Nervous System

What are supporting cells?

Nonexcitable cells that provide structural support or serve important physiological and immunological functions.

What is a neuron?

The structural unit of NS, they are specialized cells that conduct electrical impulses.

Features of neurons:

• Long life or throughout life

• Amitotic - no division

• REQUIRES O2 and nutrients

• Generate and conduct impulses

What is the cell body called ?

Perikaryon

What is found in a cell body?

Nucleus , RER , ribosomes , neurofibrils and other organelles.

I extend from cell body,short,with alot of branches and receive impulses. What am i?

Dendrites

I am a 1 meter long single nerve fibre, what am i ?

Axon

What are neuronal processes?

Cytoplasmic projections that extend from cell body.

Sensory function

transmit impulses from skin and viscera to CNS

motor function

carries impulses from CNS to muscles/glands effectors

Upper motor are in the brain?

true

Lower motor are in peripherial ?

true

Supporting cells and their function

• Microglia - less common, phagocytic

• Oligodendrocytes - make myelin

• Ependymal - lines ventricles and spinal cord

• Astrocytes - most common, metabolic

What is saltatory conduction?

Signals jump from one node of ranvier to another

What are the chemicals that affect conduction?

alcohol, sedatives, anaesthatics ( limit na channels )

What happens in synapse junction ?

Functional contuinity of chemical transmission

properties of synapes

• One way conduction

• Synaptic delay about 0.5 msec

• Fatigue