Download The Nervous System

The Nervous System
11th Grade Health
Definition
 The body system consisting of the brain, spinal cord and branching nerves
General Purpose
 Relay messages to and from the brain to all parts of the body
 Controls reflexes (involuntary actions)
 5 Senses (Touch, Sight, Hearing, Taste, Smell)
Structure & Functions
 Neuron – basic nerve cell (sensory neuron, interneuron, motor neuron)
 Cell body – control center of the cell containing the nucleus.
 Dendrites – projections branching from the cell body that bring impulses.
 Axon – thread-like extensions that carry impulses away from cell body.
 Two (2) divisions of nervous system
 Central Nervous System – brain and spinal cord
 Peripheral Nervous System – cranial nerves, spinal nerves and their branches
 Autonomic – involuntary functions – sympathetic and parasympathetic
 Somatic – voluntary functions
 Brain – mass of nerve tissue divided into three (3) parts
 Cerebrum – Largest, most complex part of the brain (2 hemispheres); controls memorization,
thinking and learning; where conscious thought occurs (cortex).
 Four (4) lobes
 frontal – voluntary movement
 parietal – sensory input; heat, cold, pain, touch, kinesthetic awareness
 occipital – vision
 temporal – hearing & smell; memory, thought, and judgment
 Cerebellum – controls balance and the coordination of muscle activity
 Brain stem – controls involuntary actions such as heart rate and breathing
 Three (3) main parts
 Medulla Oblongata – vital control center; heartbeat, breathing, digestion, BP, sneezing,
coughing, vomiting.
 Pons - facial expressions & senses
 Midbrain – eye movement & pupil reaction
 Spinal cord – thick bundle of neurons (nerve cells) protected by vertebrae
 Reflex – spontaneous response of the body to a stimulus (knee, eye)
 “Fight or Flight” response – readiness to stand your ground or escape from a stressful situation.
The Nervous System
11th Grade Health
General Care
 Rest – 6-8 hours of sleep every night is recommended
 Exercise – resistance & cardiovascular
 Diet low in processed foods, fatty meats and sugar (slows neural connections)
 Avoidance of alcohol, drugs and pesticide chemicals
 Use protective devices such as: helmets, safety belts, weight lifting belts
 Check depth of water (shallow diving)
Problems
 Concussion – bruising of the brain causing 3 or more problems in the brain (headache, impaired
vision, ringing in the ear, etc)
 Contusion – bruising of the brain causing a lump (not as serious as a concussion, but may lead to
one.
 Severed spinal cord – could cause the loss of bodily movement
 Paralysis – loss of neurological communication (movement, feeling, etc)
 Parkinson’s Disease – degeneration of nerve cells in the brain that produce dopamine; leads to
uncoordinated muscular movement
 Multiple Sclerosis – auto-immune disease; destruction of nerve cell insulation
 Alzheimer’s – mental deterioration usually associated with age
 Epilepsy – sudden episodes of uncontrolled electrical impulses in the brain (seizures)
 Cerebral Palsy – non-progressive disorder that results from damage to the brain usually between
the prenatal and early childhood stages of development
 Polio – viral infection that eventually destroys motor neurons – vaccine is given to children
 Stroke – although a circulatory emergency, its effect are on the brain and body(3 types)
First Aid
 Minimizing the movement of the head and neck if you suspect any injury to spinal cord or vertebrae
(car crashes, falls from height, etc)
 Call 911 – seek medical attention
 Concussions – don’t let victim fall asleep; stay away from activity which may lead to another
concussion (second impact syndrome)
 Stroke – paralysis on one side of the body & slurred speech/facial muscles
Relation to Other Systems
 Muscular – motor neurons help to initiate movement
 Digestive – regulation of food processing through digestive tract
 Skeletal – cranium and vertebrae provide protection for the brain and spinal cord
 Cardio-Respiratory – heart rate and breathing
 Endocrine – workhorse for the nervous, hypothalamus – pituitary link
 All other systems – brain controls functions in all other systems
Concepts:
1. Once neurons are damaged they never repair themselves.
2. Drugs can inhibit pain, increase the speed of neurons, slow the speed of neurons or control the
firing of neurons.