Transcript Chapter_25 (1)

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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 25
Communication and Control
Section 1: The Nervous System
Section 2: Responding to the Environment
Section 3: The Endocrine System
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
Bellringer
List as many functions of the brain as you can. Don’t forget
that in addition to controlling your body, your brain is also
occupied with thinking. How do you suppose your brain can
coordinate all these functions?
Record your ideas in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
Objectives
• Describe the relationship between the central nervous
system and the peripheral nervous system.
• Compare the somatic nervous system with the autonomic
nervous system.
• List one function of each part of the brain.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
Two Systems Within a System
• The CNS and PNS The nervous system has two parts:
the central nervous system and the peripheral nervous
system. The central nervous system (CNS) is your brain
and spinal cord. The CNS processes and responds to all
messages coming from the peripheral nervous system. The
peripheral nervous system (PNS) is all of the parts of the
nervous system except for the brain and the spinal cord.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
The Peripheral Nervous System
• Neuron Structure A neuron is a nerve cell that is
specialized to transfer messages in the form of fast-moving
electrical energy. The structure of a neuron is shown on the
next slide.
• Information Collection Some neurons are sensory
neurons. These neurons gather information about what is
happening in and around your body.
• Delivering Orders Neurons that send impulses from the
brain and spinal cord to other systems are called motor
neurons.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
A Typical Neuron
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Section 1
The Nervous System
Nerves
• What Is a Nerve? The central nervous system is
connected to the rest of your body by nerves. A nerve is a
collection of axons bundled together with blood vessels and
connective tissue. The structure of a nerve is shown on the
next slide.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is a Nerve?
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Section 1
The Nervous System
Somatic and Autonomic Nervous Systems
• Somatic Nervous System Most of the neurons that are
part of the somatic nervous system are under your
conscious control.
• Autonomic Nervous System Autonomic nerves do not
need your conscious control. These neurons are part of the
autonomic nervous system. The autonomic nervous system
controls body functions that you don’t think about, such as
digestion and heart rate.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
The Central Nervous System
• The Brain The brain, illustrated on the next slide, is the
main control center of the nervous system.
• The Cerebrum The cerebrum is where you think and
where most memories are stored.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Nervous System
The Central Nervous System continued
• The Cerebellum The cerebellum processes sensory
information from your body, such as from skeletal muscles
and joints.
• The Medulla The medulla controls involuntary processes
such as blood pressure, body temperature, heart rate, and
involuntary breathing.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Regions of the Brain
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Section 1
The Nervous System
The Spinal Cord
• Route to the Brain The spinal cord is made of neurons
and bundles of axons that pass impulses to and from the
brain. As you can see on the next slide, the spinal cord is
surrounded by protective bones called vertebrae.
• Spinal Cord Injury A spinal cord injury may block all
information to and from the brain. Each year, thousands of
people are paralyzed by spinal cord injuries. Many of these
injuries happen in car accidents and could be avoided by
wearing a seat belt.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Spinal Cord
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Bellringer
List the five senses, and draw the organ associated with
each sense as well as an object detected by each sense.
Can any of these objects be detected by more than one of
the senses? How could it be helpful to use more than one
sense to get information about an object?
Record your answers in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Objectives
• List four sensations that are detected by receptors in the
skin.
• Describe how a feedback mechanism works.
• Describe how light relates to sight.
• Describe how the senses of hearing, taste, and smell
work.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Sense of Touch
• Stimuli and Receptors Touch is what you feel when
sensory receptors in the skin are stimulated. Skin has
different kinds of receptors. Each kind of receptor responds
mainly to one kind of stimulus.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Responding to Sensory Messages
• Reflexes Pain receptors in your skin activate immediate,
involuntary actions called reflexes. Reflexes help you move
quickly out of the way of danger.
• Feedback Mechanisms A feedback mechanism is a
cycle of events in which information from one step controls
or affects a previous step. Your body has many different
feedback mechanisms that rely on sensory messages to
make sure your body is operating within normal perimeters.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Sense of Sight
• Reacting to Light Your pupil is an opening that lets light
enter the eye. The pupil is surrounded by the iris, a ring of
muscle. The iris controls the amount of light that enters the
eye.
• Focusing the Light Light travels in straight lines until it
passes through the cornea and the lens. Muscles in the
eye change the shape of the lens in order to focus light
onto the retina.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Sense of Hearing
• Ears Ears are organs specialized for hearing. Each ear
has an outer, middle, and inner portion. Sound waves
reaching the outer ear are funneled into the middle ear and
then the inner ear before being interpreted by the brain.
Sense of Taste
• Taste Buds Your tongue is covered with tiny bumps
called papillae. Most papillae contain taste buds. Taste
buds respond to sweetness, sourness, saltiness, and
bitterness.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Responding to the Environment
Sense of Smell
• The Nose Knows Receptors for smell are located on
olfactory cells in the upper part of your nasal cavity. An
olfactory cell is a nerve cell that responds to chemical
molecules in the air. You smell something when the
receptors react to molecules that have been inhaled.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Endocrine System
Bellringer
Unscramble the following words:
nalgd
meornoh
noclotr
Try to use each word in a sentence about the endocrine
system.
Write your answers in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Endocrine System
Objectives
• Explain why the endocrine system is important to the
body.
• Identify five glands of the endocrine system, and
describe what their hormones do.
• Describe how feedback mechanisms stop and start
hormone release.
• Name two hormone imbalances.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Endocrine System
Hormones as Chemical Messengers
• Products of Glands The endocrine system controls body
functions by using chemicals that are made by the
endocrine glands. A gland is a group of cells that make
special chemicals for your body. Chemical messengers
made by the endocrine glands are called hormones.
More Endocrine Glands
• Thyroid and Thymus Thyroid hormones control the
secretion of growth hormones for normal body growth. Your
thymus gland is important to your immune system. Cells
called killer T cells grow and mature in the thymus gland.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Endocrine System
Controlling the Endocrine Glands
• Feedback Mechanisms Endocrine glands control may
feedback mechanisms in the body.
Hormone Imbalances
• Endocrine System Disorders Occasionally, an
endocrine gland makes too much or not enough of a
hormone. For example, sometimes a child’s pituitary gland
doesn’t make enough growth hormone. As a result, the
child’s growth is stunted.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 25
Communication and Control
Concept Map
Use the following terms to complete the concept map on
the next slide: brain, neurons, medulla, cerebellum,
peripheral nerves, dendrites, spinal cord.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 25
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 25
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.