SG 6: Chap 7 Neurons

Question 1

What is a nerve?

Answer 1

is a bundle of parallel axons and dendrites that transmit nervous impulses between nerve cells and various parts of the body.

Question 2

what is a sensory neuron?

Answer 2

it conducts information towards the brain and spinal cord.

Question 3

what is a motor neuron?

Answer 3

it carries information away from the brain and spinal cord to an effector (muscle or gland)

Question 4

what is an interneuron?

Answer 4

these are located between the motor and sensory neurons. only found within the brain and spinal cord and account for more than 99% of the body neurons. JOB: integrate and interpret the sensory singnals

Question 4

What are functions of glial cells ?

Answer 4

Also known as neuroglial cells, some provide structural support for the neurons of the brain and spinal cord, others provide a steady supply of chemicals(nerve growth factor) that stimulates nerve growth, others form insulating sheaths around the axons called myelin sheath (Schwann cells) these cells can communicate w/one another & w/neurons

Question 6

How do neurons differ from glial cells In Terms of cell division?

Answer 6

Glial cells retain the ability to undergo cell division in adulthood whereas most neurons can’t.

Question 7

what is the myelin sheath?

Answer 7

composed of the plasma membrane in multiple layers of the glial (schwann) cell, it increases the of conduction of a nerve impulse & helps its repair. it covers most of the axons outside the brain and spinal cord and some w/in.

Question 8

what is a Schwann Cell?

Answer 8

forms neurons myelin sheaths. insulates individual axons and prevents messages from short circuiting between neurons.

Question 9

what are the nodes of Ranvier?

Answer 9

the gaps between the Schwann cells, where the axon is exposed. A function is that they allows nutrients and waste to enter and exit the neuron, and facilitate the rapid conduction of the nerve impulses.

Question 10

what is the gray matter?

Answer 10

is the region of the CNS that contain neuron cell bodies, dendrites and axon terminals and unmyelinated axons.

Question 11

what is the white matter?

Answer 11

regions of the CNS but mainly PNS that are myelinated nerve fibers(axons). these are important for communication over long distances.

Question 12

Saltatory conduction function?

Answer 12

is a transmission where with the assistance of myelin sheath in place, a nerve impulse “jumps” successfully from one rode of ranvier to the next. These axons are 100% faster than a single conduction.

Question 13

what is Multiple Sclerosis?

Answer 13

it is a disease in which the myelin sheaths in the brain and spinal cord are progressively destroyed. Damaged regions of the myelin sheath become hardened scars which interfere w/the transmission of nerve impulses. depending of the region of the nervous system, results can be paralysis, loss of sensation, including loss of vision.

Question 14

what is ALS ?

Answer 14

short of Amyotrophic Lateral Sclerosis. ALS is a disease in where only motor neurons throughout the brain and spinal cord die and stop sending messages to the skeletal muscles. w/out stimulation from the motor neurons, muscles gradually weaken & person loses control of body movement.
leads to respiratory failure(death) since muscles that control breathing eventually die

Question 15

What is a Nerve Impulse?

Answer 15

also known as action potential, its an electrochemical signal caused by Na+ ions and K+ ions crossing the neurons membrane to enter and leave the cell.

Question 16

What are the diff concentrations inside and outside of the cell of Na+ and K+ ions during diff stages?

Answer 16

Resting potential: + in the outside & – in the inside

action potential: – in the outside & + + in the inside

Question 17

what structures in the plasma membrane participate in the transport of these ions?

Answer 17

gated ions channels and Sodium-Potassium pumps.

Question 18

what are Ion channels when regarding a Nerve Impulse?

Answer 18

are pores in the neuron membrane that dont need cellular energy to pass through.
Na+ channels & K+ channels

Question 19

what are Pumps when regarding a nerve impulse?

Answer 19

Na+-K+ pump are special proteins that actively(using cellular energy in form of ATP to move ions across their concentration gradient) transports Na and K ions across the membrane.
pumps out 3 Na+ ions and intakes 2 K+ ions
the pump restores the original levels of charges after action potential took place back to resting potential.

Question 20

What is “resting potential?” and what is the ions concentration?

Answer 20

is a charge difference across the membrane which results from unequal distribution of ions. no conduction impulse. inside is neg, and outside is positive. Na+ greater in the outside, and K+ greater inside the neuron.

Question 21

what is action potential? and what is the ion concentration?

Answer 21

or Nerve impulse. is when the neurons receive an ecitatory signal which results in a sudden reversal in the charge difference across the membrane followed by the restoration of the original charge diff. Neg in the outside and positive in the inside.

Question 22

what happens during depolarization? Depo= deposit

Answer 22

depo= deposit Na+ gated ion channels open and Na+ ions enters which results in the ++ charges increase inside the axon membrane.

Question 23

what happens during repolarization? repo=take

Answer 23

repo=take about 1/2 way through the action potential, K+ gated ion channels open and K+ ions flow out. as k flows back out, almost returning the charge differences to resting potential.

Question 24

what is refactory period?

Answer 24

occurs after action potential when neurons cannot be stimulated. Na+ ions channels are closed and cant be opened. inside more neg than outside

Question 25

what is a synapse?

Answer 25

is the region of close proximity between a neuron and another cell, separated by a synapse cleft.

Question 26

what is a synapse cleft?

Answer 26

the gap between the presynaptic cell and the postsynaptic cell.

Question 27

what is a synpatic knob?

Answer 27

an axons branch end. these branches end with a small bulklike swelling known as a knob

Question 28

what is a presynaptic cell?

Answer 28

a cell that is sending the message

Question 29

what is a post-synaptic cell?

Answer 29

the neuron receiving the message

Question 30

In a synaptic transmission, what happens after the nerve impulse reaches the axon ending(synaptic knobs) of the pre-synaptic neuron?

Answer 30

the gates of Na+ open, Na+ ions enter the knob resulting in the release of the neurotransmitters into the synaptic cleft from the synaptic vesicles. .

Question 31

what happens after the neurotransmitters are diffused across/into the synaptic cleft?

Answer 31

the neurotransmitter binds to its receptor on the membrane of a postsynaptic neuron and an ion channel is opened.

Question 32

In a synaptic transmission, what is the role of a receptor?

Answer 32

it is a specified protein that only recognizes a particular assigned neurotransmitter. when the neurotransmitter binds to a receptor it causes the opening of an ion channel.

Question 33

what happens to the neurotransmitters after they are released?

Answer 33

they are quickly removed, so their affect is temporary. 2 ways the neurotransmitter can be released, 1 way enzymes can deactivate them and 2nd, the neurotransmitter may be actively pumped back into the presynaptic knob.

Question 34

what is Acetylcholine & Norepinephrine?

Answer 34

they are neurotransmitters that act both in the cns and pns. although both have excitatory & inhibitary affects, whatever the effect of norepinephrine has on any particular organ, acetylcholine will have the opposite.

Question 35

Acetylcholines role in neuromuscular junction?

Answer 35

Acetylcholine is the neurotransmitter that is released at every neuromuscular junction where it triggers contractions of voluntary skeletal muscles

Question 36

what is myasthenia gravis?

Answer 36

an autoimmune disease in which the body defense mechanisms attack the acetylcholine receptors. ppl with myasthenia gravis have little muscle strength.

Question 37

what are some of the neurotransmitters?

Answer 37

Acetycholine: triggers voluntary skeletal contraction, Norepinephrine: regulates mood, pleasure system of the brain, and arousal, Serotonin: promotes a generalization feeling of well-being, Dopamine: helps regulate emotions

Question 38

what is alzheimers?

Answer 38

is a progressive disease and results in loss of memory particularly on recent events followed by severe personality changes. the hippocampus and cerebral cortex lose a large amount of neurons. acetyclocline decreases as much as 90% in these regions.

Question 39

what is Prozac?

Answer 39

Its an antidepressant that specifically affects serotonin functioning, increasing the level of serotoninin the synapse by reducing its rate of removal.

Question 40

what are the bases of depression and pakinson’s disease?

Answer 40

depression: insufficient levels of the neurotransmitters: dopamine, serotonin, and norepinephrine
Pakinsons disease: is a progressive disorder that results from the death of dopamine producing neurons.

Question 41

Be able to describe the structure of a neuron and the function of each one of its parts

Answer 41

(cell body, dendrite, axon)