Coordination And Response Flashcards
1
Q
What is a stimulus?
A
A change in an organisms surroundings
2
Q
What is a receptor?
A
Detects a stimulus and transducers the stimulus energy into electrical impulses
3
Q
What is an effector?
A
A muscle or gland that brings about a response to a stimulus
4
Q
What does sensitivity mean?
A
The ability to detect or sense changes in the environment (stimuli) and to make responses
5
Q
Nervous system
A
Signals are electrical
Signals are carried by nerves
Signals produced by receptors
Localised
Fast
Short-term effects
6
Q
What does CNS stand for?
A
Central nervous system
7
Q
What is a part of the CNS?
A
Brain
Spinal cord
8
Q
What does PNS mean?
A
Peripheral nervous system
9
Q
What is a part of the PNS?
A
Nerves
10
Q
What is an axon?
A
Long thin fibre that carries electrical impulses away from the cell body
- extension of the cytoplasm
11
Q
What is a cell body (neurones)?
A
Contains most cellular structures like the nucleus and controls the neurone
12
Q
What is a dendrite?
A
Short extension forming connections with many other neurone, receptors or effectors to receive signals
13
Q
What is a myelin sheath?
A
A fatty layer that covers the axon and speeds up the electrical impulses
14
Q
What is a nerve?
A
A bundle of neurones
15
Q
What is the nervous system’s function?
A
Enables organisms to react to their surroundings and coordinate their behaviour/response
16
Q
What does a sensory neurone look like?
A
Long with cell body in the middle of the axon
17
Q
What is the role of the sensory neurone?
A
To transfer electrical impulses from a receptor to the central nervous system (CNS)
18
Q
What does a relay neurone look like?
A
Short with a small cell body at one end with many dendrites branching off it
19
Q
What is the role of the relay neurone?
A
To transfer electrical impulses from a sensory neurone to a motor neurone
20
Q
What does a motor neurone look like?
A
Along with a large cell body with many dendrites at one end
21
Q
What is the role of the motor neurone?
A
To transfer electrical impulses from the CNS to an effector
22
Q
Reflex arc
A
Stimulus —> receptor —> coordination (neurones) —> effector —> response
23
Q
What is a reflex?
A
An involuntary and rapid response to a stimulus
24
Q
Why are reflexes important?
A
They protect us from harm
25
Examples of reflexes
Blinking
Sneezing
Iris dilation
26
What is a reflex arc?
The nerve pathway that underlies our unconscious reflexes
27
What is a synapse?
Gap between two neurones, chemicals are released across a synapse
28
Synapse transmission steps
1) electrical impulse arrives down the axon
2) electrical impulse triggers the production of neurotransmitters in the vesicles
3) vesicles move towards the synaptic cleft and fuse with the membrane, releasing the neurotransmitter
4) the neurotransmitters diffuse across the synaptic cleft and attach to the receptors on the second neurone
5) this triggers another electrical impulse to start
6)neurotransmitters are broken down
(7, whole thing starts over)
29
What re the receptor cells of light called?
Rods and cones
30
Where are rods and cones found?
On the retina
31
Rod cells
Detect in black and white
More sensitive so can work in low levels of light
32
Why can’t we see colours in the dark?
Because our cone cells don’t work in low levels of light but our rod cells do
33
Cone cells
Detect in colour
Only detect bright light so don’t work well in low levels of light
Red blue and green cones
34
What do rods and cones do?
Convert the light energy into impulses that travel down the optic nerve
35
What type of neurone is the optic nerve?
Sensory neurone
36
What is the blind spot?
Point where the optic nerves leaves the eye, no receptor cells
37
What is the ciliary muscle?
A ring of muscle that contracts and relaxes to change the shape of the lens
38
What is the cornea?
Transparent layer at the front of the eye which refracts (bends) light
39
What is the fovea?
Part of the retina where light focuses
Highest density of cones
Gives sharpest image
40
What is the iris?
Controls how much light enters the pupil
41
What is the lens?
Transparent disc that can change shape to focus light onto the retina
42
What is the optic nerve?
Sensory neurone that carries impulse to the brain
43
What is the pupil?
Hole that allows light to enter the eye
44
What is the retina?
Contains light receptor cells (rods and cones)
45
What is the sclera?
Strong outer wall of the eyeball which keeps the eye in shape and muscles attach to it
46
What is the suspensory ligament?
Tissue that holds the lens in place and helps change the shape of the lens to focus on things that are close or far away
47
What does the pupil do in bright light?
Constricts
48
What does the pupil do in dim light?
Dilates
49
Dim light
Circular muscle: RELAXES
radial muscle: CONTRACTS
Pupil diameter: LARGE
Amount of light into the eye: LOTS
50
Bright light
Circular muscle: CONTRACTS
radial muscle: RELAXES
Pupil diameter: SMALL
Amount of light into the eye: LITTLE
51
What is accommodation?
A reflex that changes the refractive power of the lens
52
Near objects
Ciliary muscle: CONTRACT
Suspensory ligaments: LOOSEN
Shape of lens: SHORT AND FAT
Amount of light refracted: MORE LIGHT BENDS TOWARDS RETINA
53
Distant objects
Ciliary muscle: RELAX
Suspensory ligaments: TIGHTEN
Shape of lens: LONG AND THIN
Amount of light refracted: LESS LIGHT BENDS TOWARDS RETINA
54
What do some tissues have?
Receptors that are specific to hormones
55
What do hormone molecules act as?
Signals to trigger certain changes inside the cells
56
Examples of internal stimulus
Blood glucose levels
Temperature
Blood pressure
pH
57
Examples of external stimulus
Light
Sound
Pressure
Temperature
58
Endocrine system
Signals are chemical
Signals are carried by blood
Signals produced by glands
Systemic
Slow
Long-term effects
59
What is the pituitary gland also known as?
The master gland
60
What 2 functions does the pituitary gland have?
Tells the body what to do
Tells other glands to release their hormones
61
What 3 hormones does the pituitary gland secrete?
ADH
FSH
LH
62
What does ADH do?
Regulates water balance in the body by controlling the amount of water reabsorbed by the kidneys
63
What does ADH stand for?
Antidiuretic hormone
64
Which hormone does the thyroid gland secrete?
Thyroxine
65
What does thyroxine do?
Important for controlling your metabolism, growth and development
66
Which hormones does the pancreas secrete?
Insulin
Glucagon
67
What does insulin do?
Regulates blood glucose concentration by increasing glucose taken up by cells and also converts glucose into glycogen
68
What does glucagon do?
Raises blood glucose concentration by stimulating the liver to break down glycogen into glucose
69
Which hormone do the adrenals secrete?
Adrenaline
70
What does adrenaline do?
Prepares the body for ‘fight or flight’ by increasing the heart rate, dilating airways and releasing glucose for energy
71
Which hormone do the testes secrete?
Testosterone
72
What does testosterone do?
Controls male puberty, stimulates sperm production and maintains male reproductive tissues
73
Which hormone do the ovaries secrete?
Oestrogen
74
What does oestrogen do?
Controls the menstrual cycle, triggers ovulation and develops female characteristics
75
What is homeostasis?
The regulation of conditions inside the body to maintain a stable internal environment in response to both internal and external conditions
76
What can bright light do?
Cause damage to your retina
77
What can the pituitary gland detect and secrete?
Low levels of thyroxine
Secretes thyroid stimulating hormone (TSH)
78
Where are most of the receptors found?
Skin
Blood vessels
79
What do cells need to function properly?
Certain conditions
80
What can’t the internal environment be in a human?
Too hot or cold
Too acidic or alkaline
81
What do cells need a good supply of?
Glucose
Water
82
How does the body keep internal conditions stable?
By regulating everything to make sure it’s kept around the right levels
83
What is negative feedback?
When your body detects a change and then responds to reverse this change and bring things back to normal
84
What is thermoregulation?
The control of our internal body temperature
85
What does thermoregulation allow?
Our cells to function properly
86
What is the human body temperature?
37 degrees celsius
87
Why does our body need to be 37 degrees celsius?
It’s the perfect temperature for our enzymes to function
88
What happens if our body temperature falls?
Enzyme activity slows down
89
What happens when our body temperature rises?
Enzymes start to denature
90
What does the thermoregulatory centre act as?
A thermostat in our body
91
Where is the thermoregulatory centre?
Part of the hypothalamus within our brain
92
What do the signals sent from our receptors to the thermoregulatory centre
Receptors constantly send information about our temperature to the t.c.
93
What do the signals sent from our receptors to the thermoregulatory centre allow?
The brain to figure out if we’re too hot or too cold overall
94
What does the thermoregulatory centre do if we’re too hot?
Sends signals designed to cool us down
95
What does the thermoregulatory centre do if we’re too cold?
Bring about changes that would warm us up
96
What 3 things occur when we’re too cold?
Vasoconstriction
Erector muscles contract
Shivering
97
What does our body need to do when we’re too cold?
Conserve and generate more heat
98
How does our skin appear when we’re too cold?
Pale
99
What is vasoconstriction?
Blood vessels constrict so that less blood is at the surface so that less heat energy is lost
100
What happens when the erector muscles contract?
Hairs stand up to trap a small layer of insulating air
—> makes it harder to lose heat from our skin
101
What is shivering?
Muscles contracting automatically and rapidly
102
How does shivering help warm us up?
Requires lots of energy from respiration and all of the chemical reactions involved results in lots of heat energy being released as waste
103
What 3 things happen when we’re too hot?
Vasodilation
Erector muscles relax
Sweating
104
How does the skin appear when we’re too hot?
Red
105
What is vasodilation?
Blood vessels dilate/expand so that more blood is at the surface so more heat energy is lost
106
What happens when the erector muscles relax?
Hairs lay flat and no air is trapped so no insulation occurs
107
What is sweating?
Water and salt released by sweat glands that evaporates and takes heat energy away with it
108
How does sweating cool us down?
Lots of energy is required to evaporate water so we lose that heat energy
109
What is needed for plants to grow?
Sunlight
Water
Minerals
Air supply
Warmth
110
Plants respond to their environment to ..?
Avoid stress
Avoid being eaten
Enhance survival
Improve chances of having offspring
111
What does tropism mean?
The growth response of a plant to a directional stimulus
112
Where do positive tropisms grow?
Towards the stimulus
113
Where do negative tropisms grow?
Away from the stimulus
114
In plants where do hormones act?
Locally
115
What is an auxin?
A plant growth hormone
116
Where is auxin produced?
In the tips of shoots and roots
117
What does auxin in shoots do?
Stimulates growth
118
What does auxin do in roots?
Inhibits growth
119
What happens if the tip of the plant is removed?
There is no auxin so no growth
120
Where does auxin always accumulate in shoots?
On the shaded side
121
Where does auxin always accumulate in roots?
On the lower side
122
What is phototropism?
Plant growth response to light
123
Shoots are …?
Positively phototrophic (grow towards the light)
Negatively geotropic (grow away from the ground)
124
What does positively phototrophic mean?
Grows towards the light
125
What does negatively geotropic mean?
Grows away from the ground
126
How do positive phototropism work?
Auxin accumulates on the shades side
Auxin in the shoots stimulates growth so the shaded side grows faster than the sunny side
Causes cell elongation making it bend and grow towards the light
127
What is geotropism?
Plant growth response to gravity
128
Roots are …?
Negatively phototrophic
Positively geotropic
129
What does negatively phototrophic mean?
Grows away from the light
130
What does positively geotropic mean?
Grows towards the ground
131
How does positive geotropism work?
Auxin accumulates on the lower side
Auxin in the roots inhibits growth so the upper side grows faster than the lower side
Plant will bend downwards and grow towards gravity
132
133
Two examples of homeostasis
Body water content
Body temperature
134
What does a co-ordinated response require?
Stimulus
Receptor
Effector
135
How is the CNS linked to sense organs?
By nerves
