Transcript Chapter 24 Regulatio..

Chapter 24 Regulation
Why do you respond to changes
around you?
• Your responses are controlled by your nervous
and endocrine system.
• Together these 2 systems regulate or control,
all of your body’s responses.
Nervous system
• This system detects and responds to changes
inside and outside of your body.
• How does the nervous system do all of this?
1. The nervous system receives information about
the environment or other parts of the body.
2. Then it interprets the information.
3. Finally it responds to the information.
Nervous System
1. Peripheral Nervous System (PNS)
– Sensory Neurons
– Motor Neurons
– Associative Neurons
2. Central Nervous System (CNS)
– Brain
– Spinal Cord
Peripheral Nervous System (PNS)
• Neurons = nerve cells
– They are the basic unit of structure and function in
the PNS.
– Their job is to carry messages.
Parts of a neuron
• Cell body: contains the nucleus and most of the
cytoplasm
• Dendrite: carry messages from other neurons to
the cell body
• Axon: a long thin fiber extends from the cell body
that carries messages away to another neuron.
Different kinds of neurons
• Sensory neurons: carry
messages from the sense
organs to the spinal cord
and brain.
• Motor neurons: carry
messages from the brain
and spinal cord to muscles
or glands.
• Associative neuron:
connect sensory neurons
and motor neurons.
What kind of messages do neurons
carry?
• Impulses are sent from one neuron to the next
– They are tiny jolts of electrical chemical energy.
Central Nervous System (CNS)
• Brain = control center
• 3 parts
– Cerebrum
– Cerebellum
– Medulla
Cerebrum
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This is the large upper portion of the brain
It controls movement and speech
Interprets information from the sense organs
Cerebrum controls many functions associated
with intelligence (thinking, reasoning, and
memory)
Each half controls activities of the
opposite side of the body.
Which half of the brain do you think is
dominant in people who are left
handed?
• Right side of the brain
Cerebellum
• This portion of your brain is found at the back
of your head beneath the cerebrum and is
much smaller.
• All motor nerve impulses that begin in the
cerebrum pass through the cerebellum.
• The cerebellum adjusts the impulses so that
your movements are coordinated.
• It also helps you maintain balance.
Medulla
• Nerves from the cerebrum and the cerebellum
form a thick stalk called the brain stem at the
base of the skull.
• The medulla is the lower part of the brain stem,
which connects the brain to the spinal cord.
• It controls many involuntary actions (digestion,
breathing, blood pressure, and heart rate)
CNS – Spinal Cord
• The spinal cord is made of many nerves that
extend from the medulla all the way down the
back.
• All sensory and motor nerves found below the
neck pass through the spinal cord on their way to
the brain.
• 31 pairs of nerves extend from the spinal cord.
– These nerves branch many times and go to specific
parts of the body.
Nerve Pathway
• Synapse : gap between the dendrite of 1 neuron
and the axon of another.
• Reflex: automatic response to stimuli.
– Although the brain controls most responses it doesn’t
control reflexes
– Spinal cord controls reflexes
• Ex: touching a hot pan
Nerve Pathways
Why is a reflex reaction followed by an
“ouch”?
• While impulses are traveling along the reflex
arc the spinal cord also sends messages to the
brain.
• Once the brain receives the message and
interprets it, it sends messages to the pain
receptors in your hand.