Nervous System

Front 1

The autonomic nervous system activates involuntary effector organs. True/False

Back 1

True.

Front 2

What is a motor fiber?

Back 2

These nerve fibers transport signals from the CNS. These are also called efferent fibers.

Front 3

What 2 major components make up the CNS?

Back 3

The brain and spinal cord.
All other nerves are considered peripheral nerves.

Front 4

What are glial cells?

Back 4

Glial cells are supportive cells within the nervous system.
These cells help maintain the functional integrity of neurons.

Front 5

Name a supporting cell within the CNS.

Back 5

Astrocytes. These cells support, maintain and help in the proper growth of neurons.

Front 6

What are ependymal cells?

Back 6

These cells are found within the fluid filled cavities. They assist in the transport and circulation of fluid(CSF) that surrounds the brain and spinal cord.

Front 7

Where in the CNS are satellite cells found?

Back 7

They are found in the peripheral nervous system. They envelop the neurons which tend to group together. This grouping is referred to as a ganglia.

Front 8

What are the cells that create the myelin sheath in the PNS.

Back 8

These are Schwann cells. They are not found in the CNS.

Front 9

What are microglia?

Back 9

These cells are found in the CNS. They have an immunologic function and phagocytose pathogens and any other unwanted debris.

Front 10

How do Schwann cells differ from oligodendrocytes?

Back 10

Oligodendrocytes create myelin sheath in the CNS. Schwann cells carry out this task in the peripheral nervous system.

Front 11

Define simply what is meant by action potential.

Back 11

These are impulses which are electric in nature, that are carried along the neurons axonal length.

Front 12

Where are NIssl bodies found, and what exactly are they?

Back 12

Nissl bodies are found in the soma of a nerve cell. They are comprised of Golgi bodies and rough endoplasmic reticulum.

Front 13

Do Nissl bodies have a function.

Back 13

Though their function has been debated, it is believed that they are responsible for the production of neurotransmitters.

Front 14

Regarding a nervous cell and its dendrites, what structures permit them to respond to neurotransmitters?

Back 14

They have chemically gated ion channels. Once receptors are bound with these neurotransmitter ligands, the ion channels open and permit the passage of ions.

Front 15

Dendrites carry nerve signals away from the cell body. True/False

Back 15

False. Axons carry signals away from the soma. Dendrites receive stimuli from other neurons.

Front 16

What is a ganglion?

Back 16

Ganglions are aggregates or groups of cell bodies located in the PNS.

Front 17

What are nervous system tracts?

Back 17

Tracts make up a collection of neuronal axons that share a common place of origin as well as a a common destination. They are located in the CNS.
Tracts generally do not carry their own blood supply, as do nerves.

Front 18

Does the myelin sheath structure have a function?

Back 18

Yes. It can increase nerve signal transmission.
As a rule, the thicker the myelin sheath, the faster the speed of conduction.
Thicker is quicker.

Front 19

Schwann cells envelop or wrap neurons with what residual structure?

Back 19

Schwann cells envelop the axons of single neurons with a portion of its plasma membrane.

Front 20

Define neurilemma.

Back 20

The neurilemma comprises the nucleus and the cytoplasm of a Schwann cell which tends to wrap around an axon. These are found in the PNS.

Front 21

Oligodendrocytes may interact with the axons of several neurons. True/Falsde

Back 21

True.

Front 22

What are the three functional classifications of neurons?

Back 22

Sensory, Motor and interneurons

Front 23

Where exactly are axon potentials generated in the neuron?

Back 23

Axon potentials are genersated in what is referred to as the trigger zone. The axon hillock is believed to generate the strongest signal from the nerve body.

Front 24

In nerve cell potential mechanisms, what does the number -70 signify?

Back 24

It represents the resting membrane potential. It is measured in millivolts.

Front 25

What are ther two important ions responsible for neuronal resting membrane potential?

Back 25

Sodium and potassium.

Front 26

At the resting membrane phase, there is more sodium inside the cell. True/False

Back 26

False. There is less sodium inside. Most sodium resides before activation outside the cell.

Front 27

Nerve cells permit sodium to slowly diffuse but cross the cell membrane in order to generate a potential. True/False

Back 27

False. Nerve cells allow potassium to diffuse slowly.

Front 28

What mechanism maintains the concentration of sodium and potassium inside the cell?

Back 28

The sodium-potassium pump.

Front 29

Can potassium leave the cell freely?

Back 29

No. The quantity of potassium that exits the cell is controlled by electrostatic attraction.

Front 30

The electrochemical gradient is the sum of which 2 important factors?

Back 30

The concentration gradient
electrostatic gradient

Front 31

Define graded potential.

Back 31

When there is an alteration in membrane potential due to ionic influx or efflux in one region of neuron, and then the ions tend to diffuse away from that region.

Front 32

What is the difference in millivolts, regarding an action potential of a muscle neuron at membrane potential?

Back 32

-70, +30 mv

Front 33

What change in membrane potential is required to open the ion gates and allow the entry of sodium?

Back 33

A voltage gated sodium channel must increase from -70 to -55mv

Front 34

Briefly describe what occurs during the depolarization phase of an action potential?

Back 34

At depolarization phase, the activation gates of voltage regulated sodium channels open. At this stage, inactivation gates and voltage regulated potassiuym channels close.

Front 35

What happens at the repolarization phase?

Back 35

At repolarization, the membrane potential exceeds -70mv, while potassium is exiting the cell. Sodium is no longer entering, and membrane potential is diminishing.

Front 36

What is occurring at hyperpolarization?

Back 36

At hyperpolarization, much of the potassium has already exited the cell rendering the membrane potential below -70mV.
During hyperpolarization, both the sodium and potassium channels are relatively insensitive to changes in voltage.

Front 37

What is the position of ion channels during absolute refractory status?

Back 37

At absolute refractory status sodium channels are open or not active and potassium channels are open. At this juncture, channels cannot respond to increased voltage stimuli.

Front 38

How is relative refractory status different from absolute?

Back 38

During a relative refractory status, action potentials would require a stronger or increased stimulus.

Front 39

What is meant by maximal stimulus?

Back 39

This represents the quantity of voltage necessary to cause action potentials to fire very rapidly that their rate is moderated by the refractory period.

Front 40

Regarded myelinated neuronal regions, ions can enter only between the nodes of Ranvier. True/False

Back 40

True.

Front 41

Saltatory conduction is very much dependent at these regions on the myelin sheath. What are they?

Back 41

Nodes of Ranvier. These are spaces or gaps where extracellular fluid ions are able to reach the plasma membrane.

Front 42

Define synapse.

Back 42

A synapse represents a junction between a neuron and another continuing cell which permits the ongoing transfer of impulse.

Front 43

Define axodendritic synapse.

Back 43

When the axon of a presynaptic cell encounters a dendrite of the postsynaptic cell.

Front 44

All postsynaptic cells involved in a synaptic junction employing a chemical synapse release chemical substances into the synaptic cleft. True/.False

Back 44

False. This is true of a presynaptic cell.

Front 45

When a neuronal impulse reaches arrives at the axonal terminal of a presynaptic neuron, which specific ionic channels open?

Back 45

Calcium channels open.

Front 46

What is an IPSP, and when do they occur?

Back 46

These are inhibitory post synaptic potentials. They occur when a neurotransmitter activates channels which permit positive ions to exit the cell or negative ions to enter.

Front 47

What is an EPSP?

Back 47

Excitatory post synaptic potential? This transpires when the neurotransmitter activates certain channels which permits the entry of positive ions.

Front 48

In temporal summation of post-synaptic potentials many signals may be received over an extended period of time. True/False

Back 48

False. Should be a very short period of time.

Front 49

What occurs during spatial summation?

Back 49

In spatial summation of postsynaptic potentials, the signals are received from a variety of presynaptic cells.

Front 50

In skeletal muscle, acetylcholine is considered inhibitory. True/False

Back 50

False. It is considered excitatory.

Front 51

What effect does acetylcholine have on cardiac muscle?

Back 51

IT is inhibitory. Vagal nerve stimulation will decrease the heart rate.

Front 52

What are indirect neurotransmitters?

Back 52

The binding of indirect neurotransmitters results in membrane proteins or receptors to alter their structural shape. This in tuen will will activate second messengers in the cell.

Front 53

What is a first messenger?

Back 53

These are substances that carry signals to the cell itself.
A ligand is an example of a first messenger.

Front 54

What is a second messenger?

Back 54

These are molecules within the cell, prompted by a first messenger that allow the cell to respond to the extracellular stimulus or signal.

Front 55

G protein receptors have what effect on GTP?

Back 55

Because G protein receptors do not allow ion influx, they will activate the G protein resulting in it hydrolyzing GTP to GDP.

Front 56

After the hydrolysis of GTP, what are G proteins able to do?

Back 56

After GTP hydrolysis, they activate adenylate cyclase.
Adenylate cyclase converts ATP to cAMP(cyclic adenosine monophosphate).

Front 57

What is N-CAM?

Back 57

N-Cam is noted for its involvement in nerve regeneration and regrowth especially after injuries.
Axonal development or growth is directed by many factors. It is guided by a scaffold of proteins, nerve growth factor(NGF) repulsion molecules and N-CAM(nerve cell adhesion molecule).