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Biology Unit 5 > Response To Stimuli > Flashcards

Response To Stimuli Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is kinesis

A

A change in activity

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2
Q

What is taxes

A

A automatic response to stimuli - orientated movement towards or away from an environment

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3
Q

What is tropism

A

Only part of the organism moves towards or away from stimulus

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4
Q

Describe the reflex arc

A 
Stimulus
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Response
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5
Q

Why are reflex arcs important

A

Makes survival more likely as quick and involuntary so don’t require timely decision making

Also have from birth so don’t need to learn

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6
Q

What is the role of the voluntary nervous system

A

Carries nerve implies to body muscles and it is conscious of control. Involves skeletal muscle

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7
Q

What is the role of the autonomic nervous system

A

Subconsciously carries nerve impulses to glands, smooth muscle and cardiac muscle

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8
Q

What does the sympathetic nervous system do

A

Stimulates effectors so speeds up activity

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9
Q

What does the parasympathetic nervous system do

A

Inhibits effectors so slows down activity

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10
Q

Why are they sympathetic and parasympathetic nervous systems described as antagonistic

A

They normally oppose each other

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11
Q

What area in the brain controls changes in heart rate

A

Medulla oblongata

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12
Q

Where are chemoreceptors found

A

In walls of carotid arteries

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13
Q

Where are pressure receptors found

A

In walls of carotid arteries and aorta

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14
Q

Describe what happens to the heart of blood pressure is higher than normal

A 
Baro (Pressure) receptors
Transmit nervous impulse
To medulla oblongata
Impulse sent via parasympathetic branch
To sinoatrial node 
Causes decrease in heart rate
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15
Q

Describe what happens to the heart if blood pressure is lower than normal

A 
Baro (pressure) receptors 
Transmit nervous impulse
To medulla oblongata
Impulse sent via sympathetic branch
To sinoatrial node
Causes increase in heart rate
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16
Q

Describe what happens to heart rate if PH is lowered from high co2 concentration in blood

A

Chemoreceptors detect PH is lower
Increase frequency of nervous impulses to medulla oblongata which increases heart rate
Blood flow increased so more co2 removed by lungs
PH rises to normal
Frequency impulses reduced
Heart rate reduced to normal

17
Q

Give an example of a sensory receptor

A

Pacinian corpuscle

Senses pressure

18
Q

What is a generator potential

A

The first impulse

All impulses after this are called action potential

19
Q

What would happen if someone applied pressure to a pressure sensory receptor

A

The receptor’s shape will squash

Mechanical energy converted to electrical energy
As nerve impulse (generator potential)

20
Q

Describe how a pacinian corpuscle produces a generated potential when stimulated

A

Increase pressure changes stretch-mediated sodium channel

Sodium ions flood in

Depolarisation leading to generator potential

21
Q

What is the word to describe the neurone in nerve impulse at rest

A

Polarised

22
Q

What is the ratio of the sodium-potassium pump

A

3 sodium out

2 potassium in

23
Q

What happens to the channels when it’s at rest

A

Sodium channels closed so they’re stuck outside

Potassium channels open so they can move outside

24
Q

Describe what happens during depolarisation

A 
Sodium channels open
Sodium rushes in
Charge across membrane reversed
Action potential generated
Sodium channels close
Potassium channels open
Potassium moves out
Briefly hyperpolarised
25
Q

Why does hyperpolarisation occurs

A

Prevents it being excited again as more sodium is required to reach the threshold to create another action potential

26
Q

Why does the next cell get stimulated after action potential

A

Positive feedback

Presence of sodium in previous one encourages it

27
Q

What factors affect the speed of action potential and how

A

Myelin sheath
(Allows jump from node to node)

Big diameter of axon is faster
(Less leakage of ions so easier to maintain)

Higher temperature is faster
(Pump controlled by enzymes)

28
Q

How is a myelinated axon faster than one not myelinated

A

Less ATP used
As
Myelin sheath allows action potential to jump from node to node

Myelin acts as electrical insulator

29
Q

What is the difference between kinesis and taxes

A

Taxes is moving in a direction. Kinesis is moving but no direction

30
Q

What is the refractory period

A

Period where axon membrane can’t be depolarised so there’s no new action potential initiated

Biology Unit 5 (12 decks)

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