Transcript Central nervous system (CNS)

Communication and Control
Communication and Control
Chapter 11 – Section 1
 Central nervous system (CNS): the brain and the spinal cord. It responds to all the
messages coming from the peripheral nervous system.
 Peripheral Nervous system (PNS): all of the parts of the nervous system except for the
brain and the spinal cord. It connects all parts of the body to the CNS.
 Neuron: a nerve cell that is specialized to receive and conduct electrical impulses. Impulses
can travel as fast as 150 m/s or as slow as 0.2 m/s.
 Axons: elongated extensions of a neuron. Has a tip called the axon terminal. Information is
sent from here.
 Dendrite: short branched extensions. This is where impulses are received.
 Synapse: empty space between neurons where messages are sent.
 Two types of Neurons:
 Sensory Neuron: nerves that gather information about what is happening in and around your body.
Have special endings called receptors. Ex. touching something hot or moving from a dark room to a
lighted room. They send information to the CNS.
Communication and Control
Chapter 11 – Section 1
 Motor Neurons: Sends impulses from the brain and spinal cord to other
systems. Muscle contract when touching something hot or squinting when
seeing something bright.
 Nerve: a collection of nerve fibers (axons) through which impulses travel
between the central nervous system and other part of the body. Most contain a
collection of both motor and sensory neurons.
 PNS has two types of nerves:
 Somatic nervous system: most of the neurons that are under your conscious
control. They control voluntary movements such as writing, talking, smiling or
jumping.
 Autonomic Nervous System: nerves that do not need your conscious control.
They control body functions such as digestion and heart rate. Has two divisions.
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Sympathetic Nervous System:
Parasympathetic Nervous System
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
Brain: the mass of nerve tissue that is the main control center of the nervous system. Largest organ in
the nervous system. Is responsible for voluntary and involuntary control. Has three main parts:
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Cerebrum: largest part of your brain, where you think and where most memories are stored, controls
voluntary movements and allow you to sense touch, light, sound, odors, taste, pain, heat and cold. Has
two hemispheres:
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Left: speaking, reading, writing, and problem solving. Math and science. Directs right side of body.
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Right: spatial thinking, processing music, interpreting emotions, arts, and acting. Directs left side
of body.
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Cerebellum: 2nd largest part of your brain. Allows the brain to keep track of your body position. Helps
you to stay balanced.
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Medulla: controls involuntary processes such as blood pressure, body temperature, heart rate, and
involuntary breathing. You cannot live without it.
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Areas of the brain at work: pg. 287.
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Spinal cord: Part of the CNS and is the size of your thumb and surrounded by vertebrae.
Communication and Control
Chapter 11 – Section 2
 Integumentary system: the organ system that forms a protective covering
on the outside of the body
 Reflex: an involuntary and almost immediate movement in response to a
stimulus. Message does not go to the brain.
 Feedback mechanism: a cycle of events in which information from one step
controls or affects a previous step.
 Ex: heat receptors detect high temperatures, body becomes hot, message is
sent for blood vessels to dilate, sweating begins and temperature of body is
lowered.
 Retina: the light-sensitive inner layer of the eye: it receives images formed
by the lens and transmits them through the optic nerve to the brain
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Chapter 11 – Section 2
 Cochlea: a coiled tube that is found in the inner ear and that
is essential to hearing
 Hearing Parts:
 Ear Canal
 Eardrum
 Ear bones
 Cochlea
 Auditory nerve
Communication and Control
Chapter 11 – Section 3
 Endocrine system: a collection of glands and groups of cells
that secrete hormones that regulate growth, development,
and homeostasis. This system uses chemicals.
 Gland: a group of cells that make special chemicals for the
body. They make hormones.
 Hormone: a substance that is made in one cell or tissue and
that causes a change in another cell or tissue in a different
part of the body. Basically, chemical messengers.
 Endocrine glands can affect many organs at one time. Fight
or flight---adrenal glands release adrenaline.
Section 3
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Pituitary gland: stimulates skeleton growth and helps your thyroid gland function properly. It also
regulates the amount of water in your blood. About the size of a marble and found at the base of the
cerebrum. It also releases HGH—controls how fast everything grows. Releases hormones that control all
other glands. Referred to as the “master gland”.
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Thyroid: determines the rate at which you use energy. It controls metabolism. Located in the upper
chest and is butterfly shaped.
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Pancreas: regulates blood-glucose levels. Makes insulin and glucagon. Insulin regulates blood-glucose
levels by telling the liver to convert glucose into glycogen. Glucagon has the opposite effect. Has liver
convert into glucose and to release the glucose into the blood. Diabetes mellitus-person does not make
enough insulin. Found behind the stomach.
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Thymus: regulates the immune system. Killer T Cells mature in the thymus. These cells destroy foreign
invaders in your body.
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Parathyroid: regulates phosphate and calcium levels in the blood. It is behind the thyroid and is peasized
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Adrenal glands: helps you respond to danger. Produces adrenaline and found right above the kidneys.
Can make more than 30 hormones.