Test 112   (General physiology)

1. With regard to cerebral blood flow: 

a. is dependent on the intracranial pressure

b. is increased by hypoxia

c. is reduced by hypercapnia

d. is increased by hypothermia

e. is about 750ml/min in a 70 kg man

Answera.T  b.T  c.F  d.F  e.T
Cerebral blood flow is reduced by high intracranial pressure. It is increased by hypoxia, hypercapnia and hyperthermia.
 

2. In the heart:

a. excitation begins in the sinoatrial node

b. excitation of the ventricle begins at the apex and spread
    to the base

c. depolarization occurs from epicardium to endocardium

d. vagal stimulation slows the sinoatrial node

e. the bundle of His connects the atrioventricular node to 
    the Purkinje's fibres of the ventricle

Answera.T   b.T   c.T   d.T  e.T

 
3. Following acute haemorrhage, the following compensatory 
    mechanisms occur:

a. increased chemoreceptor discharge

b. increased level of circulating angiotensin II

c. vasoconstriction of renal efferent arterioles

d. cerebral vasoconstriction

e. increased baroreceptor stretch

Answera.T   b.T  c.T  d.F  e.F
Reduced blood volume decreases baroreceptor stretch and consequently increased sympathetic output. This gives rise to vasoconstriction except for blood vessels to the brain and the heart. The chemoreceptor discharge is increased due to hypoxia.
.

4. With regard to insulin:

a. it is a 51 amino acid peptide

b. it is formed by removal of C-chain from proinsulin

c. it is produced by the alpha cells of the pancreas

d. it alters the rate of enzyme synthesis

e. complete insulin deficiency is the most common cause 
    of diabetes mellitus

Answera.T  b.T  c.F  d.T  e.F
Insulin is produced by the beta cells of the pancreas. Partial insulin deficiency is the most common cause of diabetes mellitus.

5. The following are true about renal circulation:

a. it accounts for 25% of the cardiac output

b. it is regulated predominantly by the autonomic nervous 
    system

c.  in a normal 70 kg man, renal blood flow is about 
    1200ml/min

d. macula densa cells are found in the efferent arteriolar 
    wall 

e. blood supply to the cortex is derived mainly from the 
    vase recta
 

Answera.T   b.F  c.T  d.T  e.F
Renal blood flow is mainly under autoregulation. The blood supply to the medulla is derived mainly from the vase recta.

 
 

More MCQs