Differentiate between: (a) Myelinated and non-myelinated axons (b) Dendrites and axons (c) Rods and cones (d) Thalamus and Hypothalamus (e) Cerebrum and Cerebellum | Learn NCERT solution | Education portal Class 11 Biology | Study online Unit-21 Neural Control and Coordination



Q.9:- 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

(a) Myelinated and non-myelinated axons

Myelinated axons
Non myelinated axons
These appear whitish in colour. These appear greyish in colour.
Myelin sheath is present Myelin sheath is absent
Nodes of Ranvier are present at intervals. Nodes of Ranvier are absent.
Transmission of nerve impulse is faster. Transmission of nerve impulse is slower
Ion exchange can occur only at the nodes. Ion exchange occurs all over the surface.

(b) Dendrites and axons

Dendrites
Axons
These are extension of cyton present at anterior position. These are extension of cyton present at posterior position.
These conduct impulses towards the cell body. These conduct impulses away from the cell body.
Dendrites are always non-myelinated. Axons can be myelinated or non-myelinated.
The terminals of dendrites become receptors. The terminals of axon ends in a group of branches called terminal arborisations.

(c) Rods and cones



Rods
Cones
Rods are sensitive to dim light. Cones are sensitive to bright light only.
They have visual purple pigment called rhodopsin. They have visual violet pigment called iodopsin.
Colours are not visible with rod cells. Cones help to see colours.

(d) Thalamus and Hypothalamus

Thalamus
Hypothalamus
It represent the side of diencephalon. It represents the lower part of diencephalon.
It is the major coordinating centre for sensory and motor signalling. It is the major centre for regulation of body temperature, thirst, hunger etc.
It does not secrete any hormone. It secretes several hormones.

(e) Cerebrum and Cerebellum

Cerebrum
Cerebellum
It is part of fore brain It is part of hind brain
It consists of two cerebral hemispheres. It consists of two cerebellar hemispheres and a median vermis.
It initiates voluntary movements. It maintains posture and equilibrium.