Download Anatomy Review - Interactive Physiology

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Anatomy Review
Graphics are used with permission of :
adam.com (http://www.adam.com/)
Benjamin/Cummings Publishing Co (http://www.awl.com/bc)
Page 1. Introduction
• Neurons communicate with other cells at junctions called synapses.
• Neurons form synapses with muscles, glands, and other neurons.
Page 2. Goals
• To learn that neurons synapse with muscle cells. gland cells, and each other.
• To learn where synapses are located.
• To know that there are both electrical and chemical synapses.
• To understand the structural components of a chemical synapse.
Page 3. Neurons Communicate with Effector Organs at Synapses
• Skeletal muscle is activated by neurons of the somatic nervous system.
• Cardiac muscle, smooth muscle, and glands receive signals from neurons
of the autonomic nervous system.
Interactive Physiology
• Somatic motor neurons from the central nervous
system project directly to skeletal muscle.
• A synapse between a somatic motor neuron and a
skeletal muscle fiber is called a neuromuscular
junction.
• When an action potential arrives at a neuromuscular
junction, it initiates a series of events which excite the
underlying muscle fiber, causing it to contract.
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-42• Signals in the autonomic nervous system travel over a
two-neuron chain to their effector organ.
• The second neuron, or autonomic motor neuron,
contacts the organ.
• Signals from some autonomic motor neurons cause the
heart rate to increase.
• Signals from other neurons slow the heart.
• Action potentials to the heart may excite or inhibit it.
• Signals from some autonomic motor neurons
cause smooth muscle to contract.
• Signals from other neurons cause smooth
muscle contractions to slow or stop.
• Action potentials to smooth muscle may excite
or inhibit it.
• Signals from the central nervous system can cause glands to secrete.
* Now is a good time to go to quiz questions 1 a & b:
• Click the Quiz button on the left side of the screen.
• Work through quiz questions 1a & b.
• When you are done go to page 4. Neurons Communicate with other Neurons
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-43Page 4. Neurons Communicate with Other Neurons
• In addition to sending signals to effector organs, neurons send signals to each
other.
• Neurons can excite or inhibit other neurons.
• The neuron that synapses on the dendrites of this cell excites it and causes it to
generate an action potential.
• In this case, the neuron synapsing on the soma inhibits the cell and prevents it
from generating an action potential.
Page 5. Synapses are Found on Dendrites, Cell bodies, and Axons
• In the brain, a variety of synapses have evolved to serve complex transmission needs between neurons.
• Synapses located between axon terminals of one neuron and dendrites, soma, or axon of another are most
common.
• These are axodendritic
synapses.
• Like axosomatic synapses,
these carry input signals to
neurons.
• These are axosomatic synapses.
• Like axodendritic synapses, these carry input signals to neurons.
• These are axoaxonic synapses and they are functionally
different from axodendritic and axosomatic synapses.
• They do not provide input signals to neurons.
• Axoaxonic synapses can regulate the amount of chemical
transmitter that is released by another axon terminal, thus
inhibiting or facilitating the signal from another neuron.
Interactive Physiology
-44• Here is a synapse between two dendrites.
• Here we concentrate on studying the synapses which provide input signals to neurons, the axodendritic and
axosomatic synapses.
* Now is a good time to go to quiz questions 2a-c:
• Click the Quiz button on the left side of the screen.
• Work through quiz questions 2a-c.
• When you are done go to page 6. Electrical Synapses.
Page 6. Electrical Synapses
• There are two types of synapses, electrical and chemical. Both are
found in similar locations on neurons.
• These neurons depolarize and generate action potentials
simultaneously.
• When one neuron forms a gap junction with another neuron, an
electrical synapse is made.
• Electrical current, in the form of ions, flows directly from one
neuron to the other through the gap junction.
• These synapses are always excitatory.
• Electrical synapses have these advantages:
• fast signal transmission between neurons
• and signal transmission to a group of electrically coupled
neurons can synchronize their activity.
Page 7. Chemical Synapses
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• At a chemical synapse, neuronal membranes are separated by a gap
called the synaptic cleft.
• Electrical current cannot flow directly from one neuron to the other.
•A chemical, called a neurotransmitter, is released from the sending axon
and carries the signal to the next neuron.
• Chemical synapses transmit signals more slowly than electrical synapses
but the signal may be either excitatory or inhibitory, and the signal can be
modified as it passes from one neuron to the next.
• Chemical synapses are the most common type of synapse, and they are
associated with the most complex human behaviors, including learning
and memory.
Interactive Physiology
-45Page 8. Chemical Synapses have Two Parts
• Chemical synapses have two parts: an axon terminal of one neuron, and the cell membrane of another neuron.
• The neuron conducting an action potential toward the synapse is called the presynaptic neuron.
• The axon terminal of the presynaptic neuron contains membranous sacs called synaptic vesicles which are filled
with neurotransmitter.
• The gap separating the cells is the synaptic cleft.
• The presynaptic and postsynaptic neurons are separated by a gap of 30 - 50 nanometers.
• An action potential that reaches the axon terminal causes synaptic vesicles to fuse with it, releasing
neurotransmitter into the synaptic cleft.
• The neurotransmitter then diffuses across the synaptic cleft and binds to receptors on the postsynaptic neuron.
• The neuron receiving the signal is called the postsynaptic neuron.
• When activated, receptors on the postsynaptic neuron open ion channels.
• The movement of ions across the neuronal membrane creates an electrical signal called a synaptic potential.
• Synaptic potentials vary in amplitude and travel only a short distance.
• Thus they are very different from action potentials.
Page 9. Summary
Neurons communicate with muscles, glands, or other neurons at junctions called synapses.
Synapses are located on all parts of the neuron; those on dendrites and soma bring information to the neuron.
Electrical synapses are rapid, excitatory only, and can synchronize the activity of postsynaptic cells. Chemical
synapses are slower, may be excitatory or inhibitory, and are more flexible than electrical synapses.
The presynaptic neuron and postsynaptic neuron, separated by the synaptic cleft, make up a chemical synapse.
* Now is a good time to go to quiz questions 3-4:
• Click the Quiz button at the bottom of the screen.
• Work through quiz questions 3-4.
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Notes on Quiz Questions:
Quiz Question #1a: Synapses on Effector Organs
• This question asks you to determine what
organs are effected by somatic motor
neurons.
Quiz Question #1b: Synapses on Effector
Oorgans
• This question asks you to determine what
organs are effected by the autonomic nervous
system.
You may record your answers here:
Quiz Question #2a-c: Synapses on Neurons
• This question asks you to determine where the synapses would be.
• You may record your answers here:
Interactive Physiology
-47Quiz Question #3: Characteristics of Synapses
• This question asks you to determine differences between electrical and chemical synapses.
• Fill out this diagram as you proceed:
Quiz Question #4: The Chemical Synapses
• This question asks you to label the parts of a chemical synapse.
• Fill out this diagram as you proceed:
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Study Questions on Anatomy Review:
1. (Page 1.) Neurons communicate with other cells at junctions called ______.
a. neurotransmitters
b. synapses
c. autonomic nervous system
2. (Page 1.) Neurons form synapses with _______, ________, and ________ ________.
a. muscles
b. glands
c. neurons
d. glands, and other neurons
e. muscles, glands, and other neurons
3. (Page 3.) Skeletal muscle is activated by neurons of the ______ ______ ________.
a. somatic nervous system
b. autonomic nervous system
4. (Page 3.) Cardiac muscle, smooth muscle, and glands receive signals from neurons of the _______ ________
_______.
a. somatic nervous system
b. autonomic nervous system
5. (Page 3.) A synapse between a somatic motor neuron and a skeletal muscle fiber is called a ________ ________.
a. neuroglandular junction
b. neuromuscular junction
6. (Page 3.) When an action potential arrives at a neuromuscular junction, it initiates a series of events which excite
the underlying muscle fiber, causing it to ______.
a. secrete
b. contract
c. relax
7. (Page 3.) Label the diagram on page 3.
8. (Page 3.) Signals in the autonomic nervous system travel over a ____ _____ _____ to their effector organ. The
second neuron, or autonomic motor neuron, contacts the organ.
a. one neuron chain
b. two neuron chain
c. three neuron chain
9. (Page 3.) Signals from some autonomic motor neurons cause the heart rate to _________.
a. increase
b. decrease
c. stay constant
10. (Page 3.) Signals from some neurons ________ or ________ cause the heart rate to contract.
a. slow or stop
b. increase or speed up
c. stay constant
11. Signals from some autonomic motor neurons cause smooth muscle to ________. Signals from other neurons cause
smooth muscle contractions to ______ or _______.
a. contract, slow or stop
b. relax, slow or stop
12. (Page 3.) Action potentials to smooth muscle may _____ or ________ ____.
a. activate or deactivate it
b. excite or inhibit it
13. (Page 3.) Signals from the central nervous system can cause glands to _______.
a. stop secreting
b. secrete
14. (Page 4.) In addition to sending signals to _______ _______, neurons send signals to each other.
a. effector organs
b. various tissues
15. (Page 4.) Neurons can excite or inhibit other _________.
a. glands
b. muscles
c. neurons
16. (Page 4.) The neuron that synapses on the dendrites of this cell excites it and causes it to generate an ________
___________.
a. action potential
b. synaptic potential
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-4917. (Page 4.) The neuron synapsing on the soma inhibits the cell and prevents it from generating an _______
_________.
a. action potential
b. synaptic potential
18. (Page 5.) Label the diagrams on page 5.
19. (Page 5.) In the brain, a variety of synapses have evolved to serve complex transmission needs between neurons.
Synapses located between axon terminals of one neuron and ______, ______, or ______ of another are most
common.
a. dendrites, dendrites, or axon
b. dendrites, soma, or axon
20. (Page 5.) What are the four types of synapses?
21. (Page 6.) There are two major types of synapses, ________ and ________.
22. (Page 6.) Electrical synapses depolarize and generate action potentials simultaneously. When one neuron forms a
gap junction with another neuron, an _________ _________ is made.
a. chemical synapse
b. electrical synapse
23. (Page 6.) Electrical current, in the form of ions, flows directly from one neuron to the other through the ______
_______.
a. tight junction
b. gap junction
24. (Page 6.) Electrical synapses are always __________.
a. inhibitory
b. excitatory
25. (Page 6.) Electrical synapses have two advantages. List these advantages.
26. (Page 7.) At a chemical synapse, neuronal membranes are separated by a gap called the ______ _______.
a. synaptic cleft
b. presynaptic neuron
c. postsynaptic neuron
27. (Page 7.) Electrical current cannot flow directly from one neuron to the other. A chemical, called a ____________, is
released from the sending axon and carries the signal to the next neuron.
a. synapse
b. ion
c. neurotransmitter
28. (Page 7.) Chemical synapses transmit signals more slowly than __________ ________ but the signal may be either
________ or __________, and the signal can be modified as it passes from one neuron to the next.
a. electrical synapses, excitatory, inhibitory
b. chemical synapses, excitatory, inhibitory
29. (Page 7.) Chemical synapses are the most common type of ________, and they are associated with the most
complex human behaviors, including __________ and ____________.
a. synapse, learning and memory
b. junction, learning and memory
30. (Page 8.) Label the diagram on page 8.
31. (Page 8.) What are the two parts of a chemical synapse?
32. (Page 8.) The neuron conducting an action potential toward the synapse is called the ________ _______ .
a. presynaptic neuron
b. postsynaptic neuron
33. (Page 8.) The axon terminal of the presynaptic neuron contains membranous sacs called _________ ________
which are filled with ______________.
a. axon terminal, synaptic vesicles
b. synaptic vesicles, neurotransmitter
34. (Page 8.) The gap separating the cells is called the ________ _______.
a. synaptic cleft
b. presynaptic neuron
c. postsynaptic neuron
Interactive Physiology
-5035. (Page 8.) An action potential that reaches the axon terminal causes synaptic vesicles, to fuse with it, releasing
____________ into the _________ _________.
a. acetyl choline, postsynaptic neuron
b. neurotransmitter, synaptic cleft
36. (Page 8.) The neuron receiving the signal is called the postsynaptic neuron. When activated, receptors on the
postsynaptic neuron open ____ _________.
a. ion channels
b. voltage-gated receptors
c. passive channels
37. (Page 8.) The movement of ions across the neuronal membrane creates an electrical signal called a ________
__________. ___________ _________ vary in amplitude and travel only a short distance. Thus they are very
different from action potentials.
a. synaptic potential, Synaptic potential
b. action potential, action potential
38. (Page 8.) Place the following pictures in the order they belong in.
a.
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b.
c.
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Answers to Questions on Anatomy Review:
1. synapses
2. muscles, glands, and other neurons
3. somatic nervous system
4. autonomic nervous system
5. neuromuscular junction
6. contract
7. From top to bottom: Axon from motor neuron, Neuromuscular junction
8. two neuron chain
9. increase
10. slow or stop
11. contract, slow or stop
12. excite or inhibit it
13. secrete
14. effector organs
15. neurons
16. action potential
17. action potential
18. Diagram 1: Axon terminal, dendrite; Diagram 2: axon terminal, dendritic spine; Diagram 3: Axon terminal, soma;
Diagram 4: Clockwise: Axon terminal, axon terminal, soma; Diagram 5: Dendrite, dendrite
19. dendrites, soma, or axon
20. Axodendritic synapses, axosomatic synapses, axoaxonic synapses, synapses between two dendrites.
21. electrical, chemical
22. electrical synapse
23. gap junction
24. excitatory
25. Fast signal transmission between neurons and signal transmission to a group of electrically coupled neurons can
synchronize their activity.
26. synaptic cleft
27. neurotransmitter
28. electrical synapses, excitatory, inhibitory
29. synapse, learning and memory
30. Clockwise: postsynaptic neuron, synaptic cleft, presynaptic neuron, synaptic vesicles
31. 1. an axon terminal of one neuron 2. the cell membrane of another neuron
32. presynaptic neuron
33. synaptic vesicles, neurotransmitter
34. synaptic cleft
35. neurotransmitter, synaptic cleft
36. ion channels
37. synaptic potential, Synaptic potential
38. c, b, a
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