In a man, abducens nerve is injured. Which one ofthe following functions will be affected?
Movement of the eye ball
Swallowing
Movement of the tongue
Movement of the neck
If dorsal nerve of spinal cord is broken down then its effect is
no impulse is transmitted
impulse is transmitted but slowly
impulse is transmitted fast
no effect on impulse
One of the examples of the action of the autonomous nervous system is
knee-jerk response
pupillary reflex
swallowing of food
peristalsis of the intestines
Which one of the following depresses brain activity and produces feelings of calmness, relaxation and drowsiness?
Valium
Morphine
Hashish
Amphetamines
Which part of retina consists of only cones?
Fovea centralis
optic nerve
Blind spot
Orasmata
A.
Fovea centralis
Fovea centralis is a small, central pit composed of closely packed cones in the eye. Ability for vision is highest in the fovea.
Optic nerve is a bundle of more than 1 million nerve fibres that carry visual messages. It is composed of retinal ganglion cell axon and glial cells.
Blind spot is a small portion of the visual field of each eye that corresponds to the position of the optic disk within the retina. There are no photoreceptors in the optic disk and therefore, no image detection takes place.