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fluid compartments

Body water is distributed among certain _____,areas separated by selectively permeable membranes and differing from each in chemical composition

intracellular fluid

Where is the most of the body fluid located?

electrolytes, sodium, potassium

The most abundant solute particles by far are the _____, especially ___ in the ECF and ____ in the ICF

fluid balance

A person is a in a state of ____ when daily gains and losses are equal; normal distribution of fluids

metabolic water, preformed water

Routes of water gain are

metabolic water

is produced as a by-product dehydration synthesis reactions and aerobic respiration; water produced by the body's metabolism

preformed water

water gain through ingested food and drink

routes of water loss

1,500 ml/day in urine
200 ml/day in feces
300 ml/day in expired breath
100 mlday in sweat
400 ml/day in cutaneous transpiration

cutaneous transpiration

water lost through epidermis and then evaporated. Not the same thing as sweat, because it is not a glandular secretion

insensible water loss

Output through the breath and cutaneous transpiration is called _____, because we are not usually conscious of it

sensible water loss

Noticeable output, particularly through the urine and in case of sufficient sweating to produce obvious wetness of skin

obligatory water loss

output that is relatively unavoidable; expired air, cutaneous transpiration, sweat, fecal moisure, and the minimum urine output


fluid intake is governed mainly by _____

blood volume, blood pressure , blood osmolarity

Dehydration reduces ____ and ____, but raises ______


Fluid intake is governed mainly by _____< which monitor blood osmolarity and angiotensin level. When they sense a fluid deficity, they activate ADH secretion and the sense of thirst

volume, concentration, distribution

Body is in a state of fluid imbalance if there is an abnormality of total ___,____, or _____ of fluid among the compartments

volume depletion(hypovolemia)

occurs when water or sodium are lost without replacement. Total body water declines and osmolarity remains the same.

dehydration(negative water balance)

occurs when the body eliminates significantly more water than sodum so the ECF osmolarity rise.
-affects all fluid compartments
TBW reduced, osmolarity= hypertonic

angiotensin ii, antidiuretic hormone, hypothalamic osmoreceptors, inhibition of salivation

THirst center of anterior hypothalamus responds to

volume excess

both water and sodium are retained and the ECF remains isotonic.
TBW= elevated, osmolarity = isotonic

hypotonic hydration(positive water balance, water intoxication)

more water than sodium is retained or ingested and ECF becomes hypotonic
TBW= elevated, osmolarity=hypotonic

fluid sequestration

a condition in which excess fluid accumulates in a particular location. Most common form = edema

why electrolytes are important

chemically reactive
participate in metabolism
determine electrical potential across cell membranes
strongly affect osmolarity of body fluids and body's water content and distribution


promotes sodium and water retention, thus reduces urine output

antidiuretic hormone

promotes water reabsorption by CD , reduces water output

Natriuretic peptide

promtoes sodium and water loss

major cations

sodium , hydrogen, calcium , potassium are all ____ ___

major anions

chloride, bicabonate (HCO3-) and phosphates (Pi) are all ____ ____


principal cation in ECF; most significant solute in determining total body waater and distribution of water among fluid compartments

sodium bicarbonate(NaHCO3-)

____ plays a major role in buffering the pH of the ECF


plays the primary role in adjustment of sodium excretion


ECF osmolarity, TBW and water balance
resting and action potentials, excitability of neurons, muscles, heart
cotransport of glucose, K+ and other solutes
thermogenesis by Na+K+ pump
buffering of pH by sodium bicarbonate


homeostasis of this electrolyte is regulated by Aldosterone, ADH and NP


causes: renal failure, improper IV thereapy, high salt diets
effects: H2O retention, hypertension and edema


causes: usually hypotonic hydration
effects: disrupts neurological and cardiac function, can be lethal in hypotonic hydration


most abundant cation of the ICF and greatest determinant of intracellular osmolarity and cell volume is _____


principal determinant of ICF osmolarity and cell volume , resting and action potential , excitability of neurons muscles and heart. Cotransport, thermogenesis, cofactor for protein synthesis


Potassium homeostasis is regulated mainly by ____


causes: crush injuries, hemolytic anemia, bad transfusion, improper IV therapy, aldosterone deficiency, renal failure

effects: neuromuscular hyperexcitability, cardiac arrest, neuromuscular depression

slow onset

neuromuscular depression is an effect in ____ hyperkalemia

quick onset

cardiac arrest is an effect in ____ hyperkalemia


causes: heavy sweating, chronic vomiting or diarrhea, aldosterone hypersecretion , alkalosis

effects: reduced excitability of neurons and muscles , weakness , poor muscle tone, depressed reflexes, cardiac arrhythmia


____ imbalances are the most dangerous of all electrolyte imbalances


most abundant anions of the ECF

regulation of water output

aldosterone, antidiuretic hormone, natriuretic hormone

7.35, 7.45

Blood and tissue fluid normally have a pH of ___-____

anaerobic fermentation

lactic acid comes from

nucleic acid catabolism

phosphoric acid comes from ________

fat catabolism

fatty acids and ketones both are results of _____

carbon dioxide

carbonic acid comes from _____

hydrogen ions

pH of solution is determined soley by its _______


any chemical that releases H+ ina solution

strong acid

gives up most of its hydrogen ions and can markedly lower the pH of a solution

weak acid

keeps most hydrogen in a chemically bound form that does not affect pH.


any chemical that accepts H+

strong base

strong tendency to bind H+ and raise the pH

weak base

binds less of the available H+ and has less effect on pH


any mechanism that resists changes in pH by converting a strong acid or base to a weak one

physiological buffer

a system that stabilizes pH by controlling the body's output of acids, bases or CO2


____ system bufers the greatest quantity of acid or base, but its requires several hours to day to exert an effect

chemical buffer

substance that binds H+ and removes it from solution as its concetratio begins to rise, or releases H+ into solution as its concentration falls
can restore normal pH within a fraction of a second

buffer systems

mixtures of a weak acid and weak base

bicarbonate, phosphate, protein

3 major chemical buffer systems of the body are

bicarbonate buffer system

a solution of carbonic acid and bicarbonate ions

physiological buffer

pretains to ability of the lungs and kidneys to stabilize pH by controlling the body's output of acids, bases or CO2

chemical buffers

substances that stabilize pH by either binding or realeasing H+

phosphate buffer system

solution of HPO4(2-) and H2PO4-.
optimal pH for this system is 6.8
more important in renal tubules and icf

protein buffer system

accounts for 3/4 of all chemical buffering in body fluids


neutralize more acid or base than the either respiratory system or the chemical buffers, because they actually expel H+ from the body

fluid deficiency

a ____ occurs when fluid output exceeds intake

fluid sequestration

a state in which total body water may be normal , but the water is maldistributed in body


important in osmotic balance, formation of stomach acid, and chloride shift mechanism in respiratory and renal function


is regulated as a side effect of sodium homeostasis

pH imbalance

primary effect of chloride imbalances is a ______


necessary for muscle contraction, neurotransmission , and other casess f exocytosis, blood clotting, some hormone actions and bone and tooth development

parathyroid hormone, calcitrol, calcitonin

Calcium homeostasis is regulated by ?


causes hyperparathyroidism, hypothyroidism, alkalosis
effects:neuromuscular depression , cardiac arrythmia


causes: hypoparathyroidism, hyperthyroidism, vitamin D deficiency, dirrahea, pregnancy , lacatation, acidosis

effects:neuromuscular hyperexcitability,muscle tetany, suffocation by laryngospasm

inorganic phosphate

_____ is necessary for the synthesis of nucleic acids and phospholipids, ATP, GTP, and cAMP; activates many metabolic pathyways by phosphorylating such substances as enzymes and glucose; and it is an important acid-base buffer

parathyroid hormone

phosphate levels are regulated by _____

urinary and respiratory system

2 examples of physiological buffer systems


secrete H+ into the tubular fluid where it binds to chemical buffers and is voided from the body in the urine

respiratory acidosis

occurs when pulmonary gas exchange is insufficient to expel CO2 as fast as the body produces it

metabolic acidosis

is the result of lactic acid or ketone accumulation, excessive use of acidic drugs, such as aspirin or loss of base such as in cases of diarrhea

respiratory alkalosis

results form hyperventilation or high altitude; CO2 expired faster than it is produced

metabolic alkalosis

is rare but can be cause by overuse of antacids or loss of stomach acid through vomitting.


_____acidosis or alkalosis is a pH imbalance that the body's homeostatic mechanisms cannot control on their own, it requires clinical intervention


_____acidosis or alkalosis is an imbalance that the body's homeostatic mechanism can correct

respiratory compensation

is correction of the pH through changes in pulmonary ventilation

renal compensation

is correction of pH by changes in H+ secretion by the kidneys


Urine is usually ____ free, except if person is in state of alkalosis

acidosis, hypochloremia

Tubules secrete more NH3Cl to buffer the acid in the urine, leaving less Cl in the ECF
cause is ____ and potential effect is ____

acidosis, hypocalcemia

at low pH more ca2+ binds to plasma proteins and citrate ions, leaving less ca2+ free for metabolic uses
cause=_____ potential effect =_____

chemical buffers

buffer system reacts the quickest , but least effect of all systems

respiratory system

reaction time up to 3min, buffers less acid or base than urinary, but is more effective than chemical buffers

urinary system

reaction time is slowest , may take several hours to days, however they bufer greatest amount of acid or base


promotes potassium excretion

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