Download The Nervous System: Neural Tissue

The Nervous System: Neural Tissue
I.
Organization of the nervous system
A. Functions of the nervous system
1. _____________________________________________________________
___________________________________________
2. _____________________________________________________________
___________________________________________
3. _____________________________________________________________
___________________________________________
B. Two divisions
1. __________________ Nervous System (CNS) – __________________ &
____________________________________
2. __________________ Nervous System (PNS) – part of the nervous system
__________________ the CNS
a. __________________ nerves – carry impulses to & from the
__________________
b. __________________ nerves – carry impulses to & from the
_____________________
C. Functional Classification of Neurons
1. __________________ (afferent) neurons – carry impulses from
__________________ towards the __________________
a. __________________ – sensitive to stimuli that occur
__________________ the body (sense of touch, sight, taste, etc.)
b. __________________ – respond to stimuli __________________ the
body & monitor changes in the blood, body temp., etc.)
2. __________________ neurons (interneurons) – lie __________________
sensory & motor neurons in the CNS and __________________ incoming &
outgoing signals.
3. __________________ (efferent) neurons – carry impulses
__________________ from the CNS and to effectors (muscles or glands)
D. Two types of Neural Cells
1. __________________ – carry __________________
2. __________________ cells – __________________ cells for the neurons
a. __________________ – __________________ cells that
__________________neurons from __________________
microorganisms.
b. __________________ – __________________cells that connect
neurons to __________________ and help exchange nutrients between
capillaries and neurons.
c. ____________________________ – cover the fibers of the
__________________ neurons with __________________
__________________.
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d. ____________________________– cover the fibers of the
__________________ neurons with __________________
__________________.
E. Neuron Structure
1. __________________ - cell body
a. contains all organelles except centrioles (thus neurons are not able to
reproduce)
b. __________________ __________________– complex rough ER
network with many ribosomes.
2. __________________ – typically shorter processes that convey impulses
toward the soma.
3. __________________ – longer process (up to __________________) that
conveys signals away from the soma.
a. Each neuron will have only _________ axon, however it may be
__________________.
b. At the end of the axon will be __________________
__________________ (AKA - synaptic knobs or synaptic boutons).
c. Some axons will be covered by white, fatty insulation called a
__________________ __________________. Myelin sheaths increase
the speed of impulse transmission.
1) White matter in the brain consists of __________________ fibers
2) Gray matter consists mainly of __________________ fibers.
d. The spaces between the myelin sheaths are called
__________________of __________________.
F. Structural Classification of Neurons
1. __________________ – have a __________________ process that
emerges from the cell body. Functions mainly as an axon for the
_____________.
2. __________________ – have __________________ processes- one axon,
one dendrite. Found in the __________________ of the eye and the
__________________ mucosa.
3. __________________ – have __________________ (at least 2) dendrites
and one axon. Most __________________ neuron in the body.
II.
Neurophysiology
A. Nerve cells are able to transmit signals due to their properties of
1. __________________ – responding to a __________________
2. __________________ – able to __________________ an impulse down its
__________________
B. The Electrochemical gradient & the Resting Potential
1. The __________________ for an impulse is supplied by the
__________________.
2. Neurons create a __________________ __________________ between the
__________________ and the __________________ of the cell membrane
(Potential difference).
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3. This chemical imbalance allows the __________________ charge to travel
__________________ the __________________ of the
__________________.
4. __________________ along the cell membrane, called
__________________ __________________ __________________,
actively transport __________________of the cell &
__________________the cell.
5. The build-up of Na outside the cell & K inside the cell makes the
__________________ __________________.
6. Because the Na & K ions have different __________________, an electrical
__________________ exists between the inside & outside of the cell
membrane.
7. The __________________ __________________of a “charged” or
__________________axon is _______ mV. (The inside is negative relative
to the outside)
C. The Acton Potential
1. The transmission of an impulse down the length of an axon is called the
__________________ __________________.
2. A stimulus is applied to a __________________ membrane, which causes
the membrane to become __________________ to Na.
3. Since there is a high concentration of Na outside the cell, the Na rushes in
and changes to ionic differential to a more positive level (about ________
mV) called __________________.
4. The __________________ of a membrane at a certain area stimulates
neighboring region of the membrane and causes it to depolarize. (This
causes a __________________ __________________down the length of
the membrane).
5. The impulse is always the same __________________ and only
__________________ one way.
D. Repolarization
1. Within ________, the Na gates have __________________ and K gates
have __________________ to allow for K to flow out of the cell.
2. The loss of K helps to restore the axon to the Resting Potential of –70 mV.
(__________________)
3. The Na/K pumps are then __________________ to restore normal Na & K
levels.
E. Stimuli for Depolarization
1. The minimum stimulus needed to trigger a depolarization and an impulse is
called a __________________ __________________.
2. The _______ – _____ – ________ ________ says that action potentials will
happen completely or not at all.
3. All action potentials are alike no matter the __________________ of the
stimulus.
4. __________________ of impulse transmission is what separates
__________________ from __________________ stimulus.
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5. Stimuli not strong enough to trigger depolarization are called
__________________ stimuli.
6. Subthreshold stimuli can be __________________ to cause depolarization.
7. Suprathreshold stimuli trigger only a __________________ action potential.
8. The __________________ __________________ __________________ is
the period of time when the Na gates are open & a second stimulus can NOT
come down the axon – no matter how strong it is.
9. The __________________ __________________ __________________ is
the time immediately after the Na gates close and repolarization is still
occurring that a exceptionally strong stimulus may cause depolarization.
F. Impulses
1. Impulses travel at different speeds based upon the
a. __________________ of the axon
b. degree of __________________
2. __________________ axons (which are usually longer as well) carry
impulses __________________ than smaller axons.
3. __________________ axons carry impulses __________________ than
unmyelinated axons.
a. Myelin sheaths have spaces between them (about 1mm apart) called
__________________ __________________.
b. The current can only be carried at these nodes, thus the impulse has to
“__________________” the myelin sheath. This is called
__________________ __________________.
4. Speed of Impulse Conduction
a. Large, myelinated = __________________
b. Medium, lightly myelinated = __________________
c. Small, unmyelinated = __________________
III.
The Synapse
A. Synapse structure
1. __________________ occur __________________ the
__________________ of one cell and the __________________ of the next
cell
2. __________________ __________________– neuron conducting impulses
towards the synapse
a. The end of the axon terminates (or ends) in a __________________ or
__________________.
b. The knob contains many tiny sacs called __________________
__________________ that contain a __________________.
3. __________________ __________________– neuron conducting impulses
away from the synapse
a. The end of the dendrite has a __________________ membrane.
b. The membrane bears __________________ __________________.
4. __________________ __________________– space between the synaptic
knob & the receptor membrane__________________ wide
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B. Synaptic transmission
1. When the impulse reaches the axon terminal (knob), __________________
of the presynaptic membrane causes __________________ of the
neurotransmitter into the synaptic cleft.
2. The neurotransmitter binds to the __________________ receptors, which
causes Na ion gates to open and local __________________ to occur.
3. Neurotransmitters – two classes
1. __________________: Acetylcholine (_______), Norepinephrine,
Dopamine, etc.
2. __________________: Gamma-aminobutyric acid (________), Glycine,
etc.
C. Termination & reabsorption of neurotransmitters
1. The neurotransmitter will continue to __________________ the receptors as
long as they are __________________. The neurotransmitters must be
__________________ in one of three ways.
a. Chemical breakdown (__________________ [AChE])
b. __________________ of the neurotransmitter by the presynaptic
membrane
c. __________________ away from the synapse
IV.
Neural Disorders
A. __________________ __________________ (MS)
1. __________________ disorder that __________________ the myelin
sheaths of the axons of the optic nerve, brain, &/or spinal cord.
2. Characterized by __________________, __________________,
__________________, and __________________ coordination problems.
3. It starts at __________________, is progressive & there is no
__________________
B. __________________
1. __________________ infection that kills the motor neurons of the spinal cord
& brain
2. The dependant motor units become _______________ and _____________.
3. __________________ programs have all but eliminated this disease.
C. __________________
1. __________________ infection of the __________________ that is
transmitted by __________________ animals. The virus is absorbed
through the __________________ knob and is carried by the axons up to the
CNS.
2. __________________ __________________symptoms include headache,
nausea & muscle pain. __________________
__________________symptoms include hallucinations, muscle spasms, and
difficulty swallowing that cause saliva buildup in the mouth (foaming at the
mouth). __________________ & __________________ soon follow.
3. __________________ consists of a series of injections that contain
antibodies, which must begin almost __________________. W/o treatment,
rabies is always __________________.
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