Test 70      (General physiology)

1. The following are true about resistance to blood flow in the vessel:

a. it is dependent on the haematocrit
b. it depends on the thickness of the vessle wall
c. it is directly proportional to the length of the vessle
d. it is directly proportional to the pressure drop along the 
    vessel
e. it is inversely proportional to the fourth power of the 
   radius of the vessel

Answera.T   b.F  c.T   d.T   e.T
Resistance (R) to blood flow in a vessel can be expressed using the formula:
R=P/Q where P is the pressure gradient along the vessel and Q is the volume flow rate.
Further this formula can be converted to the Poisseuille's equation :
P/Q =R = 8nl/¶r⁴ where n is the viscosity of the blood, r is the radius of the vessel and l is the length of the blood vesselw

2. True statements about osmotic diuretics include:

a. it reduces the absorption of both salt and water
b. the urine produced is limited by the glomerular filtration 
    rate
c. mannitol reduces the vitreous volume
d. frusemide is an osmotic diuretics
e. glycerol is an osmotic diuretics

Answera.T   b.T   c.T   d.F   e.T
Osmotic diuretics are filtered byt he glomerulus, but not reabsorbed by the nephron resulting in the simultaneous loss of water and salt. Frudemide is loop diuretic. 

3. Excessive secretion of aldosterone gives rise to::

a. hypokalaemia
b. hypertension
c. alkalosis
d. polyuria
e. muscular weakness

Answera.T   b.T   c.T   d.T   e.T
Aldostone increases the secretion of potassium and hydrogen ions giving rise to hyeprnatraemia and alkalosis. The hypokalaemia causes polyuria and muscle weakness. 

4. Miosis of the pupil:

a. reduces visual field
b. increases depth of field
c. increases the visual acuity
d. reduces spherical aberration
e. increases chromatic aberration

Answera.T   b.T   c.T   d.T   e.F
Reduction of the pupil diameter means that light only enters the eye through  the centre of the pupil. As a result, spherical and chromatic aberration are reduced. This in turn gives rise to increased visual acuity and depth of field. The visual field is reduced with miosis.

5. The following receptors respond to stretch reflex:

a. carotid baroreceptor 
b. free nerve ending
c. Ruffini's endings
d. Oligodendrocytes
e. Pacinian corpuscles.

 
Answera.T   b.F   c.F   d.F   e.F
Free nerve endings, Ruffini's endings and Pacinian corpuscles are found in the skin and respond to mechanical deformation.
Oligodendrocytes produce myelination for the central nerveous system.

 
 

More MCQs