nervous system lecture simplified
TRANSCRIPT
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