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Biology > Response to stimuli > Flashcards

Response to stimuli Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a stimulus?

A

A detectable change in the internal or external environment of an organism that leads to a response in the organism

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2
Q

What does the central nervous system consist of?

A

CNS consists of brain and spinal cord

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3
Q

What does the peripheral nervous system consist of?

A

Sensory nervous system and motor nervous system

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4
Q

What does the motor nervous system consist of?

A

Voluntary nervous system and autonomic nervous system

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5
Q

What does the voluntary nervous system do?

A

Carries impulses to body muscle, under voluntary control

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6
Q

What does the sensory nervous system do?

A

Carries nerve impulses from receptors to CNS

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7
Q

What does the autonomic nervous system do?

A

Carries nerve impulses from CNS to glands, cardiac and smooth muscles

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8
Q

What is the spinal cord?

A

A column of nervous tissue that runs along the back and lies inside the vertebral column for protection

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9
Q

What are the four types of receptors?

A

Photoreceptors, chemoreceptors, thermoreceptors and mechanoreceptors

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10
Q

What is the Pacinian Corpuscle and where is it found?

A

Mechanoreceptor, deep in the skin, typically on fingers, soles of feet and external genitalia
They are also found in joints, tendons and ligaments where they enable an organism to know which joints are changing direction

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11
Q

What’s the structure of a Pacinian Corpuscle?

A

Single sensory neurone in the centre, surrounded by layers of connective tissue with a viscous gel between the tissue layers

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12
Q

What type of sodium channel is in the plasma membrane of PC?

A

Stretch-mediated sodium channel

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13
Q

When does the PC have a resting potential?

A

In its normal resting state, when the sodium channels are too narrow to allow sodium ions to pass through

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14
Q

When are the sodium channels of PC widened?

A

When pressure is applied, it becomes deformed and the membrane around the neurone stretches

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15
Q

When is a generator potential produced?

A

When the sodium ions move into the PC

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16
Q

What does the generator potential do?

A

Creates an action potential (nerve impulse) that travels to CNS

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17
Q

What is the order of cells inside the retina?

A

Ganglion cells, bipolar neurones then rod and cone cells

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18
Q

How are rod and cone cells acting as transducers?

A

Conserving light energy into electrical energy of a nerve impulse

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19
Q

How many rod cells are there in each eye?

A

120 million roughly

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20
Q

Can rod cells distinguish between different wavelengths of light?

A

No, meaning they can not identify colour

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21
Q

Where are rod cells dense or absent?

A

Greater density at the periphery and absent at the fovea

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22
Q

What are rod cells used for?

A

Detect low light intensity, so are used to see in the dark or dim lighting

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23
Q

Why are multiple rod cells connected to a single bipolar cell?

A

Much greater chance of threshold for generator potential being exceeded

24
Q

What must happen for a generator potential to be created in rod cells?

A

Pigment Rhodopsin must be broken down

25
Q

Why do rod cells give poor visual acuity?

A

Multiple neurones are stimulated in other bipolar cells but only one impulse is received by the brain

26
Q

How many types of cone cells are there?

A

Three, each respond to a different wavelength of light, meaning we can see colour

27
Q

How many cone cells are there in each eye?

A

Around 6 million

28
Q

Why do cone cells only respond to high light intensity?

A

Each cell is connected to a single neurone

29
Q

What pigment do cone cells contains?

A

Iodopsin, each type contains a specific iodopsin

30
Q

Why do cone cells need high light intensity?

A

They require higher amounts of energy to create generator potential

31
Q

Why do cone cells give good visual acuity?

A

Each connected to a single bipolar cell, so if 3 are stimulates then 3 signals are received

32
Q

Where are cone cells most dense or absent?

A

Most dense at the fovea and they are not found in the periphery

33
Q

What are the two divisions of ANS?

A

Parasympathetic nervous system and sympathetic nervous system

34
Q

What does the sympathetic nervous system do?

A

Stimulates effectors to speed up any activity, controls effectors when we exercise strenuously or experience powerful emotions and helps us cope in stressful situation by heightening our awareness and preparing us for activity (fight or flight)

35
Q

What does the parasympathetic nervous system do?

A

Inhibits effectors and slows down any activity, control activities under normal resting conditions and helps to conserve energy and replenish the body’s reserves

36
Q

What is SAN?

A

Sinoatrial node, control heart rate (pacemaker)

37
Q

How is heart rate controlled?

A

A wave of electrical activity spreads out from the SAN, causing both atria to contract. The wave enters the AVN, which conveys a wave between the ventricles across purkyne tissue (bundle of His). The wave is conducted through the AV septum to the base of the ventricles where the wave is released causing the ventricles to contract quickly at the same time

38
Q

What is AVN?

A

Atrioventricular node, a group of cells, which lies between the atria

39
Q

What is Purkyne tissue?

A

A series of specialised muscle fibres, collectively called a Bundle of His

40
Q

What centre of the brain controls the changes to heart rate?

A

Medulla oblongata

41
Q

What does increasing and decreasing HR involve?

A

Increasing: SAN and sympathetic nervous system
Decreasing: SAN and parasympathetic nervous system

42
Q

Where are chemoreceptors found?

A

In the wall of carotid arteries

43
Q

What detection causes chemoreceptors to send signals?

A

Sensitive the changes in pH, resulting from changes in CO2 concentration

44
Q

What do chemoreceptors do when PH is lowered?

A

Increase frequency of nerve impulses to the centre of medulla oblongata in control of increasing heart rate

45
Q

What are baroreceptors and where are the found?

A

Pressure receptors, found in the walls of the carotid arteries and the aorta

46
Q

When do baroreceptors operate?

A

When blood pressure is too high or low

47
Q

What do baroreceptors do when blood pressure is too high?

A

Transmit more nerve impulses to the centre of the medulla oblongata in control of decreasing heart rate

48
Q

What happens when the centre decreasing HR receives more impulses?

A

Centre send impulses via the parasympathetic nervous system to the SAN which decreases HR

49
Q

What happens when blood pressure is too low?

A

Receptors transmit more nerve impulses to the centre in the medulla oblongata that increases the HR, this centre sends impulses via the sympathetic nervous system to the SAN which increases the rate at which it beats

50
Q

What is a taxis?

A

A form of simple response where the direction is determined by the direction of the stimulus

51
Q

How are taxes classified?

A

Positive or negative

52
Q

What is kinesis?

A

Simple form of response in which the organism does not move towards or away from a stimulus, instead it changes the speed at which it moves and rate at which it changes direction

53
Q

What happens if an organism moves considerable distance into an unfavourable environment?

A

The rate of changing direction may slow so it moves in a long straight line

54
Q

What’s an example of kinesis?

A

Wood lice lose water form their body when in a dry environment , they move more rapidly and change direction which increases their chances of returning to damp conditions

55
Q

What is IAA?

A

Indoleacetic Acid is a plant growth factor that controls plant elongation

56
Q

How does IAA control phototropism?

A

Cells in root tip produce IAA, light causes IAA to move to shaded side of the plant and the cells on shaded side elongate more due to more IAA

57
Q

Where does IAA accumulate in gravitropism?

A

Lower side on horizontal growth

Biology (22 decks)

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