Download Nervous System – Basic Organization

Biology 12
Nervous System
1. What are the two basic regions of the Central Nervous System?
2. Name the two basic subdivisions of the Peripheral Nervous System.
3. Make a diagram that clearly discriminates the following regions of the spine: cervical,
thoracic, lumbar, & sacral.
4. What is meant by each of the following:
a. cranial nerve
b. spinal nerve
c. peripheral nerve
5. You have completely severed your nerve cord between the 4th and 5th cervical
vertebrae. Explain the consequences of this injury.
6. What is the difference between a nerve and a neuron (nerve fiber)?
Nerve will be composed of multiple sensory neurons and motor neurons
7. Using the diagram given to you, clearly colour, label, and five the functions of the
following parts of the brain:
Medulla oblongata*
Hypothalamus*
Pons*
Cerebellum*
Meninges
Corpus callosum*
Thalamus*
Anterior pituitary*
Posterior pituitary*
Cerebrum (showing the four lobes)
9. What is the function of the somatic nervous system? …autonomic?
You have entered into a ‘fight or flight’ situation (stress situation). Show your
understanding of how the Autonomic N.S. is involved by answering or completing the
following.
10.
a. Name those organs considered to be ‘fight or flight’ organs.
heart, lungs, brain, liver, and kidney
b. Name those organs considered to be ‘relaxed state’ (day to day operations)
organs.
stomach, intestines, heart
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11. Copy the following table onto your answer sheet and fill in with the correct words.
Neurotransmitter
Effect on ‘fight or
flight’ organs
(excite or inhibit)
Effect on relaxed state
organs
(excite or inhibit)
Sympathetic
Norepineprhine
Parasympathetic
Acetylcholine
excite
inhibit
inhibit
excite
12. Why do you suppose that each system (parasympathetic and sympathetic) must
have its own type of neurotransmitter?
They have different functions…
13. In certain (stressful) circumstances individuals have been known to perform
significant feats of strength. Outline in point form and in proper sequence, the events
that would occur as a response to both the nervous system and the endocrine
(hormonal) system stimulation (or inhibition). Start with a sensory input and the
effect first on the nervous system and end with the person doing some incredible
feat. You must include adrenalin and its role in the response. How does this physical
response enable the person to be stronger than normal?
It will allow for more ATP to be produced…more energy available
14. Sketch a sensory neuron. Label and provide a function for each of the following.
A. Dendrite
E. Cell membrane
I. Schwann cell
B. Cell body
F. Axon
C. Node of Ranvier
G. Axon bulb
D. Myelin sheath
H. Receptor
15. Observe the reflex arc below. Name each of the sites indicated by the numbers.
1. sensory receptor
2. Node of ranvier
3. cell body
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4. Synapse
5. Interneuron
6. Axon Terminal
7. Cell Body
8. Myelin sheath
9. Muscle (effector)
16. Give the basic role of each of the following kinds of neurons.
a. sensory
b. interneuron
c. motor
17.
Outline the major steps of a reflex arc, starting with detection of a stimulus by the
receptor of the sensory neuron.
Sensory dendrite perceives impulse…dendrite to cell body to axon
to dendrite, cell body and axon of interneuron and finally to the dendrite , cell body, and
axon of the motor neuron. This will stimulate the effector (muscle or gland)
18.
At the first step of the reflex arc above, the following measurements were made
at the sensory neuron, and placed in a graph form. Explain what is occurring
between/at;
A. point A
B. point B
C. point C
D. point D
E. point E
C. Depolarization
D. Repolarization
B. Threshold
E. Resting potential
A. Resting potential
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19. A sensory neuron has a long dendrite and a short axon, a motor neuron has a short
dendrite and a long axon. Where would that place the cell body of each type of
neuron near and why is this placement significant?
The cell bodies are located in the spinal column…for protection
20. For each of the following points of an action potential give its meaning, its cause
and its value in mV. Ie) explain the ion concentrations or what is happening
i) resting potential…more sodium outside, more potassium inside
ii) upswing (depolarization)…voltage regulated sodium channels open and
sodium rushed in…this causes positive ions to repel and propel down the axon
length
iii) downswing (repolarization). voltage potassium channels open and potassium
leaves cell
iv) recovery…active transport using a sodium/ potassium pump to re-establish the
concentration gradient
Create diagrams of the neuron at each stage. Show significant ions and there
relative distribution. Also draw in and label the manner in which the ions move
from one side of the membrane to the other.
21. What is the significance of having mylinated fibers? Explain what is meant by
saltatory conduction. It prevents the ions from leaking out and slowing down the impulse
22. Study the diagram below.
a.
Copy out the diagram and label each of the letters.
W- dendrite
X- Synapse
Y- axon terminal
Z- Vesicles containing neurotransmitter
b.
Label each of the following on the diagram.
i) presynaptic membrane
ii) postsynaptic membrane
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c.
For impulse transmission explain:
i) the role of Ca+2 Binds to the vesicle to assist the vesicle to bind to pre-synaptic
membrane
ii) the movement of neurotransmitter vesicles and of neurotransmitter once
released…move to the membrane…exocytosis and then they diffuse across gap
iii) the effect of inhibitory and excitatory neurotransmitters on the dendrite
(summation and the all or none law). Once the neurotransmitter binds to
the receptor proteins on the post-synaptic membrane they trigger sodium to rush
in if it is an excitory neurotransmitter, If enough sodium (threshold) reaches the
axon hillock (summation) the nerve impulse will be carried..if not it wont (all or
none). If the neurotransmitter is an inhibitory molecule it will cause potassium to
leave which lowers the resting potential and inhibits any action
iv) the significance of “threshold”
The amount of sodium that comes in must raise the potential difference to -55mV or the
action potential will not be carried
v) how neurotransmitters are removed from the synaptic cleft (2 possibilities).
Specifically explain the role of acetylcholinesterase.
The neurotransmitters can diffuse away or back into the pre-synaptic membrane
or
the enzyme acetylcholinesterase can be used to break down acetylcholine
23.
Observe the diagram below. Neuron 2 was exposed and then stimulated at point
X using an electrode. Explain what would occur between the following points
(depolarization or not).
A.
B.
C.
D.
E.
point X & point B…the area could be depolarized and action potential carried
point B & point A…nothing as the dendrite does not have neurotransmitters
point X & point C…action potential
point C & point D…crosses the synapse using neurotransmitters
Why is nerve impulse transmission only one way? the structure of the axon
terminal is meant for sending messages to the dendrite not sending and vice
versa