The nervous system is made up of neurons that transmit signals between the central nervous system (CNS) and peripheral nervous system (PNS). The CNS contains the brain and spinal cord, which coordinate sensation, movement, and homeostasis. The PNS connects the CNS to sensory receptors and effector organs. Neurons communicate via synapses using neurotransmitters like serotonin and dopamine. The CNS controls voluntary and involuntary functions while the PNS connects to sensory organs and muscles.

1. Control &
Coordination

2. The
Nervous System
Neurons
Central
Nervous System
Brain
•Spinal Cord
•
Peripheral
The
Senses
Nervous System

3. OO 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

4. Helps the body adjust to
changes in your environment

5. Stimulus
Any change inside or
outside your body that
brings about a response
Homeostasis
Regulation of steady
conditions inside the
body

6. 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

7. 
Central Nervous System =
Brain + Spinal Cord

Peripheral Nervous System =
Nerves to rest of body

8. 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

9. 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

10. Dendrites
Parts of a
Neuron
Cell Body
Axon

12. 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.

13. 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.

14. Neurotransmitters
• Acetylcholine - involved in regulating
muscles, memory, mood, sleep, and
organs (like the heart).
– Lowered amounts associated with
Alzheimer’s Disease

15. Central Nervous System
(C.N.S.)

16. 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

17. Cerebellum
 Coordinates voluntary
muscle movement
 Helps maintain balance
 When a ball is thrown to
you, the cerebellum
coordinates the proper
response to prevent injury

18. 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

19.  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.

20. 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 CNS
• motor nerves take impulse
from the CNS to the muscles
and glands that take action.

21. 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

22. Reflex Arc
When the body receives a painful stimulus (stepping
on a nail, touching a hot surface, etc), the body
responds super-fast.
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!

23. 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.

24. 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.

25. 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

26. 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.

27. TOUCH
There are at least six
types of touch receptors
in your skin:
• Hot
• Cold
• Pain
• Pressure
• Touch
• Fine touch
Senses