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IGCSEs > Biology πŸƒ | Coordination and response | 14 > Flashcards

Biology πŸƒ | Coordination and response | 14 Flashcards

1
Q

What do electrical impulses travel along?

A

Electrical impulses travel along neurones

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2
Q

What are the two parts of a mammallian nervous system?

A
  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
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3
Q

What does the CNS consist of?

A

The brain and spinal cord

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4
Q

What does the PNS consist of?

A

The nerves outside of the brain and spinal cord

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5
Q

What is the role of the nervous system?

A

Coordination and the regulation of body functions (via electrical impulses).

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6
Q

Define Dendrites

A

Tree-like projections that connect to other neurons and recieve electrical impulses from them.

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7
Q

Define Axon

A

A long fibre on a neuron which electrical impulses travel down

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8
Q

Define Myelin Sheath

A

Fatty sheaths that insulate an axon

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9
Q

What is the function of sensory neurons?

A

To send information to the central nervous system

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10
Q

Which part of the nervous system is a sensory neuron found?

A

In the Peripheral nervous system

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11
Q

What are the identifying features of a sensory neuron?

A
  • A receptor cell
  • Myelin sheaths
  • A cell body branching off at the middle of the axon
  • They are long
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12
Q

What is the function of relay neurons?

A

To directly connect a sensory neuron to a motor neuron

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13
Q

In which part of the nervous system are relay neurons found?

A

In the Central Nervous System

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14
Q

What are the identifying features of a relay neuron?

A
  • No myelin sheaths
  • Small cell body at one end with many dendrites branching off of it
  • Short
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15
Q

What is the function of motor neurons?

A

They carry impulses from the CNS to effectors (muscles + glands)

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16
Q

Where are motor neurons found?

A

In the Peripheral Nervous System

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17
Q

What are the identifying features of a motor neuron?

A
  • They have mylein sheaths
  • They are long
  • They have a large cell body at one end with long dendrites branching off of it
  • On one end, they are connected to an effector
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18
Q

What are the two parts of the PNS?

A
  • Somatic Nervous System (SNS)
  • Automatic Nervous System (ANS)
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19
Q

What is the Somantic Nervous Sytem for?

A

Voluntary control of the body movements via skeletal muscle effectors

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20
Q

What is the Automatic Nervous System for?

A

Involuntary actions via muscle and gland effectors

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21
Q

Why do Mylein sheaths exist?

A

They insulate nerve fibres so electrical impulses can be passed fast: simply jumping from uninsulated sections to other uninsulated sectons.

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22
Q

What is a voluntary action?

A

A conscious decision to carry out a particular action, with our brain involved

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23
Q

What is an involuntary action?

A

An unconcious desicion that does not involve the brain. Generally these are essential to basic survival.

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24
Q

Which type of action is quicker: voluntary or involuntary?

A

Involuntary actions are quicker

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25
Q

Define reflex arc?

A

A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors involuntarily.

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26
Q

Does the reflex arc involve the brain?

A

No.

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27
Q

Describe a reflex arc to a stimulus, in steps.

A
  1. Sensory receptor recieves stimulus
  2. The signal travels along a sensory neurone
  3. The synapse at the end of the sensory neurone carries a message to the relay neurone
  4. The signal travels along the relay neuron, transmitted to a motor neuron
  5. The signal travels along the motor neurone
  6. An effector recieves the signal and carries out a response.
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28
Q

What are examples of involuntary actions?

A
  • Coughing
  • Knee jerk reflex
  • Pupil reflex
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29
Q

Define stimulus

A

Any change either internal or external which leads to a response

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30
Q

Define synapse.

A

A junction between two neurones

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31
Q

How is information transmitted from one neuron to the next?

A

Neurotransmitters are diffused across the synaptic gap

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32
Q

How are synapses unidirectional?

A

They can pass information in only one direction because only the presynaptic neuron has vesicles of neurotransmitters

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33
Q

What is the function of vesicles in neurons?

A

Vesicles contain neurotransmitters in the presynaptic neuron, holding them until they recieve an impulse to release them.

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34
Q

What is the synaptic gap / cleft?

A

The tiny gap between two neurons: impulses do not cross it, but the neutrotransmitter chemicals do

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35
Q

What is the function of receptor proteins in synapses?

A

They detect the neurotransmitters and stimulate electrical impulses in response

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36
Q

Describe the events at a synapse when transmitting a signal.

A
  1. An impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap
  2. The neurotransmitter molecules diffuse across the gap
  3. Neurotransmitter molecules bind with receptor proteins on the next neurone
  4. an impulse is then stimulated in the next neurone
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37
Q

What is the eye?

A

The sense organ responsible for sight

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38
Q

What is an antagonistic muscle?

A

A muscle that opposes the action of another

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39
Q

In a pair of antagonistic muscles, which muscle would be the agonist and which one would be the antagonist?

A

The agonist would contract while the antagonist relaxes

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40
Q

Define sense organ

A

Groups of receptor cells responding to
specific stimuli: light, sound, touch, temperature and chemicals.

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41
Q

Cornea function

A

Refracts light

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42
Q

Iris function

A

Controls how much light enters the pupil

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43
Q

Lens function

A

Focuses light onto the retina

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44
Q

Retina function

A

Has light receptors that are sensitive to light of diferent colors

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45
Q

Optic nerve function

A

Carries impulses to the brain

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46
Q

Why do we have a blind spot?

A

Where are optic nerve sends signals to the brain, our cones and rods are distrupted

47
Q

What two muscles are involved in the pupil reflex?

A

The radial muscle and the circular muscle

48
Q

The circular and radial muscles are __

A

Antagonistic

49
Q

What are the actions of the radial and circular muscles in low light?

A

Radial muscles contract and become shorter to pull the pupil out, making it wider. The circular muscle relaxes.

50
Q

What are the actions of the radial and circular muscles in bright light?

A

Circular muscles contract and become shorter to reduce the size of the pupil. The radial muscles relax.

51
Q

Why do we have the pupil reflex?

A
  • It allows us to see better in the dark by letting more light in
  • It protects our eyes in the day from being overloaded with light
52
Q

What is the process of accomodation for?

A

For our eyes to adjust for near and distant objects

53
Q

What is the muscle involved in accomodation?

A

The ciliary muscle

54
Q

How do ciliary muscles help with accomodation?

A

Their contractions and relaxations are able to stretch the lens to different lengths that cause different amounts of refractions.

55
Q

When an object is nearby, what are the actions of ciliary muscles?

A

The ciliary muscles contract so that the lens gets rounder and thicker

56
Q

What are the suspensory ligaments?

A

They are ligaments that hold the lens in conjunction with the ciliary muscles

57
Q

When an object is nearby, what processes happen in accomodation?

A
  • The ciiary muscles contract
  • Suspensory ligaments become relaxed
  • Lens becomes rounder and thicker
58
Q

When an object is far away, what processes happen in accomodation?

A
  • The ciliary muscles relax
  • Suspensory ligaments become stretched
  • Lens becomes flatter and thinner
59
Q

When an object is near to the eye, how does refraction change?

A

The amount of refraction increases

60
Q

When an object is far from the eye, how does refraction change?

A

The amount of refraction decreases

61
Q

What are the two types of receptors in the eye?

A

Rods and cones

62
Q

Function of rods

A

Provide low detail, black & white images.

63
Q

Function of cones

A

Provide detailed, coloured images

64
Q

When are rods used?

A

In low-intensity light

65
Q

When are cones used?

A

In high intensity light

66
Q

Where in the eye are rods found?

A

Packed most tightly around edge of retina

67
Q

Where in the eye are cones found?

A

Most tightly packed at fovea

68
Q

What are the three types of cone cells?

A

Red, green, and blue. These colors are added together to create an array of visible color

69
Q

What is the fovea?

A

The part of the retina where the cone cells are very tightly packed.

70
Q

Where in the eye is light focused to?

A

To the fovea

71
Q

Define hormone

A

A chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs

72
Q

Where is adrenaline produced?

A

In the adrenal gland

73
Q

Where is insulin produced?

A

In the pancreas

74
Q

Where is testosterone produced?

A

In the testes

75
Q

Where is oestrogen produced?

A

In the ovaries

76
Q

What system are hormones and glands a part of?

A

The endocrine system

77
Q

What is adrenaline?

A

The hormone secreted in β€˜fight or flight’ situations

78
Q

What are the effects of adrenaline?

A
  • Increases heart rate
  • Increases pupil diameter
  • Increases breathing rate
79
Q

Where is glucagon produced?

A

In the pancreas

80
Q

How does speed of action compare between the nervous and hormonal system?

A

Speed of transmission is very rapin in the nervous system, but can be slow in the endocrine system

81
Q

How does duration of effect compare between the nervous and hormonal system?

A

In the nervous system, the effect is usually within seconds, but in the hormonal system, it may take years, such as in puberty

82
Q

Where is glucagon produced?

A

The pancreas

83
Q

Define homeostasis

A

The maintenance of a
constant internal environment needed by a living organism

84
Q

Via what concept does homeostasis work?

A

Negative feedback

85
Q

How does negative feedback happen in our bodies?

A

Information about the body is sent to the brain by sensory receptors. The brain then coordinates a response to keep conditions within the normal range

86
Q

What happens when blood glucose is too high?

A
  1. High blood glucose
  2. Insulin secreted
  3. Signals liver; stores excess glucose as glycogen
  4. Blood glucose concentration falls
  5. Normal blood glucose!
87
Q

What happens when blood glucose is too low?

A
  1. Low blood glucose
  2. Glycogen secreted
  3. Signals liver to break down glycogen into glucose, releasing it
  4. Blood glucose concentration rises
  5. Normal blood glucose!
88
Q

Which hormone is responsible for the storing of excess glucose?

A

Insulin

89
Q

Which hormone is responsible for the release of glucose from glycogen?

A

Glucagon

90
Q

What is type 1 diabetes caused by?

A

The death of insulin-secreting cells or lack of them.

91
Q

What is the treatment for type 1 diabetes?

A
  • Injecting insulin to lower blood glucose concentration
  • Reducing carbohydrate intake
92
Q

How do our body hairs change depending on temperature?

A

They lie flat when it is too hot, and are raised when the temperature is too high

93
Q

Which muscles are responsible for moving our body hairs?

A

Hair erector muscles

94
Q

How do hair erector muscles raise and lower hair?

A

They contract to raise hair, and relax so that hair lies flat

95
Q

Why is it beneficial for our hairs to raise in cold?

A

The raised hairs trap heat

96
Q

Define vasodilation

A

When arterioles, which supply blood to the skin-surface capillaries, dilate to allow more blood near to skin surface to increase heat loss

97
Q

In what conditions does vasodilation occur?

A

When it is too hot

98
Q

Define vasoconstriction

A

When arterioles, which supply blood to the skin-surface capillaries, constrict to allow less blood near to skin surface to increase heat loss

99
Q

In what conditions does vasoconstriction occur?

A

When it is too cold

100
Q

How does sweating help us lose heat when it is too hot?

A

Water evaporates from our skin, so our surfaces lose energy, and our temperature lowers

101
Q

How does shivering help us when its cold?

A

Shivering is muscle activity. This is an increase in metabolism, thus more release of energy via respiration, thus production of heat

102
Q

What is the role of temperature receptors in homeostasis?

A

They sense heat and send impulses to the hypothalamus to do things to stabilise body temperature

103
Q

What role does the brain have in temperature homeostasis?

A

In the hypothalamus, in the thermoregulatory centre, the use of corrective mechanisms are controlled

104
Q

Define gravitropism

A

A response in which
parts of a plant grow towards or away from gravity

105
Q

Define phototropism

A

A response in which parts of a plant grow towards or away from the direction of the light source

106
Q

Define auxins

A

The plant hormones or growth substances that control tropisms

107
Q

Where are auxins produced?

A

At cells in the tips of a plant

108
Q

Positive VS Negative phototropism

A

Positive: When part of a plant grows towards the light
Negative: When part of a plant grows away from the light

109
Q

Positive VS Negative gravitropism

A

Positive: When part of a plant grows towards gravity
Negative: When part of a plant grows away from gravity

110
Q

What tropisms do roots have?

A
  • Negatively phototropic
  • Positively gravitropic
111
Q

What tropisms do shoots have?

A
  • Positively phototropic
  • Negatively gravitropic
112
Q

How do auxins control shoot growth?

A
  1. Auxin is made in the shoot tip
  2. Auxin diffuses through the plant from the shoot tip
  3. Auxin is unequally distributed in response to light and gravity
  4. Auxin stimulates cell elongation
113
Q

How do auxins create positive phototropism?

A

Auxins accumulate in the darker side of the plant, which is not hit by light. Thus, this side of the plant grows faster and the plant grows towards light

114
Q

How do auxins create positive gravitropism?

A
  1. Auxins tend to settle at the bottom of the root
  2. This causes the tip of root cells to stop from growing, causing the cells at the top of the root to grow faster
  3. Thus, the growth of top root cells causes the root to be pushed deeper into soil

IGCSEs (68 decks)

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