Control Of Fluid, Electrolyte And Acid-Base Homeostasis

Front 1

How many barriers separate separate the ICF, interstitial fluid and plasma

Back 1

2

Front 2

what is the function of plasma membrane

Back 2

separates ICF from surrounding interstitial fluid

Front 3

what is the functional of blood vessels

Back 3

to divide interstitial fluid from plasma

Front 4

when is the body in fluid balance

Back 4

when required amounts of waterand solutes are present and correctly proportioned among compartments

Front 5

what is the largest component in the body making up 45-75% of total body mass

Back 5

Water

Front 6

what dos these processes allow:filtration reabsorption, diffusion, and osmosis

Back 6

continual exchange of water and solutes among compartments

Front 7

how is body water volume regulated

Back 7

--How much we drink ( controlled by hypo)

Front 8

how much percentage drop in water results in dehydration

Back 8

2%

Front 9

what stimulates the thirst centre in the hypothalamus

Back 9

dehydration stimulates RAA pathway which stimulates thirst centre.
it is also stimulated by neurones in the mouth and baroreceptors

Front 10

how much water is ingested in liquids

Back 10

1600ml

Front 11

how much water is ingested through food

Back 11

700ml

Front 12

how much water is obtain metabolically

Back 12

200ml

Front 13

in terms of water movement, what does increasing osmolarity of interstitial fluiddo ?

Back 13

it draws out water out of cells and makes cells shrink

Front 14

Normally, cells neither shrink or swell because____________

Back 14

intracellular and interstitial fluids have the same osmolarity

Front 15

what does decreasing osmolarity do

Back 15

makes cells swell

Front 16

changes in osmolarity most often result from.....

Back 16

changes in Na+ concentration

Front 17

what is water intoxication ?

Back 17

drinking water faster than the kidneys need it

Front 18

what does water intoxication lead to ?

Back 18

convulsions, coma or death

Front 19

what are the functions of aldesterone ?

Back 19

regulation of blood volume
blood pressure
levels on Na+ , K+, H+
in the blood

Front 20

what causes loss of excess water an solute

Back 20

urinary salt loss

Front 21

what are the 2 main solutes in ECF

Back 21

Na+ and Cl+

Front 22

what is a solute

Back 22

substance dissolved in a solution

Front 23

what are the 3 most important hormones for regulating ion concentrations in the body

Back 23

angiotensin II, aldosetrone and ANP

Front 24

Hormonal regulation of renal Na+ and Cl- reabsorption

Back 24

Increased intake of NaCl leads to increased plasma concentration of Na+ and Cl- which leads to increased osmosis of water from intracellular fluid to interstitial fluid to plasma and then leads to increased blood volume

Front 25

what are 2 things increased blood volume leads to in the regulation of Na+ and Cl-

Back 25

increased strectching of atria of the heart or decreased release of renin by juxtaglomerular cells

Front 26

ADH

Back 26

– Major hormone regulating water loss is
antidiuretic hormone (ADH)
– Also known as vasopressin
– Produced by hypothalamus, released from
posterior pituitary
– Promotes insertion of aquaporin‐2 into principal cells of collecting duct
– Permeability to water increases, produces concentrated urine
– Also stimulated by severe blood loss

Front 27

Electrolytes in body fluids

Back 27

Ions form when electrolytes dissolve and dissociate
• 4 general functions
– Control osmosis of water between body fluid
compartments
– Help maintain the acid‐base balance
– Carry electrical current
– Serve as cofactors

Front 28

most common ions in ecfs

Back 28

Na+ Cl- HCO-3

Front 29

most common ions in ICF

Back 29

K, HPO2 protein anions

Front 30

Sodium Na+

Back 30

Sodium Na+
– Most abundant ion in ECF
– 90% of extracellular cations
– Plays pivotal role in fluid and electrolyte balance because it accounts for almost half of the osmolarity of ECF
– Level in blood controlled by
• Aldosterone – increases renal reabsorption
• ADH – if sodium too low, ADH release stops
• Atrial natriuretic peptide – increases renal excretion

Front 31

how adh conserves water

Back 31

Front 32

INFLUENCE of water loss from plasma...

Back 32

Front 33

Chloride Cl‐

Back 33

– Most prevalent anions in ECF
– Moves relatively easily between ECF and ICF
because most plasma membranes contain Cl leakage
channels and antiporters
– Can help balance levels of anions in different fluids
• Chloride shift in RBCs
– Regulated by
• ADH – governs extent of water loss in urine
• Processes that increase or decrease renal reabsorption
of Na+ also affect reabsorption of Cl

Front 34

Potassium K+

Back 34

– Most abundant cations in ICF
– Key role in establishing resting membrane potential in neurons and muscle fibres
– Also helps maintain normal ICF fluid volume
– Helps regulate pH of body fluids when exchanged
for H+
– Controlled by aldosterone – stimulates principal
cells in renal collecting ducts to secrete excess K+
– Hyperkalemia can cause death by ventricular fibrilation

Front 35

Calcium Ca2+

Back 35

– Most abundant mineral in body, most in skeleton and teeth
– Plays important roles in blood clotting, neurotransmitter release, muscle tone, and excitability of nervous and muscle tissue

Front 36

what hormone regulates ca2+

Back 36

parathyroid hormone

Front 37

how does parathyroid hormone regulate ca2+

Back 37

Stimulates osteoclasts to release calcium from bone ECM
Also enhances reabsorption from glomerular filtrate

Front 38

Magnesium

Back 38

– In adults, about 54% of total body magnesium is part of
bone as magnesium salts
– Remaining 46% as Mg2+ in ICF (45%) or ECF (1%)
– Second most common intracellular cation
– Cofactor for certain enzymes and sodium‐potassium pump
– Essential for normal neuromuscular activity, synaptic
transmission, and myocardial function
– Secretion of parathyroid hormone depends on Mg2+
– Regulated in blood plasma by varying rate excreted in urine

Front 39

Phosphate

Back 39

– About 85% in adults present as calcium phosphate salts in bone
and teeth
– Remaining 15% ionized – H2PO4- , HPO42‐ , and PO43‐ are
important intracellular anions
– H2PO4- important buffer of H+ in body fluids and urine
– Same hormones governing calcium homeostasis also regulate
HPO4
2‐ in blood
• Parathyroid hormone – stimulates resorption of bone by osteoclasts releasing calcium and phosphate, but inhibits reabsorption of phosphate ions in kidneys (PTH increases urinary excretion & lowers plasma levels)
• Calcitrol promotes absorption of phosphates and calcium from GI tract

Front 40

what is hypernatremia

Back 40

implies a plasma sodium level above 145 mEq/L.

Front 41

causes of hypernatremia

Back 41

dehydation, thirst from exercise and NaCl administration

Front 42

consequences of hypernatremia

Back 42

thirst. confusion, lethergy progressing to coma. increased neuromuscular irritability evidenced by twitching and convulsions

Front 43

Hyponatremia

Back 43

represents a plasma sodium concentration below 135mEq/L

Front 44

causes of hyponatremia

Back 44

solute loss, water rentention or both e.t through vommiting and diarhea burned skin tubal drainage of stomach/

Front 45

consequences of hyponatraemia

Back 45

neurologic dysfunction due to brain swelling. mental confusion giddiness and coma musclular twitching, irritability due to excess. if accompanied by water loss it leads tolow bp and low blood volume

Front 46

Potassium level of 5.5 or higher is termed?

Back 46

hyperkalemia

Front 47

causes of hyperkaleamia

Back 47

renal failure, deficit of aldesterone, rapid intravenoys infusion, burns or severe tissues and injuries which cause K to leave cells

Front 48

consequences of hyperkaleamia

Back 48

nausea vomitting, diarhea, depression, skeletal muscle weakness

Front 49

hypokaleami

Back 49

levels of potassium lower tham 3.5mEq/L

Front 50

causes of hypokaleamia

Back 50

gastrountestinal tract disturbances, gastrointestinal suction

Front 51

consequences of hypokalaemia

Back 51

flattened T wave, muscular weakness, metabolic alkalosis, mental confusion, nausea, vomiting

Front 52

Hypocalcemia

Back 52

<8.5 mg/dL or an ionized calcium level of <4.0 mg/dL

Front 53

Hypercalcemia

Back 53

>10.5 mg/dL or an ionized calcium level of >5.0 mg/dL ; caused by malignancy or prolonged immobilization

Front 54

Hypomagnesemia

Back 54

<1.5 mEq/L ; chronic alcholism is the most common cause

Front 55

Hypermagnesemia

Back 55

>2.5 mEq/L ; due to increas intake or decrease excretion

Front 56

Hypochloremia

Back 56

<95 mEq/L

Front 57

Hyperchloremia

Back 57

>108 mEq/L ; excess replacement of sodium chloride or potassium chloride

Front 58

Hypophosphatemia

Back 58

<2.5 mg/dL; glucose and insulin administration, parenteral nutrition(feeding through IV)

Front 59

Hyperphosphatemia

Back 59

>4.5 mg/dL ; tissue trauma, chemotherapy, renal failure

Front 60

causes of hypercalcemia

Back 60

malignancy and hyperparathyroidism,bone loss related to immobility

Front 61

causes of hypocalcemia

Back 61

causes of hypocalcemia

Front 62

Respiratory acidosis

Back 62

can be caused by emphysema, pulmonary edema, injury to the respiratory centre of the medulla, airway obstruction etc
The kidneys can compensate if mild
Treatment include ventilation therapy and IV of HCO3-

Front 63

Respiratory alkalosis

Back 63

caused by hyperventilation due to overstimulation of inspiratory centre.
Kidneys can compensate if mild, a paper bag can help

Front 64

Metabolic acidosis

Back 64

caused by diarrhoea, renal dysfunction, acid accumulation (e.g. ketosis)
Hyperventilation can compensate if mild
Treatment include IV of sodium bicarbonate solution

Front 65

Metabolic alkalosis

Back 65

caused by loss of acid (mainly vomiting) or excessive intake of alkaline drugs eg diuretics or antacids
Hypoventilation can compensate if mild, need to replace electrolytes

Front 66

Kidney excretion of H+

Back 66

– Metabolic reactions produce non-volatile acids
– One way to eliminate this huge load is to excrete H+ in urine
– In the proximal convoluted tubule, Na+ /H+ antiporters secrete H+ as they reabsorb Na+
– Intercalated cells of collecting duct include proton pumps that secrete H+ into tubule fluid
– Urine can be up to 1000 times more acidic than blood
– 2 other buffers can combine with H+ in collecting duct
• HPO42‐ and NH3

Front 67

Acid‐base balance

Back 67

• Major homeostatic challenge is keeping H+ concentration (pH) of body fluids at appropriate level
• 3D shape of proteins sensitive to pH
• Diets with large amounts of proteins produce more acids than bases which acidifies blood
• Several mechanisms help maintain pH of arterial blood between 7.35 and 7.45
– Buffer systems, exhalation of CO2, and kidney excretion of H+

Front 68

– Phosphate buffer system

Back 68

• Dihydrogen phosphate (H2PO4‐) and monohydrogen phosphate(HPO42‐ )
• Phosphates are major anions in ICF and minor ones in ECF
• Important regulator of pH in cytosol

Front 69

exhalation of CO2

Back 69