1.
Define Central Nervous System (CNS):: the brain and spinal cord
2.
Define Neuroglia:: supporting cells of the nervous tissue.
3.
Define Neuron:: a nerve cell, including its axon and dendrites (conducts the impulse).
4.
Define Peripheral Nervous System (PNS):: nerves connecting the brain and spinal cord to other parts of the body.
5.
Describe a 2-neuron arc:: - sensory neuron brings sensory impulse to CNS which links directly to an efferent neuron.
- motor neuron takes impulse to muscles or glands
6.
Describe a 3-neuron arc:: - sensory neuron brings sensory impulse to CNS
- interneuron turns the impulse over to an outboard path
- motor neuron sends impulse to a muscle/gland or group of muscles/glands
7.
Describe a reflex arc:: - sensors pick up a sensation (ex: intense heat)
- creates an impulse that goes to CNS saying "your finger is on fire"
- CNS sends a message back: "take your hand off the stove or you will be a crispy critter"
- skeletal muscles contract and move your finger out of fire quickly. You are saved from an ugly burn.
8.
Describe the difference between excitatory andd inhibitory neurotransmitters:: 1) Excitatory neurotransmitters Depolarize (excite/stimulate) the postsynaptic membrane.
2) Inhibitory neurotransmitters Hyperpolarize the postsynaptic membrane.
9.
Describe the function of Astrocytes:: 1) form tight sheaths around blood capillaries in the brain.
2) form the blood-brain barrier which allows small molecules such as H2O and O2 to diffuse through the neurons. (cancer here = astrocytoma)
10.
Describe the function of Ependymal cells:: line the fluid filled cavities of the brain and spinal cord. (cancer here = ependoma)
11.
Describe the function of Microglia:: phagocytize debris and microbes.
12.
Describe the function of Oligodendrocytes:: 1) hold nerve fibers together.
2) Produce the fatty myelin sheath around nerve fibers in the brain and spinal cord.
(* are only found in the CNS)
13.
Describe the function of Schwann cells:: 1) hold nerve fibers in the PNS together.
2) produce the fatty myelin sheath around nerve fibers
(* found only in the PNS)
14.
Describe the mechanism that poduces the action potential:: - An adequate stimulus opens the Na+ channels which let Na+s difffuse in and cause the membrane to Depolarize.
- As threshold potential is reached, additional Na+ channels open and more Na+s enter the cell, causeing further Depolarization and passing the threshold potential (~59mV).
- The action potential peaks at ~+30mV when the Na+ channels close.
- Repolarization begins when K+ channels open, allowing outward diffusion of K+s.
- After a brief period of Hyperpolarization, RMP is restored by the Na-K pump and the return of the gated ion channels to their resting state.
15.
Describe the Postsynaptic neuron plasma membrane:: 1) the usual phospholipid bilayer with special protein molecules scrunched in the bilayer.
2) special proteins are receptors for the neurotransmitter molecules.
16.
Describe the repair process of nerve fibers:
(assume no extensive damage; cell body and neurilemma remain intact): - Distal portion of axon and its myelin sheath degenerate.
- macrophages clean up debris.
- remaining neurilemma and endoneurium form a pathway to injury site.
- axon regenerates through the "tube"
17.
Describe the structural class of Bipolar neurons:: 1 axon, 1 dendrite at opposite ends of cell body (impulse must go through the cell body)
18.
Describe the structural class of Multipolar neurons:: 1 axon, several dendrites (most common CNS neuron)
19.
Describe the structural class of Unipolar neurons:: 1 axon, 1 dendrite that enter the cell body at the same place (pulse can pass the cell body)
20.
Describe the Synaptic Clefft:: 1) the space between a synaptic knob and the plasma membrane of a postsynaptic neuron.
2) super narrow. 20-30 nanometers (about one millionth of an inch)
21.
Describe the Synaptic Knob:: 1) tiny bulge at the end of a terminal branch of a presynaptic neuron's axon.
2) contains numerous small vesicles full of neurotransmitter (~10,000 molecules).
22.
Explain the difference between an absolute andd relative refractory period. How long does each one last?: Absolute Refractory Period - 1/2 millisecond after the membrane passes the threshold potential. During this period the membrane will NOT respond to any stimulus, no matter how strong.
Relative Refractory Period - A period a few milliseconds after the refractory period when the membrane will only respond to very strong stimuli.
23.
Explain the difference between dendrites and axons:: The dendrites conduct impulses TO the cell body.
The axons conduct impuses AWAY from the cell body.
24.
Explain the difference between excitation/depolarization and inhibition/hyperpolarization:: 1) Excitation - stimulus --> More Na+ channels to open. More Na+s enter cell. RMP gets smaller (closer to zero). This movement of RMP toward Zero is called Depolarization.
2) Inhibition - stimulus --> More K+s to leave cell. RMP increases. This Movement of RMP away from zero (getting more negative) is called Hyperpolarization.
25.
Explain the difference between grey and white nerve fibers.: - White nerve fibers have a myelin sheath.
- Grey nerve fibers do not have a myelin sheath.
26.
Explain the difference between the Sympathetic and Parasympathetic divisions of the autonomic nervous systems.: Sympathetic
1) pathways exit at middle spinal cord
2) deals with immediate threats to the internal environment
3) produces the "flight-or-fight" response
27.
From what are the Amines synthesized?: Amino Acids
28.
From what is acetylcholine (Ach) synthesized?: Acetate and Choline (one of the B vitamins)
29.
How do gated channels keep an excess of positive ions outside the membrane?: - many potassium gated channels upen (easy for potassium transported inside to diffuse back out.
- most sodium channels are closed (once sodium is transported out, it stays out)
30.
How do myelination andd fiber diameter affect speed of conduction? Give an example.: - Myelinated fibers conduct impulses more rapidly than non-myelinated fibers.
- The larger the diameter of a fiber, the faster it conducts an impulse.
Ex: Somatic Nerves - 130m/sec.
31.
How does the myelin sheath created by the Schwann cells affect local flow of current?: It conducts the local flow of currecnt to the next Node of Ranvier thus, the action potential appears to leap from node to node.
32.
How is axon diameter related to the speed of impulse conduction?: the larger the diameter, the faster the impulse speed
33.
In a resting neuron, what positive ion is most abundant inside the plasma membrane?: Potassium Ions (K+)
34.
In a resting neuron, what positive ion is most abundant outside the plasma membrane?: Sodium Ions (Na+)
35.
List 2 common amino acid transmitters and what is the general location of each?: 1) Glutamate (CNS)
2) GABA (BRAIN)
36.
List 5 Amine neurotransmitters:: 1) Serotonin
2) Histamine
3) Dopamine
4) Epinephrine
5) Norepinephrine
37.
List all the parts and sub-parts for the Peripheral Nervous System:: A) Sensory division
B) Motor division
1) Somatic Nervous System (conscious)
2) Autonomic Nervous System (unconscious)
a) Sympathetic division
b) Parasympathetic division
38.
List and explain the difference between the 3 functional classes of neurons:: 1) Sensory neurons - transmit impulses To the brain or spinal cord.
2) Motor neurons - transmit impulses AWAY from the brain or spinal cord TO muscles or glands.
3) Interneurons - conduct impulses from AFFERENT neurons to EFFERENT neurons. Are found only in the brain and spinal cord.
39.
List the 3 structural classes of neurons:: 1) Multipolar
2) Bipolar
3) Unipolar
40.
List the 3 structures that make up a synapse:: 1) the synaptic knob
2) the synaptic cleft
3) postsynaptic neuron plasma membrane
41.
List the 4 main chemical classes of neurotransmitters:: 1) Acetylcholine
2) Amines
3) Amino Acids
4) Neuropeptides
42.
List the 5 major types of Neuroglia:: 1) Astrocytes
2) Microglia
3) Ependymal Cells
4) Oligodendrocytes
5) Schwann Cells
43.
Local Potentials:: - RMPs change when the membrane is stimulated.
- May become more or less polarized.
- If enough stimulus, you will generate a nerve impulse.
- If not enough stimulus, will only change the RMP slightly for a very small time in a very small area.
44.
Summarize the mechanism of synaptic transmission:: - When an action potential reaches a synaptic knob it causes calcium ions to rapidly diffuse into the knob (gated Ca channels open).
- The Ca ions trigger the release of the neurotransmittter molecules into the synaptic cleft.
- Neurotransmitter molecules diffuse across cleft & bind to receptor proteins, which cause gated channels to open.
- Open ion channels produce a postsynaptic potential.
- Neurotransmitter molecules bound to receptors are moved back to synaptic knob or are metabolized into active compounds.
45.
What are Axon Collaterals?: a side branch of an axon.
46.
What are neurofibrils?: Bundles of thin microtubules and microfilaments formed by the cell's cytoskeleton.
47.
What are neuropeptide neurotransmitters?: short strands of amino acids called polypeptides
48.
What are the 3 basic parts of a neuron?: 1) Cell Body (SOMA)
2) Axon
3) Dendrite
49.
What are the 3 functions of the Central Nervous System?: 1) Intergrates incoming sensory information
2) Evaluates that information
3) Initiates an outgoing response
50.
What are the 3 major parts of the nervous system?: 1) Brain
2) Spinal Cord
3) Nerves
- Cranial Nerves
- Spinal Nerves
51.
What are the functions of nissl bodies?: 1) They produce proteins called neurotransmitters which transmit nerve impulses from one nerve to another.
2) They produce other proteins which help maintain and regenerate nerve fibers.
52.
What are the functions of the endorphines and enkephalins?: Endorphines and enkephalins act like opiates to block pain.
53.
What are the nodes of Ranvier?: gaps in the myelin sheath formed by schwann cells.
54.
What causes an electric current to flow betweeen the site of the action potential and the adjacent regions of the membrane?: - At the peak of the action potential, the electrical signs inside and outside the membrane have reversed. The polarity is reversed.
- Reversed polarity causes an electrical current to flow from the part of the membrane where the action potential has been reached to adjacent membrane which is still in its resting state.
- This change is called Local Current Flow.
55.
What do gated channels do?: specific channels opened and closed by chemical and electrical stimuli for specific molecules.
- they help keep an excess of positive ions outside the membrane.
56.
What do neurofibrils do?: 1) They form a passage for rapid transport of molecules to andd from the far ends of a neuron.
2) They also separate the rough E.R. into nissl bodies.
57.
What does it mean when a membrane has a potential of -70mV?: The magnitude of the potential difference is -70mV.
- there is always a + or - sign which refers to the charge on the inside surface of the membrane.
58.
What does the Motor division of the PNS do?: carries info from the CNS to muscles and glands.
59.
What does the Sensory division of the PNS do?: picks up sensory info and delivers it to the CNS.
60.
What is a Contrallateral ("opposite side") reflex arc?: - afferent and efferent neurons are on opposite sides of the body.
(ex: nerve on right side picks up a change andd a muscle on the left side of the body is stimulated to contract.)
61.
What is a glioma?: a tumor of the neuroglia
62.
What is a Local Potential?: A slight shift away from RMP that is NOT great enough to generate an impulse. (sort of like a sub-threshold stimulus to a muscle)
63.
What is a membrane potential?: The difference in electrical charge between the inside and the outside of a plasma membrane.
- Potential/kinetic energy that is maintained by active transport.
64.
What is a nerve impulse?: A wave of electrical fluctuation that travels along the plasma membrane.
- all cell membranes are slightly charged. They are slightly positive on the outside and slightly negative on the inside.
65.
What is a neuroma?: the general name for a tumor arising from nervous system structures.
66.
What is a polarized membrane?: A membrane with a membrane potential.
- all electric potentials measured in volts. Here you use millivolts.
67.
What is a Reflex Arc?: A reflex arc is a nerve pathway to and from the CNS that forms the basis of a relex.
68.
What is a refractory period?: A brief period when the local area of neuron membrane RESISTS restimulation.
69.
What is a Resting Membrane Potential (RMP)?: The membrane potential maintained by a Nonconducting neuron's plasma membrane.
- RMP is mostly a product of ion transport mechanisms the ion pumps and gated channels.
70.
What is a saltatory conduction?: An impulse that is carried from one Node of Ranvier to the next.
71.
What is a synapse?: a junction between adjacent neurons where nerve impulses are transmitted from an axon to dendrites.
72.
What is an Acoustic Neuroma and how is it treated?: - A tumor on the sheath of Schwann cells surrounding the 8th cranial nerve.
- Treatment is microsurgery to remove the tumor.
73.
What is an action potential?: The membrane potential of an active neuron (one transmitting an impulse).
74.
What is an Ependymoma? Who most often gets it? What is the treatment andd survival rate?: - A neurological tumor arising from ependymal cells.
- It occurs most often in children.
- It may be treated with surgery and if so, postop survival is about 5 years.
75.
What is an Ipsilateral ("same side") reflex arc?: - afferent and efferent neurons are on the same side of the body.
(ex: afferent neuron enters right side of spinal cord. Efferent neuron comes out of the right side of spinal cord.)
76.
What is Glioblastoma Multiforme? Why is average survival less than a year?: - It is a ver malignant tumor arising from astrocytes.
- It spreads rapidly throughout brain white matter.
77.
What is Multiple Neurofibromatosis? Since it is benign, why is it a problem?: - Multiple benign tumors of Schwann cells in nerves of the skin.
- In some cases the tumors grow very large and are disfiguring.
- It can affect muscles, bones, and internal organs badly enough to cripple the patient.
78.
What is Myelin?: A white, fatty substance found in the myelin sheath around some nerve fibers.
79.
What is the difference between cranial and spinal nerves?: Cranial = nerves originate from the brain
Spinal = nerves originate from the spinal cord
80.
What is the difference between presynaptic and postsynaptic neurons?: When an impulse is transmitted from one neuron to another, the impulse is transmitted from the Presynaptic neuron to the Postsynaptic neuron.
81.
What is the difference between spatial andd temporal summation?: - In Spacial summation, a number of different knobs stimulate the neuron AT THE SAME TIME. The combined effect of many stimuli at one time creates an action potential on the postsynaptic neuron.
- In Temporal summation, knobs stimulate the neuron several times in rapid succession. Their effects summate OVER A BRIEF PERIOD OF TIME to produce an action potential.
82.
What is the difference between the efferent (motor) and afferent (sensory) nervous systems?: - The Efferent (motor) nervous system consists of all the nerve pathways carrying signals OUT of the brain and/or spinal cord.
- The Afferent (sensory) nervous system is all of the nerve pathways carrying signals TO the brain and/or spinal cord.
83.
What is the difference between the Somatic and Autonomic Nervous Systems?: - The Somatic nervous system pathways carry impulses to the skeletal muscles.
- The Autonomic nervous system (ANS) pathways carry impulses to the smooth muscles, cardiac muscles, and glands.
84.
What is the function of acetylcholinesterase?: It inactivates Ach bound the receptor sites.
85.
What is the function of Dopamiine?: - It is inhibitory.
- Affects emotions, moods, and motor control.
86.
What is the function of Epinephrine?: - It is excitatory or inhibitory.
- Acts as a hormone when produced in the the adrenal gland.
87.
What is the function of Histamine?: - It is excitatory.
- Affects emotions, body temp., and water balance.
88.
What is the function of Norepinephrine?: - It is excitatory or inhibitory.
- Regulates sympathetic effectors. Also involved (from brain) in emotional responses.
89.
What is the function of Serotonin?: - It is inhibitory.
- Affects mood, emotions, and sleep.
90.
What is the Neurilemma and why is it important?: - The sheath around a neuron. It is formed by schwann cells.
~ Part of its importance comes from the fact that it is essential for regenerating injured nerve fibers.
91.
What is the sodium-potassium pump?: an active transport mechanism in the plasma membrane that:
1) transports sodium and potassium ions in opposite directions and
2) at different rates
~ maintains a ratio of 3 Na+/ 2 K+
- for every 100K+ inside, 150Na+ outside
- Therefore, it is more positive outside and less positive (more negative) inside.
92.
Where are nissl bodies found?: They are found in the cell body and are a specialized form of rough E.R.
93.
Where do most malignant gliomas arise?: Malignant gliomas are actually secondary tumors that arose in some other type of tissue.
94.
Where does acetylcholine have an excitatory efffect and where does it have an inhibitory efffect?: - Excitatory effect at neuromuscular junction in skeletal muscle.
- Inhibitory effect at neuromuscular junction in cardiac muscle.
95.
Why are neuroglia susceptible to cancer but not neurons?: Neuroglia keep undergoing cell division. Neurons do not.
96.
Why do local potentials never spread to the end of a neuron's axon?: Because the change in RMP is never great enough to generate an impulse.
97.
Why doesn't an action potential move backwards?: Because the previous section is still in a refractory period and resists re-stimulation.
- That is why dendrites and axons are one-way paths for impulses.
98.
Why is most CNS damage permanent?: - CNS neurons lack the neurilemma.
- astrocytes fill up the damaged area and their scar tissue blocks axon regrowth.
