF, renault failure, burns
Results: more positive membrane potential = cells more likely to fire action potential; can lead to convulsion & cardiac arrhythmia

Question 23

Calcium Balance

Answer 23

PTH (parathyroid) and Vitamin D are important for balance

Question 24

Hypercalcemia

Answer 24

high Ca+ concentration in ECF
Cause: excessive PTH release from parathyroid, excessive vitamin D, bone disorder, and renal failure

Question 25

Hypocalcemia

Answer 25

low Ca+ concentration in ECF
Causes: Ca and vitamin D dietary deficiency, PTH deficiency, chronic renal failure