Neurons have four main regions - the cell body, dendrites, axon, and presynaptic terminals. The cell body contains the nucleus. Dendrites receive signals from other neurons and conduct them toward the cell body. The axon conducts signals away from the cell body, and presynaptic terminals transmit signals to other neurons. Neurons can be sensory/afferent neurons that carry signals from receptors to the CNS, or motor/efferent neurons that carry signals from the CNS to effectors. The myelin sheath surrounds long axons for protection, electrical insulation, and faster signal transmission.

1. Structure of Neuron
Made by
Sakshi Gupta
Xth B

2. Cells of Nervous System
Neurons or nerve
•
cells
–Receive stimuli and
transmit action
potentials
–Organization
● •Cell body or soma
● •Dendrites: Input
● •Axons: Output

3. Structure and Function
Typical Neuron has 4 Regions
Cell Body
•
• Dendrites
• Axon
• Presynaptic
Terminals

4. Functional Classification of Neurons
·Sensory (afferent) neurons
·Carry impulses from the sensory receptors
·Cutaneous sense organs
·Proprioceptors – detect stretch or tension
·Motor (efferent) neurons
·Carry impulses from the central nervous
system

5. Neuron Classification

6. Neuron Anatomy
Extensions outside
the cell body
Dendrites –
conduct
impulses toward
the cell body
Axons –
conduct
impulses away
from the cell body (only 1!)

7. Dendrites of Motor Neurons
•Short, tapering, and
diffusely branched
processes
•They are the
receptive, or input,
regions of the
neuron
•Electrical signals are conveyed as graded
potentials (not action potentials)

8. Axons: Structure
•Slender processes of
uniform diameter arising
from the hillock
•Long axons are called
nerve fibers
•Usually there is only one
unbranched axon per neuron
•Rare branches, if present, are called axon
collaterals
•Axonal terminal – branched terminus of an axon

9. Myelin Sheath
•Whitish, fatty
(protein-lipid),
segmented sheath
around most long
axons
•It functions in:
–Protection of the axon
–Electrically insulating fibers from one another
–Increasing the speed of nerve impulse
transmission