question_answer 12)

Distinguish between (a) afferent neurons and efferent neurons (b) impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre (c) aqueous humour and vitreous humour (d) blind spot and yellow spot (e) cranial nerves and spinal nerves  

Answer:

  (a)      Differences between Afferent and Efferent Neurons  

S.N.	Afferent Neuron	Efferent Neuron
1.	The afferent nerve fibres regulatory transmit impulses from tissues/organs to the CNS.	The efferent fibres transmit  impulses from the CNS to the concerned peripheral tissues/organs.

(b)      Differences between the Impulse Conduction in a Myelinated and Unmyelinated Nerve Fibre     Refer to Ans. 9 (a) of this chapter.   (c) Differences between Aqueous and Vitreous Humour  

S.N.	Aqueous Humour	Vitreous Humour
1.   2.	It is the space between the cornea and the lens. It contains a thin watery fluid.	The space between the lens and theretina is called the vitreous chamber. It is filled with a transparent gel.

  (d)      Differences between Blind and Yellow Spot              

S.N.	Blind Spot	Yellow Spoy
1.     2.	Photoreceptor cells are not present in this region,     The light focuses on that part of the retina is not detected,	Yellow shot or macula lutea is located at the posterior pole of the eye lateral to the blind spot. It has a central pit called fovea. The fovea of yellow spot is a thinned-out portion of retina where only the cones are densely packed is the point where visual cavity is greatest.

  (e)      Differences between Cranial and Spinal Nerves  

S.N.	Cranial Nerve	Spinal Nerve
1.     2. 3.	The cranial nerves originate in the brain and terminate mostly in organs head and upper body. There are 12 pairs of cranial nerves. Most of the cranial nerves contain axon and both sensory and motor neurons.	The spinal nerves originate in the spinal cord and extend to parts Of the' body bellow the head. There are 31 pair of spinal nerves. All of the spinal nerves contain axons of both sensory and motor neurons.