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14. Coordination and Response Flashcards

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1
Q

Definition of Iris

A

A coloured ring of circular and radial muscle that controls the size of the pupil and so controls the amount of light entering the eye

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2
Q

Definition of Cornea

A

A transparent, curved layer at the front of the eye that refracts the light entering and helps to focus it

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3
Q

Definition of Lens

A

A transparent, convex, flexible, jelly-like structure that refracts light to focus it onto the retina and to produce an image. This final adjustment is called accommodation.

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4
Q

Definition of Retina

A

A light-sensitive layer at the back of the eye made up of rods, which detect light of low-intensity, and cones, which detect different colours.

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5
Q

Definition of Optic Nerve

A

Transmits electrical impulses from the retina to the brain

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6
Q

Definition of Conjunctiva

A

Thin layer covering the front of the eye which protects the cornea

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7
Q

Definition of Eye Muscles

A

Allow the eyeball to move from side to side and up down

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8
Q

Definition of Sclera

A

Tough non-elastic coat, that is white in colour and protects the eyeball

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9
Q

Definition of Ciliary Muscles and Suspensory Ligaments

A

Cause the lense to change shape and so allow fine focusing onto the retina

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10
Q

Definition of Choroid

A

Layer of blood vessels inside the sclera which supplies food and oxygen to the eye

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11
Q

How does they eye respond to bright light?

A

Circular muscles of iris contract to reduce diameter of pupil.
Less light can enter and the retina is protected from bleaching.

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12
Q

How does they eye respond to dim light?

A

Radial muscles of iris contract to make the diameter of the pupil larger, allowing a larger amount of light to reach and stimulate the light-sensitive cells in the retina.

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13
Q

What is the job of the aqueos / vitreous humour?

A

They create outward pressure on the sclera, which keeps the spherical shape of the eyeball.

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14
Q

What does the ciliary body produce?

A

Aqueos humour

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15
Q

What is the blind spot?

A

Part of the retina on top of the optic nerve which doesn’t contain any light-sensitive cells.

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16
Q

How do our eyes detect light

A

STAGE 1
Light from a source travels towards the eye

STAGE 2
Light passes through the cornea and enters the eye. The cornea refracts the light rays.

STAGE 3
Light passes through the lens, which changes shape to refract the light even more. This is how the eye focuses light.

STAGE 4
Light rays hit the back of the retina. The light receptors detect the light and a nerve impulse is sent along the optic nerve to the brain.

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17
Q

What type of organ is the eye?

A

A sense organ

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18
Q

What type of receptors does it contain?

A

Light receptors

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19
Q

What are rod cells sensitive to?

A

They’re sensitive to light at LOW INTENSITIES.
Rod cells are more sensitive to light than cone cells.
They do NOT detect colour.

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20
Q

What are cone cells sensitive to?

A

They’re sensitive to COLOUR and light at HIGH INTENSITIES.

Humans have 3 different types of cone cells, each sensitive to a different range of colours (ones which respond to red, green or blue)

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21
Q

Definition of suspensory ligaments

A

Attachment between the lens and the ciliary muscles which keeps the lens in place and allows its shape to be changed by the ciliary muscles.

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22
Q

Definition of cillary muscles

A

Small muscles attached to suspensory ligaments which alter the shape of the lens

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23
Q

How does the eye focus on distant objects?

A

Ciliary muscles relax, eyeball becomes more spherical
Suspensory ligaments tighten, pulling lens thin
To focus distant objects, the lens must be thin so light rays are only slightly refracted

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24
Q

How does the eye focus on close objects?

A

Ciliary muscles contract, pull eyeball inwards (bulges forward)
Suspensory ligaments loosen, causing the lens to thicken
To focus on close objects, the lens needs to be thick to refract the light rays greatly

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25
Q

In the Iris Reflex, in what way do the circular and radial muscles in the iris work together?

A

They work antagonistically

they oppose each other in their actions
when circular muscles contract, pupil constricts
when radial muscles contract, pupil dilates

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26
Q

In what type of vision do the rod cells help?

A

Night vision

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27
Q

Where are the cone cells concentrated?

A

In the fovea

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28
Q

What is the fovea’s purpose?

A

allows objects to be examined in fine detail
- the centre only contains cones, this is where colour discrimination occurs

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29
Q

When does the fovea work in full efficiency?

A

In bright light

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30
Q

What happens if the image falls on the blind spot?

A

It cannot be seen

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31
Q

Definition of long-sightedness

A

When a person can see distant objects clearly, but close objects appear blurred

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32
Q

Definition of short-sightedness

A

When a person can see near objects clearly, but distant objects appear blurred

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33
Q

Definition of colour blindness

A

When a person cannot tell the difference between certain colours, often red or green

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34
Q

Why can long-sighted people not focus clearly on objects close-by?

A

The image is focused BEHIND their retina, not ON their retina
Due to weak eye muscles which are unable to contract enough to make lens thick enough to focus near objects.

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35
Q

What is the scientific name for long-sightedness?

A

Hyperopia

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36
Q

Why can near-sighted people not focus clearly on objects in the distance?

A

the image is formed IN FRONT of their retina
due to overstrong eye muscles which cannot relax enough to make the lens thing enough leading to light rays being bent too much so image is blurred

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37
Q

What is the scientific name for short-sightedness?

A

Myopia

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38
Q

In what 2 ways can eye-sight be corrected?

A

Glasses / contact lenses

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39
Q

How do lenses help?

A

Help focus light onto the retina

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40
Q

In what 2 more modern ways can sight problems be corrected?

A

Laser eye surgery

involves using a highly precise laser to change shape of cornea
alters refraction of light as it enters eye, enabling it to be focused onto the retina correctly
Artificial lens
- faulty eye lens can be removed and replaced by an artificial lens that focuses light onto the retina properly

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41
Q

What type of lens is used to correct long-sightedness?

A

A CONVEX lens

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42
Q

What type of lens is used to correct near-sightedness?

A

A CONCAVE lens

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43
Q

What causes colour-blindness?

A

Caused by a lack of a certain type of light receptor (cone) in the retina

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44
Q

What colours are hard to distinguish for a colour blind person?

A

red and green

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45
Q

Why do cataracts occur?

A

Occur as a result of changes in the lens

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46
Q

What happens to the lens if there’s a cataract?

A

The lens becomes less transparent, which leads to a decrease in vision. Eyes will appear cloudy.

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47
Q

What age group is most likely to develop cataracts?

A

Old people

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48
Q

How is cataracts treated?

A

Affected lens is removed and replaced with a new, artifical lens

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49
Q

When are objects most clearly seen by the rod cells?

A

At night by not looking directly a them

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50
Q

When are objects most clearly seen by the cone cells?

A

During daylight by looking directly at them

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51
Q

Why is there a layer of pigment behind the rods and cones?

A

Prevents internal reflection which might lead to multiple or blurred images.

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52
Q

How does the image differ when formed on the retina?

A

it’s inverted and diminished (smaller)
- brain corrects the inversion and change in size
INTERGRATION

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53
Q

How can we see colours which aren’t just, red, green or blue?

A

Seen by light waves hitting more than one type of cone

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54
Q

What is presbyopia?

A

A condition of old age (over 40) where people lose the ability to focus on near objects as the lens becomes less elastic

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55
Q

What does the nervous system enable humans to do?

A

Enables humans to react to their surroundings and coordinate their behavior

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56
Q

What is it made out of?

A

A network of nerves

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57
Q

What do nerves do?

A

Transmit electrical impulses between the brain, spinal cord, and the rest of the body.

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58
Q

What is the role of nerves?

A

to transmit electrical impulses

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59
Q

What is the CNS (central nervous system) made up of?

A

The brain and the spinal cord

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60
Q

What helps the CNS carry out its responses?

A

Coordinates responses via:

receptors
sensory neurones
motor neurones
effectors

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61
Q

What does the PERIPHERAL nervous system consist of?

A

Consists of neurones that travel to and from the CNS.

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62
Q

What is the peripheral nervous system’s role?

A

Connects the CNS to the body

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63
Q

What is a nerve?

A

A bundle of many neurones

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64
Q

What is a neurone?

A

An individual nerve cell

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65
Q

What do neurones do?

A

Neurones carry electrical impulses between receptors, the CNS and effectors

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66
Q

What do nerves do?

A

Nerves carry electrical impulses from the CNS to the rest of the body

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67
Q

What do receptors do?

A

detect change/ stimuli

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68
Q

What does the CNS do?

A

Coordinate a response

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69
Q

What do effectors do?

A

Carry out a response

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70
Q

What are effectors and why are they called that?

A

Often glands or muscles

Called that because they go into action when they recieve nerve impulses of hormones.

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71
Q

What are nerve impulses from sense organs to the CNS called?

A

sensory impulses

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72
Q

What are nerve impulses from the CNS to the effectors called?

A

motor impulses

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73
Q

How does the nervous system act as a COORDINATOR?

A

Acts as a coordinator by directing responses to stimuli such as changes in body conditions

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74
Q

How do sensory receptors help to coordinate a response?

A

Sensory receptors, located in sense organs, stimulate sensory neurones.

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75
Q

What do relay neurones do?

A

Relay neurones in CNS stimulate motor neurones

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76
Q

What are examples of responses that effectors can carry out?

A

muscle contraction
- hormone secretion

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77
Q

What is the junction between 2 neurones called?

A

A synapse / synaptic cleft

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78
Q

How do electrical impulses pass between neurones?

A

When an electrical impulse reaches the end of the first neurone, it triggers the release of a chemical. This chemical is called NEUROTRANSMITTER

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79
Q

How does the neurotransmitter travel?

A

Diffuses across the gap

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80
Q

Does the process of the electrical impulse travelling over the synapse slow down the speed of nerve impulses?

A

Yes

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81
Q

Do synapses control the direction of impulses? If so, how?

A

Yes
- neurotransmitter substances are synthesised on only one side of the nerve impulse, while receptor molecules are only present on one side

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82
Q

How does heroin interact with receptor molecules at synapses?

A

Stimulates receptor molecules in synapses in the brain, triggering the release of dopamine

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83
Q

How do spider toxin and the toxin released by tetanus affect the nervous system?

A

Breaks down vesicles, releasing mass amounts of transmitter substance and disrupting normal synaptic function.

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84
Q

What is a reflex?

A

A very fast, automatic response to a stimulus that does not involve direct coordination by the concious part of the brain. They are INVOLUNTARY.

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85
Q

What are reflexes coordinated by?

A

Reflex arcs

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86
Q

What does a reflex arc consist of?

A

Consists of an electrical impulse being directly transmitted from a sensory neuron, via a relay neuron, to a motor neuron, to stimulate a rapid response.

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87
Q

Why are reflexes so fast in bringing about a response?

A

This is because when the electrical impulse reaches the CNS, it often only passes through the spinal cord, and not the brain.

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88
Q

How is the brain informed that a reflex reaction has occured?

A

If the reflex signal does not initiialy pass through the brain, a seperate impulse can be sent from the spinal cord to the concious part of the brain.

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89
Q

Why are reflexes important?

A

Help protect the body from danger

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90
Q

What is reaction time?

A

Time taken for a response to occur in reaction to a stimulus

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91
Q

What are the 3 types of neurones?

A

Motor, Sensory, Relay

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92
Q

Where do motor neurones carry signals from and to?

A

From the CNS to effectors

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93
Q

Where do sensory neurones carry signals from and to?

A

From the receptors / sense organs to the CNS

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94
Q

Where do relay neurones carry signals from and to?

A

Connect motor and sensory neurones

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95
Q

Where are the cell bodies of the neurones mainly located?

A

brain or spinal cord

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96
Q

What types of neurones can a nerve contain?

A

A combination of sensory and motor nerve fibres (axons) in order to carry many different impulses

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97
Q

What is an impulse?

A

A series of electrical pulses which travel down the axon

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98
Q

At what speed does a nerve impulse travel?

A

100m/s -1

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99
Q

Are all nerve impulses similar?

A

Yes

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100
Q

What is a spinal reflex?

Examples

A

A reflex that uses relay neurones in the spine cord

  • withdrawing the hand from a hot object
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101
Q

Examples of reflexes that take place in the head?

location: not coordinated by brain

A

Iris reflex
Blinking
Coughing

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102
Q

Synapse definition

A

A junction between 2 neurones

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103
Q

What is a voluntary action?

A

One which requires a concious decision by the brain

Unlike a reflex action, it does not happen automatically
choice in selection of the response

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104
Q

What is the main function of the brain during voluntary actions?

A

To coordinate the actions so that they happen in the right sequence and at the right time and place.

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105
Q

Definition of a sense organ?

Example

A

Sense organs are groups of sensory cells, responding to specific stimuli, such as light, sound, touch, temperature and chemicals.
e.g eye / ear

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106
Q

Definition of stimulus

A

A change in the enivronment (light, tempertaure, pressure) which produces a reaction in a living organism.

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107
Q

list 5 sense organs and the stimuli they respond to

A

ear - sound, body movement (balance)
eye - light
nose - chemicals (smells)
tongue - chemicals (taste)
skin - temperature, pressure, touch, pain

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108
Q

What is the special property of sensory cells and organs?

A

They are able to convert one form of energy into another

e.g eyes can convert light energy into electrical energy (of nerve impulse)

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109
Q

Describe the reflex arc of coughing

A

STIMULUS - Particles making contact with the lining of the respiratory tree
RESPONSE - Violent contraction of the diaphragm and internal intercostal muscles

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110
Q

What is the survival value of coughing?

A

Prevents lungs being damaged or infected, so that gas exchange remains efficient

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111
Q

What is the survival value of the knee-jerk reflex?

A

The leg can support the body’s wait during walking

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112
Q

Describe the reflex arc of swallowing

A

STIMULUS - Food particles making contact with the back of the throat
RESPONSE - Contraction of the muscle of the epiglottis, which closes off the entrance to the trachea

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113
Q

What is the survival value of swallowing?

A

Prevents food entering the respiratory pathway so that lungs are not damaged

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114
Q

What does the white matter in the spine contain?

A

Contains the nerve fibres

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115
Q

What does the grey matter in the spine contain?

A

Contains cell bodies of the motor neurones

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116
Q

Can impulses travel both ways?

A

No

  • synapses act as valves, forcing impulses to travel 1 way
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117
Q

What is intergration?

A

When the CNS processes information from receptors and passes instructions to effectors to tell the organism how to respond

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118
Q

What is a cranial reflex?

A

Reflexes that use the brain as a relay centre without conscious involvement.

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119
Q

Where do learned reflexes take place?

A

In the lower regions of the brain

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120
Q

How are learned reflexes activated?

A

need a stimulus from a higher region, but once started always lead to the same response

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121
Q

What is the system called that controls the reflexes which help keep a constant internal environment in the body ?
Examples of such reflexes

A

Autonomic nervous system

e.g breathing, heart beat, peristalsis

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122
Q

How can the brain communicate with the other parts of the body?

A

Via the spinal cord

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123
Q

definition of involuntary action

A

Does not involve any consious decision by the brain

organism has no choice
response automatically follows the stimulus

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124
Q

How are learned reflexes formed?

A

Each time a particular stimulus leads to a certain response, that impulse passes along the same route
e.g talking, cycling

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125
Q

What is a transducer?

A

Something which can convert one type of energy into another

  • sense organs convert energy
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126
Q

What are the 4 types of receptors?

A

Photoreceptor - light
Chemoreceptor - chemicals
Thermoreceptor - changes in temp.
Mechanoreceptor - mechanical changes such as changes in length

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127
Q

Where can you find them?

A

p - rod cells in retina of eyes
c - taste buds
t - t in skin
m - hair cells in ear (hearing and balance)

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128
Q

Where can you find them?

A

p - rod cells in retina of eyes
c - taste buds
t - t in skin
m - hair cells in ear (hearing and balance)

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129
Q

What is a conditioned reflex?

A

Learned reflexes in which the final response has no natural relationship to the stimulus

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130
Q

Can conditioned reflexes be unlearnt? How?

A

Yes

  • if the unnatural stimulus is not repeated with the natural one`
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131
Q

What is the endocrine system?

A

A collection of endocrine glands found throughout the body that secrete hormones directly into the bloodstream

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132
Q

Definition of hormone

A

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

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133
Q

How does a hormone bring about a response?

A

Receptors on the cell membranes of cells in the target organ recognise the hormone.
The cells then respond by changing their cellular activity to bring about a particular effect.

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134
Q

5 differences between the endocrine and the nervous system?

A

transmission of chemicals / electrical impulses
transmission via blood / in nerves
slow transmission / rapid transmission
hormones dispersed throughout body / impulse sent directly to target organ
long-term effects / short-term effects

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135
Q

What is similar about the nervous and the endocrine system?

A

Can carry messages long distances in the body

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136
Q

What does the endocrine system coordinate?

A

Coordinates the activity of many different organs and bodily functions.

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137
Q

In what process does the E system play a key role in?

How?

A

HOMEOSTASIS
- enables cells to alter their activity in response to changes in body conditions

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138
Q

What can happen if the E system isn’t working properly?

A

Can prevent internal conditions from being regulated effectively.

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139
Q

What does the pituitary gland do?

A

Secretes several types of hormone in response to changes in body condition

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140
Q

What is special about some pituitary hormones?

A

Used to regulate the activity of other endocrine glands, which secrete the own hormones in response

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141
Q

What gland secretes adrenaline?

A

Adrenal gland

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142
Q

What parts of the body does adrenaline target?

A

Heart, blood vessels, liver

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143
Q

When is adrenaline released?

A

In times of fear or stress

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144
Q

Effects of adrenaline

A

increasing heart rate
increasing blood pressure
increasing blood flow to muscles
relaxing the airways and increased breathing rate
stimulating the liver to convert glycogen to glucose, which is released into the blood to increase blood glucose levels
pupils dilate

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145
Q

What do the effects of adrenaline increase?

A

the body’s metabolism

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146
Q

Advantages of increased heart rate and blood pressure

A

Increases the flow of blood to the muscles

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147
Q

Advantages of relaxing the airways and increasing breathing rate

A

Allows more oxygen to enter the lungs where it is taken up into the blood

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148
Q

Advantages of the release of glucose from the liver

A

Increases blood glucose levels, allowing more glucose to be delivered to the muscles

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149
Q

The overall advantage of adrenaline

A

Adrenaline increases the supply of oxygen and nutrients to the muscles - priming them for action

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150
Q

Why is the increase of oxygen and glucose to the brain good?

A

Primes the brain for activity

  • coordinating a response to the stress that has stimulated the secretion of adrenaline
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151
Q

What happens after the hormones have taken action and are no longer needed?

A

Do not remain permanently in the blood
- changed by the liver into inactive compounds and are excreted by the kidneys

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152
Q

Do endocrine glands deliver their secretion through ducts?

A

NO

  • hormones picked up directly from glands by the blood circulation
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153
Q

What can cause hormonal changes to be slower?

A

depend on the speed of circulatory system (time taken for hormone to travel)
time it takes for cells to change their chemical activities

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154
Q

What changes can hormones cause/ take part in?

A

growth rate, puberty, pregnancy

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155
Q

What is the adrenal medulla and what is its role?

A

Part of the adrenal gland

Receives nerve impulses from the brain and releases adrenaline

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156
Q

What is the process that leads to adrenaline being released?

A

In response to a stressful situation, nerve impulses are sent from the brain to the adrenal medulla, which releases adrenaline into the blood

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157
Q

Is the pancreas an endocrine (ductless) gland?

A

YES

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158
Q

What are islets?

A

Hormone-producing cells are arranged in small isolated groups called islets

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159
Q

what are exocrine glands?

A

glands which secrete substances through a duct or tube

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160
Q

What do the ovaries produce?

A

oestrogen and progesterone

control puberty in females (make female secondary sexual characteristics develop) including development of breasts and hips.
control the menstrual cycle and ovulation

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161
Q

What do the testes produce?

A

Testosterone

controls puberty in males, including deepening hair, stronger muscles and growth of body hair
controls development and release of sperm

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162
Q

How is hormone production controlled by feedback control?

A

hormones regulate their own production

as the level of hormone in the blood rises, it switches off (INHIBITS) its own production so that the level never gets too high
as the level of hormone in the blood falls, it switches on (STIMULATES) its own production so that the level never gets too low.

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163
Q

What 2 hormones secreted by the pituitary gland control the secretion of further hormones by the reproductive organs?

A

LH and FSH

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164
Q

In females, what do LH and FSH stimulate the secretion of?

A

oestrogen progesterone by the ovaries

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165
Q

In males, what do LH and FSH stimulate the secretion of?

A

Stimulate testes to produce testosterone

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166
Q

What are the female secondary sexual characteristics?

A

breasts develop
hips widen
pubic hair grows
eggs are released

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167
Q

What are the male secondary sexual characteristics?

A

voice deepens
pubic hair grows
facial hair grows
sperm are produced

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168
Q

Basic summary of how reproductive hormones take part in the menstrual cycle

A

Hormones stimulate the maturation and release of an egg from the ovaries approximately every 28 days.

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169
Q

Why is it important that the uterus lining thickens prior to ovulation during the menstrual cycle?

A

If an egg is fertilised, it implants itself in the uterus lining.
Uterus lining provides the fertilised egg with a supply of oxygen and nutrients, enabling it to develop into an embryo.

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170
Q

What happens if an egg is not fertilised?

A

Uterus lining breaks down and the menstrual cycle begins again.

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171
Q

What are sense organs?

A

Sense organs are a group of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.

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172
Q

What is the function of the cornea of the eye?

A

Cornea is transparent and refracts light.

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173
Q

What is the function of the iris of the eye?

A

Iris controls how much light enters the pupil.

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174
Q

What is the function of the lens of the eye?

A

Lens is transparent and can change shape to focus light onto the retina.

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175
Q

What is the function of the retina of the eye?

A

Retina contains light recepetor cells, some sensitive to light of different colours (rods - detect light intensity; cones - detect colour).

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176
Q

What is the function of the optic nerve of the eye?

A

Optic nerve sensory neurone that carries impulses from the eye to the brain.

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177
Q

What is the function of the pupil of the eye?

A

The pupil is a hole that allows light to enter the eye.

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178
Q

What is the pupil reflex?

A

This is an involuntary reflex action carried out to protect the retina from damage in bright light and allows more light to enter your eye in dim light.

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179
Q

Explain the pupil reflex limited to changes in dim light intensity and pupil diameter.

A

In dim light, the pupil dilates to allow more light to enter the eye to improve vision.

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180
Q

Explain the pupil reflex limited to changes in bright light intensity and pupil diameter.

A

In bright light, the pupil constricts to allow less light to enter the eye to protect the retina from damage (bleaching).

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181
Q

Explain the pupil reflex in terms of the antagonistic action of circular and radical muscles in the iris in regards to dim light.

A

In dim light, radical muscles contract, circular muscles relax and the pupil dilates and more light to enter the eye.

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182
Q

Explain the pupil reflex in terms of the antagonistic action of circular and radical muscles in the iris in regards to bright light.

A

In bright light, radical muscles relax, circular muscles contract and the pupil constricts and less light enters the eye to protect the retina from damage by bleaching.

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183
Q

What muscles work antagonistically in the eye?

A

The muscles that work antagonistically are the radical muscles and the circular muscles of the eye.

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184
Q

Define the accommodation of the eye?

A

Accommodation is the function of the eye in focusing on near and distant objects.

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185
Q

How can the shape of the lens be changed?

A

The lens is elastic and its shape can be changed when the suspensory ligaments attached to it become tight of loose.

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186
Q

Explain accommodation to view near objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light.

A

The ciliary muscles contract which causes the suspensory ligaments to loosen making the lens fatter and curved and light is refracted more by the lens to focus on the nearby object.

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187
Q

Explain accommodation to view distant objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light.

A

The ciliary muscles relax which causes the suspensory ligaments to tighten and pull on the lens marking it thinner and less curved and light is refracted less, allowing the eye to focus on the distant object.

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188
Q

There are two types of receptor cells in the retina: NAME THEM.

A

There are two types of receptor cells in the retina:
- Rods which are sensitive to dim light.
- Cones which distinguish between different colours in bright light.

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189
Q

Describe the distribution of rods in the retina of a human.

A

Rods are evenly distributed and less tightly packed at the periphery of the retina; absent at the fovea.

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190
Q

Describe the distribution of cones in the retina of a human.

A

Cones are found tightly packed in the fovea.

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191
Q

Outline the function of rods.

A

Greater sensitivity of rods for night vision.

192
Q

Outline the function of cones.

A

Three different kinds of cones, absorbing light of three different colours (red, blue, green) for colour vision.

193
Q

What is a nerve impulse?

A

An electrical signal that passes along nerve cells called neurons

194
Q

What does a receptor do?

A

Detects a change in stimulus

195
Q

What does the central nervous system consist of?

A

Brain and spinal cord

196
Q

What does the peripheral nervous system contain?

A

Every other part- nerves

197
Q

Define voluntary action

A

An action completed with conscious thought and under our own will

198
Q

Define involuntary action

A

An action completed without conscious thought

199
Q

Define involuntary action

A

An action completed without conscious thought

200
Q

What is a relay neurone?

A

Short and are located in the CNS , connecting sensory and motor neurones

201
Q

What is a sensory neurone?

A

Long and have a cell body branching off the middle of an axon. Carry impulses from sense organ to CNS

202
Q

What is a motor neurone?

A

Long and have a cell body at one end with long dendrites branching off. Carry impulses from the CNS to muscles and glands.

203
Q

Describe the simples reflex arc

A

Stimulus is detected by receptor in the skin
Sensory neurone sends electrical impulses to spinal cord
Electrical impulse is passed on to a relay neurone in spinal cord
Relay neurone carries impulse to motor neurone which carries it to a muscle in the arm
Muscle contracts and pulls hand up and away from hot object

204
Q

Define reflex action

A

Automatically and rapidly integrating and coordinating stimuli with the responses of effectors

205
Q

Define synapse

A

Junction between two neurones

206
Q

Describe a synapse

A

The impulse reaches the end of one neurone
Vesicles release neurotransmitters into synaptic gap
Neurotransmitter diffuses across gap and binds with receptors
New impulse is triggered in the next neurone

207
Q

Describe a synapse

A

The impulse reaches the end of one neurone
Vesicles release neurotransmitters into synaptic gap
Neurotransmitter diffuses across gap and binds with receptors
New impulse is triggered in the next neurone

208
Q

What do synapses ensure?

A

That impulses travel in one direction only

209
Q

What substances affect synapses?

A

Heroin
alcohol
nicotine

210
Q

Define sense organs

A

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

211
Q

What does the cornea do?

A

Refracts light and helps to focus it

212
Q

What does the cornea do?

A

Refracts light and helps to focus it

213
Q

What does the iris do?

A

Controls how much light enters the pupil

214
Q

What does the lens do?

A

Refracts light to focus it into the retina

215
Q

What does the retina do?

A

Contains light receptors some sensitive to light of different colours

216
Q

What is the optic nerve?

A

Transmits electrical impulses from retina to brain

217
Q

What happens when the eye gets exposed to bright light?

A

The radial muscle contracts and the circular muscle relaxes and the pupil decreases in size letting less light in

218
Q

What happens when the eye gets exposed to a lack of light?

A

The radial muscle relaxes and circular muscles contract and the pupil increases in size to let more light in

219
Q

What happens when we are looking at a distant object?

A

Ciliary muscles relax
Suspensory ligaments stretch thin
lens become thinner
light is refracted less

220
Q

What happens when we are looking at a near object?

A

Ciliary muscles contract
Suspensory ligaments slack
Lens becomes fatter
light is refracted more

221
Q

Which cells do we have in our eye?

A

Rods and cones but there are more rods than cones

222
Q

What does the fovea contain?

A

Only cone cells

223
Q

What is the fovea?

A

An area on the retina with lots of photosensitive cells so it has the highest visual activity

224
Q

When do rods function?

A

In low light intensities= night vision- greater sensitivity

225
Q

What do cones do?

A

They detect red blue and green.

226
Q

What is homeostasis?

A

Maintenance of a constant internal environment and is the control of internal conditions within set limits achieved by negative feedback

227
Q

Give examples of internal conditions

A

Temperature
blood pressure
water concentration
glucose concentration

228
Q

When does negative feedback happen?

A

When conditions change from the ideal point and returns conditions to this set point

229
Q

What are negative feedback mechanisms usually?

A

A continuous cycle of bringing levels down and then bringing them back up so that overall they stay withing a narrow range of what is considered normal

230
Q

What is the ideal body temperature for enzymes?

A

37 C

231
Q

What is hyperthermia?

A

When heat gain exceeds heat loss and the temperature rises

232
Q

What is hypothermia?

A

When heat loss exceeds heat gain and the temperature falls.

233
Q

Where is regulation controlled?

A

In the hypothalamus which contains receptors sensitive to the temperature of the blood.

234
Q

Where are there temperature receptors?

A

The skin and sends impulses via sensory neurones

235
Q

What is the top layer of the skin called?

A

Epidermis

236
Q

What is the lower layer of the skin called?

A

Dermis

237
Q

What is the dermis made of?

A

Connective tissue

238
Q

What does the connective tissue contain?

A

Elastic fibres and collagen fibres

239
Q

What happens as a person gets older?

A

Fibers lose their elasticity so the skin becomes loose and wrinkled

240
Q

What does the dermis contain?

A

Sweat glands

241
Q

What do the sweat glands do?

A

They secrete a liquid called sweat which is mostly water with small amounts of salts and urea dissolved in it

242
Q

How does sweat travel?

A

It travels up the sweat ducts and onto the surface of the skin through the sweat pores

243
Q

What happens when it is too warm?

A

Hair erector muscle relaxes lowering the hair
a thin insulating layer of air is trapped above the skin
more heat is lost to the environment by evaporation convection and radiation

244
Q

What happens when it is too cold?

A

The hair erector muscle contracts raising the hair
the hairs trap a thicker layer of air above the skin
The air insulates the skin

245
Q

What is underneath the dermis?

A

A layer of fat called adipose tissue

246
Q

What does the adipose tissue do?

A

Helps insulate the body against heat loss and acts as an energy reserve

247
Q

What is shivering?

A

When muscles in some parts of the body contract and relax very quickly

248
Q

How does shivering help?

A

Heat is generated in the muscles and warms the blood as it flows through them

249
Q

What does the dermis contain?

A

Blood vessels and nerve endings

250
Q

What do the nerve endings do?

A

They are sensitive to touch, pain, pressure and temperature

251
Q

What happens to our arterioles when we are cold?

A

They become narrower

252
Q

What is it called when our arterioles contract?

A

Vasoconstriction

253
Q

How does Vasoconstriction help?

A

Reduces the amount of heat loss from blood by radiation as less blood flows through the surface of the skin

254
Q

What happens when our arterioles when we are hot?

A

They dilate

255
Q

What is it called when our arterioles dilate?

A

Vasodilation

256
Q

How does Vasodilation help?

A

there is more blood and bc there is a lot of blood near the surface of the skin heat is readily lost from the blood into the air by radiation.

257
Q

What is an effector?

A

An effector is a part of the body that creates a response such as muscles

258
Q

What happens when the body temperature raises?

A

Temperature receptors in the skin detect an increase
Nervous impulse sent to the hypothalamus and it coordinates a response
sweat is released and blood vessels dilate

259
Q

What is produced when blood glucose rises?

A

Insulin

260
Q

What happens when blood glucose rises?

A

Insulin produced
stimulates the liver
muscle cells to convert excess glucose into glycogen

261
Q

How are blood glucose levels controlled?

A

Negative feedback mechanism involving glucagon and insulin

262
Q

Where are insulin and glucagon produced?

A

Pancreas

263
Q

Why do cells need glucose?

A

To respire to release energy

264
Q

Why is too much glucose not good for cells?

A

water moves out of the cells and into the blood by osmosis

265
Q

What is type 1 diabetes?

A

A condition where the blood glucose levels are not able to be regulated as the insulin secreting cells in the pancreas are not able to produce insulin

266
Q

What happens if you have Type 1 diabetes?

A

the blood glucose levels are too high

267
Q

How can you treat type 1 diabetes?

A

Injecting insulin

268
Q

What can having high or low blood glucose concentrations cause?

A

Damage to numerous body organs

269
Q

What is hyperglycaemia?

A

When the blood glucose concentration goes up and stays up

270
Q

What is hypoglycaemia?

A

When the blood glucose drops very low

271
Q

What can hypoglycaemia cause a person to feel?

A

very tires
confusion
irrational behaviour

272
Q

How can people monitor type 1 diabetes?

A

Levels of physical activity

their diet affects the amount of insulin needed

273
Q

Give two examples of homeostasis

A

Osmoregulation (body water content)

Thermoregulation (body temperature)

274
Q

What is thermoregulation

A

Temperature regulation

275
Q

Why is thermoregulation important?

A

Enzymes denature if temp too high
Cell membranes become fragile as temp rises
Diffusion rates rise with night temps and fall with lower temps
Liquids such as blood become more viscous (thicker) as temp falls

276
Q

What controls thermoregulation

A

The hypothalamus

277
Q

Protective functions of the skin

A

Tough water proof barriers between body and external environment
Regulates body temp
Contains sensory receptors to detect external environment changes
Protection from infection

278
Q

What are the two main layers in the skin

A

The upper epidermis and lower dermis

279
Q

What is the function of melanin

A

Absorbs ultraviolet light and protects the cells DNA from damage

280
Q

Mammals and birds are what?

A

Endotherms

281
Q

What can endotherms do

A

Maintain an internal environment that doesn’t change when external environmental temperatures change

282
Q

Amphibians reptiles insects and fish are what

A

Ectotherms

283
Q

Why can endotherms survive extreme temperatures better?

A

Temperature affects Ectotherms a lot more

284
Q

Which animal will lose heat more quickly. A mouse or an elephant?

A

A mouse because it has a big surface area to volume ratio

285
Q

What happens to sweat glands in the cold?

A

Sweat is not produced so sweat doesn’t move onto skin surface

286
Q

What happens to sweat glands in hot temps

A

Sweat produced, water in sweat evaporates from the skin. This uses heat energy from the blood which will reduce heat energy and so cool you down

287
Q

Why is it important for organism to control their internal environment?

A

So enzymes can control cell function and enzymes need specific conditions to work efficiently

288
Q

Name two ways in which organisms achieve this coordination

A

Through hormonal control (endocrine control)

Through nervous control (nervous system)

289
Q

What is the stimulus

A

Change in environment that triggers a reaction (eg a stimulus effects an endocrine gland to release a hormone)

290
Q

What is the receptor

A

This receives the stimulus (e.g a receptor molecule on a cell membrane for a hormone)

291
Q

What is the effector

A

The part of the organism that carries out the reaction to the stimulus (e.g a muscle or a gland)

292
Q

What are glands?

A

Small structures responsible for making and secreting specific chemicals

293
Q

What hormone is secreted by the pituitary gland in the brain?

A

A.D.H anti-diuretic hormone

Hormone for water regulation

294
Q

What do the adrenal glands produce?

A

Adrenaline

295
Q

Where are the adrenal glands?

A

Above the pancreas

296
Q

What does pancreas secrete

A

Insulin

Controls blood sugar levels

297
Q

What do the ovaries produce

A

Oestrogen and progesterone

298
Q

What do the testis (singular) testes(plural) produce

A

Testosterone

299
Q

How can you tell endocrine glands and exocrine glands apart?

A

Exocrine glands have tubes which secretes the hormones where as endocrine glands are just there.
ONE HAS A TUBE OR DUCT THAT LEADS/CONNECTS IT TO ANOTHER PART OF THE BODY

300
Q

How do hormones work when they reach their target organs?

A

They lock onto receptor on their target cells. This triggers a reaction. Afterwards the hormones travel to the liver and are broken down

301
Q

Explain how the adrenal gland can help an athlete running (e.g Ella because she’s a bloody pro)

A

Adrenaline is produced and passed into the blood, the breathing rate becomes quicker causing more oxygen to be taken in and more carbon dioxide removed. The heart beats faster so more oxygen is passed into the blood. This means that more respiration occurs and more energy ATP and glucose is released which increases blood sugar levels. This gives the athlete more energy and they can run faster and for longer.

302
Q

What is homeostasis

A

Maintaining a constant internal environment

303
Q

What is the conjunctiva?

A

A thin membrane protecting the eye

304
Q

What is the pupil?

A

A “black hole” that lets light in

305
Q

What is the iris?

A

A coloured thing that controls the amount of light let into the eye

306
Q

What are the ciliary muscles?

A

Muscles controlling the thickness and curvature of the eye

307
Q

What is the cornea?

A

Bends light to form an image and is also there for protection.

308
Q

What is the lens?

A

The big thing behind the pupil that fine tunes the image. (Tallula I thinks it’s the thing that we spent ages trying to cut.😂)

309
Q

What is the vitreous humour?

A

A stiff jelly that supports the back of the eye. Makes up the inside of the eye ball

310
Q

What is the suspension ligament?

A

The ligament that supports and suspends the lens

311
Q

What is the retina?

A

The back of the eye that contains rods and cones

312
Q

What’s the choroid?

A

The bit behind the retina that contains a good blood supply and melanin which absorbs light to avoid internal reflection and glare

313
Q

What is the blind spot?

A

A part with no receptors present

314
Q

What is the optic nerve?

A

It contains the sensory neurones linking the retina to the midbrain

315
Q

What is the sclera?

A

The bit behind the choroid. It is tough and fibrous to prefect the eye

316
Q

What is a fovea? (Yellow spot)

A

Contains only come cells. Most sensitive part of the retina for colour vision

317
Q

What does the eye do to focus on near objects?

A

Ciliary muscles contract which slackens the suspension ligament
Muscle tension on the lens is lower
Lens becomes fatter and more curved allowing light to refract more.

318
Q

What is the near point

A

The closet an object can be from the eye without appearing blurred.

319
Q

What is the aqueous humour?

A

A watery liquid filling the front of the eye.

320
Q

Structure of a neurone

A

Cell membrane, cytoplasm, nucleus
Dentrites (the spiky bits on the end of the main part of the cell)
Axon(the but the electric impulse travels down)
Fatty sheath (protects the axon)
Nerve ending

321
Q

What is the gap between neurones called?

A

Synapse

322
Q

What is a synapse?

A

The gap where chemical messages pass from nerve ending to other neurone.

323
Q

What is the CNS made up of

A

The central nervous system is made of the brain, spinal chord and is protected by bones, it is linked to organs via nerves.

324
Q

What are the three types of neurones called??

A

Sensory neurones, relay neurones, motor neurones

325
Q

What is geotropism or gravitropism a response to

A

Gravity

326
Q

What is a coleoptile?

A

The first shoot emerging from soil

327
Q

What is auxin

A

A plant growth hormone responsible for geotropism

328
Q

If you shine light on a plant where does the auxin go?

A

To the dark side.

329
Q

In a shoot a high concentration of auxin….

A

Causes cell elongation

330
Q

In a root a high concentration of auxin…

A

Stops cell elongation

331
Q

Directional growth response:

A

Positive (growth towards stimulus)

Negative (growth away form stimulus)

332
Q

What is phototropism a response to

A

Light

333
Q

Synapse

A

junction between two neurons

334
Q

Sense organ

A

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

335
Q

Hormones

A

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

336
Q

homeostasis

A

maintenance of a constant internal environment

337
Q

Autonomous nervous system

A

brain ( no control)

338
Q

Peripheral nervous system

A

nerves and spinal cord

339
Q

central nervous system

A

brain and spinal cord

340
Q

brain is protected by the

A

skull

341
Q

ANS is

A

independent, cant control

342
Q

Receptors:

A

parts of the body that detect stimuli

343
Q

types of receptors

A

1) thermo- receptors ( heat)
2) thigmo-receptors ( pain/pressure)
3)chemoreceptors (taste/ chemicals)
4)photoreceptors (sight)
5) audio receptors ( sound)

344
Q

Coordinators:

A

parts of the body that pass on info about stimuli to the effector

345
Q

Effectors

A

parts of the body that make a response to the stimuli
- For example: muscles and glands

346
Q

3 types of neurones

A

1) motor neurone
2) sensory neurone
3) relay neurone

347
Q

relay neuron is AKA

A

inter neurone

348
Q

motor neurons are located at the

A

terminals

349
Q

what do motor neurones do

A

takes the impulse from the brain or spinal cord to the effector

350
Q

what do sensory neurones do

A

takes the impulse from the receptor of the stimuli to the spinal cord or brain

351
Q

order when a stimuli is received

A

stimuli ➟ receptors ➟ sensory neuron ➟central nervous system

352
Q

nerve impulse

A

an electrical signal that passes along nerve cells called neurons

353
Q

impulse inside nerve cell

A

electrical

354
Q

impulse outside nerve cell

A

chemical but ➟ electrical

355
Q

1 neuron to another

A

travel through neurotransmitters

356
Q

dendrite

A

recieves impulses

357
Q

axon

A

gives impulse

358
Q

Voluntary actions

A

those we choose to make and the decisions to make them occur in our brains.
These are also known as cranial reflexes as impulses are sent to the brain before a decision is made.

359
Q

Involuntary actions

A

occur unconsciously. They are also known as spinal reflexes , as impulses don’t
reach the brain.

360
Q

Reflex arc

A

sensory neurone ➟ relay neuron ( spinal cord )
➟ motor neurone ➟ effector

361
Q

what triggers an impulse in the synapse

A

presynaptic membrane releases neurotransmitters. neurotransmitters move from their region of higher concentration to their region of lower concentration down the concentration gradient. which then binds with the complimentary neuro receptors on the surface of the post synaptic membrane triggering an impulse .

362
Q

Amphetamines and other excitatory drugs stimulate the release of neurotransmitters in the brain, which makes the person more

A

alert, suppresses appetite

363
Q

Heroin and beta-blockers are inhibitory drugs. These drugs reduce the release of neurotransmitters by

A

acting on neuron membranes

364
Q

Heroin acts on the postsynaptic neuron to reduce the transmission of neurotransmitters, and this reduces the

A

sensation of pain and creates a feeling of euphoria .

365
Q

how does the intake of heroin cause someone to go depressed?

A

heroin breaks down to form morphine, which is known to cause depression. presynaptic membrane releases morphine molecules. morphine molecules move from their region of higher concentration to their region of lower concentration down the concentration gradient. and these morphine molecules are the exact same shape as the neurotransmitters so they bind with neuro receptors on the postsynaptic membrane and block neuro transmitters from reaching the receptor, stimulating depression.

366
Q

Beta-blockers are taken to reduce

A

BP and heart rate.

367
Q

Beta-blockers lodge themselves in the receptors of

A

postsynaptic neurons, preventing impulses from flowing

368
Q

cornea description

A

The front part of the sclera. Is convex
and transparent

369
Q

cornea function

A

Protects the front of the eye and
refracts light

370
Q

iris description

A

A coloured ring of circular and radial muscle that controls the size of the pupil and so controls the amount of light entering the eye

371
Q

iris function

A

Pigmented so light cannot pass
through. Muscles contract and relax to
control the size of the pupil.

372
Q

lens decription

A

Transparent, biconvex, flexible disc
behind the iris attached by the
suspensory ligaments to the ciliary
muscles

373
Q

lens function

A

Brings light entering through the pupil
to a focus on the retina

374
Q

retina description

A

Lining of the back of the eye
containing rods and cones

375
Q

retina function

A

Screen on which images are formed as
a result of light being focused onto it
by the cornea and lens

376
Q

optic nerve description

A

Bundle of sensory neurons at the back
of the eye

377
Q

optic nerve function

A

Carries signals from the photoreceptors to the brain

378
Q

Pupil reflex

A

Radial and circular muscles are antagonistic pair. This means they work together, but their effects are produced by contrasting actions

379
Q

pupil reflex in bright light

A

In bright light, Radial muscles relax, and circular
muscles contract causing the pupil to constrict .
This reduces the amount of light entering the eye,protecting the retina.

380
Q

pupil reflex in dim light

A

In the dim light, radial muscles contract and
circular muscles relax causing the pupil to dilate . This increases the amount of light entering the eye

381
Q

Accommodation

A

the term used to describe the changes that occur in the eye when focusing on far and
near objects

382
Q

As light enters the eye

A

it must be bent so that the image can be seen clearly. Most of the refraction is done by the cornea and some by the lens.

383
Q

The shape of the lens is controlled by the

A

antagonistic muscle pair consisting of the ciliary muscle and the suspensory ligaments.

384
Q

For a distant object:

A

❖ Ciliary muscles relax
❖ The pressure inside the eye pulls the suspensory ligaments tight, pulling the lens into an elliptical shape.

385
Q

For a near object:

A

❖ Ciliary muscles contract to counteract the pressure in the eye
❖ Suspensory ligaments become slackened and the lens has a more circular shape

386
Q

There are two types of photoreceptors in the eye

A

❖ Rods
➢ Sensitive to levels of low light and send impulses when it is dark.
➢ Black and white
❖ Cones
➢ Sensitive to the light of high intensity
➢ Three types (Red, Blue, and Green) (Mixtures of these are also found)

387
Q

The fovea is the center of the retina and contains

A

cones and no rods.

388
Q

Each cone has its

A

neuron to the brain so
this area in the middle of our visual field gives us a very detailed image. The rest of the retina contains rods and few cones. This area gives us our peripheral vision which is not as detailed.

389
Q

endocrine glands

A

releases hormones directly into the blood

390
Q

Exocrine glands

A

glands which secrete substances through a duct or tube

391
Q

endocrine glands organ

A

1) pituitary gland
2) adrenal glands
3) pancreas
4) tests (male)
5) ovaries ( female)

392
Q

pituitary gland releases which hormones and effects

A

hormone:FSH, LH
effects:Controls growth, sperm and egg production

393
Q

adrenal gland releases which hormones and effects

A

hormone: adrenaline
effect:Released in fight or flight situations

394
Q

The pancreas releases which hormones and effects

A

hormone: inulin, glucagon
effect: Insulin lowers blood glucose, and glucagon increases it

395
Q

testes (male) releases which hormones and effects

A

hormone: testosterone
effect: Stimulates development during puberty

396
Q

Ovaries (Females) release which hormones and effects

A

hormone: estrogen
effects:Control menstrual cycle and stimulate development

397
Q

esponses necessary to survive in ‘fight or flight’ situations are coordinated by

A

adrenaline

398
Q

adrenaline can

A

increasing breathing rate, increased heart rate, widening the pupils so more light
enters the eye, converting glycogen in the liver to glucose, coordinates increased uptake of O 2 and changing blood distribution so O 2 and glucose get to muscles.

399
Q

how does adrenaline increase these things

A

➢ Air passages widen to allow more air into the body
➢ Arterioles in the brain and muscles dilate
➢ Arterioles in other parts of the body constrict

400
Q

Adrenaline secretion can increase as a result of

A

fear or stress

401
Q

nervous system structures

A

nerves

402
Q

endocrine system structures

A

secretory glands in cell

403
Q

nervous system form of info

A

electrical impulses

404
Q

endocrine system form of info

A

hormones

405
Q

nervous system pathways

A

along neurones

406
Q

endocrine system pathways

A

in the blood

407
Q

nervous system speed of info transfer

A

fast

408
Q

endocrine system speed of info transfer

A

slow

409
Q

nervous system longevity of responses

A

short lived

410
Q

endocrine system longevity of processes

A

slow or longlasting

411
Q

nervous system target area

A

specific effector

412
Q

endocrine system target area

A

Whole tissue or organ

413
Q

nervous system response examples

A

Muscle contraction or secretion
by glands

414
Q

endocrine system response examples

A

Conversion of glycogen to
glucose, protein synthesis, rate
of respiration

415
Q

negative feedback

A

In negative feedback, a change sets off a response that cancels out the change to restore conditions to their normal levels.

416
Q

When carbs are eaten,

A

the amount of glucose in the blood increases. The pancreas secretes insulin into
the blood which stimulates liver cells to convert glucose into glycogen. This reduces the concentration of glucose in the blood.

417
Q

When glucose levels in the blood are low

A

for example after exercise, the pancreas secretes glucagon which stimulates liver cells to break down glycogen into glucose and increase glucose concentration levels in the blood.

418
Q

Type 1 diabetes

A

The pancreas cannot produce sufficient insulin
Symptoms: tiredness, thirst, unexplained weight loss, blurred vision, frequent urination
Treatment: Insulin doses are to be taken before meals

419
Q

largest organ in the body

A

skin

420
Q

skin functions

A

❖ Protects the body from damage
❖ Stops pathogens from entering
❖ Prevents too much water loss
❖ Detects temp. changes
❖ Detects pressure changes (pain)

421
Q

controlling body temperature in the heat

A

the brain detects an increase in blood temp. The brain sends impulses to increase the rate of sweating so that more heat is lost by evaporation. Hair erector muscles contract to allow hairs to lie flat.
No shivering.

422
Q

controlling body temperature in the cold

A

the brain detects a decrease in blood temp. Sweat glands stop producing sweat, hair erector muscles relax to raise the hairs which trap air, providing insulation. Body shivers to generate heat from
respiration.

423
Q

vasodilation

A

In hotter weather, muscles of arteriole walls relax causing them to dilate/widen. There is now an increased flow of blood to capillaries which means more heat is lost to the surroundings by convection and radiation

424
Q

vasoconstriction.

A

In cooler weather, the muscles of the arteriole walls contract and make the artery narrower. Blood may also be redirected to veins via shunt vessels, under the fat layer of the skin. There is now a decreased flow of blood to capillaries which reduces the amount of heat lost by convection and radiation.

425
Q

Gravitropism

A

esponse in which parts of a plant grow towards or away from gravity
❖ Roots are positively gravitropic as they grow in the direction of gravity
❖ Shoots are negatively gravitropic as they grow upwards, away from gravity

426
Q

Phototropism

A

response in which parts of a plant grow towards or away from light
❖ Shoots are positively phototropic as they grow towards light
❖ Roots are negatively phototropic as they grow away from light. Either ways, they are not
sensitive to light

427
Q

The role of auxins

A

❖ Auxin is made solely on the shoot and root tips
❖ It then spreads throughout the plant from the tips
❖ Distributed unequally in response to light and gravity
❖ Stimulate cell elongation - eventually growth
❖ A high concentration of auxins promotes growth in the shoot but inhibits growth in the root
❖ In shoots, auxins move to the side away from light, in roots auxins move to the lower side

428
Q

positive phototropism

A

where? stem tip
direction growth? growth towards light
adv? maximum light for photosynthesis

429
Q

negative phototropism

A

where? the root tip
direction of growth? growth away from light
adv? less chance of drying out

430
Q

positive geotropism

A

where? root tip
direction of growth? towards gravity
adv? more chance of finding moisture

431
Q

negative geotropism

A

where? shoot tip
direction of growth? away from gravity
adv? more chance of finding light

432
Q

Synthetic auxins are very effective as

A

Selective Weedkillers

433
Q

why are herbicides like 2.4-D sprayed on broad level weeds?

A

tends to run off thinner leaves.

434
Q

how do auxins increase the growth rate of weeds

A

by increasing the rate of cell division

435
Q

why do all weeds eventually die

A

cannot produce enough food to sustain the growth

436
Q

Electrical impulses travel along

A

neurones

437
Q

Mammalian nervous system consist of

A

The central nervous system (CNS) consisting of the brain and the spinal cord
The peripheral nervous system (PNS) consisting of the nerves outside of the
brain and spinal cord.

438
Q

Role of the nervous system is

A

coordination and regulation of body functions.

439
Q

Reflex arc:

A

receptors detect stimulus and generate impulse, it travels to sensory
neurone, then relay neurone, then to motor neutron, then to the effector.

440
Q

A reflex action

A

a means of automatically and rapidly integrating and coordinating
stimuli with the responses of effectors (muscles and glands).

441
Q

synapse

A

A junction between two neurones

442
Q

Structure of synapse include:

A

presence of vesicles containing neurotransmitter molecules
Synaptic gap/cleft
receptor protein

443
Q

Events at a synapse:

A

An impulse stimulates the release of neurotransmitter molecules from vesicles
into the synaptic gap.
The neurotransmitter molecules move from their region of higher concentration to their region of lower concentration down their concentration gradient across the gap
Neurotransmitter molecules bind with receptor proteins on the next neuron
An impulse is then stimulated in the next neuron.

444
Q

Synapses ensure that

A

impulses travel in one direction only.

445
Q

Sense organs

A

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

446
Q

cornea function

A

refracts light

447
Q

iris function

A

controls how much light enters the pupil

448
Q

lens function

A

focuses light on to the retina

449
Q

retina function

A

contains light receptors, some sensitive to light of different colours

450
Q

retina function

A

contains light receptors, some sensitive to light of different colours

451
Q

optic nerve function

A

carries impulses to the brain

452
Q

As light intensity increase,

A

diameter of pupil decrease so that less light enters the
eye and prevent damage. The antagonistic muscles, circular muscles contract and
radial muscles relax.

453
Q

As light intensity decrease,

A

diameter of the pupil increase so that more light enters the
eye and prevents damage. The antagonistic muscles, circular muscles relax and
radial muscles contract.

454
Q

Distant object

A

Ciliary muscles relax, suspensory ligament pulled tight (tension on
suspensory ligament increase). the lens becomes thin/ less convex.

455
Q

Near object

A

Ciliary muscles contract, suspensory ligament slackened (tension on
suspensory ligament decrease). the lens becomes thick/ more convex.

456
Q

There are three different kinds of cone cells

A

red, green and blue

457
Q

Fovea is almost entirely cones,

A

packed tightly together

458
Q

Rods

A

are found further out
on the retina and are less tightly packed.
Rod cells are more sensitive at night

459
Q

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.

460
Q

Adrenal gland secrete

A

adrenaline.

461
Q

Pancreas secrete

A

insulin and glucagon

462
Q

Testes
secrete

A

testosterone

463
Q

Ovaries secrete

A

estrogen

464
Q

Effect of adrenaline:

A

increased breathing rate
increased heart rate
increased pupil diameter
increase in blood glucose concentration

465
Q

Speed of action of nervous system is faster than

A

hormonal control system. Duration
of effect of hormonal control system is longer than the nervous system

466
Q

Homeostasis

A

maintenance of a constant internal environment

467
Q

Insulin decreases

A

blood glucose concentration.

468
Q

In negative feedback:

A

There is a set point – a normal level that the system tries to maintain.
There is a ‘measuring device’ that keeps track of whether the level is within the
range of the set point.
If the level goes outside the set point, this triggers events to happen that bring
the level back into line again.

469
Q

If blood glucose concentration is too high

A

it is detected by the pancreas, pancreas
release insulin, insulin stimulate liver cells to absorb glucose from blood across the
partially permeable membrane. Liver cells convert glucose to glycogen and store
glycogen in liver cells, this results in reduction of blood glucose concentration until it
reaches the set, normal point.

470
Q

If blood glucose concentration is too low

A

it is detected by the pancreas, pancreas
release glucagon, glucagon stimulate liver cells to convert store glycogen into
glucose, and release this glucose into the blood. This results in increase of blood
glucose concentration until it reaches the set, normal point.

471
Q

Treatment of type 1 diabetes:

A

-insulin ;
-by injection / insulin pump ;
- regular blood glucose tests
regular meals and controlled diet

472
Q

If the internal temperature is above normal

A

it is detected by the brain. Vasodilation of
arterioles occur, more blood flows to the skin, so more heat is lost form the blood,
decreasing the internal temperature. Sweating occurs which gives a cooling effect
and decreases the internal body temperature

473
Q

If the internal temperature is below normal

A

it is detected by the brain.
Vasoconstriction of arterioles occur, less blood flows to the skin, so less heat is lost
form the blood, increasing the internal temperature. Adipose tissue in skin act as
insulation and reduce heat loss. Shivering produce heat and help to keep the body
warm.

474
Q

Gravitropism

A

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

475
Q

Phototropism

A

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

476
Q

examples of the chemical control of
plant growth

A

Phototropism and gravitropism

477
Q

How auxin work:

A

auxin is made in the shoot tip
auxin diffuses through the plant from the shoot tip
auxin is unequally distributed in response to light and gravity
auxin stimulates cell elongation

Biology Flashcards (20 decks)

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