The Nervous System

Don’t get nervous about the nervous system

Functions of the Nervous System

• 1. Communication and coordination– Adapt and respond to changes from both inside and

outside the body

• 2. Site of reasoning- your brain

• 3. Two main divisions – Central nervous system (CNS): brain and spinal

cord– Peripheral nervous system- the nerves

• Neuron- basic structural unit of the nervous system

• Dendrites- carry impulses towards the cell

• Axon-carry impulses away from the cell

• Myelin sheath• Synaptic terminal

– Epinephrine– Norepinephrine– Acetylcholine

• Nerves are made of many nerve cells

• Afferent-sensory nerves carry message to brain

• Efferent-motor neurons carry message from brain to muscle

• Associate- do both

• Heads up

Central nervous system

• Brain and spinal cord

• Cerebrum-largest part of brain. Responsible for reasoning, thought, memory, speech, sensation, etc.

• Divided into two halves.

• Further divided into lobes; occipital, parietal, temporal and frontal

• Cerebellum-responsible for muscle coordination

• Brain stem- most basic functions; respiration, swallowing, blood pressure. Lower part (medulla oblongata) is continuous with spinal cord

• Spinal cord- begins at foramen magnum and ends at second lumbar vertebrae

• Contains both afferent (to the brain) and efferent (motor neurons- away from the brain)

• Both the brain and spinal cord are covered by a membrane system called the meninges

• In addition, the brain has four hollow areas called ventricles. Cerebrospinal fluid is produced in the ventricles and baths the brain and spinal column

Peripheral nervous system

• Somatic system– 12 pairs cranial nerves– 31 pairs spinal nerves

• Autonomic– Sympathetic

• Fight or flight

– Parasympathetic

Disorders of the nervous system• Meningitis- inflammation of the linings of

the brain and spinal cord

• Encephalitis- inflammation of the brain

• Epilepsy-seizure disorder. Excessive discharge from neurons. 1 in 200 suffer. Grand mal or petit mal seizures

• Cerebral palsy- disturbance in voluntary muscular action

• Parkinson’s –decreased neurotransmitter

• MS multiple sclerosis- autoimmune