PHGY 216 FINAL EXAM WITH CORRECT
ACTUAL QUESTIONS AND CORRECTLY
WELL DEFINED ANSWERS LATEST
ALREADY GRADED A+
explain the haemoglobin buffer system - ANSWERS-- as CO2
leaves tissues + enters the blood --> forms H2CO3 (mediated
by carbonic anhydrase)
- H+ binds to haemoglobin + allows it to release oxygen
- some H2CO3 dissociates into HCO3- and H+
explain the phosphate buffer system - ANSWERS-Na2HPO4 +
H+ ⇌ NaH2PO4 + Na+
- acid phosphate salt can donate or accept H+
what does the phosphate system buffer - ANSWERS-most
important --> buffer urine pH, excess phosphates in the
urine buffer excreted H+
- intracellular fluid --> cells have high [acid phosphate salt]
,how do the respiratory and renal systems control pH -
ANSWERS-through the elimination of H+
the respiratory system + pH control - ANSWERS-CO2 leads to
H+ generation --> altering pulmonary ventilation
increases/decreases CO2 removal
- [H+] is the primary determinant of respiratory activity
respiratory system + pH control - arterial [H+] ↑ -
ANSWERS-stimulates respiratory centre to ↑ pulmonary
ventilation --> ↑ gas exchange + CO2 removal --> less H2CO3
--> less HCO3- and H+
respiratory system + pH control - arterial [H+] ↓ -
ANSWERS-stimulates respiratory centre to ↓ pulmonary
ventilation --> ↓ gas exchange + CO2 removal (excess CO2
builds up) --> more H2CO3 --> more HCO3- and H+
what do the kidneys remove - ANSWERS-H+ produced by
sulphuric, phosphoric + lactic acid and extra H+ produced by
carbonic acid
how do the kidneys control pH of extracellular fluid -
ANSWERS-1. excretion of H+
,2. excretion/reabsorption of HCO3-
3. secretion of ammonia
renal H+ secretion mechanism - ANSWERS-1. CO2 enters
tubular cells from the plasma, tubular fluid or produced in
tubular cells
2. CO2 and H2O form H2CO3 --> dissociates into H+ and
HCO3-
3. energy dependent carrier on the luminal membrane
transports the H+ into tubular fluid
fluid shifts (short term blood pressure control) - ANSWERS-
↓ plasma volume --> shift of fluids out of the interstitial
compartment to the plasma
what controls fluid input/output (long term pressure
control) - ANSWERS-input = thirst mechanism
output = kidneys (urine output)
control of salt input - ANSWERS-poor --> dependent on
dietary salt
, control of salt output - ANSWERS-excess salt must be
eliminated through feces, sweat and the kidneys
- kidneys plays the greatest role
causes of hypotonicity (3) - ANSWERS-renal failure -->
cannot produce concentrated urine
rapid water ingestion
over secretion of vasopressin --> promotes water retention
causes of hypertonicity (3) - ANSWERS-insufficient water
intake
vasopressin deficiency --> common with diabetes insipidus
excessive water loss --> sweating, vomiting, diarrhoea
hypothalamic osmoreceptors - ANSWERS-monitor
osmolarity of surrounding fluid --> counteract any
fluctuations in water balance
↑ osmolarity --> stimulate vasopressin secretion and thirst
vasopressin action - ANSWERS-acts on the kidneys -->
increases water absorption
ACTUAL QUESTIONS AND CORRECTLY
WELL DEFINED ANSWERS LATEST
ALREADY GRADED A+
explain the haemoglobin buffer system - ANSWERS-- as CO2
leaves tissues + enters the blood --> forms H2CO3 (mediated
by carbonic anhydrase)
- H+ binds to haemoglobin + allows it to release oxygen
- some H2CO3 dissociates into HCO3- and H+
explain the phosphate buffer system - ANSWERS-Na2HPO4 +
H+ ⇌ NaH2PO4 + Na+
- acid phosphate salt can donate or accept H+
what does the phosphate system buffer - ANSWERS-most
important --> buffer urine pH, excess phosphates in the
urine buffer excreted H+
- intracellular fluid --> cells have high [acid phosphate salt]
,how do the respiratory and renal systems control pH -
ANSWERS-through the elimination of H+
the respiratory system + pH control - ANSWERS-CO2 leads to
H+ generation --> altering pulmonary ventilation
increases/decreases CO2 removal
- [H+] is the primary determinant of respiratory activity
respiratory system + pH control - arterial [H+] ↑ -
ANSWERS-stimulates respiratory centre to ↑ pulmonary
ventilation --> ↑ gas exchange + CO2 removal --> less H2CO3
--> less HCO3- and H+
respiratory system + pH control - arterial [H+] ↓ -
ANSWERS-stimulates respiratory centre to ↓ pulmonary
ventilation --> ↓ gas exchange + CO2 removal (excess CO2
builds up) --> more H2CO3 --> more HCO3- and H+
what do the kidneys remove - ANSWERS-H+ produced by
sulphuric, phosphoric + lactic acid and extra H+ produced by
carbonic acid
how do the kidneys control pH of extracellular fluid -
ANSWERS-1. excretion of H+
,2. excretion/reabsorption of HCO3-
3. secretion of ammonia
renal H+ secretion mechanism - ANSWERS-1. CO2 enters
tubular cells from the plasma, tubular fluid or produced in
tubular cells
2. CO2 and H2O form H2CO3 --> dissociates into H+ and
HCO3-
3. energy dependent carrier on the luminal membrane
transports the H+ into tubular fluid
fluid shifts (short term blood pressure control) - ANSWERS-
↓ plasma volume --> shift of fluids out of the interstitial
compartment to the plasma
what controls fluid input/output (long term pressure
control) - ANSWERS-input = thirst mechanism
output = kidneys (urine output)
control of salt input - ANSWERS-poor --> dependent on
dietary salt
, control of salt output - ANSWERS-excess salt must be
eliminated through feces, sweat and the kidneys
- kidneys plays the greatest role
causes of hypotonicity (3) - ANSWERS-renal failure -->
cannot produce concentrated urine
rapid water ingestion
over secretion of vasopressin --> promotes water retention
causes of hypertonicity (3) - ANSWERS-insufficient water
intake
vasopressin deficiency --> common with diabetes insipidus
excessive water loss --> sweating, vomiting, diarrhoea
hypothalamic osmoreceptors - ANSWERS-monitor
osmolarity of surrounding fluid --> counteract any
fluctuations in water balance
↑ osmolarity --> stimulate vasopressin secretion and thirst
vasopressin action - ANSWERS-acts on the kidneys -->
increases water absorption
