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24 Cards in this Set

  • Front
  • Back
3 fluid compartments
1. Intracellular fluid
2. Interstitial fluid
3. plasma
Movement of water through fluid compartments
Filtration occurs between plasma and interstitial
Osmosis occurs between cells and interstitial and interstitial and plasma
-osmosis is regulated by solute concentration b/t compartments
Osmotic Gradients
-differences of water concentration on both sides of a membrane
-water moves so easily through membranes the gradients don't last very long
-if osmolarity of interstitial fluid increases when water oves out of cells to the interstitital
-if osmolarity of ICF increases, water moves into the cells from interstitial
Gender differences between water content
Adult males 60% of body weight
Adult females 55% of body weight
-Main differences depends on body composition
Muscle has large water component
Fat has LOW water content
Fluid Balance
water is present in the correct amount (volume) and in the correct places (compartment)
-dependence on electrolyte balance b/t ICF and ECF b/c electrolytes are the primary factor for water movement
-osmosis depends on electrolyte balance
-if in balance fluid intake=fluid output
Fluid Intake
1. Ingested water
-liquids we drink
-food water content
2. Metabolic Water production
-electron transport chain
-other chemical reactions
Fluid Output
1. Kidneys excrete urine
2. Skin
-encironmental conditions may increase or decrease these values
3. Lungs
-water vapor expired with breathing
4. GI tract
-required minerals for body function
-control osmosis between compartments
-maintain acid-base balance (pH)
-carry an electrical current
ICF (K, HPO4, Protein anions)
ECF (Na, Cl, HCO3)
Sodium (Na)
most abundant ECF cation
1. maintaining electrical gradient b/t cell and ECF ( for action potentials)
2. maintaining osmotic pressure for transport across cell membranes for water and some solutesE
3. Transport of some solutes across membranes
-kidneys through aldosterone
Chloride (Cl)
-most abundant ECF anion
1. balance of osmotic pressure
2. formation of HCl for digestion (pH regulation)
-indirectly by aldosterone since Cl follows Na
Potassium (K)
-most abundant ICF cation
1. ICF osmotic pressure
2. Maintaining electrical gradient b/t ECF and cell
3. Regulate pH (K are exchanged for H)
1. Aldosterone through the balance b/t K and Na
Calcium (Ca)
-most abundant ion in the body
1. stored in bones and teeth
2. small amounts in ECF
1. strength of bones and teeth
2. muscle contraction
3. blood clotting
1. PTH increases ECF Ca
2. Calcitonin decreases ECF Ca
Phosphate (HPO4)
-most is found in bones and teeth
-in fluids, most found in ICF
1. strength of bones and teeth
2. formation of ATP and phosphocreatine
3. formation of phospholipids
4. intracellular buffer
1. PTH increases ECF HPO4
2. Calcitonin removes HPO4 in blood to store with Ca
Bicarbonate (HCO3)
-found in ECF and ICF-more in ECF
1. buffering H in blood, urine, and digestive secretions
1. Respiration of CO2
2. Kidneys excretion and reabsorption
Acid Base Balance
Important part of homeostasis
1. Metabolism depends on enzymes (proteins) and are sensitive to pH
2. pH depends on free H ions in fluid compartments
Normal pH range of ECF is 7.35-7.45
Challenges to acid-base balance
1. metabolism continually produces acids
-a proton (H) donor
-acids dissociate in water to prduce H and a salt

strong acid has higher concentration of H ions
H acceptors; can take the H out of a solution
the chemicals that take H out of solution are buffers-many are salts
Maintaining pH
1. Buffer systems
bicarbonate, phosphate, protein
2. Respiratory mechanism
3. Kidney excretion of H and reabsorption of HCO3
Buffer systems
any mechanism that changes the pH by converting a strong acid to a weaker acid
-can restore pH in seconds- fast but no powerful
Bicarbonate Buffer System
PRIMARY buffer system in BLOOD
-if lactic acid is produced the H dissociates from La and is picked up by the bicarbonate
-bicarbonate binds to H and forms carbonic acid (weaker acid)
Phosphate Buffer system
-most important in ICF and kidneys (renal tubule)
-mostly b/c the concentration of phosphates is higher in ICF than ECF
-accepts H
Protein Buffer System
Proteins act as buffers in both ICF and ECF
-more in ICF is better in ICF
-the carboxyl end of the protein is usually dissociated in physiological environments
-accepts H
Respiratory mechanism- expiration of CO2
-much stronger than buffer systems but not as fast
-if CO2 is exhaled at the lungs the body fluids will contain less H
-increase in CO2 and H stimulates the resp. center to inc. ventilation > this system is a well regulated means for controlling ECF pH
Renal Control of pH
-kidneys are STRONGEST mechanism to control pH but are slow and takes hours to days
1. Renal tubules excrete H in urine
2. Renal tubules regenerate more bicarbonate
3. Renal tubules also excrete fixed acids