Nervous systemPractical class-Histology

Lecturer: Ghada Abdul Rahman Sultan

Nervous system• Receive stimuli from both internal and

external environments which are then analyses and integrated to produce appropriate coordinated responses in various effector organs.

Nervous system• 2 body systems control all the functions

of the body-

• 1. Nervous system- which works very rapidly

• 2. Endocrine system- which works more or less slowly.

Classification of nervous system• Functionally/physiologically:

• 1. Somatic nervous system (SNS)

• 2. Autonomic nervous system (ANS)

• a-sympathatic b-parasympathatic

• Anatomically and histologically:

• 1-a Central nervous system (CNS)(brain and spinal cord)

• 1-b Peripheral nervous system (PNS)(cranial and spinal nerves with their ganglia )

The basic structure units in nervous system :1- Neurons (nerve cell) 2- Supporting cellsa-Neuroglia (in CNS)b-Schwann cell(in PNS) Figure 12.4a

Dendrites

Soma

Nucleus

Nucleolus

Axon

Node of Ranvier

Internodes

Synaptic knobs

Axon hillock

Initial segment

Myelin sheath

Schwann cell

Axon collateral

(a)

Trigger zone:

Direction of

signal transmission

Terminal

arborization

Figure 12.4a12-5

• Neuron-Structural & functional unit of nervous system consist of 2 parts

• 1. Cell body/soma/perikaryon

• 2. Process/neurite

2 types of neurite-

• 1. Axon

• 2. Dendrite

(Axon & dendrite) is called nerve fiber.

• Note:

• 1. Neurons/nerve cells-Active, non-dividing cell

• 2. Neuroglia/glial cells-Non-active, dividable cell

Supporting cells of the CNS

• Glial cells of the CNS=

• Astrocytes

• Oligodendrocytes…myelination

• Microglial

• Ependymal cells12-8

Supporting cells (glial cells) of the PNS• Schwan cells

• Satellite cells

• These supporting “glial” brace and protect the

fragile neuron cells

• Act as phagocytes

• Control the chemical environment around the

nerve cells.

• More about supporting cells later 12-9

Connective tissue fasciae

Ppt #2

Difference between spinal and sympathetic ganglion

SYMPATHETIC ganglion SPINAL ganglion FEATURES

Multipolar Pseudo unipolar 1. Neurons( nerve cell )

Small & irregular Large & rounded 2. Cell bodies

Eccentric Central 3. Nucleus

Few Numerous 4. Satellite cells

Nerve fibers and cell bodies are Scattered

Nerve fibers are in bundle and cell bodies are also groups

5. Neurons & nerve fibers

Motor(Autonomic)Sensory 6. Type of ganglia

Non-Myelinated nerve fiber Myelinated nerve fiber7.Myelin sheath

Endoneurium

Adipose tissue

Perineurium

Epineurium

Fibroblast

Axons

Node of Ranvier

Schwan cell

Satellite cells

Myelin sheath

Nucleus

Nucleolus

Nucleus

Nucleolus

Non myelinated nerve fiber Collagen fiber

Supporting epithelial cell

Myelin sheath

Motor end palate

Skeletal muscle