Download Autonomic Nervous System

6
The Nervous
System
Lesson 6.1: Overview of the Nervous System
Lesson 6.2: Transmission of Nerve Impulses
Lesson 6.3: Functional Anatomy of the Central
Nervous System
Lesson 6.4: Functional Anatomy of the Peripheral
Nervous System
Lesson 6.5: Injuries and Disorders of the
Nervous System
Chapter 6: The Nervous System
Lesson 6.1
Overview of the
Nervous System
Do Now
Pick three words and write the definition of each. All
words are on page 201.
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Central Nervous System
Peripheral Nervous System
Afferent Nerves
Efferent Nerves
Somatic Nervous System
Autonomic Nervous System
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Today’s Objectives
• Differentiate between the central nervous system
and peripheral nervous system, and explain the
function of each.
• Explain the differences between afferent and
efferent nerves.
• Describe the functions of the somatic and
autonomic branches of the nervous system.
• Identify the general role of the glial cells.
• Describe the anatomical structure of a typical
neuron.
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Nervous System Overview
• The nervous system controls voluntary movement
by activating skeletal muscle, but also directs the
involuntary functions of smooth muscle in internal
organs and cardiac muscle.
• By automatically controlling the functions of
smooth muscle and cardiac muscle, the nervous
system ensures that these life functions are able to
occur without conscious thought.
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Nervous System Overview
• organization of the nervous system
– two major divisions categorized by:
• Structural
• Functional
– the efferent nerves
• nervous tissues
– neuroglia
– neurons
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Organization of the Nervous System
• Two major divisions
– Central nervous system (CNS)
– Peripheral nervous system (PNS)
• Peripheral nervous system divided into subdivisions:
– sensory receptors
– afferent (sensory) nerves
– efferent (motor) nerves
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Two Major Divisions
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Major Divisions
– Central Nervous System (CNS)
• Includes the brain and spinal cord.
• The CNS directs the activity of the entire nervous system.
– Peripheral Nervous System
• Includes spinal nerves that transmit information to and
from the spinal cord
• Cranial nerves transmit information to and from the brain.
• Also includes sensory receptors which respond to stimuli
such as pressure, pain, or temperature.
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– Afferent Nerves
• Nerves that transmit impulses from the sensory receptors
in the skin, muscles, and joints to the CNS
– Efferent Nerves
• Nerves that carry impulses from the CNS out to the
muscles and glands.
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The Efferent Nerves
• There are two functional subdivisions of the efferent
(motor) nerves
– somatic nervous system
• Stimulates skeletal muscles causing them to develop tension.
• Voluntary control
– autonomic nervous system
• Controls the cardiac muscle of the heart and the smooth muscles
of the internal organs.
• Involuntary control
• Includes two separate branches
– sympathetic
– parasympathetic
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Nervous Tissues
• 2 Categories of tissues
– neuroglia
• also known as glial cells
• support the neurons
• protect the neurons
– neurons
• transmit nerve impulses
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Neuroglia
• Within the central nervous system there are 4 types of glial cells.
–
–
–
–
astrocytes
microglia
ependymal
oligodendrocytes
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Central Nervous System Glial Cells
– Astrocytes
• Positioned between neurons and capillaries.
• Protect the neurons from any harmful substances in the
blood.
– Microglia
• Absorb and dispose of dead cells and bacteria
– Ependymal
• Form protective coverings around the spinal cord and
central cavities within the brain.
– Oligodendrocytes
• Wrap around nerve fibers and produce a fatty insulating
material called myelin.
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Neuroglia
• peripheral nervous system includes 2 forms of glial cells
– Schwann cells
• Form the fatty myelin sheaths around nerve fibers
– satellite cells
• Serve as cushioning support cells
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Neurons
• Glial cells provide support and protection for the
nervous system, but it is the neurons that transmit
information in the form of nerve impulses.
• Typical neuron has a long, tail-like projection called an
axon.
• dendrites
– send information to cell body
• cell bodies
– Includes a nucleus and mitochondria
• axons
– send information away from cell body
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Neuron Types by Function
• sensory neurons (afferent)
– send impulses toward CNS
– Impulses from the skin and organs to the spinal cord and brain.
– Provides information about the external and internal environments.
• motor neurons
– send impulses away from CNS
– Transmits impulses from the brain and spinal cord to the
muscles and glands, directing body actions.
• interneurons
– bridges between neurons
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Neuron Structures
• bipolar
– one axon
and one
dendrite
• unipolar
– one axon
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• multipolar
– one axon
and many
dendrites
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Review and Assessment
Match these words with 1–4 below: sympathetic
nervous system, myelin, synapse, axon.
1. high alert
2. transmits impulses away from cell body
3. fatty insulating material
4. gap between neurons
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END
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Exit Ticket
1) Which of the following is not a major division of
the nervous system?
a. Central Nervous System
b. Peripheral Nervous System
c. Afferent Nervous System
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2) T or F: The central nervous system has afferent
nerves that carry impulses TOWARDS muscles and
glands.
3) When sending nerve impulses, the purpose of the
myelin sheaths are to:
a. Decrease the speed of the transmission.
b. Increase the speed of the transmission.
c. Block any messages being sent.
d. None of the above.
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Chapter 6: The Nervous System
Lesson 6.2
Transmission of
Nerve Impulses
Do Now
• Work on the “Learning the Key Terms” Worksheet
• Chapter 6 Lesson 2 begins on page 202, or use
the glossary which begins on page 579.
• You have 8 minutes to complete the worksheet.
• Turn the worksheet into Mr. B when you are
finished.
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Today’s Objectives
Lesson 6.2 Transmission of Nerve Impulses
• Define action potential and explain how action
potentials are generated.
• Explain the factors that influence the speed of
neural impulse transmission.
• Describe how impulses are transmitted across the
synapse.
• Discuss the roles played by neurotransmitters.
• Describe the three types of reflexes and explain
how they work.
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Intro
• Neurons have one behavior property in common
with muscles: Irritability – the ability to respond
to a stimulus.
• However, neurons have an aspect of irritability
that muscles DO NOT have: converting stimuli
into nerve impulses.
• Nerve impulse = a tiny electrical charge that
transmits information between neurons.
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Transmission of Nerve Impulses
• Action Potentials
– When a neuron is inactive, there are potassium ions
(K+) inside the cell and sodium (Na+) ions outside the
cell membrane.
– Inside of the membrane is more negatively charged than
the outside (Polarized).
– When a stimulus is involved it changes the charge so
the inside is more positive (Depolarized)
– This change in charge is known as an Action Potential.
– Following the discharge of the action potential, it goes
back to it original charge (Repolarization)
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Transmission of Nerve Impulses
• Impulse Transmission
– 3 factors the sped at which a nerve impulse travels:
• Myelin sheath
– The presence of a myelin sheath acts as an electrical insulator and
causes the action potentials to “jump”.
– This increases the speed in which an impulse travels.
• Diameter of Axon
– The larger the axon, the more ions available to conduct the
current.
» Example: A large diameter pipe moves more water compared
to a small diameter pipe.
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Impulse Transmission
• Transmission at Synapses
– Neurotransmitters
• Chemical messengers
– excitatory effect
• Activates muscle fibers
– Inhibitory effect
• Blocks pain messages
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Transmission of Nerve Impulses
• Temperature
– Warm temperatures increase ion diffusion rates.
– This increases the speed at which impulses will travel.
– Cold temperatures decrease diffusion rates.
» Example: when you hold an ice cube you have a
numbing sensation. The cold area takes longer to send
information about touch, pain, pressure, and
temperature to your brain.
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• Reflexes
– Simple, rapid, involuntary, programmed responses to
stimuli.
– 2 Categories of reflexes:
• Somatic
– Involve the skeletal muscles.
– Example: withdrawing your hand quickly from something hot
even before you realized that it was hot.
• Autonomic Reflexes
– Send involuntary stimuli to the cardiac muscle of the heart
and the smooth muscle of internal organs.
– Stimulates involuntary muscles.
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Review and Assessment
Fill in the blanks with: reflexes,
saltatory conduction, neurotransmitter,
or action potential.
1. A(n) _______________ is an all or
none response.
2. _______________ occurs only in
myelinated axons.
3. _______________ are rapid,
involuntary responses.
4. The axon terminal has tiny vesicles
filled with _______________.
1.
2.
3.
4.
Action Potential
Saltatory conduction
Reflexes
neurotransmitter
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END
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Exit Ticket
1) Some factors that can influence the speed of a
nerve impulse are:
a. body temperature
b. diameter of the axon
c. presence of a myelin sheath
d. all of the above
e. none of the above
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2) T or F: An action potential is generated when an electrical charge
produced in a nerve or muscle fiber through stimulation.
3) Reflexes are ___:
a. complex, slow, and voluntary responses
b. complex, fast, and involuntary responses
c. simple, rapid, and involuntary responses
d. simple, slow, and voluntary responses.
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4) Somatic reflects involve which type of muscles
and which type of action?
a. Skeletal muscle, involuntary
b. Skeletal muscle, voluntary
c. Cardiac, voluntary
d. Cardiac, involuntary
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Chapter 6: The Nervous System
Lesson 6.3
Functional Anatomy of the
Central Nervous System
The Brain
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cerebrum
diencephalon
brain stem
cerebellum
meninges
blood-brain barrier
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Cerebrum
• cerebral cortex
– gyrus
– sulcus
– fissure
• lobes
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–
–
–
frontal
parietal
occipital
temporal
• primary motor cortex
• primary somatic sensory cortex
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Cerebrum
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Diencephalon
• thalamus
• hypothalamus
• epithalamus
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Brain Stem
• midbrain
• pons
• medulla oblongata
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The Brain
• cerebellum
• blood-brain barrier
• meninges
– dura mater
– arachnoid mater
– pia mater
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Spinal Cord
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Review and Assessment
True or False?
1. The gyri divide the brain into 4 regions.
2. The hypothalamus regulates blood pressure.
3. The meninges has 3 layers.
4. The cerebellum coordinates balance.
5. The pons is also called the interbrain.
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Chapter 6: The Nervous System
Lesson 6.4
Functional Anatomy
of the Peripheral
Nervous System
Functional Anatomy of the Peripheral
Nervous System
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nerve structure
cranial nerves
spinal nerves and nerve plexuses
autonomic nervous system
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Nerve Structure
• endoneurium
– covers axons
• perineurium
– bundles fascicles
• epineurium
– wraps nerves
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Cranial Nerves
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Spinal Nerves and Nerve Plexuses
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•
•
•
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31 pairs
dorsal root
ventral root
dorsal ramus
ventral ramus
plexuses
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Autonomic Nervous System
• preganglionic and postganglionic neurons
• sympathetic nerves
– fight-or-flight action
• parasympathetic nerves
– resting or digesting action
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Review and Assessment
Match these words with 1–4 below: efferent,
ganglion, optic, perineurium.
1. wraps fascicles
2. motor
3. a cranial nerve
4. enlarged junction
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Chapter 6: The Nervous System
Lesson 6.5
Injuries and Disorders of
the Nervous System
Injuries to the Brain and Spinal Cord
• traumatic brain injury
• cerebral palsy
• spinal cord injury
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Traumatic Brain Injury
• violent impact to head
– mild
– moderate
– severe
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Cerebral Palsy
• damage to brain
– before birth
– during birth
– during infancy
• motor function impairment
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Spinal Cord Injuries
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•
•
•
C1–C3: usually fatal
C1–C4: quadriplegia
C5–C7: paralysis of lower extremities
T1–L5: paraplegia
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Common Diseases and Disorders of the
CNS
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•
meningitis
multiple sclerosis
epilepsy
Parkinson’s disease
dementia and Alzheimer’s disease
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Review and Assessment
Match these words with 1–4 below: quadriplegia,
multiple sclerosis, dementia, cerebral palsy.
1. inflammation destroys myelin sheath
2. loss of memory and thinking
3. loss of function below the neck
4. may begin before birth
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