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74 Cards in this Set
- Front
- Back
What is taxis? |
Directional movement in response to a stimulus
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What is kinesis
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Non-directional movement in response to a stimulus.
Increase in number of turns to escape poor environment. |
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What and how is passed on in nervous communication?
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Electrical impulses along neurones.
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Describe pathway of nervous communication
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Stimulus > Receptors > Sensory Neurone > Relay Neurone in central nervous system > Motor Neurone > Effectors > Response
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Why do we have reflexes?
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To prevent harm to the body.
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What is a reflex?
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A rapid involuntary response to a stimulus.
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Nervous system vs hormonal system
What carried to where? Speed of response? Spread of effect? Lasting of effect? |
Nervous- electrical impulses carried by neurones, fast, localised and short lived.
Hormonal- hormones carried in blood, slow, widespread and long lasting. |
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2 types of cell that act as effectors?
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Muscle cells
Cells in glands |
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What is role of receptor?
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To detect stimuli.
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Explain why nervous control is localised and short lived
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Neurotransmitters are secreted directly onto cells.
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What is a chemical mediator?
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Chemical messenger that acts locally.
Secreted from cells all over body. Target cells are right next to where chemical mediators are produced. Only have small distance so quick response. |
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What is histamine and how does it work?
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Chemical mediator. Increases permeability of capillaries nearby to allow more immune system cells to move to infected area.
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What is prostaglandin and how does it work?
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Chemical mediator. Involved in inflammation, fever, blood pressure regulation and clotting.
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Why do chemical mediators only provide a local response?
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Secreted from
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Why do chemical mediators produce a faster response than hormones?
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Short distance to travel so quicker response.
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What triggers release of histamine?
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Injury or infection.
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What are two types of chemical mediator?
How do they work? |
Prostaglandins and histamine.
Prostaglandins involved in inflammation, fever, BP regulation and clotting. Histamine increases permeability of cells to WBCS so more immune system cells can arrive. |
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1cm to __mm to __µm to __nm
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1cm = 10mm = 10,000µm = 10,000,000nm
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Magnification=
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Image size/Actual size
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Rod cells
Location Black and white/colour How many rods to neurones Sensitivity to light Visual acuity? Why? |
Peripheral area of retina
Black and white Many rods to one neurone High sensitivity to light Low visual acuity- many rods to one neurone so light from two objects cannot be told apart. |
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Cone cells
Location Black and white/colour How many cones to neurones Sensitivity to light Visual acuity? Why? |
Fovea
Colour 1 rod to neurone Low light sensitivity Good visual acuity- 1 cone to 1 neurone so can tell close light sources apart |
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How is generator potential produced?
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Stimulus detected, cell membrane becomes more permeable, more ions enter. PD changes and gen potential produced.
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What type of stimulus does Pacinian corpuscle respond to?
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Mechanical. Pressure.
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Structure of Pacinian Corpuscle?
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End of a sensory neurone. Wrapped in connective tissue called lamellae.
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Explain how stimulus triggers AP in Pacinian Corpuscle?
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Stimulated and lamallae are deformed and press on nerve ending. This causes stretch mediated sodium channels to stretch and open Na+ ions diffuse into cell and cause generator potential. If reaches threshold- AP will fire
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Rods/cones which give better visual acuity? Why?
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Cones have 1 cone to 1 neurone.
Can tell different light sources as 2 different points |
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4 differences between Rods and Cones?
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Visual acuity
Rods at edge, cones at fovea. Rods black and white, cones in colour. Rods more light sensitive. Many rods to one neurone. 1 cone to 1 neurone. |
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Two proteins involved in establishing resting potential.
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Sodium potassium pumps.
Potassium ion channels. |
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Ratio of AT of sodium potassium pumps?
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3 sodium out 2 potassium in
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What is diffused out of membrane when establishing resting potential?
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Potassium ions down conc. gradient
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Which side of membrane is more positive?
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Outside
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What 3 factors effect speed of AP conduction?
Explain how |
Myelination- allows charge to jump between Nodes very quickly.
Axon diameter- wider diameter, less resistance Temperature- higher temp quicker diffusion, although too high and proteins denature |
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Explain process of AP
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Stimulus causes sodium ions to open and sodium diffuse into the neurone making inside less negative.
Depolarisation- if reaches threshold then more sodium ion channels open +ve feedback. Repolarisation- Na+ close and K+ open causing them to diffuse back out. Hyper polarisation- K+ channels are too slow to close and there is an overshoot of ion movement Resting potential- ion channels reset. |
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What is refractory period?
Why important? |
After AP neurone can't trigger AP again because ion channels are recovering.
Acts as time delay and stops overlapping APs. Makes sure unidirectional |
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What are waves of depolarisation?
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When AP happens some ions diffuse sideways. this causes nearby ion channels to open and causes a wave of depolarisation.
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Explain the all or nothing principle
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once threshold is reached an AP will always fire with same change in voltage, no matter stimulus size.
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What does bigger stimulus cause in terms of AP
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more frequent APs to be fired
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After AP why can't cell cause another AP?
What effects does this have? |
Refractory period.
Makes separate impulses and causes unidirectionality |
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How is conduction along a myelinated neurone different to non myelinated neurone.
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Faster
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Give 3 factors that affect speed of AP conduction?
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Diameter of axon
Temperature Myelination |
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Draw a synapse
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Neurone- synaptic knob, pre/postsynaptic knob, synaptic cleft, recepors, vesicles with neurotransmitter in.
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Draw a cholinergic synapse
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Neurone- synaptic knob, pre/postsynaptic knob, synaptic cleft, recepors, vesicles with ACh in.
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Summarise how a nerve impulse is transmitted
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AP arrives and causes Ca2+ ions to open.
These diffuse into synaptic knob. Influx of Ca2+ causes synaptic vesicles to fuse with presynaptic membrane and ACh is released into the cleft. ACh diffuses across and is picked up by receptors. The leftover ACh is either broken down by enzymes or resorbed by presynaptic membrane. |
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What is a neuromuscular junction?
Special features |
It is a specialised cholinergic synapse between motor neurone and a muscle cell.
More receptors. Always triggers response in muscle cell. Forms clefts which hold ACh |
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What are two types of summation?
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Spatial and temporal
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Describe temporal summation
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Where 2 impulses arrive in quick succession from the same presynaptic neurone. This increases the likelihood of threshold being reached.
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Describe spatial summation
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where 2/more presynaptic neurones release their neurotransmitters to the same postsynaptic neurone. The small amount combines to reach threshold level.
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3 types of cell with receptors for neurotransmitters
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Neurone, muscle, gland
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Describe the movement of Ca2+ ions following the arrival of an action potential at a cholinergic synapse?
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AP stimulates voltage gated Ca2+ ion channels in the presynaptic neurone to open so Ca2+ ions diffuse into the synaptic knob.
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Explain how ACh leaves the presynaptic neurone and causes an AP in the postsynaptic neurone.
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Influx of Ca2+ causes vesicles to fuse with presynaptic membrane the ACh diffuses across the membrane into the receptor on the postsynaptic neurone. If threshold is reached the influx in postsynaptic causes an AP on the postsynaptic membrane.
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What is a neuromuscular junction?
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A synapse between a motor neurone and a muscle.
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3 muscle types
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Smooth
Cardiac Skeletal |
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What is the A band?
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Anisotrophic- length of the myosin
A is dark. A. |
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What is the I band?
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Isotrophic- the non myosin section of muscle.
I for light I. |
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Whats M line?
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The middle line
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Whats Z line?
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Z line is the end lines?
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What is the H zone?
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the Myosin section with no actin crossed over.
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Describe the process of a muscle contraction.
1st stage. |
1) Arrival of AP- AP arrives from motor neurone which depolarises the sarcolemma. Depolarisation spreads down the T tubules to sarcoplasmic reticulum. This causes Ca2+ ion release. Ca2+ ions bind to troponin causing it to change shape. This pulls tropomyosin off the binding site.
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Describe the process of a muscle contraction.
2nd stage. |
Movement of the actin filament.
Ca2+ ions also activate the ATPase to break down ATP to provide the energy for power stroke. |
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Describe the process of a muscle contraction.
3rd stage. |
Breaking of the cross bridge
ATP also provides the energy to break the cross bridge. The myosin head then detaches and reattaches to a new binding site. |
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Describe the process of a muscle contraction.
4th stage. |
Return to resting state
When the muscle is unstimulated Ca2+ ions leave their binding sites on the troponin molecules and care moved by AT into the sarcoplasmic reticulum. The troponin molecules return to original places so the tropomyosin reblocks the binding site. |
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3 ways that ATP can be produced
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Aerobic respiration
Anaerobic respiration ATP phosphocreatine system |
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How does Phosphocreatine produce ATP
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ADP+PCr-->ATP+Cr
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Explain slow twitch muscle fibres?
Explain their adaptions? |
Contract slowly and work for long time without tiring.
Energy released by aerobic respiration. Adaptions: Lots of mitochondria, lots of blood vessels, rich source of myoglobin (stores oxygen). |
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Explain fast twitch muscle fibres?
Explain their adaptions? |
Short bursts of power.
Energy released by anaerobic resiration using glycogen. PCr stores to generate ATP. |
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Describe A band
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Dark, presence of thick myosin.
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Name 2 proteins found between actin filaments that help myofilaments slide past each other.
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Troponin and tropomyosin
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Explain how Ca2+ ions in sarcoplasm allow formation of cross bridges.
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Ca2+ bind to troponin causing it to change shape and pull tropomyosin away and expose binding site allowing myosin head to attach
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Describe role of ATP in muscle contraction.
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Broken down to provide energy to break cross bridges.
Provides energy for the power stroke. |
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Describe how ATP is generated from PCr.
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ADP+PCr--->ATP+Cr
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Give 1 advantage and 1 disadvantage of ATP generation from PCr.
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Quick generation of ATP.
Used in short bursts. Doesnt require oxygen or produce lactate. Runs out v quickly |
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Give 3 ways of generating ATP
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Anaerobic/aerobic respiration. Phosphocreatine-ATP system.
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Give 3 ways slow twitch muscle fibres are adapted
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Lots of mitochondria
Lots of blood vessels Lots of myoglobin |
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Give 1 way fast twitch muscle fibres are adapted
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Stores of phosphcreatine
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