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PHYSIOLOGY > ME01 - Nerve & Synaptic Physiology > Flashcards

ME01 - Nerve & Synaptic Physiology Flashcards

1
Q

Communications and control network that allows an organism to interact in appropriate ways with its environment

A

Nervous System

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2
Q

Involved in Myelin formation around axons in the peripheral nervous system

A

Schwann Cell

Each Schwann cell myelinates only one axon

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3
Q

Myelinating Cells

A 
C-O-P-S
CNS
Oligodendrocytes
PNS
Schwann cells
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4
Q

Importance of Myelination

A

Increases speed of AP conduction
Restricts flow of ionic current to small myelinated portions of the axon between adjacent sheath cells (Nodes of Ranvier) – Saltatory conduction

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5
Q

Encapsulate dorsal root and cranial nerve ganglion cells

Regulate their microenvironment in a fashion similar to that used by the astrocytes

A

Satellite Cells

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6
Q

PARTS OF NEURON

A

CELL BODY - metabolic and integrative center of the neuron
DENDRITES - processes extend outward (arbor vitae)
AXON - long fibrous process that originates from axon hillock; divides into presynaptic terminals ending in synaptic knobs (terminal button)
Contain granules or vesicles which contain neurotransmitter

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7
Q

Divisions of NS
CNS -
PNS -

A

CNS - central hub, all info is being processes, Brain and Spinal Cord
PNS - Interface between Env’t and CNS, Sensory neurons, somatic motor neurons and autonomic motor neurons

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8
Q

Process whereby neurons transduce env’t energy into neural signals
Accomplished by sensory receptors
Ex. Mechanical, Light, Sound, Chemical, Thermal

A

Sensory Detection

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9
Q

Information and Processing, which is a function of NS, includes:

A

Transmission of information via neural networks
Transformation of information by recombination with other information
Perception of sensory information
Storage and retrieval of information
Planning and implementation of motor commands
Thought processes and conscious awareness
Learning
Emotion and motivation

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10
Q

Totality of na organism’s response to its environment

A

Expression of Behavior

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11
Q

Function of NS which plays a role in processing and storage of information

A

Language

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12
Q

Special forms of information processing that permit behavior to change appropriately in response to previously experience env’t challenges

A

Learning and Memory

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13
Q

Major Cell Types in the NS
Neurons -
Neuroglia -

A

Neurons - nerve cells; for communication and signaling
Neuroglia - nerve glue; sustain neurons both metabolically and physically: MAINTAIN internal milieu of the nervous system

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14
Q

Types of Neuroglia:
Microglia -
Macroglia -
Ependymal cells -

A

Types of Neuroglia:
Microglia - macrophage in the brain; removes injury or disease
Macroglia - supportive matrix of CNS; protects neurons
Ependymal cells - epithelial lining in ventricular spaces of brain
Special Ependymal cell: CHOROID PLEXUS - prod. of CSF

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15
Q

Types of Macroglia
In the CNS
In the PNS

A

In the CNS: Astrocytes and Oligodendroglia

In the PNS: Schwann Cell and Satellite Cells

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16
Q

Star-shaped
Regulate CNS microenvironment
Foot processes form the BLOOD-BRAIN BARRIER

A

ASTROCYTES

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17
Q

TYPES OF ASTROCYTES
Fibrous -
Protoplasmic -

A

Fibrous - many intermediate filaments, in white matter

Protoplasmic - granular cytoplasm, in gray matter

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18
Q

involved in myelin formation around axons of CNS

Many central axons can be myelinated by single ________

A

OLIGODENDROCYTE

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19
Q 
TYPES OF NERVE FIBERS
FIBER TYPE          FUNCTION     DIAMETER  VELOCITY MYELINATION
A    a
      ß
      y
      ∫ (s)

B
C dorsal root
sympathetic

A

FIBER TYPE FUNCTION DIAMETER VELOCITY MYELINATION
A a Proprioception 12-20 70-120 Myelinated
ß Touch, pressure 5-12 30-70 Myelinated
y Motor to musc. spindle 3-6 15-30 Myelinated
∫ (s) Pain, Cold, Touch 2-5 12-30 Myelinated

B Preganglionic autonomic

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20
Q

Type of Fibers Unmyelinated

A

Type C

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21
Q 
Classification of Sensory Neurons
Ia
Ib
II
III
IV
A

Ia - Annulospiral endings of muscle spindle (A alpha)
Ib - Golgi tendon organs (A alpha)
II - Flower-spray endings of muscle spindle (Aß, Ay)
discrete cutaneous tactile receptors -pressure and touch
III - Temperature, Crude touch, Pricking pain (A∫ (s)
IV - Unmyelinated fibers carrying pain, itch, temp, crude touch (C)

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22
Q

Ability to respond to env’t changes called STIMULI

Highest degree of development of this property seen in neurons

A

Excitability

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23
Q

Any change in the env’t that will influence an organism and cause a response

A 
Stimulus
Mechanical - pinching, pricking
Chemical - acid, alkali
Thermal - Change in temp
Electrical - electrical stimulation
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24
Q 
Elementary Attributes of Stimulus
Modality - 
Location
Intensity
Duration
(An effective stimulus is MILD)
A

Modality - type of energy; Adequate stimulus is most sensitive
Location - site on body where stimulus originated
Intensity - Response amplitude or frequency of action potential
Duration - Time from start to end of response in receptors

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25
Q

What is a sensory unit

A

Sensory unit = single sensory axon and all its peripheral branches

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26
Q

Spatial distribution from which stimulus produces response

A

Receptive field

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27
Q

Sensation from receptors of peripheral edge of stimulus is inhibited compared to sensation from central receptors

A

Lateral inhibition

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28
Q

Magnitude of sensation felt is proportional to the intensity of the stimuli

A

Weber-Fechner Law

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29
Q

Frequency of action potentials in sensory nerves decline over time

A

Desensitization/Adaptation

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30
Q

Receptors can be classified as

A

Rapidly adapting - Phasic receptors

Slowly adapting - Tonic receptors

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31
Q

Graph of threshold stimulus vs stimulus duration

A

Strength-Duration Curve

32
Q

Stimulus strength required to reach threshold should __________ during prolonged stimulation

A

DECREASE

33
Q

An asymptote wherein the curve flattens out with long stimulus durations

A

Rheobase

When stimulus is below the rheobase, stimulation is ineffective even when stimulus duration is very long

34
Q

Stimulus duration equal to twice the rheobase

A

Chronaxie

35
Q

Chronaxie and Excitability

A

LOWER the Chronaxie, the MORE excitable a nerve is

36
Q

Strength-Duration and Conduction Velocity

Curve shifted to the _______ for slower nerve fibers

A

RIGHT

Longer stimulus duration would be needed to bring SLOWER NERVE FIBERS to threshold

37
Q

Once threshold is reached, full fledged AP is produced
Further increase produce no change or increment
AP fails to occur if stimulus is subthreshold in magnitude

A

All-Or-None Principle

38
Q

Junction that permits neurons to pass electrical or chemical signal to other cells

A

Synapse

39
Q 
Types of Synapse
Parameter             NERVE CONDUCTION  SYNAPTIC TRANSMISSION
type of event
continuity of neurons
directionality
conduction delay
neurotransmitters
speed of propagation
A

Parameter NERVE CONDUCTION SYNAPTIC TRANSMISSION
type of event Electrical Chemical
continuity of neurons Continuous Non-continuous (cleft)
directionality Multi directional Unidirectional
conduction delay Absent Present
neurotransmitters Absent Present
speed of propagation +++ ++

40
Q

Plaque like structures in which plasma membranes of coupled cells become closely apposed

A

Gap Junction

41
Q

Time required for multiple steps in chemical neurotransmission

A

Synaptic delays

42
Q

ARRANGEMENT OF SYNAPSES
One-to-One
One-to-Many
Many-to-One

A

Presynaptic neurons&raquo_space; Postsynaptic neurons
One-to-One - neuromuscular junction
One-to-Many - motoneurons on renshaw cells
Many-to-One - widespread in CNS/PNS

43
Q

EVENTS IN SYNAPTIC TRANSMISSION

A

1 - Synthesis and Storage of Neurotransmitter (formation of Ach)
2 - Depolarization and Calcium Influx (depolarization opens Ca chann)
3 - Release of Neurotransmitters
4 - Binding of Neurotransmitter to Postsynaptic Membrane (binding of Ach to Ach receptor cause increase Na+ and K+ conductance)
5 - Generation of Postsynaptic Potential - MEPP
6 - Depolarization of Effectors - AP in adjacent muscle tissure
7 - Terminaiton of Neurotransmitter Action - ACh is degraded by AChE

44
Q

Small molecules endogenous chemicals transmit signals from neuron to target cell across synapse

A

Neurotransmitter

45
Q

Essential Characteristics of Neurotransmitters

A

Precursors/Synthesis enzymes located in presynaptic neuron
Available in sufficient quantity affect postsynaptic cells
Capable of binding to postsynaptic receptors
Biochemical mechanism for inactivation

46
Q

Where is ACh secreted

A

Large pyramidal cells in motor cortex
Basal Ganglia (Nucleus basilis of Meynart)
Skeletal Muscles
All preganglionic of ANS
Postganglionic of Parasympathetic and Sympa NS

47
Q

Where is Norepi and Epi secreted

A

Brain stem
Hypothalamus
Locus ceruleus in the pons
Postganglionic neurons of sympathetic NS

48
Q

Function of Norepi and Epi

A

Control overall activity and mood of mind,

Increasing level of waefulness

49
Q

Where is Dopamine secreted

A

Substantia Nigra

Action terminated by DAR

50
Q

Where is Glycine secreted and function

A 
Spinal cord (Renshaw cells)
Inhibitory transmitter
51
Q

Where is GABA secreted and function

A

Spinal cord, cerebellum, basal ganglia

Inhibitory transmitter

52
Q

Where is GLUTAMATE secreted and function

A

Presynaptic terminals of sensory pathways

PREVALENT EXCITATORY neurotransmitter

53
Q

Where is SEROTONIN secreted and function

A

Median raphe of brainstem
Inhibitory
Mood and Sleep

54
Q

Where is NO secreted and function

A

areas responsible for long-term behavior and memory
Short-acting inhibitory
Not preformed and stored in vesicles, it is synthesizes almost instantly as needed

55
Q 
Neurotransmitter             ORIGIN                       FUNCTION     
Acetylcholine
Norepinephrine
Dopamine
Serotonin
A

Neurotransmitter ORIGIN FUNCTION
Acetylcholine basal forebrain learning, memory
Norepinephrine locus ceruleus of pons arousal, wakefulness
Dopamine substantia nigra of basal ganglia fine tuning movement
Serotonin median raphe of brain stem mood, sleep

56
Q

NT purely excitatory

A

Glutamate

57
Q

NT purely inhibitory

A

Glycine, GABA, Serotonin

58
Q

NT may be inhibitory or excitatory

A

ACh, NorEpi and Epi, Dopamine,

59
Q

Synaptic Information
EPSP
IPSP

A

EPSP - inputs that depolarize bring it CLOSER to threshold, Na+K+
IPSP - inputs that hyperpolarize move it away from threshold, Cl-

60
Q

Process of adding up post synaptic potentials and respond to their net effect

A

Summation

61
Q

Types of Summation
SPATIAL
TEMPORAL

A

SPATIAL - when two EPSPs arrive at PSN simultaneoulsy, produce greater depolarization

TEMPORAL - when EPSPs arrive at PSN rapid succession, overlap in tume adding in stepwise fashion

62
Q

Process where one neuron enhances the effect of another neuron
EPSPs bring membrane potential nearer to threshold

A

Presynaptic Facilitation

63
Q

Opposite of facilitation
One presynaptic neuron suppresses another one
IPSPs bring MP farther from threshold

A

Presynaptic Inhibition

64
Q

Bringing additional neurons into play as stimulus becomes stronger
Enables Nervous System to judge stimulus strength by which neurons, how many of them are firing

A

RECRUITMENT

65
Q

Neurons function in larger ensembles

A

Neuronal Pool

Ex. Neuronal Pool for Rhythm of breathing

66
Q

Zones of Neuronal Circuits
Discharge Zone
Facilitated Zone

A

Discharge Zone - input neuron acting alone can make PS cells fire
Facilitated Zone - presynaptic input neuron synapse with other neurons in the pool, can stimulate to fire only with assistance of other input neurons

67
Q

Subliminal Fringe

A

If they are not discharged by afferent volley

They have excitability increased

68
Q

Decrease in expected respons

Occurs due to presynaptic fibers SHARING postsynaptic neurons

A

Occlusion

69
Q

Signals from multiple inputs unite to excite single neuron

A

Convergence

70
Q

Types of Convergence

A

Convergence from
Single Source
Multiple separate sources

71
Q

Input from just one neuron may produce output through dozens of neurons

A

Divergence

72
Q

Types of Divergence

A

Amplifying - input signal spreads to INC no of neurons as it passes through successive orders of neurons in its path,
Ex. CST

Divergence into Multiple Tracts - signal is transmitted in two directions from neuronal pool
Ex. Dorsal columns, thalamic pathways

73
Q

Known as Close chain Circuit
Send prolonged or repetitious signals until one neuron fail to fire or inhibitory signals stops one of neurons from firing

A

Reverberation

74
Q

One input neuron diverges to stimulate several circuit of neurons
OUTPUT CEASE once all neurons in the circuit have fired
Continued firing after the stimulus stop is called AFTERDISCHARGE

A

PARALLEL-AFTER-DISCHARGE

75
Q

Classification of Neurons based on

NUMBER OF PROCESSES

A

UNIPOLAR - one process, different segments that serve as receptives
BIPOLAR - two specialized processes (dendrites and axon)
PSEUDO-UNIPOLAR - single process splits into two, both of which function as PDF,
MULTIPOLAR - more than 2 specialized processes

PHYSIOLOGY (13 decks)

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