The Human Nervous System Chapter 15

Strange Sneezing Situations

 

I. CENTRAL NERVOUS SYSTEM (CNS):

-made up of brain & spinal cord which are protected by cranium & vertebrae
-also protected by:

1) meninges- 3 tough membranes that enclose & protect brain + spinal cord
2) cerebral spinal fluid- liquid that cushions nervous tissue from shock and fills space between meninges, in ventricles (4 spaces with in brain),& in spinal canal of spinal cord

A. BRAIN

1. receives 20% of blood from the heart (glucose is the major energy source)
2. has 3 divisions, each having specialized functions

a. Cerebrum- largest part (2/3 of brain); center of intelligence & awareness; controls thought, memory, learning, emotions, seeing, hearing, taste, smell, touch
-these are examples of voluntary movements

b. Cerebellum- controls balance & muscular behavior
c. Medulla- controls breathing, heartbeat, digestive tract movements; gland secretions, coughing, sneezing, swallowing, vomiting
-these are examples of involuntary movements

Details on CEREBRUM
-largest part of the brain
-Fissure is groove dividing cerebrum into left + right hemispheres
-Cerebral Cortex made of gray matter which consists of interneurons & cell bodies of motor neurons
-Convulsions are folds which increase the surface area of gray matter

CEREBRAL CORTEX- (outermost layer) has 3 functions
1. sensory areas-receives and interprets impulses from sense receptors
2. motor areas- initiates impulses for all voluntary movement
3. associative areas- responsible for memory, learning, and thought

B. SPINAL CORD

1. lies within the column of the vertebrae which is continuous with the brain.
2. inner layer of cord has "H" shaped gray matter and white matter surrounding it
3. it has two main functions

a. connecting brain to the peripheral nerves
b. controls reflexes

REFLEX ARC involves

receptor

-->

sensory

-->

interneuron

-->

motor

-->

effector

Innate Behavior: behavior is present at birth

a. reflexes- involuntary, automatic responses to a given stimulus (no brain involvement) ex.) knee jerk, withdrawal reflexes
b. instincts- complex inborn behavior patterns consisting of senses or a chain of reflexes ex.) building a nest, spinning a web

Acquired Behavior: learned behavior which involves a chain of responses

a. conditioned responses- a new stimulus is substituted for the original in a reflex action ex.)Pavlov's dog
b. habits- learned behavior that becomes automatic ex.) smoking, writing
c. voluntary behavior- purposeful; under conscious control ex.) cooking, memorizing

II. PERIPHERAL NERVOUS SYSTEM {located outside CNS}

-cranial nerves (nerves connect to the brain; 12 pairs)
-spinal nerves (nerves that connect to the spinal cord; 31 pairs)
-it consists of 2 specialized nervous systems

A. Somatic Nervous System: controls voluntary muscles

1. consists of sensory & motor neurons

B. Autonomic Nervous System: made of nerves that control cardiac muscle, glands & smooth muscle. It coordinates involuntary actions.

-consists of motor neurons

1) Parasympathetic Nervous System

2) Sympathetic Nervous System

-both parts of the autonomic nervous. system. are antagonistic to each other

Ganglia and plexuses-serve as relay centers that direct impulses made of motor neurons

III. Some ANOMALIES of the Nervous System

A. Cerebral Palsy- A congenial (existing at birth but not hereditary) disease characterized by a disturbance of the motor functions.

B. Meningitis- inflammation of the membranes surrounding the brain & the spinal cord.

C. Stroke- A disease resulting from a cerebral hemorrhage or a blood clot in the cerebral vessel which may result in brain damage.

D. Polio- A viral disease of the CNS which may result in Paralysis and is preventable through immunization.

E. Rabies- A contagious infection of the CNS, caused by specific virus that enters the body through the bite of an animal.

Take an online quiz

Biology Trivia

1. What are the four primary tastes distinguished by the tongue? answer

2. Name the disorder which is caused during pregnancy to a fetus that leads to uncoordinated muscle actions. Also, name the type of peripheral nervous system that is affected. answer

3. Do the rapid movements of the eyes during the stage of sleep called REM sleep serve any practical use for the eye? answer

return to Mr. Via's syllabus