Test 55  (general physiology)

1. Cerebral blood flow is increase in: 

a. chronic anaemia 

b. inhalation of 5% carbon dioxide 

c. seizures 

d. inhalation of hyperbaric oxygen 

e. raised intracranial pressure 

Answera.T   b.T   c.T   d.F   e.FThe cerebral blood flow is decrease in inhalationof hyperbaric oxygen and raised intracranial pressure.

2. The following are true about the sodium channels: 

a. they are made up of polypeptide chains 

b. have the highest densities at the nodes of Ranvier 

c. open in response to depolarization 

d. remain open as long as depolarization is maintained. 

e. blocked by tetrodotoxin 

Answera.T   b.T   c.T   d.F   e.TThe channels open within 1 ms of depolarization.The channels remain open for a maximum of afew milliseconds after depolarization.
 

3. The cerebral blood flow: 

a. is increased by hypercapnia 

b. is increased by hypoxia 

c. accounts for 15% of the total cardiac output 

d. is increased if isoflorane is used during general 
    anaesthesia 

e. is controlled mainly through the autonomic system 

Answera.T   b.T   c.T   d.T   e.FAutonomic system play only a minor partin the regulation of cerebral blood flow.

4. The blood-brain-barrier: 

a. contains the foot processes of astrocytes 

b. contains endothelial cells with tight junction 

c. allows transport in one direction only ie from the 
    vascular system into the brain 

d. does not allow diffusion of water 

e. contains more mitochondria in the endothelial than those 
    found elsewhere. 

Answera.T   b.F   c.F   d.T   e.TWater passes throught the blood-brain-barriervia diffusion.
 

5. The following are true about the antidiuretic hormone: 

a. it is produced by the anterior pituitary gland 

b. it reduces the cardiac output 

c. it increases the renal absorption of sodium 

d. it decreases the release of ACTH 

e. it increases the peripheral resistance 

Answera.F   b.T   c.T   d.F   e.TAntidiuretic hormone is produced by the hypothalamus and secreted by  the posterior pituitary gland.The cardiac output is reduced due to theincrease in the total peripheral resistance and its direct negative inotropiceffect. The ACTH is increased in response to the antidiuretic hormone.