Control & Coordination
The Nervous System
Neurons
Central Nervous System
•Brain
•Spinal Cord
Peripheral Nervous System
The Senses
Organization in the Body
BODY
A collection of systems
SYSTEM
Several organs working together;
each system has one major role
ORGAN
A distinct body part that carries
out one or more main functions
TISSUE
A group of similar cells that
carry out a specialized job
CELL
ORGANELLE
The basic building block of all
living things, plant or animal
Specialized structures inside a
cell that have specific functions
Helps the body
adjust to changes in
your environment
Stimulus
Any change inside or
outside your body that
brings about a response
Homeostasis
Regulation of steady
conditions inside the
body
The Nervous System
Central Nervous System =
Brain + Spinal Cord
Peripheral Nervous System =
Nerves to rest of body
Neurons
Building blocks of the nervous system
100 billion neurons in your brain alone
30,000 on a pinhead
They communicate with each other
thousands of times a second.
Bundles of neurons make up NERVES
3 Types of Nerve Cells
Sensory Neurons
Receive information form a sensory receptor
and send impulses to the CNS
Interneurons
Relay impulses from sensory neurons to
motor neurons
Motor Neurons
Carry impulse from the CNS to muscles and
glands through out the body
Parts of a
Neuron
3 MAIN PARTS
 Dendrites - receive
messages from other
neurons
 Cell Body – nucleus is
found here
 Axon - sends messages
to other neurons
Dendrites
Parts of a
Neuron
Cell Body
Axon
 Space between each neuron
 Neurotransmitters are the messengers that
travel across each synapse
 They are chemical signals that neurons use to
talk to each other, which is what makes your
brain work. They help determine how you feel,
think and act.
Neurotransmitters
• Serotonin - involved in mood (such as
helping you to feel happy), sleep, mental
health, blood pressure and heartbeat.
• Dopamine - important in helping to
regulate physical movement, pleasure,
and thought.
– Missing in patients with Parkinson's Disease.
Neurotransmitters
• Acetylcholine - involved in regulating
muscles, memory, mood, sleep, and
organs (like the heart).
– Lowered amounts associated with
Alzheimer’s Disease
Central Nervous System
(C.N.S.)
Cerebrum
 Largest part of the brain
 Interprets impulses from
the senses
Responsible for:
 thinking and learning
 creativity
 five senses
 memory and emotion
 problem-solving
 decisions
Cerebellum
 Coordinates voluntary
muscle movement
 Helps maintain balance
 When a ball is thrown to
you, the cerebellum
coordinates the proper
response to prevent injury
Brainstem
 Controls involuntary
actions
 Connects the brain to the
spinal cord
 Regulates heart rate,
breathing, swallowing,
blinking, and more
Made up of:
the midbrain
pons
medulla
Spinal Cord
 Made up of bundles of
neurons
 Carries impulses to and
from the brain
 Together, the brain and
spinal cord make up the
Central Nervous System
(C.N.S.)
Fun fact:
 The spinal cord is about
45 cm long in men and 43
cm long in women.
Peripheral Nervous System
(P.N.S.)
 Connects the C.N.S. with the
rest of the body
• sensory nerves take impulse
from stimulus (sensory
receptors) to the the CNS
• motor nerves take impulse
from the CNS to the muscles
and glands that take action.
Reflex
REFLEX
An involuntary, automatic response to a
stimulus controlled by the spinal cord
Like when the doctor uses the rubber
mallet on your tendon below your knee
Movement when someone
unexpectedly throws something at you
Reflex Arc
When the body receives a painful stimulus (stepping on a
nail, touching a hot surface, etc), the body responds
super-fast.
Reflex Arc
A short-cut an impulse takes for a quicker response
Path of reflex arc:
STIMULUS sensory receptor sensory nerve
spinal cord (interneuron) motor nerve
muscle RESPONSE
An impulse continues up to the brain to be interpreted by
the cerebrum, BUT, meanwhile the affected area has
already produced a response!
Autonomic Nervous System
(part of the P.N.S.)
Fight or flight
• Often referred to as your 'fight-or-flight' system,
your sympathetic nervous system prepares your
body for emergencies. It shunts your blood to
your muscles and increases your blood pressure,
heart rate and breathing rate, enabling you to
cope with stressful situations.
Rest and digest
• Your parasympathetic nervous system maintains
and restores your energy. It directs blood to your
digestive tract and makes sure you actively
digest food. It also maintains your blood
pressure, heart rate and breathing rate at a low
level. That's why it is sometimes called your 'rest
and digest' system.
Return
to
normal
Fight
or
flight
Senses
Vision
Sensory Receptors
Rods sense brightness
Cones sense color
The retina, in the back of your eye, has cells that
are sensitive to light. They connect directly to your
brain.
Senses
Hearing
 Sound waves make your
eardrum vibrate.
 Small bones in your ear
vibrate (hammer, anvil,
stirrup)
 Vibrations go through the
snail-like cochlea, which
turns them into nerve
impulses to your brain.
Taste
 10,000 taste buds in your
mouth
 Your tongue picks up four
types of taste:
•
•
•
•
sweet
sour
bitter
salty
 Sweet and salty are least
sensitive
 Bitter ones are most
sensitive
Senses
Senses
Smell
 Odor particles drift into your nose
 Stimulate sensory receptors – olfactory
cells – in nasal passages
 Sensory receptors send impulses to
your brain to be interpreted.
Touch
There are at least six
types of touch
receptors in your skin:
• Hot
• Cold
• Pain
• Pressure
• Touch
• Fine touch
Senses
Questions
• What are the main parts of the brain?
What is the function of each?
• Describe a neuron – What is it? What
types are there? What are the parts of a
neuron?
• What is the central nervous system?
• What is the peripheral nervous system?
Questions
• What is a stimulus? Response?
• An involuntary, automatic response to a
stimulus is what? What path does the
impulse take?
• Define homeostasis.
Helpful Resource
• http://www.morphonix.com/software/educat
ion/science/brain/game/specimens/specimen
s.html