Differentiate between: (a) Myelinated and non-myelinated axons (b) Dendrites and axons (c) Rods and cones (d) Thalamus and Hypothalamus (e) Cerebrum and Cerebellum

(a) Myelinated and non-myelinated axons:-
Myelinated Axons:-
1. Transmission of nerve impulse is faster
2. Myelinated axon has a myelin sheath.
3. Node of Ranvier is present between adjacent myelin sheaths.
4. Found in the brain, the spinal cord, the cranial and spinal nerves
5. Schwann cells are observed inside the myelin sheath
Non-myelinated Axons:-
1. Transmission of nerve impulse is slower
2. Myelin sheath is absent
3. Node of Ranvier is absent
4. Found in autonomous and somatic neural systems
5. Schwann cells are not observed inside the myelin sheath

(b) Dendrites and axons:-
Dendrites:-
1. Dendrite is a small projection arising from the neuron. It conducts the nerve impulse toward the cell body.
2. Nissl’s granules are present in dendrites.
3. Dendrites are always non-myelinated.
Axons:-
1. Axon is a single, long projection that conducts the nerve impulse away from cell body to the next neuron.
2. Nissl’s granules are absent from axons.
3. Axons can be myelinated or non-myelinated.

(c) Rods and cones:-
Rods:-
1. Rods help in twilight vision.
2. They have visual purple pigment called rhodopsin.
3. Rods are the photoreceptor cells of the retina that are sensitive to dim light.
Cones:-
1. Cones help in colour vision.
2. They have visual violet pigment called iodopsin.
3. Cones are the photoreceptor cells of the retina are sensitive to bright light.

(d) Thalamus and Hypothalamus
Thalamus:- Thalamus is the part of the forebrain that receives nerve impulses of pain, temperature, touch, etc., and conducts them to the cerebral hemisphere.
Hypothalamus:- Hypothalamus is the part of the forebrain that controls involuntary functions such as hunger, thirst, sweating, sleep, fatigue, sexual desire, temperature regulation, etc.

(e) Cerebrum and Cerebellum:-
Cerebrum:- Part of the forebrain that controls voluntary functions. It is the place where intelligence, will power, memory, etc.
Cerebellum:- Part of the hindbrain that controls voluntary functions and controls the equilibrium.

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