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1. A level master > Reflex arcs > Flashcards

Reflex arcs Flashcards

1
Q

What is a stimulus?

A

A detectable change in the internal of external environment of an organism

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2
Q

Stimuli are detected by …

A

Receptors

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3
Q

Name the structure labelled B on the diagram

A

Spinal cord

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4
Q

A response is produced by an ….

A

Effector

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5
Q

Give two examples of an effector

A

Gland or muscle

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6
Q

Name the type of neurone ahown on the diagram

A

Motor neurone

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7
Q

Name the strucutre labelled D on the diagram

A

Effector (in this case a muscle)

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8
Q

Give the sequence of events that lead from a stimulus to a response

A

Stimulus –> Receptor –> Coordinator–> Effector –> Response

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9
Q

The simplest type of nervous response is called a …

A

Reflex

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10
Q

The central nervous system consists of …

A

Brain and spinal cord

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11
Q

What is the function of a sensory neurone?

A

Carry electrical impulses from receptors to central nervous system

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12
Q

Name the neurone labelled C on the diagram

A

Motor neurone

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13
Q

What is the function of a motor neurone?

A

Carry electrical impulses from central nervous system to effectors.

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14
Q

Why are reflexes important?

A

Protect from danger
Maintain posture

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15
Q

Give two features of a reflex arc

A

Immediate - only 3 neurones involved. Minimum number of synapses
Specific - one stimulus leads to one response
Involuntary - happens without conscious though
Innate - present from birth

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16
Q

Name three receptors

A

Pacinian corpuscle
Rod cell
Cone cell
Thermoreceptor
Osmoreceptor
Chemoreceptor

17
Q

Name the neurone labelled A on the diagram

A

Sensory neurone

18
Q

When does the heart rate need to increase?

A

Exercise/increased muscle contraction
Fight or flight response

19
Q

Name the receptors that detect and increase in carbon dioxide in the blood,.

A

Chemoreceptors

20
Q

Where in the body are the chemoreceptors that detect an increase in carbon dioxide in the blood

A

Carotid arteries
Aortic arch

21
Q

What effect does the sympathetic nervous system have on the rate rate?

A

Increases heart rate and stroke volume

22
Q

What effect does noradrenaline have on the heart rate?

A

Increases heart rate

23
Q

What effect does the parasympathetic system have on the heart rate?

A

Decreases heart rate

24
Q

Name the neurotransmitters released by the sympathetic and parasympathetic system on the SAN

A

Sympathetic - noradrenaline
Parasympathetic - acetylcholine

25
Q

What effect does the parasympathetic nervous system have on the heart rate?

A

Decreases heart rate and stroke volume

26
Q

Name the three neurones found in a reflex arc

A

Sensory neurone
Relay neurone
Motor neurone

27
Q

Where is the coordinator for the heart rate reflex?

A

Medulla or hypothalamus (in the brain)

28
Q

For what is SAN an abbreviation for?

A

Sinoatrial node

29
Q

For what is AVN and abbreviation for?

A

Atrioventricular node

30
Q

Describe the role of the SAN and AVN in controlling the contraction of the heart

A

SAN generates a wave of excitation over the atria
Atria contract
Blood is forced into the ventricles
AVN sends electrical impulse down the bundle of His to heart apex
Impulse passes to Pukinje fibres which cause the ventricles to contract

31
Q

Where is the SAN located?

A

Wall of the right atrium

32
Q

When a wave of electrical activity reaches the AVN, there is a short delay before the impulse is generated in the Bundle of His. Explain why this is important.

A

Allow atria to empty/contract
Blood enters the ventricles

33
Q

What is the function of the dendrites?

A

Pass elecrical impulses from the relay neurone to the cell body of the motor neurone

34
Q

What is the function of the myelin sheath?

A

Electrical insulator

Allows impulses to jump between Nodes of Ranvier

35
Q

Where in the body are the motor neurone cell body and dendrites found?

A

Spinal cord

36
Q

What is the function of the axon?

A

Pass electrical impulses from the cell body to the axon terminals (muscle)

1. A level master (40 decks)

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