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Biology : Response > Response to stimuli + Control of the Heart Rate > Flashcards

Response to stimuli + Control of the Heart Rate Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a stimulus?

A

a change in the external and internal environment.

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2
Q

What is a response?

A

an effect brought about in response to a stimulus.

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3
Q

What are the two advantages to organisms being able to respond to stimuli?

A
  1. Organisms are more likely to survive if they can respond to changes in their external environment.
  2. Organisms can maintain optimum conditions for metabolic reactions if they can respond to changes in their internal environment.
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4
Q

What types of organisms have simple responses?

A

simple organisms like ants.

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5
Q

What are taxes?

A

directional movement in response to stimulus.

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6
Q

What is kinesis?

A

random movement in response to a stimulus.

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7
Q

What are tropisms?

A

The growth of a plant in response to a directional stimulus using certain growth factors.

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8
Q

What are growth factors?

A

Hormoene-like chemicals that speed up or slow down plant growth.

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9
Q

How do growth factors like auxins cause plant growth?

A

They cause the cells just behind where the auxins are produced to elongate.

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10
Q

What is an important auxin we must know?

A

IAA indoleacetic acid

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11
Q

Explain how IAA causes the shoots to grow towards the light.

A

IAA builds up on the side of the shoot that is not facing the sun and it promotes growth. That side of the shoot grows quicker compared to the other side which causes the shoot to bend towards the light.

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12
Q

Explain how IAA causes the roots to grow towards gravity.

A

IAA builds up on the bottom of the roots and it inhibits growth meaning the top side grows faster and that causes the roots to bend downwards towards gravity.

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13
Q

What are receptors and what is their role?

A

They detect stimuli and they are usually special cells or proteins on the cell surface membrane of a cell.

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14
Q

What are effectors and what is their role?

A

They bring about an effect in response to a stimulus and they are usually a muscle or a gland.

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15
Q

What is the role of the sensory neurone?

A

It carries an electrical impulse from the receptors to the relay neurone.

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16
Q

What is the role of the relay neurone?

A

It carries an electrical impulse to the CNS where the information can be processed and then passes an electrical impulse to the brain.

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17
Q

What is the role of the motor neurone?

A

It carries an electrical impulse from the relay neurone to the effector.

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18
Q

What is the role of the CNS?

A

It processes information and sends an electrical impulse to the effector.

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19
Q

Why are the responses that go through the simple reflex arc automatic/involuntary?

A

The impulse travels along the spinal cord but does not go to the conscious part of the brain.

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20
Q

Why are the responses that go through the simple reflex rapid?

A

because you don’t have to waste time thinking about your actions.

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21
Q

What is the CNS made up of?

A

The brain and the spinal cord.

22
Q

What is the peripheral nervous system?

A

All the neurones that connect the CNS to the rest of the body.

23
Q

What systems make up the peripheral nervous system?

A

somatic and automatic systems

24
Q

What is the somatic system responsible for?

A

conscious activities

25
Q

What is the automatic system responsible for?

A

unconscious activities

26
Q

What makes up the automatic nervous system?

A

The parasympathetic and sympathetic nervous system.

27
Q

What is the parasympathetic nervous system responsible for?

A

it calms the body down

28
Q

What is the sympathetic nervous system responsible for?

A

It speeds the body up.

29
Q

Why is the heart described as myogenic?

A
30
Q

Where is the SAN located and what is its function?

A

It is located in the right atrium and it is responsible for being the pacemaker of the heart.

31
Q

Describe the myogenic response of the heart.

A

The SAN gets an electrical impulse from the medulla which causes it to to send waves of depolarisation to the atrial walls, causing them to contact. This causes the atria to contract. The waves of electrical activity are then transferred to the AVN and the AVN passes those waves to the bundle of His. The electrical activity then moves between the ventricles to the bottom of the heart and into the Purkinje fibres . These carry the waves of electrical activity into the walls of the ventricles and cause them to contract from the bottom up.

32
Q

Why is there a slight delay before the AVN acts?

A

To make sure that the atria have emptied of blood.

33
Q

Where are baroreceptors found?

A

the aorta and carotid arteries

34
Q

Where are chemoceptors found?

A

aorta, medulla, carotid arteries

35
Q

What happens when there is high blood pressure?

A

The baroreceptors in the aorta and carotid arteries detect the increase in pressure and send an impulse to the medulla along the sensory neurone. The medulla sends an impulse along the parasympathetic neurone and these release acetylcholine which binds to receptors in the SAN and causes heart rate to slow down and blood pressure to reduce.

36
Q

What happens when there is low blood pressure?

A

The baroreceptors in the aorta and carotid arteries detect the decrease in pressure and send an impulse to the medulla along the sensory neurone. The medulla sends an impulse along the sympathetic neurone and these release noradrenaline which binds to receptors in the SAN and causes heart rate to speed up and blood pressure to increase.

37
Q

What happens when there are low levels of oxygen, high levels of carbon dioxide and a low PH?

A

The chemoreceptors in the aorta and carotid arteries detect this and send an impulse to the medulla along the sensory neurone. The medulla sends an impulse along the sympathetic neurone and these release noradrenaline which binds to receptors in the SAN and causes heart rate to speed up and blood pressure to increase.

38
Q

What happens when there are high levels of oxygen, low levels of carbon dioxide and high pH?

A

The chemoreceptors in the aorta and carotid arteries detect this and send an impulse to the medulla along the sensory neurone. The medulla sends an impulse along the parasympathetic neurone and these release acetylcholine which binds to receptors in the SAN and causes heart rate to decrease and blood pressure to decrease.

39
Q

What causes the resting potential of a receptor cell?

A

The inside of the cell is slightly more negatively charged compared to the outside as there are more sodium and potassium ions on the outside and this means there is a potential difference and that is the resting potential.

40
Q

What causes the generator potential of a receptor cell?

A

When a stimulus is detected the cell membrane becomes excited and it lets more ions move in and out of the cell. This alters the potential difference and that is called the generator potential.

41
Q

What causes the action potential of a receptor cell?

A

If the generator potential is large enough then an action potential is triggered.

42
Q

What are Pacinian corpuscles?

A

They are receptors that detect mechanical stimuli

43
Q

How are action potentials triggered in Pacinian Corpuscles?

A

The lamellae are deformed and press on the sensory nerve ending. This causes the deformation of the stretch-mediated sodium ion channels. The channels allow the sodium ions to diffuse into the cell. This creates a generator potential. If it is large enough it will trigger an action potential.

44
Q

What are photoreceptors?

A
45
Q

Why do we have a blind spot?

A
46
Q

How do photoreceptors work?

A
47
Q

What type of photoreceptors are there in the eye?

A
48
Q

Why are rods very sensitive to light?

A

One rod is connected to many bipolar neurones meaning many weak generator potentials can be combined to reach the threshold and trigger an action potential.

49
Q

Why are rods low in visual acuity?

A

One rod is connected to many bipolar neurones meaning light coming from two points close together can’t be told apart.

50
Q

Why are cones not very sensitive to light?

A

One cone is connected to one bipolar neurone so it takes more light to create a generator potential larger than the threshold and trigger an action potential.

51
Q

Why are cones high in visual acuity?

A

One cone is connected to one bipolar neurone so when light from two points hits two cones two action potentials go to the brain and you can tell the two points apart.

Biology : Response (4 decks)

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