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biology > Module 5 - Communication, Homeostasis and Energy > Flashcards

Module 5 - Communication, Homeostasis and Energy Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is homeostasis?

A

the maintaining of a relatively constant internal environment

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2
Q

what is cell signalling?

A

communication at a cellular level

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3
Q

what is cell signalling used for?

A

transferring local signals e.g. between neurones and synapses
transferring signals across large distances using hormones

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4
Q

what is the role of neurones?

A

transmit electrical impulses rapidly so we can respond to stimuli internally and externally

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5
Q

what is the structure of a neurone?

A

cell body. dendrons, dendrites, axon

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6
Q

what are the 3 main types of neurone?

A

sensory, relay, motor

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7
Q

what is the structure of a sensory neurone?

A

one dendron, cell body in centre of axon

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8
Q

what is the structure of a relay neurone?

A

many short axons and dendrons, cell body at the start of the neurone (along with dendrites)

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9
Q

what is the structure of a motor neurone?

A

long axon, many short dendrites with cell body

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10
Q

what pathway does an electrical impulse follow?

A

receptor –> sensory neurone –> relay neurone –> motor neurone –> effector

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11
Q

what do Shwannn cells do?

A

produce layers of plasma membrane by growing around the axon multiple times to create a myelin sheath

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12
Q

what does MS stand for?

A

multiple sclerosis

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13
Q

what is MS?

A

an autoimmune disease that attacks the myelin sheath of neurones

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14
Q

why does a myelin sheath increase speed of transmission?

A

allows the electrical impulse to jump between the nodes of Ranvier, insulates the axon

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15
Q

name 2 features of sensory receptors:

A

they are specific to a single type of stimulus

they act as transducers

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16
Q

name 4 types of sensory receptor:

A

mechanoreceptor, chemoreceptor, thermoreceptor, photoreceptor

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17
Q

what is the stimulus for a mechanoreceptor?

A

pressure and movement

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18
Q

name an example of a mechanoreceptor:

A

Pacinian corpuscle

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19
Q

name the sense organ for mechanoreceptors:

A

skin

20
Q

what is the stimulus for a chemoreceptor?

A

chemicals

21
Q

name an example of a chemoreceptor:

A

olfactory receptor

22
Q

name the sense organ for chemoreceptors:

A

nose

23
Q

what is the stimulus for a thermoreceptor?

A

heat

24
Q

name an example of a thermoreceptor:

A

end-bulbs of Krause

25
Q

name the sense organ for thermoreceptors:

A

tongue

26
Q

what is the stimulus for photoreceptors?

A

light/light wavelengths

27
Q

name an example of a photoreceptor:

A

cone cells

28
Q

name the sense organ for photoreceptors:

A

eyes

29
Q

what is the role of a transducer?

A

creating a generator potential by converting a stimulus into a nervous impulse

30
Q

where are Pacinian corpuscles found?

A

deep within your skin, fingers, soles of feet, joints

31
Q

how does a Pacinian corpuscle convert mechanical pressure into a nervous impulse?

A
  1. resting potential - stretch mediated Na+ channels are normal/narrow
  2. when pressure is applied, shape changes and membrane stretches
  3. when membrane stretches, Na+ channels open and Na+ ion diffuse into the neurone
  4. influx of Na+ changes membrane potential - becomes depolarised. results in generator potential
  5. generator potential creates action potential
32
Q

what is resting potential?

A

a neurone is not transmitting an impulse

33
Q

What is the membrane potential for resting potential?

A

about -70mV (outside membrane is more positively charged than the inside of the axon)

34
Q

what is threshold potential?

A

a certain mV the stimulus has to reach so that an action potential can be triggered

35
Q

what is the membrane potential for threshold potential?

A

about -60mV

36
Q

what is depolarisation?

A

energy of a stimulus temporarily reverses charges on axon membrane

37
Q

what is action potential?

A

this is when a response happens towards a stimulus

38
Q

what is the membrane potential for action potential?

A

+40mV

39
Q

what is repolarisation?

A

K+ ions diffuse out of the axon. axon becomes more negative inside than outside

40
Q

what is hyperpolarisation?

A

a dip in negativity due to an influx of K+ ions leaving the axon

41
Q

what 2 stages are part of the refractory period?

A

repolarisation, hyperpolarisation

42
Q

how does an action potential occur?

A
  1. neurone is at resting potential.
  2. stimulus triggers sodium voltage-gated channels to open, membrane more permeable to Na+ ions. Na+ ions diffuse inside the axon, inside of neurone less negative.
  3. depolarisation causes more Na+ ion channels to open (positive feedback)
  4. action potential occurs at +40mV. Voltage-gated Na+ ion channels close, voltage-gated K+ ion channels open
  5. K+ ions diffuse out the axon. Reduces charge, inside of axon more negative than the outside.
  6. Hyperpolarisation - influx of K+ ions leaving the neurone. Voltage-gated K+ ion channels close.
  7. sodium-potassium pumps restore membrane potential and axon returns to resting potential.
43
Q

what is the all-or-nothing principle?

A

if threshold potential is reached, a response will be triggered. no matter how large the stimulus is, the same sized action potential will be triggered

44
Q

what is spatial summation?

A

a number of presynaptic neurones connect to one postsynaptic neurone

45
Q

what is temporal summation?

A

a single presynaptic neurone releases a neurotransmitter as a result of an action potential several times over a short period

biology (8 decks)

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