JAMES VALLEY VOCATIONAL TECHNICAL CENTER

Neuron: Nerve Cell n Basic structural unit nervous system n Consists of: –nucleus –nerve fibers /dentrites –axon

Nerves n Sensory Nerves: –carry messages to brain and spinal cord from body n Motor Nerves: –carry messages from brain and spinal cord to body

n Connecting or Mixed Nerves: –Carry both sensory and motor messages

Divisions of CNS n CNS - central nervous system: –consists of brain and spinal cord

n Peripheral Nervous System –a. any nerves outside the brain and spinal cord –b. Autonomic nervous system: controls involuntary body functions

Central Nervous System n 1. Brain: –a. Mass of nerve tissue –b. Protected by membranes & the cranium or skull

C. Cerebrum n Largest section of the brain n Responsible for: –reasoning, thought, memory, speaking, sensstion, sight, hearing, voluntary body movement

D. Cerebellum n Responsible for: –coordination of muscles, balance, posture, & muscle tone

E. Midbrain n Responsible for: –conducting impulses between brain parts –certain eye reflexes

Pons n Responsible for: –conducting messages to other parts of the brain –Reflex actions such as chewing, production of saliva

G. Medulla Oblongata n Lowest part of brain stem n Connects to the spinal cord n Responsible for: –regulating heart beat, respirations, swallowing, coughing, b/p

2. Spinal Cord n Goes down back of body from Medulla Oblongata n Surrounded and protected by vertebrae n Responsible for reflex actions n Carries sensory and motor messages

3. Meninges n Consists of 3 membranes n Covers and protects the brain and spinal cord

Three Membranes n C. Dura mater –thick, tough outer layer n D. Arachnoid membrane –middle delicate weblike layer n E. Pia mater –inner most layer with blood vessels to nourish the nerves

4. Ventricles n Four hallow spaces located in the middle of the brain. n Connected to each other n Filled with fluid called cerebrospinal fluid

Cerebrospinal Fluid n Circulates continuously n Serves as shock absorber to protect brain and spinal cord

n Carries nurients to parts of brain and spinal cord n helps remove metabolic products & wastes n after circulation, absorbed into the blood vessels of the dura mater.

Peripheral Nervous System n Made of all nerves outside the brain and spinal cord n Consists of cranial and spinal nerves

A. Cranial Nerves n 12 pairs & their branches n Some responsible for special senses: sight, hearing, taste, smell n Others receive sensations: touch, pressure, pain, temperature

B. Spinal Nerves n 31 pairs & their branches n carries messages to & from the spinal cord n Both sensory and motor nerves

n 31 spinal nerves: –8 cervical –12 thoracic –5 lumbar –5 sacral –1 coccygeal

3. Autonomic Nervous System n Helps maintain a balance in involuntary functions of the body. But allows the body to react in times of emergency.

2 divisions of ANS n Sympathetic nervous system –acts in emergency n Parasympathetic –counter acts the sympathetic ns after the emergency

n SNS –increase heart rate –increase resp. rate –increase b/p –decrease digestive system activity n PNS –decrease heart rate –decrease resp. rate –decrease b/p –increase digestive system activity