ANATOMYANATOMY

NERVOUS SYSTEMNERVOUS SYSTEM

OVERVIEWOVERVIEW

Nervous SystemNervous System

The nervous system The nervous system of the human is the of the human is the most highly organized most highly organized system of the body.system of the body.

The overall function of The overall function of the nervous system is the nervous system is to to control and control and coordinate the human coordinate the human body.body.

NERVOUS SYSTEMNERVOUS SYSTEM

The nervous system The nervous system consists of theconsists of the brain, brain, the spinal cord and the spinal cord and the nerves.the nerves.

The functional, The functional, structural unit of the structural unit of the nervous system is the nervous system is the nerve cell called thenerve cell called the neuron.neuron.

NeuronsNeurons

The neuron has The neuron has extensions of various extensions of various lengths from its cell lengths from its cell body called body called Dendrites Dendrites and Axons.and Axons.

Each cell body may Each cell body may have many dendrites, have many dendrites, but only one axonbut only one axon..

NeuronsNeurons

The Dendrites receive The Dendrites receive an impulse, pass it to an impulse, pass it to the the cell bodycell body, then to , then to the axon where it is the axon where it is passed on to passed on to muscle,muscle, glands or another glands or another neuron.neuron.

NeuronsNeurons

There are three types of neurons:There are three types of neurons: SensorySensory Motor or connectingMotor or connecting AssociativeAssociative

• Neurons do not connect with each other but send Neurons do not connect with each other but send impulses over spaces called synapses.impulses over spaces called synapses.

Divisions of the nervous systemDivisions of the nervous system

The central nervous The central nervous system includes the brain system includes the brain and the spinal cord. The and the spinal cord. The nerves of the spinal cord nerves of the spinal cord and brain do not have the and brain do not have the special coating called special coating called neurilemma which allows neurilemma which allows nerve cells to repair. nerve cells to repair. (paralysis or death may (paralysis or death may occur)occur)

Nervous system divisionsNervous system divisions

The peripheral The peripheral nervous system is nervous system is composed of all the composed of all the nerves extending nerves extending from the brain (cranial from the brain (cranial nerves) and spinal nerves) and spinal cord. (spinal nerves)cord. (spinal nerves)

Peripheral systemPeripheral system

The peripheral nervous The peripheral nervous system connects the system connects the central nervous system to central nervous system to various body structures. various body structures. Cranial nerves carry Cranial nerves carry impulses to and from the impulses to and from the brain, spinal nerves carry brain, spinal nerves carry impulses to and from the impulses to and from the spinal cord.spinal cord.

Autonomic systemAutonomic system

The autonomic The autonomic system controls the system controls the involuntaryinvoluntary or or automatic activities of automatic activities of vital internal organs, vital internal organs, such as the heart, such as the heart, blood vessels and blood vessels and organs of organs of digestion.digestion.

The brainThe brain

The brain is a The brain is a complex mass of complex mass of tissue protected by tissue protected by the bony structure of the bony structure of the cranium. The the cranium. The brain is further brain is further protected by protected by membrane coverings membrane coverings called the meninges called the meninges and cerebrospinal and cerebrospinal fluid.fluid.

The brainThe brain

There are three major There are three major parts of the brain.parts of the brain. The cerebrumThe cerebrum The cerebellumThe cerebellum The brain stemThe brain stem

The CerebrumThe Cerebrum

The cerebrum is the The cerebrum is the largest part of the largest part of the brain, divided into two brain, divided into two hemispheres. Each hemispheres. Each hemisphere is divided hemisphere is divided into four lobes.into four lobes. The frontalThe frontal The parietalThe parietal The occipitalThe occipital The temporalThe temporal

Lobes of the brainLobes of the brain

Each lobe of the cerebral hemispheres Each lobe of the cerebral hemispheres control specific functions .control specific functions . #1 The frontal lobe:#1 The frontal lobe:

• The cells in the right half control the voluntary The cells in the right half control the voluntary motor motor movements of the left side of the body, and movements of the left side of the body, and the left side controls the right side. The frontal the left side controls the right side. The frontal lobe also controls lobe also controls speech.speech.

Lobes of the brainLobes of the brain

#2 The parietal lobe:#2 The parietal lobe:• This area receives and interprets nerve impulses This area receives and interprets nerve impulses

from the from the sensorysensory receptors for pain, touch, heat receptors for pain, touch, heat and cold. The parietal lobe also helps determine and cold. The parietal lobe also helps determine distancedistance, size and shape., size and shape.

#3 The occipital lobe:#3 The occipital lobe:• Located over the back of the brain over the Located over the back of the brain over the

cerebellum contains the visual area controlling cerebellum contains the visual area controlling eyesight.eyesight.

Lobes of the brainLobes of the brain

#4 The temporal:#4 The temporal:• Located on the sides of the brain, the temporal Located on the sides of the brain, the temporal

lobe contains areas which control lobe contains areas which control auditory hearingauditory hearing and and olfactory smell.olfactory smell.

The CerebrumThe Cerebrum

The outer layer of the The outer layer of the cerebrum is gray cerebrum is gray nerve tissue called nerve tissue called the cerebral cortex. It the cerebral cortex. It is formed with deep is formed with deep folds causing folds causing elevated portions elevated portions called convolutions called convolutions and furrows and and furrows and groves called groves called fissures.fissures.

The cerebrumThe cerebrum

This folding (convolutions and fissures) This folding (convolutions and fissures) increase the surface area of the cerebral increase the surface area of the cerebral cortex. The cerebral cortex controls cortex. The cerebral cortex controls thoughts, judgment, memory, reasoning, thoughts, judgment, memory, reasoning, and will power.and will power.

Under the gray matterUnder the gray matter

Beneath the gray matter Beneath the gray matter of the cerebral cortex lies of the cerebral cortex lies the thalamus, and the thalamus, and hypothalamus. The hypothalamus. The thalamus acts as a relay thalamus acts as a relay center for sensory center for sensory impulses to the cerebral impulses to the cerebral cortex. The cortex. The hypothalamus controls hypothalamus controls temperature, sleep, water temperature, sleep, water balance and chemical balance and chemical activities.activities.

The cerebellumThe cerebellum

This part of the brain This part of the brain located at the back located at the back and lower part of the and lower part of the brain coordinates the brain coordinates the muscular muscular movements movements of the body, such as of the body, such as balance in walking balance in walking and sitting.and sitting.

The brain stemThe brain stem

The brain stem is The brain stem is made up of three made up of three parts. The midbrain, parts. The midbrain, the pons and the the pons and the medulla. This part of medulla. This part of the brain controls the brain controls respiration, heart and respiration, heart and blood vessels.blood vessels.

The Spinal cordThe Spinal cord

The spinal cord is The spinal cord is made up of nerve made up of nerve fibers protected by fibers protected by the bony structure of the bony structure of the vertebra and the vertebra and spinal fluid. The spinal fluid. The function of the spinal function of the spinal cord is to serve as a cord is to serve as a pathway to and from pathway to and from the brain.the brain.

DiseasesDiseases

Nerve cells often do Nerve cells often do not repair themselves not repair themselves so damage can cause so damage can cause permanent loss of permanent loss of function. Damage to function. Damage to the brain and spinal the brain and spinal cord by force and cord by force and injury may result in injury may result in death or paralysis.death or paralysis.

DiseasesDiseases

Other disease Other disease include:include: Parkinson'sParkinson's SeizuresSeizures Multiple sclerosisMultiple sclerosis Cerebral vascular Cerebral vascular

accident (CVA or accident (CVA or stroke)stroke)

Infections and tumors Infections and tumors also may affect the also may affect the nervous system.nervous system.

Vocabulary WordsVocabulary Words