Download the nervous system

Functions of the
Nervous System
• Controls and Coordinates
functions throughout the body
• Responds to internal and
external stimuli
How does it do it?
• Cells carry messages from one part of the body
to another
• The messages in the nervous system are
electrical signals called impulses
• The cells that transmit the impulses are called
neurons
– Made of:
• Dendrite
• Axon
• Myelin Sheath
Neurons
3 Main Types:
Sensory neurons – carry messages from
sense organs to the spinal cord and brain
Motor neurons – carry messages from
the brain to muscles and glands
Interneurons – connect sensory and
motor neurons
Sending Messages
• An impulse begins when it is stimulated
either by another neuron or the
environment
• The impulse is sent through many neurons
and cells
• The space between the cells is called the
synapse
• Neurotransmitters are chemicals that help
the impulse cross over the synapse
Parts of the Nervous
System
• The Central Nervous System:
– Relays messages, processes information, and
analyzes information
– Includes the brain and spinal cord
• The Peripheral Nervous System:
– Sensory Division: transmits impulses from
sense organs
– Motor Division: transmits impulses from the
central nervous system to the muscles and
glands
The Brain
• Cerebrum – voluntary and conscious thought
• Cerebellum – coordinates and balances actions
• Brain Stem – regulates flow of information, controls body
functions like breathing, blood pressure, etc.
• Thalamus and Hypothalamus – receives information
from sense organs, analyzes feelings like hunger and
thirst
The Spinal Cord
• Connects the brain to the rest of the body
– Acts like a telephone line sending a message
• Controls simple reflexes (like sneezing
and blinking)
The Senses
• Special neurons, called sensory receptors,
react to specific stimuli like light or sound
• The five major types of sensory receptors are:
Sense damaged cells
– Pain Receptors
Changes in temperature
– Thermoreceptors
– Mechanoreceptors Pressure, touch, sound, motion
Chemical Changes
– Chemoreceptors
Light
– Photoreceptors
Where are these receptors found?