Question

Differentiate between :

(a) Myelinated and non-myelinated axons

(b) Dendrites and axons

(c) Rods and cones

(d) Thalamus and Hypothalamus

(e) Cerebrum and Cerebellum

Answer 1

$\text{(a) Myelinated and non-myelinated axons}\begin{array}{cc}\text{Myelinated axons}& \text{Non myelinated axons}\\ \text{These appear whitish in colour.}& \text{Myelin sheath is absent due to which white colour is not seen.}\\ \text{Nodes of Ranvier are present at intervals.}& \text{Nodes of Ranvier are absent.}\\ \text{Transmission of nerve impulse is faster.}& \text{Transmission of nerve impulse is slower.}\\ \text{Ion exchange can occur only at the nodes.}& \text{Ion exchange occurs all over the surface.}\end{array}$

$\text{(b) Dendrites and axons}\begin{array}{cc}\text{Dendrites}& \text{Axons}\\ \text{These are extension of cyton present at anterior position.}& \text{These are extension of cyton present at posterior position}\\ \text{These conduct impulses towards the cell body.}& \text{These conduct impulses aways from the cell body.}\\ \text{Dendrites are always non-myelinated.}& \text{Axons can be myelinated or non-myelinatd.}\\ \text{The terminal of dendrites become receptors.}& \text{The terminals of axon ends in a group of brancehs called terminal arborisations.}\end{array}$

$\text{(c) Rods and cones}\begin{array}{cc}\text{Rods}& \text{Cones}\\ \text{Rods are sensitive to dim light.}& \text{Cones are sensitive to bright light only.}\\ \text{They have visual purple pigment called rhodopsin.}& \text{They have visual violet pigment called iodopsin.}\\ \text{Colours are not visible with rod cells.}& \text{Cones help to see colours}\end{array}$

$\text{(d)Thalamus and Hypothalamus}\begin{array}{cc}\text{It represent the side of diencephalon.}& \text{It represents the lower part of diencephalon.}\\ \text{It is th emajor coordinating centre for sensory and motor signalling.}& \text{It is the major centre for regulation of body temperature, thirst, hunger etc.}\\ \text{It does not secrete any hormone.}& \text{It secretes several hormones.}\end{array}$

$\text{(e)Cerebrum and Cerebellum}\begin{array}{cc}\text{It is part of fore brain.}& \text{It is part of hind brain.}\\ \text{It consists of two cerebral hemispheres.}& \text{It consists of two cerebellar hemispheres and a median vermis.}\\ \text{It initiates voluntary movements}& \text{It maintains posture and equilibrium.}\end{array}$