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A: In the nervous system generation of action potential depends upon influx of sodium ions into axoplasm.
R: Influx of sodium ions during nerve impulse generation is due to efflux of potassium ions.
A: Presence of myelin sheath increases the rate of conduction of nerve impulse.
R: Ionic channels are absent in the area covered by myelin sheath therefore, depolarization occurs only at the nodes of Ranvier, resulting in saltatory or jumping conduction.
A: Receptors in the tendon, joints give information regarding the position and movements of different parts of the body.
R: These are termed as noci-receptors.
A: Sharpest vision is in fovea centralis.
R: The relationship of receptor to bipolar cells to ganglion cells is 1 : 1 : 1 within fovea centralis.
Fovea centralis is the area of most acute vision of the retina and here the ratio of rods, cones and bipolar cells and ganglion cells is 1:1:1. This acute vision is due to the high number of cones in the fovea centralis.
A: Postganglionic nerve fibre of parasympathetic nervous system have acetylcholine while sympathetic nervous system have adrenaline as the neurotransmitter.
R: Sympathetic nervous system inhibits the intestinal peristalsis while parasympathetic stimulates peristalsis.
Sympathetic system inhibits peristalsis of intestine while parasympathetic system enhances it
A: Transmission of the nerve impulse across a synapse is accomplished by neurotransmitters.
R: Transmission across a synapse usually requires neuro-transmitters because there is small space, i.e., synaptic cleft, that separates one neuron from another.
A: Sense organs do not interpret the stimulus, it is done by the brain.
R: Sense organs are transducers. They transform the energy of a stimulus to the energy of nerve impulses.
Sense organs act as transducers, they transform the sensation into nerve impulse and transmit via sensory neurons to the brain where the association and interpretation of the sensation occurs in their respective sensory areas.
A: The imbalance in the concentration of Na+, K+ and proteins generates the resting potential.
R: To maintain the unequal distribution of Na+ and K+, the neurons use electrical energy.
A: Retina is arranged anatomically in reverse order from what might be expected.
R: The receptor cells are, towards the outside and ganglionic cells towards the inside and light must pass through the nerve cells to reach them.
A: The brain reaches between 75 and 80 percent of adult size within the first two years, and its full size at the age of 6 years.
R: From an evolutionary point of view, human gestation period is belived to be shortening.