Part 1: The Nervous System ANATOMY & PHYSIOLOGY. Three Functions of the Nervous System: Sensory...
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- Slide 1
- Part 1: The Nervous System ANATOMY & PHYSIOLOGY
- Slide 2
- Three Functions of the Nervous System: Sensory Input: Gathers
stimuli (receives information) Integration: Processes and
interprets information Motor Output: Causes a response to muscles
or glands
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- Slide 3
- Organization of the Nervous System: Central Nervous System
(CNS): brain & spinal cord Peripheral Nervous System (PNS):
spinal & cranial nerves Sensory Division (a.k.a. Afferent):
nerves carrying info to the CNS from the body Motor Division
(a.k.a. Efferent): nerves carrying info from the CNS to the muscles
or glands This includes: Somatic Nervous System: voluntary control
(skeletal muscles) Autonomic Nervous System (ANS): involuntary
control (smooth & cardiac). This includes: sympathetic &
parasympathetic. Structural Classification: Functional
Classification:
- Slide 4
- Supporting Cells of the Nervous System: 1. Microglial cells:
support neurons & carry out phagocytosis 2. Oligodendrocytes:
form myelin within the brain; occur in rows along nerve fibers 3.
Astrocytes: found between neurons & bvs; support, regulate
[nutrients] & [ions], & form scar tissue following a CNS
injury. 4. Ependymal cells: membrane like structure that covers
parts of the brain (choroid plexuses) & forms inner linings of
brain (ventricles) & spinal cord (central canal).
- Slide 5
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- Slide 6
- Neurons: Nerve Cells Neurons vary in size, shape & function
Mature neurons do NOT divide All neurons have: A cell body is the
main component of a neuron. It contains cytoplasm, a cell membrane,
a nucleus, & organelles. The ER of a cell body is called the
chromatophilic substance or nissl bodies (perform protein
synthesis).
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- Slide 7
- Neuron Anatomy: Dendrites and axons are nerve fibers that
attach to the cell body (most neurons have these). Dendrites
(usually more than 1 on a cell body) are the communication means of
one neuron to the next. They receive messages. These are short
branched fibers. Axons take impulses away from the cell body. They
are usually one fiber with side branches.
- Slide 8
- Large axons have a covering sheath called a myelin sheath (a
membrane of lipoprotein). The myelin sheath is composed of Schwann
cells (neuroglial cells). The gaps between the myelin sheaths are
called nodes of Ranvier. In the CNS, white matter are the fibers
that are myelinated while gray matter are the fibers that are
unmyelinated.
- Slide 9
- http://www.google.com/imgreshttp://www.google.com/imgres?
- Slide 10
- A neuron:
- Slide 11
- Terminology: Nuclei: clusters of cell bodies in the CNS
Ganglia: small clusters of cell bodies in the PNS (outside the CNS)
Tracts (or nerve tracts): bundles of nerve fibers running through
the CNS Nerves: fibers running through the PNS White Matter:
myelinated fibers Gray Matter: unmyelinated fibers
- Slide 12
- Types of Neurons: Structural Classification: 1. Bipolar
neurons: 2 nerve fibers, one at each end (1 axon & 1 dendrite).
Found in the nose, eyes, & ears. 2. Unipolar neurons: 1 nerve
fiber from the cell body that has 2 branches (1 branch acts as a
dendrite & the other branch acts as an axon). 3. Multipolar
neurons: many nerve fibers, 1 axon and many dendrites. Found in the
brain & spinal cord.
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- Slide 13
- Types of Neurons: Functional Classification: 1. Sensory
neurons: carry impulses from peripheral body parts to brain &
spinal cord (from PNS to CNS). Most are unipolar, some bipolar. 2.
Interneurons: carry impulses between neurons. Multipolar neurons.
3. Motor neurons: carry impulses from the brain & spinal cord
to the effectors (muscles & glands outside of the NS) to carry
out a response. Multipolar.
- Slide 14
- Nerve Impulses: An unmyelinated nerve fiber carries an impulse
slower than a myelinated nerve fiber. Nerve impulses range in speed
according to their diameter (thicker=faster). Ex: skeletal muscle
travels ~120 meters/second Nerve impulses respond in an all-or-none
response. More stimuli= more impulses (per second), not stronger
intensity of impulses.
- Slide 15
- Nerve Impulses: A synapse is a junction between 2 communicating
neurons. The neurons are NOT connected. A synaptic cleft is the gap
between these 2 neurons. A nerve impulse must jump this gap. A
neurotransmitter is a chemical that enables the impulse to jump the
synaptic cleft.
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- Slide 16
- Neurotransmitters: There are 2 types: Excitatory (increase
membrane permeability) -impulse will likely occur Inhibitory
(decrease membrane permeability) -impulse will not likely occur
There are at least 50 known neurotransmitters, including these
groups: Acetylcholine (stimulates skeletal muscles) Monoamimes
(epinephrine, norepinephrine, dopamine, & serotonin) Several
amino acids Peptides
- Slide 17
- Reflexes: These are rapid, involuntary responses A reflex arc
is the simplest nerve pathway that contains only a few neurons. The
withdrawal reflex is a protective reflex (pulling your finger away
from a hot pot) b/c it limits tissue damage. In addition to this
reflex, interneurons also trigger a response to pain. Somatic
reflexes include skeletal muscles (pulling your hand away from a
hot stove). Autonomic reflexes include smooth and cardiac muscles
as well as glands (pupils dilating, mouth watering) The knee-jerk
reflex is a nerve pathway involving only 2 neurons (1 sensory &
1 motor).
- Slide 18
- http://www.mhhe.com/socscience/intro/ibank/ibank/0022.jpg
Withdrawal Reflex:
- Slide 19
- This slide show was developed by Dana Halloran, Cardinal Mooney
High School, Sarasota, FL. Used with her personal permission,
adapted and amended by Rosa Whiting, Manatee School for the Arts,
Palmetto, FL.