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Nervous System Bio 12 > Nervous System > Flashcards

Nervous System Flashcards

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Biology 101 flashcards
1
Q

What is the Central Nervous System

A

The spinal cord and brain

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2
Q

What is the Peripheral Nervous System

A

Automatic NS (unconscious control) and Somatic NS (conscious control)

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3
Q

What are the 2 parts of the Autonomic NS

A

The sympathetic NS (fight or flight) and the parasympathetic (non-emergency situations)

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4
Q

What does the Somatic NS do

A

Controls skeletal muscle and exterior sense organs (including skin)

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5
Q

what does the sympathetic NS cause in the body during emergencies

A

-heart rate increases
-perspiration increases, salivation decreases
-breathing rate increases
-pupils dilate
-energy is diverted from non-essential processes

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6
Q

what’s the main neurotransmitter in the sympathetic NS

A

noradrenalin

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7
Q

what’s the main neurotransmitter in the parasympathetic NS

A

acetylcholine

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8
Q

what are the 3 parts of neurons and their functions

A

-dendrites: receive messages
-cell body: main part, contains nucleus and organelles
-axons: carries messages away from cell body to the next neuron

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9
Q

what are 3 main types of neurons

A

-sensory neuron: long dendrites from sensory receptors to spinal cord and brain
-interneuron: within spinal cord or brain
-motor neuron: from spinal cord or brain to muscle or gland (effector)

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10
Q

what are cells with myelination called

A

Schwann cells

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11
Q

what are the gaps between myelinated cells called

A

Nodes of Ranvier

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12
Q

what is the point of myelination

A

to speed up the process of transmission and is used for long pathways such as the spinal cord to extremities
-it is faster and more energy efficient

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13
Q

what is nerve conduction

A

electrochemical change that moves in one direction along the length of a nerve fibre

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14
Q

what is resting potential

A

-there is more Na+ ions outside the axon and more K+ ions inside the axon when not conducting impulses
-voltage difference is around -60mV

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15
Q

what are the 3 phases of nerve pulse transmission

A
  1. resting phase
  2. action phase
  3. recovery phase
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16
Q

describe the resting phase

A

-equals -60mV, negative polarity comes from large organic negative ions in the axoplasm
-Na+ concentrated more on outside, K+ on inside
-active transport evens out concentration when there is no impulse

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17
Q

describe the action phase

A

-starts with the stimulation of an action potential
-upswing: -60mV to 40mV, membrane is permeable to Na+ ions so they move inside and the axon becomes positive on the inside, this is depolarization
-downswing: 40mV to -60mV, membrane becomes permeable to K+ ions so they move outside, this is repolarization

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18
Q

what is an action potential

A

the change of potential when a nerve is stimulated and there is an impulse

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19
Q

describe the recovery phase

A

-K+ ions move back inside the axon
-Na+ ions move back outside the axon
-another nerve impulse cannot happen yet

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20
Q

what is the difference between non-myelinated and myelinated cells

A

-speed with myelination = 200 m/s, speed w/o = 0.5 m/s
-w/o myelination, the nerve impulse must depolarize and repolarize along the nerve fibre while with myelination it can jump from node to node

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21
Q

what is a synapse

A

region between end of axon and cell body/dendrite to which it is attached

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22
Q

what is a synaptic ending

A

swollen endings of axons that contain neurotransmitters

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23
Q

what is the presynaptic membrane

A

the membrane of the axon synaptic ending

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24
Q

what is the postsynaptic membrane

A

the membrane of the dendrite of the next neuron

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25
Q

what is the synaptic cleft

A

the space between the presynaptic and postsynaptic membrane

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26
Q

what are neurotransmitters

A

-chemicals that transmit the nerve impulses across a synaptic cleft
-are small molecules
-can be single amino acids, short chains, or derivatives of proteins

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27
Q

what are synaptic vesicles

A

vesicles that contain neurotransmitters, which reside near the surface of the synaptic ending

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28
Q

what is step 1

A

nerve impulse travels along the axon, reaching the synaptic ending (K+ out, Na+ in)

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29
Q

what is step 2

A

arrival of nerve impulses at synaptic ending changes membrane (Ca+2 flows into endings)

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30
Q

what is step 3

A

Ca+2 ions cause contractile proteins (balloon strings) to pull synaptic vesicles to inner surface of the presynaptic membrane

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31
Q

what is step 4

A

vesicles fuse with presynaptic membrane, releasing neurotransmitters into the synapse

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32
Q

what is step 5

A

-neurotransmitters diffuse across synaptic cleft to receptors on postsynaptic membrane
-the receptors control selective ion channels, binding of a neurotransmitter to its specific receptors opens the ion channels

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33
Q

what is step 6

A

Ions move, changing the voltage of the presynaptic membrane, this either moves the voltage closer to the threshold voltage (excitatory synapse) or hyperpolarizes the membrane (inhibitory synapse)

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34
Q

what is step 7

A

neurotransmitters are quickly deactivated to prevent them from continually acting on postsynaptic membrane, this can occur by:
a) neurotransmitter is degraded by enzymes (eg: acetylcholinesterase breaks down acetylcholine)
b) synaptic ending reabsorbs the neurotransmitters after which it may be refused (eg: serotonin) or broken down (eg: noradrenalin)

35
Q

why is transmission across a synapse 1-way

A

only the ends of axons have synaptic vesicles that are able to release neurotransmitters to affect the potential of the next neurons

36
Q

what does the brain and nervous system function depend on

A

the balance between the excitatory and inhibitory synaptic transmitters

37
Q

when does a neuron fire

A

when the amount of excitatory neurotransmitters received is sufficient to overcome the amount of inhibitory transmitters received

38
Q

what is local excitation

A

the process allows neurons to fine-tune to the environment when a neuron cannot fire

39
Q

what are some examples of excitatory transmitters

A

acetylcholine, adrenalin, noradrenalin, serotonin, dopamin

40
Q

what are some examples of inhibitory transmitters

A

GABA, serotonin, endorphins, enkephalins

41
Q

what do endorphins and enkephalins do

A

they act as natural pain relievers in the brain, opiates like morphine, heroin, and opium mimic the actions of endorphins and enkephalins

42
Q

describe the PNS

A

-voluntary and involuntary control
-in PNS nerves, there are bundles of axons
-consists of nerves with long dendrites and/or long axons because neuron cell bodies are only found in the brain, spinal cord, and ganglia

43
Q

what are 3 types of nerves

A

sensory nerves, motor nerves, and mixed nerves

44
Q

describe sensory nerves

A

-long dendrites and short axons
-made up of bundles of sensory neurons
-carry messages to brain and spinal cord

45
Q

describe motor nerves

A

-short dendrites and long axons
-made up of bundles of motor neurons
-carry messages from brain and spinal cord

46
Q

describe mixed nerves

A

-contain sensory nerves’ long dendrites and motor nerves’ long axons

47
Q

how many cranial nerve pairs are attached to the brain

A

12, they serve the face, head, and neck except for the Vagus nerve which serves the internal organs

48
Q

how many pairs of spinal nerves do we have

A

31, spinal nerves are mixed nerves leaving the spinal cord by 2 branches (roots) which lies within the vertebral column

49
Q

how can the dorsal root be indentified

A

by the dorsal root ganglion (where all the cell bodies of sensory neurons are)

50
Q

what does the ventral root contain

A

axons of motor neurons that conduct impulses away from the spinal cord

51
Q

where do the 2 roots join

A

just before the spinal nerve leaves the vertebral column

52
Q

describe the SNS

A

-includes all the nerves serving the musculoskeletal system and exterior sense organs (including skin)
-exterior sense organs are receptors and muscle fibres are effectors that react to stimulus

53
Q

what are reflexes

A

automatic reactions to stimuli, both internal and external
-can involve brain (blinking) or not (moving hand from hot stove)

54
Q

what is step 1 of a reflex arc

A

receptor (eg: in skin)- generates nerve impulse

55
Q

what is step 2 of a reflex arc

A

sensory neuron- takes message up to CNS, impulses move along dendrite, proceed to cell body, and go from cell body to axon in grey matter of cord

56
Q

what is step 3 of a reflex arc

A

interneuron- passes message to other interneurons in brain and back or straight to motor neuron

57
Q

what is step 4 of a reflex arc

A

motor neuron- takes messages away from CNS to axon of spinal nerve

58
Q

what is step 5 of a reflex arc

A

effector- receives impulse and reacts; glands secrete or muscles contract

59
Q

what happens in the CNS

A

sensory information is received and motor control is initiated

60
Q

what is the CNS protected by

A
  1. bone: skull, vertebrae
  2. meninges: 3 protective membranes
  3. cerebrospinal fluid: fluid for cushioning and protection (also found in central canal of spinal cord and ventricle of the brain)
61
Q

what does the spinal cord contain

A
  1. central canal: filled with cerebrospinal fluid
  2. gray matter: containing cell bodies and short fibers (dorsal cell bodies receive sensory information and ventral cell bodies send motor information)
  3. white matter: containing long fibers of interneurons that run together in bundles called tracts that connect the cord to the brain
62
Q

what is the difference between ascending and descending tracts

A

ascending takes information to the brain while descending carries information down from the brain

63
Q

how much does the brain weigh

A

3 pounds and consists of hundreds of billions of neurons and glial cells

64
Q

describe the medulla oblongata

A

-lies closest to the spinal cord
-controls: heart rate, breathing, organ function, and reflexes like coughing, sneezing, vomiting, etc.

65
Q

describe the cerebellum

A

-second largest portion of the brain
-functions in: balance and complex muscular movement
-responsible for maintaining normal muscle tone, posture, and balance
-receives sensory information from the inner ear which senses balance

66
Q

describe the thalamus

A

-receives all sensory impulses (except for smell)
-sends them to appropriate regions of the cortex for interpretation
-the thalamus connects to various parts of the brain and is part of the RAS (reticular activating system), which sorts out incoming stimuli, passing on to the cerebrum only those that require immediate attention

67
Q

describe the hypothalamus

A

-one of the most important sites for the regulation of homeostasis
-maintains: internal environment; contains centres for hunger, sleep, thirst, body, temperature, blood pressure, etc.
-controls pituitary gland (serves as link between nervous system and endocrine systems)
-plays role in sexual response and mating behaviors, the fight or flight response, and pleasure

68
Q

what are the 4 lobes

A

frontal lobe, parietal lobe, temporal lobe, occipital lobe

69
Q

describe the cerebrum

A

-largest, most prominent, highest developed part of the brain
-consciousness is only in this part
-intellect, learning, memory, and sensations are formed here
-outer layer is the cortex
-divided into left and right hemispheres along with 4 lobes

70
Q

describe the frontal lobe

A

-movement
-higher intellectual process (eg: problem solving, concentration, planning, judging the consequences of behaviors)
-moving the tongue to speak (left side only)

71
Q

describe the parietal lobe

A

-sensations such as touch, temperature, pressure, pain
-understanding speech and using words (forming responses)

72
Q

describe the temporal lobe

A

-hearing, smelling
-(interpretation of experiences, memory, visual scenes, music, and complex sensory patterns)

73
Q

describe the occipital lobe

A

-vision
-combining visual experiences with other sensory experiences

74
Q

what connects the lobes together

A

corpus callosum- horizontal connecting piece of the brain
-transmits messages

75
Q

what side of the brain controls the left side of the body

A

the right side of the brain controls the left side of the body and vice versa (exception of smell)

76
Q

what is the first way a drug can act

A

drug stimulates release of a neurotransmitter (more is released than normally would)

77
Q

what is the second way a drug can act

A

drug blocks release of neurotransmitter (less is released)

78
Q

what is the third way a drug can act

A

drug combines with neurotransmitter to prevent its breakdown (does not break down so the signal lasts for longer)

79
Q

what is the fourth way a drug can act

A

drug mimics neurotransmitter (more signals sent)

80
Q

what is the fifth way a drug can act

A

drug blocks receptors so neurotransmitter cannot be detected

81
Q

how do stimulants work

A

stimulants either enhance excitatory transmitters or block inhibitory transmitters

82
Q

how do depressants work

A

depressants either block excitatory transmitters or enhance inhibitory transmitters

83
Q

what part of the brain can drugs affect

A

the RAS and limbic system

84
Q

what does re-uptake mean

A

absorption of a presynaptic nerve ending of a neurotransmitter that it has secreted

Nervous System Bio 12 (1 decks)

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