Topic 14 and Topic 15 Flashcards
(79 cards)
1
Q
A stimulus is
A
A stimulus is a detectable change in the internal or external environment of an organism that leads to a response in the organism.
2
Q
Stimuli are detected by
A
Receptors
3
Q
A coordinator
A
Formulates a suitable response to a stimulus
4
Q
An effector
A
Produces a response which has been detected by the receptors
5
Q
A taxis is
A
A taxis is a simple response whose direction is determined by the direction of a stimulus
6
Q
What is positive taxis
A
Movement towards a stimulus
7
Q
What is negative taxis
A
Movement away from a stimulus
8
Q
Positive Phototaxis
A
Moving towards light
9
Q
Negative phototaxis
A
Moving away from the light
10
Q
A kinesis is
A
A kinesis is a form of response where the organism changes speed at which it moves and the rate at which it changes direction
11
Q
A tropism is
A
A tropism is the growth of part of a plant in response to a directional stimulus
12
Q
The CNS is
A
Made up of the brain and the spinal cord
13
Q
The peripheral nervous system is
A
Made up of pairs of nerves that are from either the brain or the spinal cord
14
Q
Phototropism definition
A
The movements of plants in response to light
15
Q
Gravitropism definition
A
Plants response to gravity
16
Q
Hydrotropism definition
A
Plants response to water
17
Q
IAA is
A
An auxin which controls plant cell elongation
18
Q
Sensory neurones…
A
Carry nerve impulses from receptors towards the central nervous system
19
Q
Motor neurones…
A
Carry nerve impulses away from the central nervous system to effectors
20
Q
The voluntary nervous system…
A
Carries nerve impulses to body muscles and is under conscious control
21
Q
The autonomic nervous system…
A
Carries nerve impulses to glands, smooth muscle and cardiac muscle
22
Q
An involuntary response to a stimulus is called?
A
A reflex
23
Q
Reflex arc definition
A
The pathway of neurones involved in a reflex
24
Q
The Pacinian corpuscle
A
Is a receptor which responds to mechanical pressure
25
What are two things receptors can be?
They can be cells (e.g photoreceptor cells) or proteins on cell surface membranes (e.g glucose receptors are proteins found in cell membranes)
26
What is a generator potential
Energy converted from the stimulus into a nervous impulse by a receptor
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What channel is in the centre of a Pacinian corpuscle
Stretch mediated sodium channel
28
At resting state the stretch mediated sodium channels in the Pacinian corpuscle are…
Too narrow to allow sodium ions to pass along them so has a resting potential
29
When pressure is applied to the Pacinian corpuscle…
It becomes deformed and the membrane around its neurone becomes stretched which widens the sodium channels so sodium ions diffuse into the neurone
30
How do the sodium ions change the potential of the membrane?
The influx of sodium ions depolarises the potential of the membrane producing a generator potential
31
Where are light receptor cells found and what are they?
They are found in the retina and they are rod and cone cells
32
Rod cells…
Can only see in black and white
33
The different types of cone cells
There are three for different range of wavelengths of lights and they contain iodopsin pigment
34
The autonomic nervous system…
Controls the subconscious activities of internal muscles and glands
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The sympathetic nervous system…
Is part of the autonomic nervous system and it stimulates effectors so speeds up activity
36
The parasympathetic nervous system…
Is the other part of the autonomic nervous system which inhibits effectors and and slows down activity
37
The heart is myogenic what does that mean?
The contraction of the muscle is initiated from within the muscle itself instead of by nervous impulses from outside
38
Control of heart rate 1
A wave of electrical excitation spreads out from the sinoatrial node across both atria causing them to contract
39
Control of heart rate 2
A layer of non-conductive tissue prevents the wave from crossing to the ventricles
40
Control of heart rate 3
The wave of excitation enters a second group of cells called the atrioventricular node which is between the atria
41
Control of heart rate 4
After a short delay, the atrioventricular node produces a wave of electrical excitation between the ventricles along muscle fibres which make up the bundle of His
42
Control of heart rate 5
The bundle of His conducts the wage through the atrioventricular septum to the base of the ventricles
43
Control of heart rate 6
The wave of excitation is released from the Purkyne tissue, causing the ventricles to contract quickly at the same time from the bottom of the heart upwards
44
Changes to the heart rate are controlled by…
Changes to the heart rate are controlled by an area of the brain called the medulla oblongata
45
Two centres in the medulla oblongata
One centre that increases heart rate, which is linked to the sinoatrial node by the sympathetic nervous system and one centre that decreases heart rate, which is linked to the sinoatrial node by the parasympathetic nervous system
46
Chemoreceptors
Are found in the wall of the carotid arteries and are sensitive to changes in the pH of the blood that result from changes in CO2 concentration
47
Pressure receptors
Found in the walls of the carotid arteries and the aorta
48
when the blood pressure is higher than normal, pressure receptors…
when the blood pressure is higher than normal, pressure receptors transmit more nervous impulses to the centre of the medulla oblongata which decreases heart rate
49
When blood pressure is lower than normal, pressure receptors…
when the blood pressure is lower than normal, pressure receptors transmit more nervous impulses to the centre of the medulla oblongata which increases heart rate
50
The nervous system uses nerve cells to…
The nervous system uses nerve cells to pass electrical impulses and stimulate their target cells by secreting chemicals called neurotransmitters
51
The hormonal system produces…
The hormonal system produces hormones that are transported in the blood plasma to their target cells
52
Neurones definition
Specialised cells adapted to rapidly carrying electrochemical changes called nerve impulses from one part of the body to another
53
A motor neurone is made up of…
A cell body, dendrons (which divide into dendrites which carry nerve impulses towards the cell body), an axon (a single long fibre that carries nerve impulses towards the cell body), Schwann cells (surround the axon protecting it), a myelin sheath, nodes of Ranvier
54
Sensory neurones
Transmit nerve impulses from a receptor to an intermediate or motor neurone
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Motor neurones
Transmit nerve impulses from an intermediate or a relay neurone to an effector such as a gland or a muscle
56
Relay neurones
Transmit impulses between neurones
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the phospholipid bilayer of the axon membrane prevents...
sodium and potassium ions diffusing across it
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channel proteins?
span through the phospholipid bilayer and sometimes allow sodium or potassium ions through them by facilitated diffusion
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carrier proteins?
actively transport potassium ions into the axon and sodium ions out of the axon, called the sodium-potassium pump
60
what charge is on the axon
the inside of an axon is negatively charged to the outside which is called the resting potential
61
action potential?
when the charges reverse so the inside of the axon is positively charged so it has been depolarised
62
resting potential?
the inside of the axon is negatively charged to the outside
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why does depolarisation occur
depolarisation occurs because the channels in the axon membrane change shape and open or close depending on the voltage of the membrane
64
where on the axon does the depolarisation occur?
at a particular point on the axon membrane instead of the full axon membrane
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at resting potential what happens to the channels?
some potassium voltage-gated channels are open but the sodium voltage-gated channels are closed
66
action potential definition
means that the axon membrane is transmitting a nerve impulse
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resting potential definition
means that the axon membrane is not transmitting a nerve impulse
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as one region of the axon produces an action potential...
as one region of the axon produces an action potential and becomes depolarised it acts as a stimulus for the depolarisation of the next region of the axon
69
the previous region of the axon membrane...
the previous region of the axon membrane returns to its resting potential so it undergoes repolarisation
70
what do synapses do
they transmit information from one neurone to another by neurotransmitters
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what neurone releases the neurotransmitters
the presynaptic neurone
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what are neurones seperated by
a small gap called the synaptic cleft
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what is the rounded end part of the axon called?
the synaptic knob which has lots of mitochondria and endoplasmic reticulum
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where is the neurotransmitter stored
the synaptic vesicles
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2 features of synapses
they can only pass information in one direction, they can do summation which trigger a new action potential if the latest action potential was of a low-frequency
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2 functions of synapses
they allow a single impulse along one neurone to initiate new impulses in lots of different neurones at a synapse so a single stimulus can create lots of responses and they allow multiple impulses to be combined at a synapse.
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Function process of synapse
a neurotransmitter is made in the presynaptic neurone and is stored in the synaptic vesicles, when an action potential reaches the synaptic knob the vesicles fuse with the presynaptic neurone to release the neurotransmitter, it then diffuses across the synaptic cleft and binds with receptor proteins in the postsynaptic neurone
78
synapses that produce new action potentials in the postsynaptic neurone are called
excitatory synapses
79
what is a cholinergic synapse
a synapse which releases the neurotransmitter acetylcholine
