1. Lesson 4: The Nervous System

3. NERVOUS SYSTEM:  The system made up of the brain, spinal cord, and all the nerves of the body that regulates the body’s response to stimuli. Nervous System

4.  The 2 parts of the Nervous System are the:  CENTRAL NERVOUS SYSTEM  PERIPHERAL NERVOUS SYSTEM

5.  The CENTRAL NERVOUS SYSTEM is made up of the brain and the spinal cord.  It receives and transmits information to and from the peripheral nervous system.

6. BRAIN:  Control center of the nervous system. SPINAL CORD:  The part of the body that functions as a relay station to and from the body and the brain.  Nerve impulses to the body from the brain must go through the spinal cord.  The spinal cord could function on its own. Central Nervous System

7. REFLEX:  An automatic behavior of the body that involves movement activated by the spinal cord.  It does not use the brain.  This movement occurs before one is aware of it.  Ex: emergency situation:  Swerving to avoid on oncoming car.  Spinal cord acts before the brain gets a chance.  Spinal neurons are short, direct and strong:  They have very few synapses to show them down.  The reflexes provide an automatic protective device for the body.

8. HOW A REFLEX WORKS:  A stimulus to the skin sends a nerve impulse to the spinal cord.  The spinal cord sends an impulse to the muscle causing it to contract.

9.  The PERIPHERAL NERVOUS SYSTEM is made up of all the nerves of the body outside the brain and the spinal cord.  It is all the nerves outside the Central Nervous System.  Composed of the spinal and cranial nerves.  These connect the CNS to the rest of the body.  It sends information to and receives information from the Central Nervous System.

10.  Most nerves in the PNS are SPINAL NERVES:  Nerves that interact with the brain via the spinal cord.  They connect the brain to the body.  The others are CRANIAL NERVES:  Nerves that interact directly with the brain located in the head, back and shoulders.  They do not link via the spinal cord.  They connect the brain to the head. Spinal Nerves LUMBAR

11. Cranial Nerves

12.  The two parts of the Peripheral Nervous System are the:  SOMATIC NERVOUS SYSTEM  AUTONOMIC NERVOUS SYSTEM

13.  The SOMATIC NERVOUS SYSTEM is the part of the Peripheral Nervous System that contains sensory nerves and motor nerves.  It picks up SENSATION.  It controls the skeletal muscles and voluntary (deliberate or conscious) MOVEMENT of the body.

14.  SENSORY NERVES:  They pick up sensation and bring it to the brain and spinal cord.  MOTOR NERVES:  They get instructions from the brain and spinal cord and put the muscles into action.

15.  Autonomic means “automatic,” “independent,” “functions on its own,” and “without conscious control.”  The Autonomic Nervous System controls most bodily activities are not under one’s control.  It controls the automatic (unconscious or involuntary) internal bodily functions.  This system runs much of the body all by itself.  Ex: breathing, digestion, heartbeat, saliva production, movement of pupils, etc…

16.  It carries nerve impulses from the brain and spinal cord to the glands, organs, etc…  This system controls the following:  Glands.  Pupils.  Liver.  Lungs.  Stomach.  Heart.  Other Vital Organs…  The ANS can be overridden by the higher brain:  Panic, shock, stress, etc…  Survival mechanisms in a crisis.

17.  The two parts of the Autonomic Nervous System are the:  SYMPATHETIC NERVOUS SYSTEM  PARASYMPATHETIC NERVOUS SYSTEM

18.  They determine how much energy an organ should have and when it should have it.  They balance the body when sudden changes in energy are needed.  In the absence of an emergency, the two parts of the ANS balance each other.  Their function is to produce a balanced response in the body when sudden changes in energy are needed.  They both conduct nerve impulses from the CNS to the body’s internal organs.

19. SYMPATHETIC NERVOUS SYSTEM:  The part of the ANS that energizes the body and prepares it for an emergency.  It conducts nerve impulses from the CNS to the organs.  It is made up of nerves that stimulate internal organs.  Its purpose is to stimulate activity.  It expends energy.

20.  The SNS acts as an accelerator in an emergency.  SNS increases heart rate, slows digestion, raises blood pressure, causes liver to make more sugar, dilates pupils, etc…  Examples:  A person who is running will see his body respond by increasing heart rate, stimulating lung capacity, etc…  The reaction a body has when it is frightened, or in danger.

21. PARASYMPATHETIC NERVOUS SYSTEM:  C alms the body down after an emergency.  Para means “opposite of.”  Counter (opposite) system to the SNS.  It is made up of nerves that inhibit internal organs.  Conserves body’s energy and gets the system back in balance after the SNS has been activated.  It reduces or conserves energy.  The PNS acts as a brake in an emergency; it is the braking mechanism that slows down the SNS.

22.  If the spinal cord is severed, the parts of the body below the damage have no way of communicating with the brain:  Those parts are immediately paralyzed.  PARALYSIS:  The loss of the ability to voluntarily move a part of the body.  Often, it also involves a loss of sensation of that body part.  It can be temporary or permanent.  It can be partial or complete.

23.  In order to move, a muscle must be stimulated by a nerve.  Paralysis can be caused by damage to :  Brain cells.  Muscles.  CNS (brain and spinal cord).  PNS (other nerves in the body).  Cut nerve cells do not regenerate and paralysis is permanent.  The amount of the body paralyzed by an injury depends on the area of the spinal cord injured. Mike Utley Detroit Lions

24. Forms of Paralysis: (Plegia=paralysis)  PARAPLEGIC:  Paralyzed in the legs.  Caused by spinal cord damage below the neck.  Ex: Mike Utley (Los Angeles Rams Football Player).  QUADRIPLEGIC: (4)  Paralyzed in the arms and legs.  Caused by spinal cord damage in the neck region.  Damage to the brain stem can result in paralysis of muscles that control automatic functions of the body such as breathing and swallowing:  Ex: Christopher Reeves. Christopher Reeves Superman