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Anatomy and Physiology I > Lesson 14 > Flashcards

Lesson 14 Flashcards

1
Q

synapse

A

point where an axon terminal meets the next cell

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2
Q

electrical synapse

A

direct physical contact between cells, links cytoplasm of adjacent cells

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3
Q

electrical synapse characteristics (4)

A
  • locked together at gap junctions (connexons)
  • allows ions to pass between cells
  • produce continuous local current and action potential propagation
  • found in areas of the brain, eye, ciliary ganglia (PNS), cardiac muscle cells
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4
Q

chemical synapse

A

signal transmitted across a gap by chemical neurotransmitters; cells do not touch

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5
Q

who discovered the synaptic cleft?

A

Ramon y Cajal

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6
Q

how did Otto Loewi demonstrate that neurons can communicate by releasing chemicals?

A

Flooded exposed hearts of two frogs with saline, stimulated the vagus nerve of the first frog and its heart slowed. He removed the saline from the first frog and found found it slowed heart rate of the second frog.

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7
Q

where do electrical synapses occur?

A

neurons, neuroglia, cardiac, and single-unit smooth muscle

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8
Q

advantage of electrical synapses

A

much faster, no delay for release, diffusion, and binding of neurotransmitter

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9
Q

disadvantages of electrical synapses

A

cannot integrate information

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10
Q

synaptic cleft

A

gap between presynaptic neuron and postsynaptic neuron; typically only 20 um wide

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11
Q

postsynaptic density

A

the postsynaptic neuron membrane contains a certain density of neurotransmitter receptors and ion channels

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12
Q

synaptic delay

A

since chemical synapses are not directly in contact with the postsynaptic cell and require the release of a neurotransmitter to stimulate/inhibit the target cell, there is delay of 0.2-0.5 msec

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13
Q

If information is being passed along a series of neurons…

A

the fewer synapses found between the transmission of the information means the faster response; important for reflexes

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14
Q

synaptic fatigue

A

occurs when neurotransmitters cannot recycle fast enough to meet demands of intense stimuli

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15
Q

two major chemical categories of neurotransmitters

A
  1. acetylcholine
  2. amino acids
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16
Q

acetylecholine

A

formed from acetic acid and choline

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17
Q

amino acids

A

include glycine, glutamate, aspartate, and y-aminobutyric acid (GABA)

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18
Q

monoamines (biogenic amines)

A

synthesized from amino acids; ex. serotonin and the catecholamines

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19
Q

catecholamines

A

epinephrine, norepinephrine, and dopamine

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20
Q

serotonin

A

a CNS neurotransmitter that affects attention and emotional states. decreased serotonin production may be responsible for some cases of severe chronic depression

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21
Q

norepinephrine (NE)

A

aka noradenaline; released at adrenergic synapses; has excitatory and depolarizing effects and is widely distributed in the brain and portions of the ANS

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22
Q

dopamine

A

a CNA neurotransmitter that may be excitatory or inhibitory that is used for movement control. Damage to neurons that produce dopamine involved in Parkinson’s disease and cocaine use

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23
Q

monoamines affect the cell _____

A

indirectly, through a second messenger system (G protien)

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24
Q

gases

A

nitric acid (NO) and carbon monoxide (CO) synthesized as needed rather than store in vesicles; these gases affect cells by diffusing into a cell and affecting intracellular enzymes

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25
Q

neuropeptides

A

chains of 2-40 amino acids; ex. cholecystokinin (CCK) and endorphins; indirect effect
- stores in large secretory granules
- function as hormones or neuromodulators

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26
Q

endorphins relieve pain perception by inhibiting the release of the neuropeptide _____ at synapses that relay pain sensations

A

substance P

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27
Q

three kind of synapses

A
  • excitatory cholinergic synapse (ACh)
  • inhibitory GABA-ergic synapse (GABA)
  • excitatory adrenergic synapse (NE)
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28
Q

cholinergic synpase

A

acetylcholine is the neurotransmitter; located between all neuromuscular junctions, many CNS synapses, all neuron-to-neuron, neuromuscular synapses in the PNS

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29
Q

steps in acetylcholine synaptic transmission (4)

A
  1. action potential depolarizes the axon terminal, opens voltage-gated Ca2+ channels
  2. Ca2+ enters and causes exocytosis of the vesicles containing ACh
  3. ACh diffuses across cleft, binds to postsynaptic sodium receptors that the open and allow Na+ to enter the postsynaptic cell via diffusion
  4. entry of Na+ depolarizes the cell by generating a postsynaptic potential
30
Q

_____ is reabsorbed by the synaptic terminal to form more _____ while the _____ is absorbed by the postsynaptic cell or other cells/tissues in the area

A

choline, ACh, acetate

31
Q

GABA-ergic synapse

A

y-aminobutyric acid (GABA) is an amino acid neurotransmitter

32
Q

steps in a GABA synapse (3)

A
  1. action potential triggers release of GABA into synaptic cleft
  2. GABA receptors are chloride channels
  3. allows Cl- to enter the cell causing hyperpolarization of the postsynaptic membrane
    - postsynaptic neuron is inhibited
33
Q

adrenergic synpase

A

norepinephrine (NE) is the neurotransmitter

34
Q

steps in a adrenergic synapse

A
  1. monoamines and neuropeptides bind to G-protein coupled receptors on postsynaptic membrane
  2. activate a second-messenger system such as cyclic AMP
    - slower response that others
    - advantage of enzyme amplification
35
Q

to end a signal…

A
  • presynaptic neuron stops releasing neurotransmitter
  • neurotransmitter already in the synapse is cleared in various ways
36
Q

neurotransmitter degradation

A

enzyme in synaptic cleft breaks down the neurotransmitter

37
Q

acetylcholinesterase (AChE)

A

breaks down ACh into acetate and choline

38
Q

reuptake

A

neurotransmitter or its broken down products are reabsorbed into the axon terminal

39
Q

diffusion

A

neurotransmitter or its broken down products simply diffuse away from the synapse into nearby ECF

40
Q

neuromodulators

A

chemicals secreted by neurons that have long term effects on groups of neurons

41
Q

what can neuromodulators cause? (2)

A
  • may alter the rate of neurotransmitter synthesis, release, reuptake, or breakdown
  • may adjust sensitivity of postsynaptic membranes
42
Q

Nitric oxide (NO)

A

simple neuromodulator; gas enters the postsynaptic cell and activates second messenger pathways (Ex. relaxing smooth muscle)

43
Q

_____ are chains of amino acids that can act as neuromodulators

A

neuropeptides

44
Q

_____ and _____ are neuropeptides that inhibit pain signals in the CNS (aka opioids)

A

enkephalins and endorphins

45
Q

neural integration

A

the ability to process, store, and recall information and use it to mae decisions

46
Q

What is a tradeoff to neural integration?

A

Chemical transmission involves synaptic delay that makes information travel slower that is would if there was no synapse

47
Q

characteristics of neural integration

A
  • chemical synapses allow for decision making
  • brain cells are incredibly well connected, allowing for complex integration
48
Q

two types of postsynaptic potentials

A

EPSP (excitatory postsynaptic potential)
IPSP (inhibitory postsynaptic potential)

49
Q

EPSP - excitatory postsynaptic potential

A

voltage change from the RMP toward threshold

50
Q

IPSP - inhibitory postsynaptic potential

A

voltage becomes more negative than it is at rest

51
Q

what does an EPSP usually result from?

A

Na+ flowing into the cell

52
Q

what does and IPSP usually result from?

A

Cl- entry or K+ exiting from the cell

53
Q

what type of neurotransmitters cause EPSPs?

A

glutamate and aspartate

54
Q

what type of neurotransmitter cause IPSPs?

A

glycine and GABA

55
Q

what type of neurotransmitter can both excite and inhibit cells, depending on its type?

A

acetylcholine and norepinephrine

56
Q

ACh _____ skeletal muscle and _____ cardiac muscle

A

excites, inhibits

57
Q

summation

A

the process of adding up postsynaptic potentials and responding to their net effect

58
Q

where does summation occur?

A

in the trigger zone

59
Q

a neuron’s response depends on whether or not the _____ input is excitatory or inhibitory

A

net

60
Q

temporal summation

A

a single synapse generates EPSPs so quickly that each is generated before the previous one fades

61
Q

spatial summation

A

EPSPs from several different synapses add up to threshold at the axon hillock

62
Q

presynaptic facilitation

A

occurs when one presynaptic neuron enhances another one; increases necessary synaptic transmisison

63
Q

presynaptic inhibition

A

occurs when one presynaptic neuron suppresses another; reduces of halts unwanted synaptic transmission

64
Q

neural coding

A

converting stimulus information into meaningful patterns of action potentials

65
Q

labeled line code

A

mechanism for transmitting qualitative information; depends on what neurons fire
ex. optic nerve input labeled as light

66
Q

heavy metal poisoning

A

chronic exposure to heavy metals can damage neuroglia and lead to demyelination which causes axons to irreversibly deteriorate (arsenic poisoning)

67
Q

diphtheria

A

disease caused by bacterial toxin
- damages Schwann cells and destroys PNS myelin sheath
- can lead to fatal paralysis
- rare occurrence since disease vaccine is available

68
Q

multiple sclerosis

A

autoimmune disorder caused by inflammation of nerve triggered by immune cells (immune cells probably triggered by virus of defective gene)
- demyelination disease affecting CNS axons
- vision, speech, balance, and motor coordination affected

69
Q

what is multiple sclerosis treated with?

A

corticosteroids (anti-inflammatory agents) and interferon to slow the disease progression

70
Q

Guillain-Barre syndrome

A

autoimmune disorder that is trigger by a virus;
- demyelination disease affecting peripheral nerves
- sensation of weakness or tingling of the legs that spreads to arms
- progression leads to paralysis (diaphragm also affected)
- most fully recover but some continue to have residual weakness

Anatomy and Physiology I (22 decks)

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