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Biology Unit 5 > 3.5.1 - Stimuli > Flashcards

3.5.1 - Stimuli Flashcards

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1
Q

Receptor definition

A

Cells/ tissues/ organs… That detect stimuli

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2
Q

Stimulus definition

A

Detectable change in the internal/ external environment in an organism that produces a response

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3
Q

The two parts that make up the nervous system?

A

The central nervous system and the peripheral nervous system

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4
Q

The two parts of the CNS?

A

Brain and spinal cord

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5
Q

The two parts of the PNS?

A

Sensory nervous system and the motor nervous system

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6
Q

Movement of nerve impulses with the motor neurones?

A

From the CNS to the effector

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7
Q

Movement of the nerve impulse with the sensory neurones?

A

From the receptors to the CNS

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8
Q

Two parts of the motor nervous system?

A

The voluntary and the autonomic system

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9
Q

Where is the nerve impulse carried to through the voluntary nervous system?

A

Towards the body muscles

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10
Q

Where is the nerve impulse carried to through the automatic nervous system?

A

Towards glands

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11
Q

Reflex arc definition

A

Pathway of neurones involved in a reflex

Stimulus - Receptor - Sensory neurone - Relay neurone - Motor neurone - effector - response

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12
Q

Reflex definition

A

Involuntary response to a sensory stimulus

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13
Q

Synapse

A

Point where you he axon of one neurone connects with the dendrite of another neurone or with an effector

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14
Q

Effector definition

A

Cells/ tissues/ organs/ organ systems that carry out the response

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15
Q

Coordinator definition

A

The brain/ spinal cord which connects information from receptors to the appropriate effector

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16
Q

Sensory reception chain

A

Stimulus - Receptor - Coordinator - Effector - Response

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17
Q

Taxis definition

A

A response who’s direction is determined by the direction of the stimulus. The organism will move whole body towards/ away from a stimulus

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18
Q

Taxis example - Algae

A

The (single celled) algae will move towards the light, for more efficient photosynthesises = positive phototaxis

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19
Q

What is positive chemotaxis, and an example?

A

The organism will move towards the chemical, typically to aid chance of survival.
For example, bacteria may move to an area of high glucose concentration to use as a food source

20
Q

Kineses definition?

A

A response where an organism doesn’t move towards/ away from a stimulus, but the more unpleasant the stimulus, the more rapidly it moves and changes direction

21
Q

Which response to a stimulus involves random movements?

A

Kinesis

22
Q

Kinesis example - woodlice

A

If an area is dry, the woodlice move faster and change direction more frequently, to increase the chance of moving to a different area

23
Q

Tropism definition?

A

Growth movement of part of a plant towards/ away from a stimulus

24
Q

Tropism example?

A

Plants grow towards the light for more efficient photosynthesis = positive phototropism

25
Q

The spinal cord is?

A

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

26
Q

The two parts making up the autonomic nervous system?

A

The sympathetic nervous system:
Stimulates effectors, speeding up an activity, helping us cope with stressful situations. (Fight or flight)
The parasympathetic nervous system:
Inhibits effectors, slowing down an activity, concerned with conserving energy and replenishing body’s reserves

27
Q

Antagonistic definition? And example?

A

The actions of 2 things usually oppose each other

E.g. The parasympathetic and sympathetic nervous systems

28
Q

Resting heart rate for normal adult?

A

70bmp

29
Q

Part of brain that controls changes to the heart rate?

A

Medulla oblongata

30
Q

The 2 centres of the medulla oblongata?

A

1) a centre that increases heart rate = sympathetic nervous system
2) a centre that reduces the heart rate = parasympathetic nervous system

31
Q

Role of chemoreceptors?

A

Detect changes to the pH of the blood (carbon dioxide forms an acid which lowers the pH) and sends impulses to keep heart rate normal

32
Q

If pH too low in blood?

A

If there’s a low pH (more C02), chemoreceptors increase frequencies of impulses via sympathetic nervous system
The heart rate increases.
The increased blood flow means C02 is being removed by the lungs, therefore carbon dioxide levels return to normal, and pH

33
Q

Where are chemoreceptors found?

A

Wall of the carotid arteries (arteries that serve the brain)

And the aorta

34
Q

Which receptors detect changes to blood pressure? Where are they found?

A

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

35
Q

What happens when blood pressure is lower than normal?

A

The pressure receptors transmit a nervous impulse to the centre in the medulla oblongata that increases heart rate. This centre sends via sympathetic nervous system to sinistral node, increasing heart rate

36
Q

Features of pacinian corpuscle?

A

Responds only to mechanical pressure
Converts information from the stimulus to a form that can be understood by the body (nerve impulses)
Has stretch-mediated sodium channels

37
Q

Structure of the pacinian corpuscle?

A

The nerve ending of the neurone is in the middle, surrounded by many layers of connective tissue separated by gel. Surrounding everything is a capsule

38
Q

Resting state for the pacinian corpuscle?

A

The stretch mediated sodium channels are too narrow for sodium to pass along. Neurone has a resting potential

39
Q

What happens when pressure is applied to a pacinian corpuscle?

A

It changes shape and the membrane around the neurone becomes stretched.
This widens the sodium channels, allowing sodium to diffuse into the neurone.
The potential of the membrane changes (becomes depolarised) = generator potential, which in turn creates an action potential (nerve impulse)

40
Q

Difference in numbers of rod/ cone cells?

A 
More rod (120m each eye)
Less cone (6m each eye)
41
Q

Rod cell function?

A

Detects black and white images, with low light intensities (eg at night)

42
Q

Come cell function?

A

Detects colour images, with higher light intensities

43
Q

Why rod cells respond to low light intensities?

A

There are a number of rod cells attached to a single bipolar cell = greater chance of exceeding threshold required for a generator potential to occur

44
Q

How a generator potential occurs in rod/ cone cells?

A

The pigments in these cells must be broken down
For rod cells, low light intensity is sufficient for this to occur
For cone cells, only high light intensity can break the pigment down

45
Q

Visual acuity definition and difference between rod/ cone cells?

A

Rod cells have low visual acuity, because 2 close dots appear as 1. This occurs because there are multiple cells for each bipolar cell, so only a single impulse is stimulated

Cone cells have high visual acuity, because 2 close dots appear as 2. This is because each cell has 1 bipolar cell, so 2 separate impulses are generated

Biology Unit 5 (8 decks)

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