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lc biology > nervous system > Flashcards

nervous system Flashcards

1
Q

what is the nervous system responsible for

A

coordination of activities in the body… allows animal to respond to internal + external changes called stimuli

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2
Q

name the two parts the nervous system is divided into and name these giving an example of what each consists of

A

CNS- central nervous system consists of brain + spinal cord
PNS - peripheral nervous system consists of a vast network of nerves that carry messages between the CNS + rest of the body

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3
Q

name + describe the 4 processes involved in making a response to a stimulus

A

Reception: stimulus detected by neurons + nerve cells

Transmission: message passes along neurons in the PNS from receptors to the CNS, and then to effectors e.g muscles.

Integration: incoming messages are sorted, processed + response is decided upon… happens in the CNS, especially the brain

Response: carried out by effectors e.g muscles/glands when they are stimulated by neurons

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4
Q

define neuron

A

nerve cell… basic units of the nervous system

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5
Q

there are three types of neurons, name + describe each type

A

Sensory (afferent) neurons take messages from sense organs to the CNS

Motor (efferent) take messages from the CNS to muscles + glands causing them to respond

Interneurons: short neurons not enclsoed in a myelin sheath that carry information between sensory + motor neurons. found only in the CNS

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6
Q

define receptor

A

a group of cells that detect a stimulus

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7
Q

what is a nerve ending

A

connects sensory neurons to receptor cells or sensory organs

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8
Q

what is a dendrite

A

a fibre that carries impulses towards the cell body

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9
Q

what is an axon

A

carries impulses away from cell bodies

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10
Q

define Schwann cells and state where they are found

A

located along the length of neurons, make the myelin sheath

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11
Q

what is the myelin sheath

A

fat rich membrane that insulates electrical impulses

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12
Q

what is a ganglion

A

a group of cell bodies located outside the CNS

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13
Q

where are the cell bodies of sensory neurons found

A

outside the CNS

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14
Q

where are the cell bodies of motor neurons found

A

within the CNS

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15
Q

draw a labelled diagram of a sensory and motor neurons

A
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16
Q

draw a labelled diagram of an interneuron

A
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17
Q

what are neurotransmitter swellings and where are they found

A

ends of each axon breaks into many axon terminals. these small branches end in a swelling called a neurotransmitter swelling. these release chemicals that carry the impulse from one nerve cell to another. the chemicals are neurotransmitters and are stored in vesicles in the swellings

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18
Q

describe how nerve impulses are transmitted

A

a neuron receives a stimulus of sufficient strength (above the threshold). an impulse travels along the dendrite and axon to the neurotransmitter swellings. this movement involves the movement of ions (H+, K+, Na+). if the threshold isnt reached, nothing happens

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19
Q

what is the all or nothing rule

A

the the threshold is reached an impulse is carried. if the threshold is not reached, no impulse is carried

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20
Q

describe the terms threshold

A

the minimun stimulus needed to cause an impulse to be carried

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21
Q

what is a resting neuron

A

when a neuron is not carrying an impulse ions are pumped in and out of the axon. this results in a negative inside and a positive outside in the axon

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22
Q

describe the movement of impulse

A

once the threshold is reached the axon/dendron changes its permeability to ions. the inside of the axon becomes positive, outside is negative at the site of stimulation. this causes the next section to alter its permebility in a similar way. a chain reaction is set up. a movement of positive charge moves along the inside of the axon. ATP is needed to cause these changes . once the impulse has moved along, the area behind is restored to the resting state

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23
Q

describe the refractory period

A

a short timespan after a neuron has carried an impulse during which a stimulus fails to cause a response (motor neuron hasnt send the impulse to the effectors)

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24
Q

what is meant by the speed of an impulse

A

the speed at which an electrical impulse travels along a neuron

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25
Q

what factors affect the speed of an impulse

A

whether myelin is present/absent - 2m/s if absent, 120m/s if present. diameter f the axon/dendrite, larger the diameter, faster the impulse

26
Q

what is a synapse

A

a region where two neurons come into close contact, commonly found between the axon terminals of one neuron and the dendrites of another

27
Q

what is a synaptic cleft

A

tiny gap between the two neurons at a synapse

28
Q

draw a labelled diagram of a synapse

A
29
Q

explain how neurotransmitters are activated

A

electrical impulses cannot cross a synapse. ions stimulate the neurotransmitter swellings in the presynaptic neuron to release a chemical (neurotransmitter) that diffuses rapidly across the synaptic cleft and combines with receptors on the post synaptic neuron. this causes the electrical impulse to be regenerated

30
Q

where are neurotransmitters made + give an example

A

some are made in cell bodies of neurons, others are made in neurostransmitter swellings. over 60 are known, e.g ACh and dopamine

31
Q

how are neurotransmitters inactivated

A

it is broken down by enzymes and the digested neurotransmitters re reabsorbed back into the neurotransmitter swellings where they can be recycled

32
Q

give 4 functions of synapses

A

transmit impulses from one neuron to another to an effector.
they control the direction of the impulse
they prevent overstmulation of effectors
the impulse can be blocked by certain chemicals (drugs/nerve blocks)

33
Q

what part of the nervous system does the brain belong to

A

central nervous system

34
Q

explain the function of the brain

A

acts as an interpreting centre to sort and process incoming impulses and decides a response

35
Q

describe the structure of the brain

A

composed of 12,000 million neurons. has grey matter (cell bodies + synapses) and white matter (nerve fibres aka dendrites and axons). brain uses 20% of the body’s energy

36
Q

how are the brain + spinal chord protected

A

bone covered in three membranes called meninges. the space between the inner two meniniges is filled with cerebrospinal fluid which acts as a shock absorber and as an exchange medium between the blood + brain

37
Q

what is the largest part of the brain, describe its structure and functions

A

cerebrum, contains 75% of neurons in hte brain
it is divided into the left + right cerebral hemispheres.
outer part is called the cerebral cortex and is grey
innter part has white matter and has millions of nerve fibres tha connect different areas of the cortex and two sides of the brains
functions include: controlling voluntary movement, recieving and interpreting impulses, thinking, memory, emotions
-> the right hemisphere controls the left side of the body and the left hemisphere controls the right side of the body

38
Q

what is the second largest part of the brain,describe structure + functions

A

cerebellum, heavily folded, controls muscular coordination, allows smooth, refined muscular action and controls balance. responses are involuntary (not conciously controlled)

39
Q

what is the medulla oblongata

A

connects the spinal chord with the rest of the brain. contain clusters of nerve cells that control involuntayr actions such as breathing (detects co2 concentration), blood pressure, sneezing, coughing

40
Q

describe the thalamus and hypothalamus

A

thalamus: located below the cerebrum + relays all incoming messages to relevant parts of the brain.
hypothalamus: lies below the thalalmus and regulates internal environment of the body (homeostasis). links the pituitary gland to regulate hormone production

41
Q

label the regions of the brain with the senses they control

A
42
Q

describe a nervous system disorder, causes, symptoms, prevention + treatment

A

parkinson’s disease
cause: failure to produce neurotransmitter dopamine resulting in inability to control muscle coordination
symptoms: trembling of hands/legs, muscles become stiff + rigid
prevention: no known way
treatment: physio, special exercises, treatment with drugs to stimulate dopamine- can all help but not stop degredation of the brain

43
Q

what does the spinal chord consist of + what is its function

A

composed of nerve tissues. surrounded by bony vertebrate that protect it. transmits impulses to and from the brain + controls many reflex action

44
Q

where is the spinal cord located + what does it look like

A

located in the neutral canal of the vertebrae. appears as an outer ring of white matter (axons only) surrounding an inner H shape region of grey matter (cell bodies + dendrites). at the centre is the central canal containing cerebrospinal fluid

45
Q

distinguish between grey + white matter in the spinal cord

A

white matter = axons only, inner H shape grey matter( cell bodies and dendrites). centre of grey matter is central canal with cerebrospinal fluid

46
Q

distinguish between ventral + dorsal roots

A

dorsal root carries sensory neurons into the spinal cord. ventral root carries motor neurons out

47
Q

draw a labelled diagram of a TS of the spinal cord

A
48
Q

what are the swellings in the dorsal root called

A

ganglia

49
Q

what does the PNS consist of

A

nerve fibres outside the brain + spinal cord. made up of long dendrites or axons taking impulses to or from the CNS. cell bodies of sensory nerves are located in the ganglia in the PNS

50
Q

what is a reflex action

A

an automatic, involuntary response to a stimulus

51
Q

what is a reflex arc

A

the neurons forming the pathway taken by nerve impulses in a reflex action make up a reflex arc. these are the unit of function of the nervous system

52
Q

give examples of reflex actions

A

grasp reflex, movement of the iris in the eye, breathing, blinking

53
Q

what is the function of a reflex action

A

fast responses to protect the body from damage

54
Q

describe the mechanism of a withdrawl reflex

A

receptors in the fingers are stimulated by a hot flame, sensory neurons carry an impulse into the spinal cord. neurmerous synapses are made with other neurons. an interneuron carries the impulse to the brain, motor neurons take the impulse straight out of the spine to the effector, causing us to pull our hand back from the flame

55
Q

draw a labelled diagram of a reflex arc

A
56
Q

are neurotransmitters carried in the blood

A

no

57
Q

give two ways a nervous system response differs from a hormonal response

A

nervous = fast, hormonal = slow. nervous = electrical, hormonal = chemical

58
Q

name the type of particle whose movement in and out of neurons is an essential feature of a nerve impulse

A

ion

59
Q

how is a neuron adapted to carry impulses

A

insulated, has axons, dendrites and neurotransmitters

60
Q

draw a labelled diagram of a neuron including axons, dendrites and myelin sheath

A

lc biology (25 decks)

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