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Anatomy & Physiology > Chapter 12 - Neural Tissue > Flashcards

Chapter 12 - Neural Tissue Flashcards

0
Q

Extra cellular fluid contains?

A

High concentrations of Na+ and Cl- ions

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1
Q

Intracellular fluid contains?

A

High concentration of K+ ions

Negatively charged proteins

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2
Q

How do ions enter or leave the cell at resting potential?

A

Leak channels or active transport mechanisms

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3
Q

Types of passive forces

A

Chemical Gradients
Electrical Gradients
Electrochemical Gradients

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4
Q

Chemical Gradients

A

Concentration gradient, drives K+ out of cell through open K+ channels.

(Na+ moves in)

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5
Q

Electrical Gradients

A

K+ leaves cell more rapidly than Na+ enters

Cytosol exhibits a net loss of + charges

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6
Q

Electrical Gradients: What happens to the cell membrane?

A
  • Net loss of + charges, leaving an excess of - charges proteins
  • Extracellular fluid near cell membrane displays net gain of + charges
    • and - charges are separated by cell membrane, thus a potential difference arises
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7
Q

Electrochemical Gradients

A

•Sum of chemical and electrical forces acting on that ion across the cell membrane

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8
Q

Na+/K+ exchange pump

A
  • Are involved in active forces across the membrane

* Exchanges 3 intracellular Na+ ions for 2 Extracellular K+ ions

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9
Q

Changes in the Transmembrane Potential

A
  • Passive channels

* Active channels

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10
Q

Passive channels

A

AKA leak channels; always open

Permeability varies from moment to moment

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11
Q

Active channels

A

AKA gated channels; open/close in response to specific stimuli

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12
Q

Classes of Active Channels

A
  • Chemically regulated channels
  • Voltage regulated channels
  • Mechanically regulated channels
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13
Q

Chemically regulated channels

A

Open/close when they bind to specific chemicals (most abundant on the dendrites and cell body of neuron)

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14
Q

Voltage regulated channels

A

Open/close in response to changes in the transmembrane potential

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15
Q

Mechanically regulated channels

A

Open/close in response to physical distortion of the membrane surface

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16
Q

Graded (local) potentials

A
  • Changes in the transmembrane potential

* Can’t spread far from the site of stimulation

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17
Q

Events at a Graded Potential

A
  • Stimulus causes gated channels to open
  • Depolarization
  • Repolarization
  • Hyperpolarization
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18
Q

Depolarization

A

Na+ ions rush into cell causing a shift in the transmembrane potential toward 0mv

*the degree of depolarization decreases with distance away from the stimulation site

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19
Q

Repolarization

A

Stimulus is removed; normal membrane permeability is restored and transmembrane potential returns to resting level

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20
Q

Hyperpolarization

A

Inside of the cell becomes more negative than normal

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21
Q

Action potentials

A

Propagated (spread) changes in the membrane potential, once initiated affects the entire excitable membrane

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22
Q

The membrane potential returns to the resting state due to ________.

A

The diffusion of ions through leak channels

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23
Q

Generation of Action Potential

A
  • Depolarization
  • Activation
  • Inactivation
  • Return to normal permeability
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24
Q

Depolarization (Generation of AP)

A

Graded polarization brings an area of excitable membrane to threshold (-60mv to -55mv)

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25
Q

Activation (Generation of AP)

A

Activation of Na+ channels and rapid depolarization
•Voltage regated Na+ channels open
•Na+ ions enter cell
•Transmembrane potential goes from -60mv to +30mV

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26
Q

Inactivation (generation of AP)

A
  • inactivation of Na+ channels (close)
  • activation of K+ channels (open)
  • repolarization begins
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27
Q

Return to permeability (Generation of AP)

A
  • Na+ channels regain normal properties
  • K+ channels begin closing; hyperpolarization occurs
  • membrane returns to resting state
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28
Q

Absolute vs Relative refractory periods

A

Last stage of AP

29
Q

Propagation of AP

A

The way an AP spreads along an excitable membrane

30
Q

Continuous propagation

A

Occurs along unmyelinated axons

31
Q

Saltatory propagation

A

Occurs along myelinated axons

32
Q

Electrical synapse

A

Direct physical synapse between cells

*occur in some areas of the brain

33
Q

Cholingeric Synapses

A
  • Synapse that releases acetylcholine (ACh)
  • Arriving action potential depolarizes synaptic knob
  • Calcium ions enter cytoplasm of synaptic knob
34
Q

Neurotransmitters

A

Norepinephrine (NE), Dopamine, Serotonin, Nitric Acid (NO), Carbon Monoxide (CO)

35
Q

Postsynaptic Potential

A

Graded potentials that develops in the postsynaptic membrane in response to a neurotransmitter

36
Q

Excitatory post synaptic potentials (EPSP)

A

Graded depolarization caused by neurotransmitters

37
Q

Inhibitory post synaptic potentials (IPSP)

A

Graded hyperpolarization caused by neurotransmitters

38
Q

Temporal summation

A

Repeatedly; at 1 synapse

39
Q

Spatial summation

A

Simultaneous stimuli and multiple synapse

40
Q

Somatic sensory

A
  • External (touch, pressure, pain, temp)

* cardiac muscle

41
Q

Somatic motor

A
  • controls skeletal muscles

* voluntary

42
Q

Efferent

A
  • motor

* down and out

43
Q

Afferent

A
  • sensory

* up and in

44
Q

Threshold for an axon is between _____ and _____ mV

A

-60 mV and -55 mV

45
Q

Depolarization _____ to _____ mV

A

10 to 15

46
Q

A stimulus that shifts the resting membrane potential from ______ to ______ mV will _______?

A

-70 to -62 mV; will not produce an action potential, only a grade depolarization

47
Q

Normal resting potential is about _______ mV

A

-70

48
Q

Membrane potential

A
  • -40mV to -80 mV
  • ions have concentration grad item across the membrane (K+)
  • High concentration inside
  • Low concentration outside (of membrane)
49
Q

Types of synapses

A

Neuromuscular Junction

Neuroglandular Junction

50
Q

Neuromuscular junction

A

Synapse between neuron and muscle

51
Q

Absolute refractory period

A
  • Sodium channels open or inactivated

* No action potential possible

52
Q

Relative refractory period

A
  • Membrane potential almost normal

* Very large stimulus can initiate action potential

53
Q

Neurons are classified as?

A

Anaxonic
Bipolar
Unipolar
Multipolar

(On basis of the relationship of the dendrites to the cell body and the axon)

54
Q

Anaxonic neuron

A

Have more than two processes (all dendrites)

55
Q

Bipolar neurons

A

Have two processes separated by the cell body

56
Q

Unipolar neurons

A

Have 1 single elongated process (with the cell body located off to side)

57
Q

Multipolar neurons

A

Have more than 2 processes (single axon, multiple dendrites)

58
Q

Structure of neurons

A

Presynaptic cell
Postsynaptic cell
Synaptic cleft

59
Q

Presynaptic cell

A

Neuron that sends messages

60
Q

Postsynaptic cell

A

Cell that receives message

61
Q

Synaptic cleft

A

Gap that separates pre and Postsynaptic membrane

62
Q

Presynaptic membrane

A

Synaptic surface where neurotransmitter release occurs

63
Q

Postsynaptic membrane

A

Portion of the plasma membrane of a Postsynaptic cell that is part of a synapse

64
Q

Neuroglia in the CNS

A

Ependymal cells
Astrocytes
Oligodendrocytes
Microglia

65
Q

Ependymal cells

A 
Line ventricles (brain) and central canal(spinal)
Assist in producing, circulating, and monitoring CSF
66
Q

Astrocytes

A

Maintain blood-brain barrier
Provide structural support
For scar tissue after injury

67
Q

Oligodendrocytes

A

Myelinate CNS axons

Provides structural framework

68
Q

Microglia

A

Remove cell debris, wastes, and pathogens by phagocytosis

69
Q

Neuroglia in PNS

A

Satellite cells

Schwann cells

70
Q

Satellite cells

A
  • Surround neuron cell bodies in ganglia

* Regulate 02, CO2, nutrient, and neurotransmitter levels around neurons in ganglia

71
Q

Schwann cells

A

Surround all axons in PNS
Myelination of peripheral axons
Repair process after injury

Anatomy & Physiology (11 decks)

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