nervous system lecture simplified

THE NERVOUS SYSTEM

Prepared by:

RENALYN D. GONZALESTeacher II

Halang Banaybanay E/SAmadeo District

a system that coordinates and controls the various activities of the body, both voluntary and involuntary.

General Function

Brain

Spinal Cord

Neurons (Nerve cells, nerves)

Major Parts

PARTS AND FUNCTION OF EACH

PART OF THE NERVOUS SYSTEM

THE BRAIN

Brain

the soft, spongy, gray substance found inside the skull or cranium

Brain

weighs about 1 to 3 kilograms

covered by a gray matter called the cerebral cortex

What Protects the Brain

Skull (Cranium)

The hard, bony structure that protects the brain

Layers of the Meninges

protected by three layers of tissues called meninges

Dura Mater

The outer layer (dura mater) lines the skull

Arachnoid

The middle layer (arachnoid) supplies food and oxygen and also acts as a shock absorber

The inner layer (pia mater) prevents bacteria from entering the brain.

Pia Mater

Cerebrospinal Fluid (CSF)

The fluid circulating in the spaces called ventricles found within the brain and the spinal cord

Cerebrospinal Fluid (CSF)

Functions:cushions the brain

helps in the distribution of chemical substances within the nervous system

a thin layer about 3 to 4 mm, of gray, uninsulated cell bodies (without myelin coating)

serves to protect the white, insulated nerve fibers inside the brain

What are Convolutions

Convolutions

The folds and wrinkles of the brain

General Function

Brain

the master control unit of the body

used to think, learn, remember, hear, see, smell, taste, feel and touch

Brain

controls every activity of the body such as breathing, muscle movement, heartbeat and blood pressure

also controls emotions and feelings

PARTS OF THE BRAIN

Parts of the Brain Cerebrum

Cerebellum Brainstem

Diencephalon

THE CEREBRUM

the largest and uppermost part of the brain

has special areas to receive messages about sight, hearing, smell, taste and touch

has other areas that control movement, personality and intelligence

enables us to think, memorize, recognize and be aware of the things happening in the surroundings

receives and interprets the messages of the five senses

divided into two hemispheres (left and right)

What Divides the Cerebrum

Corpus Callosum

The largest set of white nerve fibers that divides/ connects the right and the left hemispheres

RIGHT HEMISPHERE- controls the muscles of the LEFT side of the body- specialized for spatial relationship, imagination, insight and appreciation of art and music

LEFT HEMISPHERE- controls the muscles of the RIGHT side of the body- specialized for scientific skills, numeracy skills, written and spoken language and analytic thought

Regions of the Cerebrum

Frontal Lobe

Parietal Lobe

Temporal Lobe

Occipital Lobe

Insular Lobe

Voluntary control of skeletal muscles; personality; intellectual process; verbal communication

Cutaneous and muscular sensations; understanding and utterance of speech

Interpretation of auditory sensations; auditory and visual memory

Integration of movements in focusing the eyes; correlation of visual images with previous experiences; conscious seeing

Memory; integration of other cerebral activities

THE CEREBELLUMThe “Little Brain”

the second largest part of the brain

found under and behind the cerebrum

Coordinates movements of the muscles and maintains posture

If damaged, the arms and legs cannot be moved

THE BRAINSTEM

the base of the brain

consists of the medulla oblongata, the midbrain and the pons

Controls involuntary actions such as heartbeat and breathing

conveys messages between the spinal cord and the brain

takes care of reflex actions such as coughing and blinking

Parts of the Brainstem

Medulla oblongata

- regulates the reflex responses controlling respiration, heartbeat, blood pressure and other involuntary processes

Pons-relays impulses between different parts of the brain

Midbrain-controls movement of the eyes, dilation of pupils, focusing of lens

THE DIENCEPHALON

Parts of the Diencephalon

responsible for sensory relay in the brain

the “traffic cop” that directs information

controls motivated behavior by regulating the release of hormones from the pituitary gland.

responsible for the 4 F’s: Fighting, fleeing, feeding and sex.

Small pea-sized gland of the endocrine system, often called the “Master Gland”

Small gland of the endocrine system that controls melatonin production that’s sometimes referred to as the “third eye.”

THE SPINAL CORD

Spinal Cord

The part of the CNS contained within the spinal column that extends from the skull to the first or second lumbar vertebra

A channel through which messages travel from the different parts of the body to the brain and back

Responsible for automatic actions called reflex actions

Internal Structure of the Spinal Cord

also known as “substantia grisea”, and is made up of cell bodies.

Gray Matter

also called as “substantia alba”, is composed of nerve fibers.

White Matter

What is a reflex action?

a rapid, automatic action or response made by the body without action of the brain

Reflex Action

can be a motor or conditioned reflex

A kind of reflex in the form of a movement

e.g. blinking when something suddenly comes too close to the eyes

Motor Reflex

A kind of reflex that can be developed through memory

How one responds to certain signals or situations

Conditioned Reflex

Is based, at least, upon previous experience

Varies from one individual to another

Conditioned Reflex

Examples:

Hearing an ice cream van might make someone’s mouth water.

Seeing and smelling the food you like enables one to associate its appearance and odor with its taste

Path of Message in a Reflex Action

They protect us from harm.

The automatic action of reflexes usually causes one to act correctly and quickly enough to avoid danger.

Importance of Reflex Actions

THE NEURONSNerve Cells

Neuron

The basic unit of the nervous system commonly known as a nerve cell

Neuron

Carry messages (impulses) from one part of the body to another

PARTS OF A NEURON

Cell Bodycontains the nucleus and other cellular structures

Cell Bodyvaries in shape; may be round, oval star-shaped or pyramidal

A long nerve fiber that extends from the cell body

Axon

Carries nerve impulses away from the cell body to other neurons

Axon

Microscopic nerve fibers like tiny trees that receive impulses and send them to the cell body

Dendrites

Short and often branched repeatedly

Dendrites

KINDS OF NEURONSAccording to the direction of the nerve

impulse being transmitted

From the Latin word “afferie” which means “to carry to or in.”

Sensory Neurons (Afferent)

Transmit impulses from the sense organs, the skin, the muscles and the internal organs to the spinal cord or brain

Sensory Neurons (Afferent)

From the Latin word “efferre,” meaning “to carry out or away”

Motor Neurons (Efferent)

Transmit impulses from the interneurons to the muscles, glands and internal organs of the body.

Motor Neurons (Efferent)

Transmit impulses from sensory to motor neurons and process incoming information

Interneurons

Found in the CNS

Interneurons

What is a synapse?

the space between the end of the axon of one neuron and the dendrite of another

controls the overloading of messages sent to the brain

What are neurotransmitters?

chemicals that pass across a synapse from an axon to a dendrite

TWO MAJOR DIVISIONS OF THE NERVOUS SYSTEM

Central Nervous System (CNS)- includes the brain and the spinal cord

Peripheral Nervous System (PNS)- includes the nerves that are linked with the CNS and their motor and nerve endings

stores, processes and sends information to muscles and glands

CENTRAL NERVOUS SYSTEM (CNS)

ORGANIZATION OF THE CENTRAL NERVOUS

SYSTEM

carries messages to and from the CNS

PERIPHERAL NERVOUS SYSTEM (PNS)

consists of 43 pairs of nerves leading from the brain and spinal column to other parts of the body

PERIPHERAL NERVOUS SYSTEM (PNS)

12 pairs are cranial nerves and 31 are spinal nerves that originate in the spinal cord

PERIPHERAL NERVOUS SYSTEM (PNS)

MAJOR DIVISIONS OF THE PERIPHERAL NERVOUS

SYSTEM

DIVISIONS OF THE AUTONOMIC NERVOUS

SYSTEM

ORGANIZATION OF THE PERIPHERAL NERVOUS

SYSTEM

AN OVERVIEW OF THE ORGANIZATION OF THE

NERVOUS SYSTEM

How does the Nervous System

work?

Stimuli are detected by receptor cells which turn them into nerve impulses. These impulses travel along the sensory nerves. They are then transmitted to the nerve centers in the CNS. Then, they are interpreted by the brain. A response is then sent along the motor nerves to the effector cells in the concerned organs.

The Communication System of the Body