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biology > chapter 13 - neuronal communication > Flashcards

chapter 13 - neuronal communication Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is homeostasis

A

maintaining relatively constant internal environment

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2
Q

what is cell signalling

A

communication of cells

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3
Q

what signal is used between neurones and synapes

A

neurotransmitter

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4
Q

what signal is used between large distances

A

hormones

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5
Q

what is a stimulus

A

changes in internal and external environment

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6
Q

what are neurones

A

specialised nerve cells

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7
Q

what are the features of neurones

A

cell body
dendrons
axons

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8
Q

what is function of cell body

A

has high number of endoplasmic reticulum and mitochondria to produce neurotransmitters

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9
Q

what is function of dendrons

A

short extensions from cell body to transmit electrical signals towards cell body

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10
Q

what is function of axons

A

singular elongated nerve fibres that transmit impulses away from cell body

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11
Q

what is a sensory neurone

A

transmit impulses from sensory receptor cells to a relay neurone, motor neurone or brain
Have one axon and one dendron

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12
Q

what are relay neurones

A

transmit impulses between neurones
have many short axons and dendrons

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13
Q

what are motor neurones

A

transmit impulses from relay neurone or sensory neurone to effector
have one long axon and many short dendrites

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14
Q

what is myelin sheath made of

A

schwann cells produce layers of plasma membrane around axon

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15
Q

what does myelin sheath do

A

acts as insulating layer so myelinated neurones to conduct electrical impulse at faster speed

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16
Q

what is a node of ranvier

A

gaps between schwann cells so electrical impulses jump from one node to next as it travels along neurone

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17
Q

what are the features of a sensory receptor

A

specific to a single type of stimulus
act as transducer- convert stimulus to nerve impulse

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17
Q

what are the features of a sensory receptor

A

specific to a single type of stimulus
act as transducer- convert stimulus to nerve impulse

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18
Q

what are 4 types of sensory receptors

A

mechanoreceptor
chemoreceptor
thermoreceptor
photoreceptor

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19
Q

what is pacinian corpuscles

A

specific sensory receptor that detected mechanical pressure in skin

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20
Q

how does pacinian corpuscle convert mechanical pressure into nervous impulse

A

1) in resting state, stretch mediated sodium ions channels are closed
2) when pressure is applied, corpuscle changes shape causing membrane of neursone to stretch
3) sodium ion channels open so sodium ions diffuse in depolarising the membrane resulting in generator potential
5) generator potenital creates an action potential that passes along sensory neurone

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21
Q

what is resting potential in axon

A

inside of membrane is more negative than outside so is polarised ( -70mV)

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22
Q

how is resting potential created

A

sodium ions are actively transported out of axon whereas potassium ions are actively transported into axon by specific intristic protein ( sodium potassium pump). 3 sodium move out and 2 potassium move in
sodium diffuse back into axon down electrochemical gradient and potassium ion diffuse out but most sodium gated ion channels are closed so inside becomes negative

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23
Q

what happens during action potential

A

1) neurone has resting potential
2) stimulus trigger ssome sodium voltage gated ion channels to open making membrane more permabel to sodium ions
sodium io0ns diffuse inside neurone making it less negative cuasing even more sodium ion channels to op0en ( positive feedbacj) . At 40 mV voltage sodium ion channels close so inside becomes more negative as potassium moves out
more potassium diffuse out causoing hyperpolarisation
then potassium volatgae channel close repolarising neurone

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24
Q

what is saltatory conduction

A

action potential jumping from one node to one node faster than wave of depolarisation which needs ATP for repolarisation

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25
Q

what factors affect speed of action potential

A

myelination

axon diameter - the bigger the diameter, fatser the impulse as there is less resistance in flow of ions in cytoplasm

temperature

26
Q

what is all or nothing

A

a certain threshold value will always trigger same sized action potential response no matter how big the stimulus
only affects frequency

27
Q

what is a synapse

A

junction between 2 neurones

28
Q

how is synaptic knob adapted to its function

A

swollen end of presynaptic neurone
contains many mitochondria and large amounts of ER to create neurotransmitters

29
Q

what is excitatory neurotransmitter

A

result in depolarisation of post synaptic neurone
creates action potential is threshold is reached
e.g. acetylcholine

30
Q

what is inhibitory neurotransmitter

A

result in hyperpolarisaton of postsynaptic membrane
prevents action potential
E.G. GABA

31
Q

how are impulses transmitted across synapses?

A

1) action potential at end of presynaptic neurone causes depolarisation which cause calcium ion channels to open
2)calcium ions diffuse into presynaptic knob
3)calcium ions cuase synaptic vesicles to fuse with presynaptic membrane releasing neurotransmitter into synaptic cleft by exocytosis
4) neurotransmitter diffuses across synaptic cleft and binds with specific receptor molecule on postsynaptic membrane causing sodium ion channels to open
5) sodium ions diffuse into postsynaptic neurone triggering action potenital and impulse is propagated along postsynaptic neurone

32
Q

what is the role of synapses

A

1) ensure impulses are unidirectional as neurotransmitter receptors are only at postsynaptic membrane

2) allow an impulse from one neurone to a number of neurons at multiple synapses to create different responses

3) a number of neurones may feed in same synapse with single postsynaptic neurone

33
Q

what is spatial summation

A

when many presynaptic neurones connect to one postsynaptic neurone each releasing neurotransmiter

34
Q

what is temporal summation

A

when a single presynaptic neurone releases neurotransmitters serveral times

35
Q

what does central nervous system consist of

A

brain and spinal chord

36
Q

what does peripheral nervous system consist of

A

neurones that connect CNS to rest of body
sensory neurones that carry nerve impulses from receptors to CNS
motor neurones that carry nerve impulses from CNS to effectors

37
Q

what is somatic nervous system

A

part of peripheral nervous system
under concious control

38
Q

what is autonomic nervous system

A

works constantly
under unconscious control
involuntary

39
Q

what is sympathetic nervous system

A

part of autonomic nervous sytem
increases activity

40
Q

what is parasympathetic nervous system

A

decreases activity

41
Q

what protective membrane surrounds the brain

A

meninges

42
Q

what is cerebrum

A

controls voluntary controls like learning , memory, personality and conscious thought

43
Q

what is cerebellum

A

controls unconscious functions such as posture and balance

44
Q

what is medulla oblongata

A

used in autonomic control like controlling heart rate and breathing rate

45
Q

what is hypothalamus

A

regulatory centre for temperature and water balance

46
Q

what is pituitary gland

A

stores and releases hormones that regulate body functions

47
Q

what are functions of hypothalamus

A

-controls complex patterns of behaviour like sleeping and feeding
- monitor composition of blood plasma
- produce hormones as it is an endocrine gland

48
Q

what is the anterior pituitary( front)

A

produces 6 hormones such as FSH

49
Q

what is posterior pituitary ( back)

A

stores and releases hormones produced by hypothalamus such as ADH

50
Q

what is a skeletal muscle

A

responsible for movement
voluntary

51
Q

what is cardiac muscle

A

found in heart
myogenic

52
Q

what is smooth muscle

A

involuntary
found in walls of organs like stomach
found in walls of blood vessels and digestive track

53
Q

what are muscle fibres made of

A

sacrolemma ( plasma membrane)
nuclei
sarcoplasm
t-tubules
lots of mitochondria
sarcoplasmic reticulum
myofibrils containing actin and myosin

54
Q

what is z-line

A

contains actin
distance between 2 z-lines is sacromere

55
Q

what is Heavy zone

A

only myosin present
lighter band

56
Q

what is A zone

A

myosin and areas where myosin and actin overlaps
dark bands

57
Q

what happens during contraction

A

myosin filaments pull actin filaments closer towards centre of sarcomere resulting in light band becoming narrower, z - lines moving closer shortening sarcromere, h -zone becoming narrower

58
Q

what is the structure of myosin

A

globular heads that are hinged which allows them to move back and forwards
head has binding site for actin and ATP

59
Q

what is the structure of actin

A

has binding site for myosin heads
binding sites blocked by tropomysosin held in place by troponin

60
Q

how is tropomyosin removed from blocking binding site in actin

A

1) action potential reaches neuromuscular junction and stimulates calcium ion channels to open diffusing in
2) calcium ions in synaptic knob cause synaptic vesicles to fuse with presynaptic membrane
3) acetylcholine is released into synaptic cleft by exocytosis and diffuses across synapse which binds to receptors on postsynaptic membrane ( sarcolemma) opening sodium ions channel resulting in depolarisation
4)acetylcholine broken down by acetylcholinesterase into choline and ethanoic acid preventing muscle from being overstimulated and diffuse back into neurone recombined to acetylcholine using atp from mitochondria
5)depolarisation of sarcolemma travel through t-tubules to sarcoplasmic reticulum stimulating it to open calcium ion channel to open which diffuse down concentration gradient to sarcoplasm
6) calcium ions bind to troponin causing it to change shape which pulls on tropomyosin away from actin-myosin binding site
7) now the actin and myosin can form acti-myosin cross bridge

61
Q

what does atp do to myosin

A

causes myosin head to detach from actin filament

62
Q

how is myosin returned to orginal position

A

calcium ions in sarcoplasm activates ATPase activity which hydrolyses ATP to ADP and phosphate

63
Q

what are 3 sources of energy for muscles

A

aerobic respiration
anaerobic respiration
creatine phosphate

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