821. In relation to acid base balance in the body
A. Respiratory compensation in metabolic alkalosis is limited by carotid and aortic chemoreceptor response
B. HC03 concentration will decrease in compensated respiratory acidosis
C. The rate of renal H+ secretion is not affected by PC02 in respiratory acidosis
D. Chloride excretion is decreased in respiratory acidosis
E. Hepatic glutamine synthesis is decreased in chronic metabolic acidosis

822. The action potential of a neuron
A. Is initiated by efflux ofNa
B. Is terminated by efflux ofK
C. Declines in amplitude as it moves along the axon
D. Results in transient reversal of the concentration gradient ofNa across the cell membrane
E. Is not associated with any net movement ofNa or K across the cell membrane

823. The functions of tropomyosin in skeletal muscle include
A. Releasing calcium after an action potential
B. Sliding on actin to produce shortening
C. Binding to myosin during contraction
D. Acting as a “relaxing protein” at rest by covering up the sites where myosin binds to actin
E. Generating A TP which passes to the contractile mechanism

824. Regarding the autonomic nervous system
A. Does not have a reflex arch like somatic nervous system
B. Has Dopamine is the main transmitter
C. Has cholinergic division which increases activity of the intestinal musculature and increases gastric secretion
D. Neurotransmitter Noradrenaline is metabolised by pseudocholinesterase
E. Is not involved with visceral sensation

825. Lymph flow is
A. An average 500 mLIhr into the circulation
B. Proportional to interstitial fluid pressure
C. Increased with decreased interstitial fluid protein
D. Decreased with contraction of muscles
E. Decreased with elevated capillary pressure

826. Regarding extracellular volume maintenance
A. Control of sodium balance is the major mechanism maintaining ECF volume
B. A rise in ECF volume stimulates vasopressin secretion
C. Osmotic stimuli override volume stimuli in the regulation of vasopressin secretion
D. Vasopressin causes Na retention by the kidney
E. Angiotensin II inhibits aldosterone secretion

827. Regarding renal compensation in respiratory acidosis and alkalosis
A. The rate of HC03 reabsorption is inversely proportional to the arterial PC02
B. In respiratory acidosis, HC03 reabsorption is reduced
C. Changes in plasma chloride concentration are proportional to HC03 concentration
D. In respiratory alkalosis, renal H+ secretion is increased
E. HC03 reabsorption depends upon the rate of H+ secretion by the renal tubular cells

828. Regarding calcium metabolism
A. Approximately 60% of filtered calcium is reabsorbed by the kidney
B. Absorption of calcium in the gastrointestinal tract is mainly by passive diffusion
C. The extent of calcium binding by plasma proteins is inversely proportionate to the plasma protein level
D. Levels of 1,25 dihydroxycholecalciferol fall in the presence of increased plasma calcium
E. The majority of calcium present in bone is readily exchangeable

829. Toxins that increase the cAMP content of the intestinal mucosa cause diarrhoea because they
A. Increase Cl secretion into the intestinal lumen
B. Increase Na absorption in the small intestine
C. Increase K secretion into the colon
D. Increase NaIK. cotransport K secretion into the colon
E. None of the above

830. Which of the following is not synthesised in postganglionic sympathetic neurons
A. L-dopa
B. Dopamine
C. Noradrenaline
D. Adrenaline
E. Acetylcholine

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