Module 7 Anatomy And Physiology

Front 1

Nerves

Back 1

Bundles of neuron axons and their coverings, which are found outside the CNS.

Front 2

Ganglia

Back 2

Collections of neuron cell bodies that are found outside the CNS.

Front 3

Spinal Nerves

Back 3

Nerves that originate from the spinal cord.

Front 4

Cranial Nerves

Back 4

Nerves that originate from the brain.

Front 5

Somatic Motor Nervous Stystem

Back 5

PNS neurons that transmit action potentials from the CNS to skeletal muscles.

Front 6

Autonomic Nervous System

Back 6

PNS neurons that transmit action potentials from the CNS to skeletal muscles.

Front 7

Sympathetic Division

Back 7

Division of the ANS that generally prepares the body for increased energy expenditure.

Front 8

Parasympathetic Division

Back 8

Division of the ANS that regulates resting and nutrition-related functions such as digestion, defecation, ad urination.

Front 9

Afferent Neurons

Back 9

Neurons that transmit action potentials from the sensory organs to the CNS.

Front 10

Efferent Neurons

Back 10

Neurons that transmit action potentials from CNS to the effector organs.

Front 11

Association Neuron

Back 11

A neuron that conducts action potentials from one neuron to another neuron within the CNS.

Front 12

Excitability

Back 12

The ability to undergo an action potential in response to a stimulus.

Front 13

Potential Difference

Back 13

A measure of the charge difference across the cell membrane.

Front 14

As you read this question, cells in your eyes are sending information to your brain which your brain uses to form an image of the words that you read. Is this information being sent along afferent or efferent nerves?

Back 14

This information is traveling along afferent nerves since those are the nerves that carry information from the sensory organs (your eyes) to the CNS (your brain).

Front 15

When you are digesting food, smooth muscles contract your stomach. Is this controlled by the afferent or efferent division of the PNS? You can be even more specific than that. What would be the most specific way to describe the nerves involved in this situation?

Back 15

The efferent division is being used since signals are sent to effector organs that are, in this case, smooth muscle cells. The most specific you can be is that the parasympathetic division of the autonomic nervous system is being used. Since smooth muscles are involved, this is the autonomic nervous system, and digestion-related activities are stimulated by the parasympathetic division of the autonomic nervous system.u7

Front 16

Back 16

a. presynaptic terminal
b. node of Ranvier
c. collateral axon
d. Golgi apparatus
e. nucleus
f. nucleolus
g. dendrites
h. mitochondrion
i. cell body
j. axon hillock
k. axon
l. myelin sheath formed by Schwann cell

Front 17

Back 17

a. epineurium
b. fasicle
c. axon
d. endoneurium
e. perineurium

Front 18

Name the six types of neuroglia and their functions.

Back 18

~Oligodendrocytes--bind CNS neurons together and insulate the axons.

~Schwann cells--Insulate PNS neurons

~Microglia--Fight infection with phagocytosis

~Ciliated ependymal cells--Move cerebrospinal fluid so that it stays homogenous

~Non-ciliated ependymal cells--secrete cerebrospinal fluid

~Astrocyte--Form the blood-brain barrier

Front 19

What are the differences between a sensory nerve, a motor nerve, and a mixed nerve? What is the most common kind of nerve in the body?

Back 19

A sensory nerve contains axons that carry only sensory information from receptors to the CNS, while a motor nerve contains axons that carry signals only from the CNS to effector organs such as muscle and glands. A mixed nerve carries both.

Front 20

An axon is covered by an oligodendrocyte. Is it part of the CNS or PNS? Will it regenerate a new axon if severed?

Back 20

Oligodendrocytes are neuroglia found only in the CNS. The axon will not regenerate, as it must have Schwann cells to be able to regenerate.

Front 21

An axon is covered by several Schwann cells. If it is severed, will it definitely heal? Why or why not?

Back 21

The axon will not necessarily heal. Not only must it have Schwann cells, but the axon must also be well-aligned with its severed part in order for the Schwann cells to guide the re-growing end of the axon to it.

Front 22

At one point on the axon, there is a high concentration of K+ outside the cell and a high concentration of Na+ inside the cell. Is the neuron at rest?

Back 22

No--more K+ must diffuse out of the cell for the neuron to be at rest.

Front 23

At one point on the axon, there is a high concentration of Na+ outside the cell and a high concentration of K+ inside the cell. Is the entire neuron at rest?

Back 23

You cannot tell! At that POINT on the axon, there is no action potential because the Na+ are on the outside and the K+ are on the inside. However, that is just one point on the axon. The axon could have action potentials traveling farther along it. So, at that point, the axon is at rest, but there could be activity along it.

Front 24

A stimulus creates a change in the potential difference between the inside and outside of the cell so that the inside is less negative, but no action potential is created. What is this called?

Back 24

This is a subthreshold stimulus. It caused some Na+ to move into the cell, but not enough to trigger an action potential.

Front 25

The following steps occur during anaction potential. Put them in the proper order.

a. Na+ gates open, and the K+ gates begin to open. Sodium ions rush into the cell according to the dictates of diffusion.
b. Na+ and K+ gates are closed. Sodium-potassium exchange pump brings the system back to its original state.
c. Na+ and K+ gates are closed. Na+ are concentrated outside the cell; K+ are concentrated inside the cell.
d. Na+ gates close, and potassium gates fully open. K+ rush out of the cell according to the dictates of diffusion.

Back 25

c.
a.
d.
b.

Front 26

There is a specific name given to step a and a specific name given to step d. What are the names?

Back 26

Step a is called depolarization--the sodium is rushing into the cell and the potential difference becomes positive. Step d is called repolarization--the potassium is rushing out of the cell, bringing the potential difference back to negative.

Front 27

What keeps an action potential on an axon from stimulating another action potential that will travel back towards the cell body?

Back 27

The absolute refractory period will keep this from happening. The action potential can stimulate another action potential, but not in the area that the action potential just left, as it is in its absolute refractory period. Therefore, it can only stimulate action potentials farther down the axon.

Front 28

Why do myelinated axons carry action potentials faster than unmyelinated axons?

Back 28

Myelinated axons allow saltatory transmission. this is a faster way to send the action potential, but not in the area that the action potential just left, as it is in its absolute refractory period. Therefore, it can only stimulate action potentials farther down the axon.

Front 29

When you cut yourself, you feel an instant, sharp pain, followed a bit later by a dull ache. Why do you get these two different pains, and why do they come in that order?

Back 29

The sharp pain comes first because it is traveling down the axons of your pain receptors using saltatory conduction. The dull ache gets to your CNS a split second later because those signals are traveling down different axons using continuous conduction.

Front 30

When you press your finger lightly against an object, you feel a certain amount of pressure. Pressing harder against that same object causes you to feel more pressure. What is the difference between the action potentials in these two situations?

Back 30

The difference is the frequency of the action potentials.the action potentials are the same since they work on the all-or-nothing principle. It is the frequency of the action potentials which determine the strength of the signal. (It is also true that you might stimulate more receptors that would stimulate more neurons to respond).

Front 31

Back 31

a. Ca2+ channel
b. synaptic vesicle
c. Na+ channels
d. presynaptic terminal
e. synaptic cleft

Front 32

A neural signal needs to travel a long way through the body. It needs to have exactly the same properties at its destination as it did when it started. Should this signal be sent along one very long axon or a few shorter axons that are connected by synapses?

Back 32

If the neural signal needs to be exactly the same the entire way, a long axon should be used. Synapses regulate signals and, therefore, change them. Neuron axons send signals to the destination unchanged.

Front 33

The potential difference in a postsynaptic neuron changes from -85 mV to -95 mV at the point of a synapse. What has happened? What can you say about the relative amounts of K+ and Na+ outside the membrane?

Back 33

An inhibitory postynaptic potential has occurred. The synapse, then, is an inhibitory synapse, and that means K+ concentration will be higher outside the membrane than in the resting state. The Na+ concentration will be unchanged (higher outside), since inhibitory synapses control only K+ channels.

Front 34

Twelve action potentials are traveling down an axon in a very short time period. They reach a synapse, and the postsynaptic neuron sends only two action potentials down its axon. Is this an excitatory synapse or an inhibitory synapse?

Back 34

This is an excitatory synapse. An excitatory synapse regulates signals by requiring several action potentials on the presynaptic neuron to trigger one signal on the postsynaptic neuron.

Front 35

In the example above, is this temporal summation or spatial summation? How do you know?

Back 35

This is temporal summation since only one presynaptic neuron is involved, and it produces many action potentials within a short time.

Front 36

We discussed three kinds of circuits which can be formed by neurons. Name the three circuits an what they are used for.

Back 36

Converging Circuit--many inputs are reduced to a limited output.

Diverging Circuit--one input stimulates many outputs.

Oscillating Circuit--prolongs the effect of a stimulus; it re-stimulates itself.