Download The Nervous System

The Nervous System:
Communication of the Human Body
Sarah White
Per. 7
State Standards
As a result of the coordinated structures and functions of organ
systems, the internal environment of the human body remains
relatively stable (homeostatic) despite changes in the outside
environment. As a basis for understanding this concept:
 b. Students know how the nervous system mediates communication
between different parts of the body and the body's interactions with the
environment.
 c. Students know how feedback loops in the nervous and endocrine
systems regulate conditions in the body.
 d. Students know the functions of the nervous system and the role of
neurons in transmitting electrochemical impulses.
 e. Students know the roles of sensory neurons, interneurons, and
motor neurons in sensation, thought, and response.
Purpose - Control Body Functions
 Central
 Hypothalamus regulates
body temperature
 Brain sends impulses to
body to maintain
homeostasis
 Parts of brain control
actions
 Peripheral
 Senses send messages
along neurons
 Go to brain and spinal
Click picture for Homeostasis Animation
cord
 Messages travel along
neurons to destination
organs
Purpose - Responds to Stimuli
 Central
 Recognizes stimuli
 Decides what to do
 Sends/Receives
messages
 Peripheral
 Carries messages to tell
brain
 Carries messages to tell
organ systems
Purpose - Nerve Impulse
Impulse - electrical signals
carried by nervous system
 An impulse begins when a
neuron is stimulated by another
neuron or by the environment.
 The Nerve Impulse is like a chain
of dominoes
 Ions pass through the cell
membrane, passing the
message along

 Changes the charge with sodium
and potassium ions

Synapse
At the end of a neuron, impulse
jumps a gap (synaptic cleft)
 Neurotransmitter chemicals
travel across the gap and attach
to the next cell

Click on picture and scroll to watch
“Neural Transmission” Animation.
*All underlined text from textbook
Resting Potential - negative
charge inside
 Action Potential - impulse makes
it positive

Central Nervous System
 Relays messages, processes
information + analyzes
information
 Composed of Brain and
Spinal Cord
 Protected by skull and
vertebrae
 Wrapped in three layers of
connective tissue - meninges
 Cerebrospinal fluid
 coats the brain and spinal
cord to prevent shock and
damage
 Allows nutrients and waste
products to move between
blood and nervous tissue
Brain
 Cerebrum - largest part
 Responsible for voluntary
activities such as thought
and decisions
 Divided into right and left
halves connected by corpus
callosum (band of tissue)
 Each half receives and
sends messages to the other
side of the body
 Right is said to be more
creative and artistic
 Left may be more
controlling of math and
analysis
 Divided into lobes named for
the parts of the skull
Contains approximately 100 billion neurons!
Brain
 Cerebrum made of
two surfaces
 Outer surface called
cerebral cortex
 Gray matter - densely
packed nerve cell
bodies
 Interprets messages
from senses and
controls body
movements
 Inner surface
 White matter - made
up of bundles of
axons with myelin
sheaths
Brain
 Cerebellum - second largest
 Located at back
 Coordinates and balances
actions of muscles
 Brain Stem - connects brain
and spinal cord
Pons
 Pons & Medulla oblongata
 Regulate flow of information
between brain and body
 Control blood pressure,
heart rate, breathing
 Thalamus - receives
Medulla Oblongata
messages from sense organs
and sends to proper area of
brain
 Hypothalamus - recognition
and analysis of hunger, thirst,
fatigue, anger, temperature
Spinal Cord
 Thirty-one pairs of
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
nerves branch out
 Reflexes - quick,
automatic response to
stimulus are taken care
of by the spinal cord
 The messages for
reflexes don’t go to the
brain…Why?
It takes too long
Peripheral Nervous System
 Nerves and cells not part of
the brain or spinal cord
 Cranial nerves - stimulate
head and neck
 Spinal nerves
 Ganglia - nerve cell bodies
 Sensory - takes messages
from sense organs to
brain/spinal cord
 Motor - takes messages from
brain/spinal cord to muscles
and glands
 Two divisions of peripheral
nervous system
 Somatic
 Autonomic
Somatic Nervous System
 Controls activities you
are aware of
 Movement of muscles
connected to bones
 Uses motor neurons
 Also involves reflexes
 Reflex arc - the path
an impulse takes from
the sensory receptor -> body part that
responds
Autonomic Nervous System
 Controls involuntary
movements
 Regulates heartbeat and
digestion
 Sympathetic and
Parasympathetic Branches
 Both control opposite actions
on the same organ systems
 Similar to Gas/Brake Pedals
in a car
Neurons

Cell Body - consists of nucleus
and most of the cytoplasm


Dendrites - spread from the cell
body


Most of the activity takes place
here
Carry impulses from the
environment or other neurons
toward the cell body
Axon - long fiber
Carries impulses away from cell
body
 Ends in axon terminals


Myelin Sheath - insulating
membrane


Surrounds an axon
Nodes - gaps where the axon
membrane is exposed

Impulses jump from one node to
the next
 Increases the rate at which the
impulse can go
Neurons
 Sensory - carry impulses to
the brain and spinal cord
from the sense organs
 Ex: recognize a sound,
movement, taste, texture,
smell
 Motor - carry impulses away
from the brain to cause a
reaction in another organ
 Ex: move a muscle, produce
enzymes in glands
 Interneurons - connect
Interneuron
Sensory
Motor
sensory and motor neurons,
pass impulses in between the
two types
Sensory Receptors
 NOT the typical 5 Senses
 All send messages to the
brain
 Pain receptors
 Located throughout the
body except the brain
 Respond to chemicals
released by damaged cells
 Pain usually indicates
danger, injury or disease
 Thermoreceptors
 Located in skin, body core,
and hypothalamus
 Respond to changes in
temperature
Sensory Receptors

Mechanoreceptors
Located in skin, skeletal muscles,
and inner ears
 Respond to touch, pressure,
stretching of muscles, sound, and
motion


Chemoreceptors
Located in nose and taste buds
 Respond to chemicals in external
environment


Photoreceptors
Located in eyes
 Respond to light

Malfunction
 Alzheimer’s Disease
 Mental function deteriorates,
but motor skills are kept
intact
 Results in restricted memory,
thoughts, and behavior,
confusion, impaired
judgment, communication,
and visuospatial skills,
decrease in speaking skills,
etc
 Production of some brain
chemicals is reduced
 Cause unknown, but
 Age and family history
 Certain genes
 Abnormal protein deposits in
brain
are suspected causes
Malfunction
 Charcot-Marie-Tooth Disease
(CMT)
 Patients gradually lose




feeling in their legs, arms,
and extremities (hands, feet)
Disorder in the peripheral
nerves that control sensory
info in the muscles
Is hereditary
Normally not life-threatening
until it affects breathing
Symptoms include extreme
foot deformities such as a
very high arch, clawed toes,
or very flat feet, problems
with balance, walking, or
running, and very thin lower
legs
Promotion
 Eat healthy foods with lots




good fat, Vitamin D, and
Vitamin B12
Wear a helmet and seat
belt to prevent paralysis or
brain damage
Avoid drugs, alcohol, and
tobacco
Take time to relax
Use your brain!
 Write (pencil and paper)
or draw with precision to
ensure best condition