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the nevous system Flashcards

1
Q

what is the role of the endocrine system

A

it transmits chemical signals called hormones to receptive cells

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2
Q

are hormones generally slow or fast acting. can they affect more than one region throughout the body

A

relatively slow acting

they can affect one or more regions of the boy

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3
Q

name some of the simplest animals with nervous systems

A

hydras, jellies and other cnidarians

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4
Q

what features of an animal mean that it has a more specialised nervous system

A

elongated, bilaterally symmetrical bodies

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5
Q

what is cephalization

A

clustering of sensory neurons and interneurons at the anterior (front) end of the body. nerves that extend towards the posterior (rear) end enable these anterior neurons to communicate with cells elsewhere in the body

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6
Q

neurons that carry out integration form which type of nervous system

A

the central nervous system

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7
Q

neurons that carry information in and out of the CNS form what type of nervous system

A

the peripheral nervous system

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8
Q

what are ganglia

A

segmentally arranged clusters of neurons that act as relay points in transmitting information

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9
Q

what forms the CNS

A

the brain and the spinal chord

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10
Q

what forms the PNS

A

nerves (spinal nerves and cranial nerve) and ganglia

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11
Q

what are the two components of nervous tissue

A

neurons - transmit nerve impulses glia - nourish, insulate and replenish neurons

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12
Q

give an example of a glial cell and its function

A

schwann cells - produce myelin sheaths surrounding axons in the PNS and oligodendrocyte, their counterparts of the CNS

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13
Q

how are the simplest nervous systems arranged

A

in nerve nets (a series of interconnected neurons)

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14
Q

What does the PNS do

A

transmits information to and from the CNS

it regulates movement and the internal environment by nerves and glia

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15
Q

in the PNS ………… neurons transmit information to the CNS

A

afferent (sensory)

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16
Q

in the PNS ……….. neurons transmit information away form the CNS

A

efferent (motor/autonomic)

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17
Q

what are the 5 major glial cells in the nervous system

A 
CNS 
- oligodendrocytes
- astrocytes 
- microglia 
- ependymal cells 
PNS
- schwann cells
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18
Q

during development, where does the central nervous system develop from

A

the dorsal nerve chord

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19
Q

the cavity of the dorsal nerve cord gives rise to the narrow………….. of the spinal cord and the ………. of the brain

A

central canal

ventricles

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20
Q

the canal and ventricles of the brain are filled with what

A

cerebrospinal fluid

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21
Q

how is cerebrospinal fluid made

A

in the brain by filtering arterial blood

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22
Q

what is the role of cerebrospinal fluid

A

it supplies the CNS with nutrients and hormones and carries away waste. it drains into the veins

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23
Q

what is a reflex

A

a rapid involuntary response to a particular stimulus

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24
Q

why are reflexes rapid

A

sensory information activates neurons without having to travel from the spinal cord to the brain and back

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25
Q

what are the 2 efferent components of the PNS

A

motor system and the autonomic nervous system

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26
Q

what do the neurons of the motor system do

A

carry signals to skeletal muscles

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27
Q

is motor control voluntary or involuntary

A

can be either

e.g. raising your hand is voluntary but the knee jerk reflex is controlled by the spinal chord

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28
Q

what do the neurons of the autonomic nervous system do

A

carry signals to smooth and cardiac muscle

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29
Q

is the autonomic nervous system voluntary or involuntary

A

involuntary

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30
Q

what are the 2 divisions of the autonomic nervous system

A

sympathetic and parasympathetic

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31
Q

what organ systems does the autonomic nervous system regulate

A

digestive, cardiovascular, excretory and endocrine

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32
Q

what is the enteric/intrinsic nervous system

A

network of neurons that exerts direct and partially independent control of the digestive tract, pancreas and gallbladder

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33
Q

what does activation of the sympathetic nervous system result in

A 
arousal and energy generation 
e.g. 
the heart beats faster
digestion is inhibited 
the liver converts glycogen to glucose 
adrenal medulla increases secretion of epinephrine
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34
Q

what does activation of the parasympathetic nervous system result in

A 
promote calming and a return to self maintenance functions "rest and digest"
e.g. 
heat rate decreases
digestion id enhanced 
glycogen production increases
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35
Q

in which process does the parasympathetic nervous system complement the sympathetic nervous system rather than antagonizing it

A

regulation of reproductive activity

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36
Q

how do the parasympathetic and sympathetic nervous systems differ in organization and signals released

A

parasympathetic nerves exit the CNS at the base of the brain or the spinal cord and form synapses in ganglia near or within an internal organ

sympathetic nerves typically exit the CNS midway along the spinal cord and form synapses in ganglia located just outside the spinal cord

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37
Q

what are preganglionic neurons

A

they release acetyl choline as a neurotransmitter

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38
Q

what are postganglionic neurons

A

parasympathetic division - release acetyl choline

sympathetic division - release nor epinephrine

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39
Q

what is it that enables the sympathetic and parasympathetic divisions to bring about posit e effects in organs

A

the difference in neurotransmitters

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40
Q

what are the 3 major regions of the vertebrate brain

A

forebrain, midbrain and hindbrain

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41
Q

what are the components and function of the forebrain

A

olfactory bulb, cerebrum, thalamus and hypothalamus

functions - smell, regulation of sleep, learning ad any complex processing

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42
Q

what is the function of the midbrain

A

coordinates routing of sensory input

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43
Q

what are the components and function of the hindbrain

A 
cerebellum 
function - controls involuntary activities, such as blood circulation and coordinates motor activities such as locomotion
44
Q

which part of the brain generally increases in size with evolution of the brain

A

the cerebrum (forebrain)

45
Q

what is the role of the cerebrum

A

controls skeletal muscle contraction and is the centre for emotion, learning, memory and perception

46
Q

what is the outer layer of the cerebrum called and what are its functions

A

cerebral cortex
function - perception, voluntary movement and learning
left side controls the right side of the body and voice versa

47
Q

what does the cerebellum coordinate

A

coordinates movement and balance and helps in learning and remembering motor skills

48
Q

generation and experience of emotions involve the brain structures grouped as what system

A

the limbic (reward) system - contains the amygdala, olfactory bulb, nucleus accumbens hippocampus and parts of the thalamus

49
Q

what is the function of the amygdala

A

storage and recall of emotional memory

50
Q

what are the 4 lobes of the cerebral cortex

A

frontal
parietal
temporal
occipital

51
Q

what are the functions of the frontal lobe of the cerebral cortex

A

decision making, planning, control of skeletal muscles, forming speech

52
Q

what are the functions of the parietal lobe of the cerebral cortex

A

sense of touch, integration of sensory information

53
Q

what are the functions of the occipital lobe of the cerebral cortex

A

processing visual stimuli and pattern recognition, combining images and object recognition

54
Q

what are the functions of the temporal lobe of the cerebral cortex

A

hearing

55
Q

what are neurons

A

nerve cells that transfer information within the body

56
Q

most of a neurons organelles, including its nucleus are located where

A

in the cell body

57
Q

the cells body of a neuron is studded with dendrites. what are dendrites

A

highly branched extensions that receive signals form other neurons

58
Q

as neuron has a single axon. what is an axon

A

an extension that transmits signal to other cells

59
Q

which is longer, axons or dendrites

A

axons

e.g. those that reach from the spinal cord in the giraffe to the muscle cells in its feet

60
Q

the junction at the end of the axon that branches to the receiving cell is called what

A

the synapse

61
Q

the part of the axon branch that forms the synapse is called what

A

synaptic terminal

62
Q

what are neurotransmitters

A

chemical messengers

63
Q

what do neurotransmitters do

A

pass information from the transmitting neuron to the receiving cell

64
Q

in describing a synapse what is the transmitting neuron referred to as

A

presynaptic cell

65
Q

in describing a synapse what is the receiving cell (neuron, muscle gland cell etc) referred to as

A

post synaptic cell

66
Q

what are neuron supporting cells called

A

glia

67
Q

what are the 3 stages of information processing by a nervous system

A

sensory input, integration ad motor output

68
Q

what are sensory neurons

A

transmit information about external stimuli e.g. light, touch or smell
or internal conditions such as blood pressure or muscle tension

69
Q

what are interneurons

A

they form the local circuits connecting neurons in the brain or ganglia
they are responsible for integration (analysis and interpretation) of sensory input

70
Q

what are motor neurons

A

they transmit signals to muscle cells, causing them to contract

71
Q

what happens at the synapse

A

the electrical signal is converted into a chemical signal

72
Q

what is resting potential

A

the membrane potential characteristic of a non conducting excitable cell, with the inside of the cell more negative than the outside - imbalance in charge

73
Q

what is action potential

A

an electrical signal that propagates (travels) along the membrane of a neuron or other excitable cell as a non graded (all-or-one) depolarization.

74
Q

what is the membrane potential

A

the voltage (difference in electrical charge) across the plasma membrane

75
Q

in most neurons the concentration of ………….. is higher inside the cell and the concentration of ………… is higher outside the cell

A

potassium

sodium

76
Q

what maintains the sodium and potassium gradient of a neuron

A

the sodium potassium pump

77
Q

how does the sodium potassium pump maintain the ion gradient

A 
3 sodium ions bind 
pump hydrolyses ATP
phosphorylation 
conformation change 
sodium ions released
2 potassium ions bind 
dephosphorylation
conformation change 
potassium ions released 
cycle repeats
78
Q

how many potassium ions are pumped into the cell

A

2

79
Q

how many sodium ions are pumped out of the cell

A

3

80
Q

what is a gated channel

A

a channel that opens or closes in response to a stimulus

e.g. voltage change or ligand binding/unbinding

81
Q

what is hyperpolarization

A

increase in the magnitude of the membrane potential, making the inside of the cell even more negative

82
Q

what is depolarization

A

reduction in the magnitude of the membrane potential the inside of the cell gets less negative

83
Q

if hyperpolarization or depolarization only causes a shift in the membrane potential what is this known as

A

graded potential - they decay with time and distance from their source

84
Q

action potential

A

if a depolarization shifts the membrane potential sufficiently the result is a massive change in membrane voltage

85
Q

how are action potentials different to graded potentials

A

action potentials have a constant magnitude and can regenerate in adjacent regions of the membrane
action potentials can therefore spread along axons, making them well suited for transmitting

86
Q

if a depolarization increases the membrane potential to a level called ………… the voltage gated sodium channels open

A

threshold

87
Q

describe the steps in generation of action potential

A

1: the gated sodium and potassium channels are closed. ungated channels maintain the resting potential
2: a stimulus opens some sodium channels. Sodium inflow depolarizes the membrane
3: depolarization opens most sodium channels while the potassium channels remain closed. sodium influx makes the inside of the membrane positive with respect to the outside
4: most sodium channels become inactivated blocking sodium inflow. most potassium channels open permitting potassium outflow which makes the inside of the cell negative again
5: the sodium channels close but some potassium channels are still open. as these potassium channels close and the sodium channels become unblocked (though still closed) the membrane returns to its resting state.

88
Q

what are the 5 steps in generation of action potential

A 
resting state
depolarisation 
rising phase of the action potential 
falling phase of the action potential 
undershoot
89
Q

describe the resting state in generation of an action potential

A

the membrane of the axon is a at resting potential most voltage gated channels are closed. some potassium channels are open

90
Q

describe depolarization in generation of an action potential

A 
a stimulus (neurotransmitter) depolarizes the membrane. sodium channels open allowing an influx of sodium into the cell.
if the stimulus is sufficiently strong to reach the threshold then sodium inflow persists causing further depolarisation 
this opens more gated sodium channels allowing even more sodium influx
91
Q

describe the rising phase of the action potential

A

once the threshold is crossed, the positive feedback cycle rapidly increases the membrane potential

92
Q

describe the falling phase of the action potential

A

voltage gated sodium channels inactivate stopping the influx into the cell
voltage gated potassium channels open causing rapid outflow of potassium
this rapidly decreases the membrane potential

93
Q

describe the undershoot

A

the membrane’s permeability to potassium is higher than at rest
gated potassium channels close
membrane returns to resting potential

94
Q

what is the refractory period

A

the downtime when a second action potential cannot be initiated due to inactivation of sodium gated channels at the end of the previous action potential cycle

95
Q

is the magnitude and duration of the action potential the same along the entire axon

A

yes - because an action potential is an all or none event

96
Q

where does a nerve impulse start and finish

A 
cell body (axon hillock)
synaptic terminal
97
Q

why don’t action potentials ever travel back towards the cell body

A

the area behind the travelling zone of depolarization has its sodium channels inactivated and is in the refractory period so can’t respond to further input

98
Q

the rate of action potential production is proportional to what

A

signal strength

99
Q

a wide axon provides ……… resistance to the current associated with action potential

A

less

100
Q

vertebrates have narrow axons but are insulated which increases the rate of action potential. what is the layer of insulation called

A

myelin sheath

101
Q

what are myelin sheaths produced by

A

glia:
oligodendrocytes in the CNS
Schwann cells in the PNS

the myelin sheaths are mainly made from lipids which are poor conductor, so good insulators

102
Q

which disease is caused by destruction of myelin sheaths

A

multiple sclerosis

103
Q

what are the gaps in the myelin sheath called

A

nodes of ranvier - voltage gated sodium channels are restricted to these

104
Q

what is saltatory conduction

A

rapid transmission of a nerve impulse resulting from action potential jumping from one node of ranvier to another, skipping the myelin sheathed regions of the membrane

105
Q

what carries information across a synapse

A

neurotransmitters

106
Q

Near the synapse the action potential activates voltage-gated…………… channels

A

calcium channels

107
Q

calcium ions enter through the membrane and cause what

A

synaptic vesicles to fuse with the synaptic membrane releasing the neurotransmitters

A (17 decks)

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