Chapter 27 Flashcards
2 fluid compartments in body
Intracellular – cytosol
Extracellular – interstitial fluid and plasma
Percent of total body mass that is fluid
55%-65%
Difference in total body mass fluid percentage in males and females
60% in males
55% in females
Percentage of body mass fluid that is intracellular/extracellular
2/3, 1/3
Percent of interstitial fluid in extracellular fluid
80%
Percent of plasma in extracellular fluid
20%
Plasma membrane
Separates intracellular fluid from interstitial fluid
Blood vessel walls
Separates interstitial fluid from blood plasma
Capillary walls
Allow exchange to occur
3 ways body gains water
Metabolic water, ingested food, ingested liquid
via ingestion and metabolic synthesis
***ingested liquid is way for most gain
4 ways body loses water
GI tract, lungs, skin, and kidneys
via urination, perspiration, exhalation, and feces
***kidneys is how you lose the most
Metabolic water
Water formed from oxidation of nutrients in the cells (byproduct of ETC)
Process produces metabolic water
ETC
Dehydration
Water loss > water gain
4 stimuli for thirst response
- Increase of blood osmolarity
- Decrease in blood volume
- Decrease blood pressure
- Dry mouth
What the stimuli that affect thirst response affect
Variety of structures:
- Osmoreceptors
- Atrial volume receptors
- Baroreceptors
- Kidneys
*** All lead to stimulation of thirst center
Location of thirst center
Hypothalamus
What the responses of increased intake of water does
Alleviates the problems indicated by stimuli (negative? feedback stimulus)
Main type of elimination of excess water
Urination
Major factor in determining fluid volume in the body
Amount of urinary salt loss
Obligatory water movement
Term used to describe “wherever solutes go, water follows”
2 main solutes/ions in urine
Sodium and chloride ions
3 major hormones that control sodium and chloride ion concentrations
- Angiotensin II
- Aldosterone
- Atrial natriuretic peptide (ANP)
Major hormone that regulates water loss from kidneys
Antidiuretic hormones (ADH)
How hormones that control sodium, chloride, and water
- Start with stimulus (incr/decr blood volume or blood pressure, incr/decr blood osmolarity, incr/decr in sodium ion levels, etc.)
- How stimulus affects body (kidneys, hypothalamus, osmoreceptors, baroreceptors, adrenal glands, heart, etc.)
- What rxns occured to alleviate problem indicated in stimulus?
What happens when cell is placed in isotonic solution
Stays the same
What happens when a cell is placed in a hypertonic solution
Swell
What happens when a cell is placed in a hypotonic solution
Shrink
Water intoxication
When excess body water causes cells to swell dangeously
What happens to sodium ion concentration in extracellular fluid
Decreases (hyponatremia)
What happens to osmolarity of excess fluid
Decreases
Water moves (in/out) of cell during water intoxication
In?
4 main functions of electrolytes
- Control osmosis of H2O b/w fluid compartments
- Help maintain acid-base balance
- Carry electrical current
- Serve as cofactors
Most abundant ion in extracellular fluid
Sodium
Most abundant ion in intracellular fluid
Potassium
Most abundant anion in extracellular fluid
Chloride
Most abundant anion in intracellular fluid
HPO42-
Most abundant cation in extracellular fluid
Sodium
Most abundant cation in intracellular fluid
Potassium
Where proteins are most abundant
Intracellular fluid
Most abundant mineral in body
Calcium
Electrolyte that’s used as a buffer
Phosphate
Normal pH range of arterial blood
7.35-7.45
Three mechanisms of maintaining pH range of arterial blood
Buffer systems, exhalation of CO2, kidney excretion of H+
Buffer systems
Chemicals that prevent body fluids from undergoing large changes in pH by regulating fluctuation in H ion concentration (works by picking up/releasing H ions as needed)
Protein buffer system
- Proteins have both amino acid w/ free acid group (can disassociate/act like acid when pH rises) and amino acid with free amino group (can disassociate and act like base when pH drops)
- Hemoglobin = main protein buffer in blood
Carbonic acid-bicarbonate
- Bicarbonate ions act as a weak base, and carbonic acid acts as a weak acid
» pH drops, bicarbonate removes excess H ions
» pH rises, carbonic acid releases H ions
Phosphate buffer system
Dihydrogen phosphate acts as weak cid, monohydrogen phosphate acts as weak base
» pH rises, dihydrogen phosphate releases H ions
» pH drops, monohydrogen phosphate removes excess H ions
Exhalation of CO2
CO2 released in respiration unites w/ water in blood to produce carbonic acid, makes blood more acidic
» Exhaling CO2 leads to less acid production and rise in pH
» Retaining CO2 leads to more acid production and drop in pH
How respiratory system helps to regulate pH
Alters ventilation rate
Kidney excretion of H ions
Allow for pH adjustments
- H ions and bicarbonate ions can be reabsorbed into blood/secreted into filtrate as needed for pH adjustment
How urinary system helps regulate pH of body fluids
Alters filtrate of pH, therefore altering blood pH as well
Acidosis vs. alkalosis
Blood pH < 7.35, blood pH > 7.45
Respiratory acidosis
Blood pH drops due to excessive retention of CO2
Respiratory alkalosis
Blood pH rises due to excessive loss of CO2
Metabolic acidosis
Arterial blood level of bicarbonate ions decreases
Metabolic alkalosis
Arterial blood level of bicarbonate ions increases
