Anatomy Chapter 11 Part Two

Front 1

Repolarization resets __________ conditions, not ionic conditions

Back 1

electrical

Front 2

After repolarization, Na+/K+ pumps restore _______ conditions

Back 2

ionic

Front 3

Not all depolarization events produce what

Back 3

APs

Front 4

For an axon to fire, depolarization must reach what

Back 4

threshold

Front 5

At threshold, membrane has been depolarized by how many mV's?

Back 5

15-20

Front 6

At threshold, Na+ permeability (increases/decreases)

Back 6

increases

Front 7

At threshold, the influx of ____ exceeds ____

Back 7

Na+ exceeds K+

Front 8

At threshold, what feedback cycle begins?

Back 8

Positive feedback

Front 9

An AP either happens ___________ or not at all

Back 9

completely

Front 10

Propagations allows APs to serve as ________

Back 10

signals

Front 11

Na+ influx causes local ________-

Back 11

currents

Front 12

Local currents cause the depolarization of adjacent membrane areas in the direction _______ AP origin (towards terminals)

Back 12

away from origin

Front 13

Since Na+ channels closer to the AP origin are inactivated, no new what is generated there

Back 13

AP

Front 14

Once initiated, an AP is what

Back 14

self-propagating

Front 15

Self-Propagation of an AP:

In nonmyelinated axons, each successive segment of membrane _________, then ___________

Back 15

depolarizes, then repolarizes

Front 16

NTs are important in the functioning of __________ synapses

Back 16

chemical

Front 17

___________ synapses are the most rapid

Back 17

electric

Front 18

All APs are alike and independent of __________ intensity

Back 18

stimulus.

Front 19

Strong stimuli cause an AP to occur more ___________

Back 19

frequently

Front 20

CNS determines stimulus intensity according to the _________ of impulses

Back 20

frequency

Front 21

A higher frequency indicates a stronger _______

Back 21

stimulus

Front 22

When voltage gated Na+ channels open, neurons cannot respond to another what

Back 22

stimulus

Front 23

The ABSOLUTE REFRACTORY PERIOD is the time from the opening of the _____ channels until they reset

Back 23

Na+

Front 24

The absolute refractory period ensures that each AP is what type of event?

Back 24

all-or-none

Front 25

The absolute refractory period enforces ____-____ transmission of nerve impulses

Back 25

one way

Front 26

What period follows the absolute refractory period?

Back 26

the Relative Refractory Period

Front 27

In the relative refractory period, most Na+ channels return to their ______ state

Back 27

resting

Front 28

In the relative refractory period, some ___+ channels are still open

Back 28

K+

Front 29

In the relative refractory period, what is occurring?

Back 29

repolarization

Front 30

In the relative refractory period, the threshold for AP generation is _______

Back 30

elevated (harder to achieve threshold)

Front 31

In the relative refractory period, the inside of the membrane is more ________ than its resting state

Back 31

negative

Front 32

During the relative refractory period, only a ________ stimulus can stimulate an AP

Back 32

exceptionally strong

Front 33

Conduction velocities of neurons varies _______

Back 33

widely

Front 34

Rate of AP propagation depends on (2)

Back 34

Axon Diameter

Degree of Myelination

Front 35

Axon diameter affects rate of AP propagation because larger diameter fibers have _____ resistance to local current flow so faster impulses can be conducted

Back 35

less

Front 36

Degree of myelination affects rate of AP propagation because continuous conduction in nonmyelinated axons is slower than _______ conduction in myelinated ones

Back 36

saltatory

Front 37

Myelin sheaths insulate and prevent what

Back 37

leakage of charge

Front 38

Saltatory conduction is only possible in what type of axons

Back 38

myelinated

Front 39

Saltatory conduction is how much faster than other types?

Back 39

30 times

Front 40

Voltage gated Na+ channels are located where

Back 40

myelin sheath gaps

Front 41

APs are only generated where?

Back 41

myelin sheath gaps

Front 42

Electrical signals appear to jump _________ from gap to gap

Back 42

rapidly

Front 43

MS is an __________ disease that affects (primarily) young adults

Back 43

autoimmune

Front 44

In MS, what is destroyed in the CNS?

Back 44

myelin sheaths

Front 45

In MS, the immune system attacks what

Back 45

myelin

Front 46

In MS, the immune system turns myelin to hardened lesions called what

Back 46

scleroses

Front 47

In MS, impulse conduction ________ and eventually _______

Back 47

slows, ceases

Front 48

In MS, demyelinated axons increase ___ channels, causing cycles of relapse and remission

Back 48

Na+

Front 49

Symptoms of MS

Back 49

visual disturbances

weakness

loss of muscular control

speech disturbances

urinary incontinence

Front 50

Treatment for MS

Back 50

drugs that modify the immune system's activity

Front 51

Prevention of MS

Back 51

High blood levels of vitamin D

Front 52

NERVE FIBER CLASSIFICATION (3)

Back 52

Diameter

Degree of Myelination

Speed of conduction

Front 53

Types of nerve fibers

Back 53

Group A, B and C

Front 54

Group A fibers have a ______ diameter and are myelinated.

Back 54

large

Front 55

Group A fibers transmit at _____ m/s

Back 55

150 m/s

Front 56

Group A fibers include somatic sensory and motor fibers of the skin, along with

Back 56

skeletal muscles and joints

Front 57

Group B fibers have an ________ diameter and are lightly myelinated

Back 57

intermediate

Front 58

Group B fibers transmit at ____ m/s

Back 58

15 m/s

Front 59

Group C fibers have the _______ diameter and are unmyelinated. Occur in the ANS

Back 59

smallest

Front 60

Group C fibers transmit at _____ m/s

Back 60

1 m/s

Front 61

Neurons are functionally connected by what

Back 61

synapses

Front 62

Axodendritic is between

Back 62

axon terminals of one neuron and dendrites of another

Front 63

Axosomatic is between

Back 63

axon terminals of one neuron and the soma of others

Front 64

Less common types:

axoaxonal is from

Back 64

axon to axon

Front 65

Less common types:

dendrodendritic is from

Back 65

dendrite to dendrite

Front 66

Less common types:

somatodendritic is from

Back 66

dendrite to soma

Front 67

Presynaptic neurons conduct impulses towards the ________

Back 67

synapse

Front 68

Presynaptic neurons ______ information

Back 68

send

Front 69

Postsynaptic neurons transmit electrical signals ________ from the synapse

Back 69

away

Front 70

Postsynaptic neurons ________ information

Back 70

receive

Front 71

Postsynaptic neurons in the PNS may be a (3)

Back 71

neuron

muscle cell

gland cell

Front 72

Most neurons function as (post/pre synaptic neurons)

Back 72

Both!

Front 73

Electrical signals are ____ common than chemical signals

Back 73

less

Front 74

Neurons of electrical synapses are electrically coupled and joined by what type of junction that connect cytoplasm of adjacent neurons

Back 74

gap junctions

Front 75

Communication in electrical synapses is ______

Back 75

rapid

Front 76

Electrical synapse communication may be ____-directional or ____-directional

Back 76

uni or bi directional

Front 77

Electrical synapses synchronize what

Back 77

activity

Front 78

Electrical synapses are most abundant in what type of tissue?

Back 78

embryonic nervous tissue

Front 79

Chemical synapses are specialized for the release and reception of what

Back 79

NTs

Front 80

Chemical synapses are typically composed of what two parts

Back 80

Axon terminal (presynaptic neuron)

NT receptor (postsynaptic neuron)

Front 81

The two parts of a chemical synapse are separated by a what

Back 81

synaptic cleft

Front 82

An electrical impulse is changed to a _________ impulse across a synapse and then back into electrical

Back 82

chemical

Front 83

How wide is a synaptic cleft? (nm)

Back 83

1/1,000,000 of an inch

30-50 nm

Front 84

Synaptic clefts prevent nerve impulses from _________ passing from one neuron to the next

Back 84

directly

Front 85

Transmission across a synaptic cleft is a _________ event

Back 85

chemical

Front 86

Transmission across a synaptic cleft depends on release, diffusion, an receptor binding of a what

Back 86

NT

Front 87

Transmission across a synaptic cleft ensures _____________ communication between neurons

Back 87

unidirectional

Front 88

When an AP arrives at an axon terminal, what voltage-gated channels open?

Back 88

Ca2+

Front 89

Synaptotagmin protein binds to Ca2+ and promotes the fusion of synaptic vessicles with what

Back 89

the axon membrane

Front 90

The final step in the transfer of information across chemical synapses is the

Back 90

exocytosis of NTs into the synaptic cleft.

Front 91

At a higher impulse frequency, more ___ are released

Back 91

neurotransmitters

Front 92

Post synaptic receptors are often __________ gated ion channels

Back 92

chemically

Front 93

When a NT binds to a post synaptic receptor, it causes an excitatory or inhibitory event, which is a what

Back 93

graded potential

Front 94

NT effects can be terminated how quickly?

Back 94

Within a few milliseconds

Front 95

NT effects are terminated in 3 ways

Back 95

Reuptake (by astrocytes/axon terminal)

Degradation (by enzymes)

Diffusion (away from syn. cleft)

Front 96

The time needed for NTs to be realeased, diffuse across the SC and bind to receptors is known as what? (and takes how long?)

Back 96

synaptic delay

.3-.5 ms

Front 97

Synaptic delay is the _____- limiting step of neural transmission

Back 97

rate-limiting

Front 98

NTs can cause graded potentials. Their strength varies on (2)

Back 98

Amount of NT released

Time NT stays in area

Front 99

Post synaptic potential EPSP stands for:

Back 99

Excitatory Postsynaptic potentials

Front 100

Post synaptic potential IPSP stands for

Back 100

Inhibitory Postsynaptic Potential

Front 101

EPSPs make that area of the neuron more what

Back 101

positive

Front 102

IPSPs make it ________ for a neuron to fire

Back 102

harder

Front 103

In NT binding, Na+ is ________ than K+ efflux

Back 103

greater than

Front 104

The Na+ influx causes a net depolarization that is called a what

Back 104

EPSP (not an AP)

Front 105

EPSPs can help trigger an _______ if they are of great enough strength

Back 105

AP

Front 106

If an EPSP triggers an AP, it travels first to what?

Back 106

The axon hillock

Front 107

IPSPs reduct the postsynaptic neuron's ability to produce a what?

Back 107

Action Potential

Front 108

IPSPs make a membrane more permeable to ____ and ____

Back 108

K+ and Cl-

Front 109

If K+ channels open, what happens to the concentration of K+?

Back 109

It moves out of the cell

Front 110

If Cl- channels open, what happens to the concentration of Cl-?

Back 110

Cl- moves into the cell

Front 111

Neurotransmitters ____________ a cell (the inner membrane becomes more negative)

Back 111

hyperpolarizeeeee

Front 112

A single EPSP cannot induce a what

Back 112

AP

Front 113

IPSPs and EPSPs can _________ to induce an AP

Back 113

summate

Front 114

Most neurons receive both excitatory and inhibitory inputs from thousands of other neurons, but an AP only results from what

Back 114

EPSPs predominating and reaching threshold

Front 115

What is one or more presynaptic neurons transmitting impulses in rapid-fire order?

Back 115

Temporal Summation

Front 116

What happens when postsynaptic neurons are stimulated simultaneously by a large number of terminals at the same time?

Back 116

Spatial summation

Front 117

Repeated use of a synapse increases the ability of the presynaptic cell to

Back 117

excite a post synaptic neuron

Front 118

Repeateduse of synapse increases ability of presynaptic cell to excite postsynapticneuron because ____ concentration increases in the presynaptic terminal and postsynaptic neuron

Back 118

Ca2+

Front 119

A brief high frequency stimulation partially _________ the postsynaptic neuron

Back 119

depoarlizes

Front 120

What chemically gated channels allow for Ca2+ entry?

Back 120

NMDA

Front 121

Ca2+ activates _________ enzymes that promote more effective responses to subsequent stimuli

Back 121

kinase

Front 122

Excitatory NTs released by one neuron are inhibited by another via the ____________ synapse

Back 122

axoaxonal

Front 123

There are fewer NTs released and smaller EPSPs formed during _____________ inhibition

Back 123

presynaptic

Front 124

Threshold is elevated and only exceptionally strong stimuli could trigger an AP during what period?

Back 124

Relative Refractory Period

Front 125

Stronger stimuli are interpreted when the CNS receives _________ APs

Back 125

more frequent

Front 126

Opening chloride channels in the postsynaptic membrane will result in an __________ postsynaptic potention

Back 126

inhibitory

Front 127

______________ are the language of the nervous system

Back 127

NTs

Front 128

How many NTs have been identified?

Back 128

50+

Front 129

Most neurons make ___+ NTs

Back 129

two or more

Front 130

NTs are usually released at _________ stimulation frequencies

Back 130

different

Front 131

NTs are classified by (2)

Back 131

chemical structure

function

Front 132

ACh is divided into

Back 132

acetyl acid

choline

Front 133

What was the first identified NT?

Back 133

ACh

Front 134

What are two biogenic amines?

Back 134

Catecholamines

Indolamines

Front 135

Dopamine, Norepinephrine, and epinephrine are all what?

Back 135

Catecholamines

Front 136

Serotonin and histamine are both what?

Back 136

Indolamines

Front 137

Biogenic amines are involved in what two things?

Back 137

emotional behaviors

biological clock

Front 138

Imbalances of biogenic amines result in what?

Back 138

mental illness

Front 139

Glutamate, Aspartate, Glycine, and GABA are all what?

Back 139

Amio Acids

Front 140

Substance P, Endorphins, and Gut-Brain Peptides are all examples of

Back 140

Peptides

Front 141

What is the mediator of pain signals?

Back 141

Substance P

Front 142

Beta endorphin, dynorphin, and enkephalins are all examples of what?

Back 142

Endorphins

Front 143

Endorphins act as natural opiates in that they...

Back 143

reduce pain reception

Front 144

Somatostatin and cholecystokinin are both examples of

Back 144

gut-brain peptides

Front 145

ATP and Adenosine are both considered what?

Back 145

Purines

Front 146

Adenosine is an important _________

Back 146

inhibitor

Front 147

What blocks adenosine receptors?

Back 147

Caffeine

Front 148

Nitric oxide, carbon monoxide, and hydrogen sulfide gases are considered what?

Back 148

Gasotransmitters (DANGEROUS)

Front 149

slide 119

Back 149

.