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Biology > Topic Six > Flashcards

Topic Six Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is a stimulus?

A

a change in the environment that is detected by a receptor

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2
Q

what is a receptor?

A

transforms environmental stimuli into electrical nerve impulses

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3
Q

what is an effector

A

organs that produce a response to a stimulus

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4
Q

what is the order

A

receptor -> sensory -> relay (CNS) -> motor -> effector

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5
Q

what is a reflex?

A

rapid + involuntary response to a stimulus

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6
Q

what are dendrites?

A

short-branched fibres that convert chemical info from neurones/receptors into electrical signals

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7
Q

what is the function of an axon?

A

elongated fibre that transmits electrical signals to terminal regions for communication

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8
Q

what is a soma?

A

the cell body containing nucleus and organelles

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9
Q

what is the purpose of myelin sheath?

A

improves electrical conduction via saltatory conduction

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10
Q

what is; membrane potential?

A

unequal distribution of ions on different sides of membrane, creating a potential difference

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11
Q

what is resting potential?

A

the charge difference when a neutron is at rest, ~ 70 mV

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12
Q

how is resting potential maintained?

A

1) there is a higher conc. of K+ inside & higher conc. of Na+ outside
2) 3 Na+ out for every 2 K+ in
- creates an electrochemical gradient = cell is more -ve then outside
3) cell is more permeable to K+
4) Na+ is actively transported out & K+ in (using ATP)

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13
Q

What are the 3 steps making an action potential?

A
  • depolarisation
  • repolarisation
  • refectory period
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14
Q

what happens in depolarisation?

A
  1. in response to stimulus, Na+ channels open up
  2. as Na+ have higher conc. outside, Na+ diffuses down the electrochemical gradient into the cell
  3. influx of sodium causes membrane potential to be more positive
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15
Q

what happens in repolarisation?

A
  1. increase in Na+ inside = K+ channels open
  2. K+ is more conc. inside, K+ diffuses down the electrochemical gradient out of the cell
  3. efflux of k+ causes membrane potential to go back to -ve.
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16
Q

what happens in the refectory period?

A
  1. At rest, Na+ = outside & K+ = inside
  2. after depolarisation + repolarisation, ionic distribution is reversed
  3. before neurone can re-fire; resting potential has to be restored by using sodium-potassium pump
  4. It pumps Na+ out and K+ in
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17
Q

how are nerve impulses “1D”?

A
  • depolarisation = when ion channels open + cause a change in membrane potential
  • ion channels are voltage-gated
  • so depolarisation at one point of axon, triggers the opening of ion channels in the next segment
  • causes depolarisation to spread along the length of an axon as a unidirectional “wave”
18
Q

what is the all-or-nothing principle?

A

an action potential of the same magnitude (-55mV) will generate as long as threshold potential is reached.

19
Q

what is myelin made of?

A

protein + phospholipids made by Schwann cells

20
Q

what is the difference in myelinated vs non-myelinated neurones?

A

in myelinated: action potentials ‘hop’ between nodes of ranvier
in non-mylenated: action potentials move along in a continuous wave of depolarisation

21
Q

what is the process of synaptic transfer?

A
  1. Action potential arrives at axon terminal + triggers opening of voltage-gated Ca2+ channels
  2. Ca2+ diffuses into the cell + promotes the fusion of vesicles with cell-membrane, = exocytosis happens, releasing neurotransmitters.
  3. Neurotransmitters bind to specific receptors on post-synaptic membrane & opens ion channels
  4. channel openings generates an electrical impulse in post-synaptic neurone
  5. neurotransmitters are recycled or broken down
22
Q

what do neurotransmitters do?

A
  • released in response to depolarisation of axon terminal of a pre-synaptic neurone
  • they bind to receptors on post-synaptic cells + trigger (excitatory) or prevent (inhibitory) a response
23
Q

what do excitatory neurotransmitters do?

A

cause depolarisation by opening Na+ or Ca2+ channels

24
Q

what do inhibitory neurotransmitter do?

A

cause hyperpolarisation by opening K+ or Cl- channels

25
Q

what is acetylcholine and what does it do?

A

neurotransmitter released at neuromuscular junctions + binds to receptors on muscle fibres to trigger muscle contraction
- stored in vesicles until released via exocytosis
- binds to a cholinergic receptor
- broken down by Acetylcholinestrase (AChE)

26
Q

what is meant by antagonistic muscles?

A

as one contracts the other relaxes

27
Q

What do endotherms do?

A

Gain heat from reactions in their body

28
Q

What do ectotherms do?

A

Gain heat from outside their bodies

29
Q

What is the process of vasoconstriction

A
  • diameter of arteries near the skin is smaller
  • takes blood away from the surface of the skin so less heat is lost
30
Q

What is the process of vasodilation?

A
  • diameter of arteries near skin is larger
  • brings blood closer to the surface of the skin - more heat lost
31
Q

What is glycogenesis and when does it happen?

A

Glucose -> glycogen
When glucose conc is increased, liver removes glucose from blood + converts it to glycogen

32
Q

What is glycogenolysis?

A

Glycogen -> glucose
When glucose conc is lower, liver converts glycogen to glucose + diffuses back into the blood

33
Q

What is Gluconeogenisis and when does it happen?

A

Production of glucose from non-carbs
When glycogen supply is finished

34
Q

What is the second messenger model for adrenaline?

A
  1. Adrenaline binds to a transmembrane protein receptor
  2. protein changes shape on the inside of the membrane
  3. change in shape = activation of adenyl cyclase enzyme
  4. enzyme converts ATP -> CAMP
  5. cAMP binds to protein kinase enzyme .:. changes Shape + activates it
  6. active protein kinase enzyme carauses glycogen-> glucose
  7. glucose moves out of cell by facilitared diffusion through channel proreins
35
Q

What is the pancreas?

A

Produces insulin + glucagon
Has regions of hormone producing cells: islets of langernans

36
Q

What do alpha cells do?

A

Produce glucagon

37
Q

What does beta cells do?

A

Produce insulin

38
Q

what happens in selective reabsorption?

A
  1. Na+ actively transported out into blood capillaries,
    Na+ concentration in cells decreases
  2. Na+ diffuse down the conc. gradient from tubule lumen into epithelial cells via carrier proteins (facilitated diffusion)
  3. carrier proteins = co-transport so another molecule is carried along
  4. molecules that have been co-transported into the cells then diffuse into the blood.
39
Q

what happens in ultrafication?

A

hydrostatic pressure
small substances (glucose + water) pass out
via pores in endothelium

40
Q

what is the electrical conduction of the heart beat?

A

SAN sends electrical impulse = stimulates contraction of myocardium
impulse = atria to contract + stimulates AVN
AVN sends signals down the septum via bundle of his
bundle of his innervates purkinje fibres in ventricular wall = ventricular contraction

41
Q

control of heart rate: low blood pressure

A
  • high conc of CO2 = pH of blood decreases
  • chemoreceptors detect decrease = increase in f of impulses to the centre of medulla oblaganta = increase heart rate
  • increase in f of impulses via sympathetic nervous system so SAN increases heart rate
  • increase blood flow = more CO2 removed so conc back to normal
  • chemoreceptors decrease f od nerve impulses to medulla obloganta
  • medulla obloganta decreases f of impulses to the SAN = decrease in heart rate
42
Q

control of heart rate: high bp

A

pressure receptors transmits more nerve impulses to the medulla obloganta
sends impulses via parasympathetic nervous system to SAN = decrease heart rate

Biology (11 decks)

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