Term
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Definition
| Daily balance between amount of water gained & amount of water lost to environment |
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Term
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Definition
| ions released through dissociation of inorganic compounds, conduct electrical current in solution |
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Term
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Definition
| Balances production and loss of hydrogen ions |
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Term
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Definition
| diffusion of water from high to low concentration |
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Term
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Definition
| movement of solutes from high to low concentration |
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Term
| Basic concepts in regulation of fluids and electrolytes |
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Definition
1. All homeostatic mechanisms that monitor & adjust body fluid composition respond to changes in ECF, not in ICF
2. No receptors directly monitor fluid or electrolyte balance
3. Cells cannot move water molecules by active transport
4. Body’s water or electrolyte content will rise if dietary gains exceed environmental losses, and will fall if losses exceed gains |
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Term
| Antidiuretic hormone (ADH) |
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Definition
Stimulates water conservation at kidneys
Reducing urinary water loss, concentrating urine
Stimulates thirst center, promoting fluid intake |
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Term
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Definition
Secreted by suprarenal cortex in response to
Rising K+ or falling Na+ levels in blood
Activation of renin–angiotensin system
RAAS system is activated by drop in plasma volume or blood pressure at juxtaglomerurlar complex in nephron
Decline in filtrate osmotic concentration at DCT |
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Term
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Definition
ANP and BNP are released by cardiac muscle cells in response to abnormal stretching of heart walls-elevated blood pressure or increase in blood volume
Reduce thirst
Block release of ADH and aldosterone
Cause diuresis – fluid loss at kidneys
Lower blood pressure and plasma volume |
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Term
| When the body loses water... |
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Definition
Plasma volume decreases
Electrolyte concentrations rise |
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Term
| When the body loses electrolytes... |
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Definition
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Term
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Definition
| Pushes water out of plasma into interstitial fluid |
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Term
| Net colloid osmotic pressure |
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Definition
| Draws water out of interstitial fluid into plasma |
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Term
| If ECF osmotic concentration increases... |
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Definition
| Fluid becomes hypertonic to ICF, water moves from cells to ECF |
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Term
| If ECF osmotic concentration decreases... |
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Definition
| Fluid becomes hypotonic to ICF, water moves from ECF to cells |
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Term
| Sodium (Na+)- dominant cation in ECF |
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Definition
Sodium salts provide 90% of ECF osmotic concentration
Sodium chloride (NaCl)
Sodium bicarbonate (NaHCO3) |
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Term
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Definition
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Term
| Total amount of Na+ in ECF represents balance between 2 factors: |
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Definition
1. Na+ uptake across digestive epithelium
Enter through absorption, carrier-mediated transport
Rate depends on amount of Na+ in diet
2. Na+ excretion in urine and perspiration
Kidneys most important site of Na+ regulation
Eat too much, water follows, blood volume & pressure rises |
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Term
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Definition
low salt
ECF Na+ concentration <136 mEq/L |
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Term
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Definition
High salt
ECF Na+ concentration >145 mEq/L |
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Term
| Factors in tubular secretion of K+ (excretion) |
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Definition
Changes in concentration of ECF:
Higher ECF concentration increases rate of secretion
Changes in pH:
Low ECF pH lowers peritubular fluid pH
H+ rather than K+ is exchanged for Na+ in tubular fluid
Rate of K+ secretion decreases
Aldosterone levels:
Affect K+ loss in urine
Ion pumps reabsorb Na+ from tubular fluid in exchange for K+ from peritubular fluid
High K+ plasma concentrations stimulate aldosterone |
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Term
| Functions of Calcium ions |
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Definition
Muscular and neural activities
Blood clotting
Cofactors for enzymatic reactions
Second messengers |
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Term
| Hormones and calcium homeostasis |
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Definition
1. Parathyroid hormone (PTH) and calcitriol
-Raise calcium concentrations in ECF
2. Calcitonin
-Opposes PTH and calcitriol- decreases [Ca2+] |
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