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Organ Systems > Part 7 > Flashcards

Part 7 Flashcards

0
Q

describe the function of a Cell body ?

A

Genetic and metabolic machinery for neurotransmitter synthesis. necessary for a cell to exist.

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1
Q

what are the structural features of a neuron?

A

Cell body, Axon, Dendrite, synapse

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2
Q

what is the function of an Axon?

A

propagates action potential

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3
Q

describe a dendrite?

A

filamentous extensions of cell body

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4
Q

what is a synapse?

A

axon terminal

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5
Q

what are cell bodies called in the CNS and PNS?

A

CNS - Nucleus

PNS - Ganglion

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6
Q

what are axons called in the CNS and PNS?

A

CNS - tract

PNS - nerve

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7
Q

all neurons in the PNS are surrounded by ?

A

Glia (Schwann Cells)

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8
Q

Gaps between Schwann Cells are called?

A

Nodes of Ranvier

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9
Q

4 Types of connective tissue surrounding nerves ?

A

Epineruium
perineurium
endoneurium
basement membrane

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10
Q

Epineurium ?

A

surrounds the whole nerve

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11
Q

Perineurium ?

A

surrounds fascicles of nerve fibers

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12
Q

endoneurium ?

A

surrounds individual axons

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13
Q

Basement Membrane ?

A

protein matrix secreted by Schwann cells

• forms a protein interface between Schwann cells and endoneurium

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14
Q

Nerve Fascicles ?

A

Bundles of axons that target single muscles or skin regions

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15
Q

Nervi Nervorum ?

A

bundles of axons that innervate CT layers of nerves

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16
Q

Vasa Nervorum?

A

Blood vessels to CT, axons and Glia in nerves

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17
Q

What is Neuropathy ?

A

Neural disease due to damage to axons or glial cells

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18
Q

What are some common causes of Neuropathy ?

A

Diabetes, kidney failure, alcoholism, nutritional deficiency, trauma,auto immune disease.

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19
Q

How does Axonal degeneration progress?

A

damage begins at the hands and feet distally and moves proximally

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20
Q

Explain demyelination

A

degeneration of glia and the unwinding of myelin sheaths around axons

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21
Q

what is Guillain-Barre ?

A

Demyelination of motor fibers due to an autoimmune response to infection, surgery or immunization

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22
Q

What is Multiple Sclerosis?

A

demyelination disease in the CNS

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23
Q

what is paresthesia ?

A

burning or tingling (pins and needles) feeling due to neuropathy

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24
what is hyperalgesia ?
exaggerated pain response to normally painless stimuli
25
Explain sprouting in relation to Nerve regeneration
Branching by axon proximal to injury. | Basement membrane tunnels, created by Schwann cells, guide axons, using laminin.
26
What is Laminin?
neurite promoting glycoprotein, component of the basement membrane that is increased on the surface of schwann cells
27
Whats the speed of Axon regrowth for PNS and CNS?
PNS - 1mm/day | CNS - minimal due to lack of basement membrane
28
Gray matter is made up of ?
H shaped region of cell bodies dendrites and axons
29
why is White matter 'White'?
myelin, glial cells surround many axons making it look 'white'
30
rootlets extend out from ?
dorsal and ventral horns and converge into roots
31
dorsal and ventral roots exit the vertebral column and unite to become ?
the spinal nerve
32
Spinal nerve splits into two rami?
Dorsal and Ventral rami (aka Peripheral nerves)
33
Where is the cell body found in the sensory neurons and motor neurons?
Sensory neuron - Dorsal root ganglion | Motor neuron - Ventral horn
34
sympathetic neurons are found in nearly all nerves. they have two types of cell bodies
preganglionic - found in gray matter, projects axon to sympathetic ganglion postganglionic - forms sympathetic ganglion, projects axons to periphery.
35
this membrane constituent can increase permeability to water soluble molecules and stiffens membranes to help form lipid rafts
cholesterol
36
types of membrane proteins?
transmembrane (alpha helix, beta barrel) membrane associated lipid linked protein attached
37
what are the benefits to carbohydrates connecting transmembrane proteins to the ECM?
carbohydrates bind lectins which mediate cell-cell adhesions | ex. blood clotting and inflammation.
38
the most common transmembrane protein that crosses the membrane bilayer?
alpha helix
39
the alpha helix can make multiple crossings or a single crossing across the membrane, explain the difference?
multiple crossings - create a pore used as an ion channel | single crossing- acts as a signal receptor
40
Ion specificity of a channel depends on ?
- charge distribution: positive channel will only allow negative through. - diameter and shape of channel: (size of ion is determined more by hydration shell than size of atom)
41
what causes the sodium potassium pump to alter conformation?
donation of phosphate by ATP
42
membrane polarization created by a single ion is known as?
equilibrium potential
43
this potential is generated by the net flux of all ions?
membrane potential (Vm)
44
product of net driving force and permiability
net flux
45
sum of concentration and electrical gradients
net driving force
46
ease of flux through a channel
permeability
47
this ion has a high net flux, high permeability and concentration and electrical gradients are in opposite directions, reducing net driving force.
K+
48
this ion has a low net flux, low permeability and concentration and electrical gradients are in the same directions, increasing net driving force.
Na+
49
3 types of ion gaiting properties ?
Voltage gated ligand gated mechanically gated
50
Voltage gated ion channels are located at ? and work by ?
Location : axion hillock and nodes of Ranvier | stimulus : de/hyper polarizing current which changes conformation and permeability
51
ligand gated ion channels are located at ? and work by ?
location: neural or other cell surfaces stimulus: neurotransmitters, ligands
52
mechanically gated ion channels are located at ? and work by ?
location: skin, retina..etc | stimulus : pressure, touch, light..
53
Receptor Stimulus increases Na+ permeability yielding?
a graded depolarization of the membrane potential
54
At what location does the triggering of the all or none action potential take place?
nodes of Ranvier
55
what mechanism causes the all or none action potential at the nodes of Ranvier?
influx of Na+ ions from the receptor potential depolarizes and opens Na+ gated ion channels.
56
briefly explain the 4 phases of action potential
* Incoming positive ionic current depolarizes membrane to threshold level of voltage. * At threshold, rapid depolarization to positive value,~50mV (Na) * Repolarization to initial potential * Hyperpolarization, ~-70mV (K)
57
what happens during depolarization?
Na channel opens in response to depolarization (at threshold) • Potential almost reaches +50mV (Na)
58
what causes repolarization?
Na channel spontaneously inactivates | • K channels opens
59
what happens during hyperpolarization
* K channel still open; K flux happens through both leak & volt-gated channels * Potential almost reaches >-70mV (K)
60
what type of channels do not participate in action potentials?
non gated, leakage K+ channels
61
internal depolarization causes the protein configuration to?
open the outer portion of the channel
62
initial depolarization and overshoot is strong because ?
Na influx has a high driving force
63
why does Na+ have a high driving force?
both concentration and electrical gradients are in the same direction and summate.
64
what is excitability?
sensitivity of the cells ability to produce an action potential
65
what two variables can alter excitability?
– Concentration gradient – Channel permeability and/or threshold potential
66
how does hyperkalemia (increasing extracellular K+ level) affect concentration gradient?
causes prolonged depolarization, Na+ channels are inactivated, the threshold is raised and the cell becomes less excitable. • Decreasing extracellular K+ has reverse effect
67
channel permeability can be altered by ?
channel blocking and protein reconfiguration. (lidocaine is an example of channel blocking)
68
describe the refractory period
only happens in unmyelinated axons. the period of time after an action potential during which the membrane channels are less responsive to stimuli
69
whats the difference between an absolute refractory period and a relative refractory period?
Absolute - channels cannot be activated | relative - takes a greater stimulus to create action potential.
70
describe conduction in a myelinated axon.
AP’s are only produced in nodes of Ranvier and the axon hillock because this is where the voltage-gated channels are.
71
What is Saltatory conduction?
refers to the skipping of AP generation from one node to the next.
72
Why does amplitude decrease along a myelinated area of an axon?
because current leaks out through non-gated K+ channels.
73
demyelination occurs due to Guullian - barre and MS, what does this due to conduction
conduction is slowed or halted because excess current leaks out through non-gated K channels. This reduces the available current for the next node of Ranvier.
74
How many axons does a neuron usually have?
One
75
How many dendrites does a neuron usually have?
Many
76
Na-K pump pumps __ Na ions out and __ K ions in against their concentration gradients. This results in what?
3; 2; Results in a net loss if one charge.

Organ Systems (20 decks)

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