National University

Faculty of medical laboratoryphysiology : MLS-PHYO-121

Dr: Tagwa Elsheikh Mohammed alhassanTel: 0121994567

CNS Physiology

Dept.Of Physiology

Central nervous

system

LECTURE NO (-)

The sensory system:

provide us with information about the

internal and the external environment:

The sensory receptors:

Special structure found at the peripheral

ends of afferent neurons

Properties of receptors:

1. Specificity:

Each types of receptor is most sensitive to specific from

of energy

Example:

For touch receptors, the stimulus is mechanical energy

For temperature receptors, the stimulus is thermal

energy

For pain receptors, the stimulus is not specific (i.e. any

form of energy can causes pain if it causes tissue

damage)

2. Adaptation:

Some receptors stop generation of action

potentials when a stimulus of constant

strength is applied for long time

Examples:

Touch receptors are rapidly adapting

Proprioceptors are slowly adapting

Pain receptors do not adapt at all

Sensory cortex:

Receives the ascending impulses through the

sensory tracts, and then gives perception about

type, site and strength of stimulation

Sensation from each side of the body is

represented on the opposite side at the brain

The motor system

The central nervous system consist of:

• The spinal cord

• The brain

Function of spinal cord

1. Contain ascending and descending tracts

2. Acts as integrating center for spinal cord

reflexes

The brain

The brain is divided into:

- Bain stem

- Diencephalon

- Cerebellum

- Cerebrum

The brain stem

Consist of:

1. Medulla

2. Pons

3. Midbrain

Contain vital centers (cardiac & respiratory

center)

Brain stem

the diencephalons

Contain:

Thalamus

hypothalamus

hypothalamus

1. Control release of hormones from

pituitary gland

2. Control water intake (thirst center)

3. Control body temperature (temperature

regulatory center)

Cerebellum

Lies posterior to the brain stem

Function:

Control balance of the

body

Cerebrum

Cerebrum

Consist right & left hemispheres

Each hemispheres is divided into:

Frontal lobe:

1. Has motor area

2. Area of smell

Temporal lobe:

1. Has area of hearing

2. Area of memory

Parietal lobe

1. Has sensory area

2. Area for speech

Occipital lobe:

Has area of vision

Basal ganglia

Collection of nucleus in the brain

Function:

Participate in control of voluntary

movement

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