Water Flashcards
What population has the most water and why? Then what? Then what? Why do females have less water content than males? Which has the least?
- infants high because low body fat & bone mass
- adult males next
- adult females because higher fat, less skeletal muscle (Adipose tissue least hydrated of all)
- least = old age
How many L is total body water?
40L
What are the 2 main fluid compartments? Which one has more? What 2 types of ECF? What is IF? What is the order of abundance?
intracellular fluid (ICF) - 2/3
extracellular fluid (ECF) = 1/3
- plasma
- interstitial fluid - fluid b/t cells
ICF > IF > plasma
Water is a universal ___.
solvent
What are solutes? What are the 2 classifications? What are some examples? Which has greater osmotic power? What unit is Electrolyte Concentration in? What does it measure?
- Solutes: what is dissolved in water
- Classified as nonelectrolytes and electrolytes
- Nonelectrolytes: Do not dissociate (most organic)
- glucose, lipids, creatinine, and urea
- Electrolytes: Dissociate into ions, conduct electrical current
ex. acids/basis - Greater osmotic power (ability to shift fluids) than nonelectrolytes
-milliequivalents per liter (mEq/L): # of electrical charges per liter sol
What is the major cat and anion of the ECF?
What are they for ICF? What also is found there more?
ECF
cation = Na+
anion Cl-
ICF
cat = K+
anion = HPO42–
more soluble proteins
What is found in the blood plasma (4), IF (4), ICF (8)?
blood plasma = Na, Cl, HCO3, protein anions
IF = Na, HCO3, Cl, H2O
ICF = K, Mg, HCO3, HPO4, SO4, protein anions, CO2, O2
___ is the most abundant solutes in body fluids, and they cause ___ to happen.
- Electrolytes most abundant solutes in body fluids
- cause chemical reactions to hapen
___ and ___ pressures regulate continuous exchange and mixing of fluids. Where does water go if you increase ECF osmolality? Decrease ECF osmolality?
Osmotic and hydrostatic pressures
↑ ECF osmolality (solute concentration increases) → water leaves cell
↓ ECF osmolality → water enters cell
How does fluid move between plasma and IF?
Between IF and ICF?
- across capillary walls
- across selective cell membrane
How much water should you in and ouput a day? What are some examples of input? (3) of output? (4)
2500ml
input = beverages, food, and metabolic water
ouput = urine (60%), insensible water loss (lost through skin and lungs), perspiration, and feces
What happens when there is a rise in osmolality with ADH & thirst? What center is responsible for it? What is this an example of?
increase = ADH released, stimulates thirst decrease = ADH inhibition, inhibits thirst
-hormones help regulate electrolytes in the urinary system to regulate water (involves the endocrine, nervous, and renal system)
Thirst mechanism is governed by which center? What detects what and is activated by (4)?
- Governed by hypothalamic thirst center
- Hypothalamic osmoreceptors detect ECF osmolality
activated by ↑ Plasma osmolality Dry mouth Decreased blood volume or pressure Angiotensin II or baroreceptor input
What are inhibitory feedback mechanisms for the thirst center?
Drinking water causes:
- Relief of dry mouth
- Activation of stomach and intestinal stretch receptors
Thirst mechanism for regulating water intake - chart
What are obligatory water losses?
insensible water loss, feces, sensible water loss (urine)
Solute concentration and volume or urine is a function of ___ (3).
fluid intake, diet, and water loss
Mechanism of ADH control in water output - chart
High or low ADH creates dilute/concentrated urine? What happens to the volume of body fluids?
↓ ADH → dilute urine and ↓ volume of body fluids
↑ ADH → concentrated urine; reabsorption of water → ↑ volume of body fluids
What are some factors that lower blood volume? (6)
intense sweating, vomiting, or diarrhea; severe blood loss; traumatic burns; and prolonged fever
What is dehydration? - image
When does it occur? What does this do to osomotic pressure in the ECF? What happens to the cells?
ECF water loss
intense sweating, vomiting, or diarrhea; severe blood loss; traumatic burns; and prolonged fever
What is hypotonic hydration/water intoxication? When causes it? What happens to the ECF osmotic pressure? What happens to the cells?
- cellular overhydration
- renal insufficiency or rapid excess water ingestion
What is edema? (2) What is it a result of? (2) Why is it bad? (3)
- accumulation of IF → tissue swelling (not cell swelling)
- screw up balance between IF and ECF
- Result of ↑ fluid out of blood or ↓ fluid into blood
- Increases diffusion distance for nutrients and oxygen
- Results in low blood pressure and severely impaired circulation
Why is electrolyte balance important? (4)
Salts control fluid movements; provide minerals for excitability, secretory activity, membrane permeability
How does salt enter body (2) and lost (4)
Salts enter body by ingestion and metabolism; lost via perspiration, feces, urine, vomit
True or false
Na is the Only cation exerting significant osmotic pressure
true
Which ion controls ECF volume and water distribution?
What is the homeostatic importance of ECF ___ concentration and body ___ content? How are they regulated?
Na
True or false
Na + never secreted into filtrate
Where does it move back and forth instead?
true
keeps moving back and forth between IF and the cell
Water in filtrate follows Na only if ___. What is the mechanism?
ADH present
↑ Na+ in urine → ↑ water loss (water follows salt)
what is the mechanism of aldosterone release in the regulation of Na and K? - image
What does aldosterone do to urine output? blood volume?
- decreased urinary output; increased blood volume
- granular cells
What are the 3 ways blood pressure is increased through the renal, nervous, and endocrine system? chart
Why is K balance important? How is it balanced? Most important factor affecting K+ secretion? What is the mechanism? What hormones influence K+ levels?
- Affects RMP in neurons and muscle cells (especially cardiac muscle)
- regulating amount secreted into filtrate
- concentration in ECF
- High K+ diet → ↑ K+ content of ECF → K+ entry into principal cells → K+ secretion
- Influence of aldosterone = K secretion
Maintaining body’s Ca2+ levels in ECF is important for (4)
Blood clotting
Cell membrane permeability
Secretory activities
Neuromuscular excitability - most importan
What is the purpose of Cl-? Is it reabsorbed? Wha happens in acidosis?
- Helps maintain osmotic pressure of blood
- 99% of Cl– is reabsorbed under normal pH conditions
- When acidosis occurs, fewer chloride ions are reabsorbed
Alkalosis if pH > ___ and acidosis is arteriole pH < ___.
Alkalosis or alkalemia: arterial pH >7.45
Acidosis or acidemia: arterial pH <7.35
True or false
Most H+ produced by metabolism
true
How is H+ produced?
H+ liberated when CO2 converted to HCO3– in blood
Concentration of hydrogen ions regulated sequentially by in order of quicket to slowest (3)
- Chemical buffer systems
- Brain stem respiratory centers: act within 1–3 min
- Renal mechanisms: most potent, but require hours to days to effect pH changes
___ dissociates completely, which ____ affects pH.
___ dissociates partially, which ____ pH change.
___ dissociates easily in water, which ___ H+.
___ accepts H+ more slowly.
Strong acids dissociate completely in water; can dramatically affect pH
Weak acids dissociate partially in water; are efficient at preventing pH changes
Strong bases dissociate easily in water; quickly tie up H+
Weak bases accept H+ more slowly
What is a chemical buffer system and what are the 3 types?
-system of one or more compounds that act to resist pH changes when strong acid or base is added
Bicarbonate buffer system
Phosphate buffer system
Protein buffer system
The bicarbonate buffer system is a mixture of ___ (2) that buffers the ___ (location).
The reserve of ___ is called the alkaline reserve. It is controlled by the ___ (organ).
H2OC3 supply is controlled by ___ system,
What happens when strong acid is added? Strong base?
- Mixture of H2CO3 (weak acid) and salts of HCO3– (e.g., NaHCO3, a weak base)
- Only important ECF buffer
- all available HCO3– (alkaline reserve)
- HCO3– concentration closely regulated by kidneys
- H2CO3 supply controlled by the respiratory system
strong acid added = HCO3– ties up H+ and forms H2CO3
strong base added = causes H2CO3 to dissociate and donate H+ which ties up the base to form H2O
(NaOH + H2CO3 → NaHCO3 + H2O)
How does the respiratory system regulate H+? What happens in CO2 unloading? What happens when ECF is basic? What happens to the H+ that is produced when hold onto CO2?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–
- Respiratory system eliminates CO2
- CO2 unloading (breathing out) shifts reaction to the L and H+ forms H2O
- CO2 loading (breathing in) shifts reaction to the R and H+ buffered by proteins
- when ECF basic, want to hold onto (breathe in more) CO2 so shift equation to R to produce H+ to neutralize base
- H+ disposed of thru the urinary system
What happens in hypercapnia?
hypercapnia (increased CO2) increases H+ which activates increased respiration so more CO2 removed from body and H+ concentration reduced
Respiratory system impairment causes acid-base imbalances.
What does hypoventilation and hyperventilation cause?
- hypoventilation = respiratory acidosis because not breathing out CO2 so go up in H+
- hyperventilation = respiratory alkalosis because breathing out CO2 so go down in H+
How does the renal system regulate acid-base balance? What does reabsorbing and excreting HCO3- do to H+?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–
- balance HCO3-
- reabsorbing one HCO3– same as losing one H+
- Excreting one HCO3– same as gaining one H+
What are the 2 classes acid-base abnormalities?
-respiratory or metabolic
Respiratory acidosis/alkalosis is indicated by fluctuations in ___.
What causes respiratory acidosis? Because ___ accumulates in the blood pH ___.
What causes respiratory alkalosis? Because ___ is eliminated.
PCO2 level
Respiratory acidosis
- decrease in ventilation or gas exchange
- CO2 accumulates in blood
- Characterized by falling blood pH and rising PCO2
Respiratory alkalosis
- hyperventilation often due to stress or pain
- CO2 eliminated faster than produced
What causes metablic acidosis? It is characterized by ___ pH and HCO3-
Metabolic alkalosis is characterized by ___. What causes it?
-low blood pH and HCO3–
Ingestion of too much alcohol (→ acetic acid)
Excessive loss of HCO3– (e.g., persistent diarrhea)
Accumulation of lactic acid (exercise or shock), ketosis in diabetic crisis, starvation, and kidney failure
- rising blood pH and HCO3–
- vomiting of acid contents of stomach or by intake of excess base (e.g., antacids)
What does acidosis and alkalosis do to the nervous system?
Blood pH below 6.8 → depression of CNS
Blood pH above 7.8 → excitation of nervous system
If acid-base imbalance due to malfunction of physiological buffer system,
___ system attempts to correct metabolic acid-base imbalances
___ attempt to correct respiratory acid-base imbalances
Respiratory system attempts to correct metabolic acid-base imbalances
Kidneys attempt to correct respiratory acid-base imbalances
Respiratory compensation of metabolic:
Acidosis
Alkalosis
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–
Acidosis = stimulates respiratory centers to increase rate & depth of breathing to eliminate CO2
-HCO3 - low
Alkalosis = shallow breathing to let CO2 accumulate in blood
-HCO3 - high
Renal Compensation for Respiratory Acid-Base Imbalance
Alkalosis
Acidosis
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–
respiratory acidosis
- due to hypoventilation
- increases HCO3–
respiratoy alkalosis
-decrease HCO3–
