Unit 6

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What is the scientific name for a nerve impulse/signal?
Action Potential
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What is the gap between two nerves called?
Synapse
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What opens after an action potential arrives at the synapse (the neuromuscular junction)?
Calcium Channels
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The opening of the calcium channels in the neuromuscular junction causes...?
Vesicles (which contain transmitter) to bind to the presynaptic membrane.
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What is the name of the transmitter in the neuromuscular junction/synapse?
Acetylcholine
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Where is the transmitter stored?
In the Vesicles.
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The vesicles release Acetylcholine into the...?
Synaptic Cleft
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Acetylcholine diffuses across the synaptic cleft and bonds to...?
The receptors on the Post-Synaptic Membrane.
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What is the Post-Synaptic Membrane?
A muscle fibre membrane.
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What triggers the Sodium Channels to open?
The binding of Acetylcholine to the post-synaptic membrane.When the sodium channels open, sodium rapidly enters the cell causing...?
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When the sodium channels open, sodium rapidly enters the cell causing...?
Depolarisation
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What does depolarisation trigger?
An action potential.
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Through what does the action potential travel deep into the muscle fibre?
T-Tubules
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The action potential sent deep inot the muscle fibre, causes...?
Calcium channels to open, allowing for the diffusion of calcium into the muscle tissue.
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This diffusion of calcium into the muscle tissue, causes...?
Muscle Contraction
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What are the two types of 'filament' in muscle called?
Myosin (thick filaments) and Actin (thin filaments)
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The structure of Actin is...?
Two thin strands [of actin] twisted together.
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The structure of Myosin is...?
Two thick strands [of myosin] , with bulbous heads twisted together.
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Actin is joined to the...?
Z-Line
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Myosin is joined to the...?
M-Line
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What is the name for one full set of actin and myosin?
The Sacromere
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After calcium ions diffuse into the muscle fibres, they bind to what, causing what...?
The Calcium ions bind to the Tropomyosin and cause it to move; revealing the myosin binding sites.
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Tropomyosin is wrapped around...?
Actin
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An ATP molecule is broken down into ADP+Pi by which enzyme?
ATPase
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ADP attaches to...?
The myosin bulbous head.
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A Cross-Bridge is formed when a...?
Myosin head and ADP molecule attach to/bind with the actin.
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After binding with the actin, the myosin heads then move, in what is called a...?
"Power Stroke"
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Whilst moving the actin fibre along, the myosin heads...?
Release ADP.
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After pulling the actin fibre along, the myosin heads...?
Attach to ATP molecules.
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The bonding with the ATP molecules causes...?
The myosin heads to detach from the actin fibres.
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As this process repeats, the actin...?
Overlaps the myosin more, shortening the sacromere and muscle.
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This process is called...?
Muscle Contraction
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What are the three different types of muscle?
Smooth muscle, skeletal muscle and cardiac muscle.
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What role does skeletal muscle play?
It moves the body.
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What role does smooth muscle play?
It transports blood around the body.
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What role does cardiac muscle play?
It allows for the heart to contract and send blood around the body.
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Muscle cells are...?
Multi-nucleated
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Muscles are made up of millions of...?
Myofibrils
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Many myofibrils make...?
One muscle cell.
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Muscle cells are multi-nucleated because...?
Many muscle cells fused together to create one cell.
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The name of the cytoplasm in a muscle cell is...?
The Sarcoplasm
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The sarcoplasm holds many...? and ...?
Mitochondria and Endoplasmic Reticulum
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Myofibrils consist of two proteins...? and ...?
Myosin and Actin
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Myosin is also known as...?
The thick filament.
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Actin is also known as...?
The thin filament.
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In a myofibril, actin consists of...?
Two strands of actin twisted together.
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In a myofibril, myosin consists of...?
Long tailed proteins with bulbous heads, twisted together.
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The sarcomere is the area between...?
One Z-Line and the next Z-Line.
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Which protein is bound to the Z-Line?
Actin
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Which protein is bound to the M-Line?
Myosin
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What are the two different types of muscle fibre called?
Fast Twitch and Slow Twitch
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Slow Twitch muscle fibres have fewer/greater numbers of mitochondria?
Greater
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Fast Twitch muscle fibres have fewer/greater numbers of mitochondria?
Fewer
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Slow Twitch muscles produce...? through aerobic respiration.
ATP
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Fast Twitch muscles are able to...?...?
Respire anaerobically
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Slow Twitch muscle is used for...?
Endurance exercise
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Fast Twitch muscle is used for...?
Brief, high intensity exercise
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The round bellied part of the synapse is called...?
The Synaptic Knob
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The synaptic knob and attached cell are called...?
The pre-synaptic cell
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The next cell (on the other side of the synapse) is called...?
The post-synaptic cell
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The gap in between the pre-synaptic cell and the post-synaptic cell is called...?
The synaptic cleft.
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On the synaptic cleft there are...?
Neurotransmitter receptors
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On the synaptic cleft, there are also...?
Sodium channels.
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The membrane around the pre-synaptic cell is called the...?
Plasma membrane
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When an action potential arrives at the synaptic knob, it causes what to happen/
Voltage gated calcium channels open, allowing for calcium ions to diffuse into the synaptic knob.
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The diffusion of calcium ions into the synapse causes...?
Vesicles (which contain neurotransmitter) to fuse with the pre-synaptic membrane.
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The fusion of the vesicles to the pre-synaptic membrane causes...?
the neurotransmitter molecules to move into the synaptic cleft.
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The neurotransmitter molecules then...?
Diffuse across the synaptic cleft and bind with the neurotransmitter receptors on the post-synaptic cell membrane.
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The neurotransmitter receptors trigger...?
The opening of sodium channels, which allows for the rapid diffusion of sodium ions into the post-synaptic cell.
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The diffusion of sodium ions into the post-synaptic cell stimulates...?
Another action potential in the second cell (the post-synaptic cell).
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What, in the synaptic cleft break, down the neurotransmitter molecules?
Enzymes
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Why do the enzymes break down the neurotransmitter molecules?
To prevent the constant stimulation of the post-synaptic membrane.
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The broken down neurotransmitter molecules are...?
Recycled into the vesicles in the pre-synaptic cell, and used again.
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When one nerve rapidly fires many action potentials (high frequency), resulting in the mass movement of neurotransmitter molecules across the synaptic cleft, it is called?
Temporal Summation
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When many nerves fire many action potentials onto one cell, triggering many action potentials (and many neurotransmitters to be sent across the synaptic cleft), it is called...?
Spatial Summation
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The Cell body in a nerve cell is at...?
The top of the cell.
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Dendrites are attached to the...?
Cell Body.
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The cell body also houses the...?
The cell body also houses the...?
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Action potentials move...?
Down the dendrites to towards the centre of the cell body.
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The coating covering the axon is called the...?
Myelin Sheath
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The Schwann Cells produce...?
The Schwann cells produce the myelin sheaths around the axons.
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The Nucleus of the Schwann Cell is located...?
In the Myelin Sheath.
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The gaps between the myelin sheaths are called...?
The Nodes of Ranvier
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The end of a nerve cell is called...?
The axon terminal.
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The axon terminal is connected to...?
An effector or another nerve/neurone.
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Pressure on a baroreceptor (Pacinian Corpuscle) causes...?
Stretch-mediated sodium channels to open, allowing sodium ions to diffuse in.
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The sodium ions from the stretch mediated sodium channels...?
Travel up the axon until the myelin sheath is reached.
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In the Node of Ranvier, more...?
Sodium ions diffuse into the axon(until a charge of 40mV is reached and the voltage gated sodium channels close), creating a positive charge (of 40mV) inside the axon, and a negative charge outside the axon.
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At the other end of the myelin sheath, there is a...?
Negative charge.
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The positive charge moves through...?
The myelin sheath to the Node of Ranvier.
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Sodium ions are then then pumped out of the axon through what?
Pumped out of the the axon (using a sodium/potassium pump), and move back (along the concentration gradient) to their original Node of Ranvier.
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The movement of the action potential (sodium ions) through/around the myelin sheath is called...?
Saltatory Conduction
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What is the resting potential inside an axon?
-65mV to -70mV
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How is the resting potential created?
Through the active transport of sodium ions out of the axon (until a potential of 40mV is reached outside the cell) and the active transport of potassium ions into the axon through a Na+/K+ pump, until a charge of -65 to -70mV is reached.
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A Na+/K+ pump (Sodium Potassium pump) moves...?
Three sodium ions out of the axon and two potassium ions into the axon.
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Some potassium...
Moves out of the axon through the 'leaky' potassium channels.
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What does the Threshold Potential do?
The threshold potential acts as a filter on the stimulus.
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What is the voltage of the threshold potential?
-55mV
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If a stimuli isn't strong enough to change the potential to -55mV...?
An action potential will not be triggered.
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The movement of sodium ions into the axon is called...?
Depolarisation
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The active transport of sodium ions out of and potassium ions into the axon is called...?
Repolarisation
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What happens in repolarisation?
3Na+ are pumped out and 2K+ are pumped into the axon.
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The ...? also open in repolarisation.
Potassium channels
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The time after a stimulus where a nerve is unresponsive to any more stimuli is called...?
The refractory period
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The refractory period limits the number of action potentials to...?
an average of 100/s
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There can only be one action potential in the...?
Absolute refractory period.
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Above 0mV there has to be...?
A period of repolarisation to allow for another action potential.
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What is the first stage of the reflex arc?
A receptor detects a stimulus.
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What is the second stage of the reflex arc?
A sensory neurone transmits the action potential from the receptor to the Central Nervous System.
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What is the third stage of the reflex arc?
A relay neurone coordinates a response by triggering action potentials in the motor neurones.
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What is the fourth stage of the reflex arc?
Action potentials travel down the motor neurone, triggering a response.
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What is the fifth stage of the reflex arc?
The action potentials cause the effector to move, removing the body part from the stimulus.
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What is Homeostasis?
The maintanence of a constant internal environment.
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Homeostasis ensures that the cells in the body can...?
Function normally, despite external factors, as they are in an environment which meets their needs.
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Homeostasis also protects --- which are key in metabolic reactions.
Enzymes
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Hoemostasis controls the...?
pH, temperature of the body, water potential and blood glucose levels.
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The contorl system of homeostasis is split into six steps. The first step is...?
A stimulus triggers a change in the variable (the element which is monitered and controlled by homeostasis).
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The second stage of the control system of homeostasis is...?
The change being detected by a receptor.
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The third stage of the control system of homeostasis is...?
Input; where the information (action potential) is sent along the afferent pathway to the brain.
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The fourth stage in the control system of homeostasis is...?
The control centre (brain) - the medulla oblongata recieves the action potential.
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The fifth stage of the control system of homeostasis is...?
Output; where the information is sent along the efferent pathway to the effector.
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The sixth stage of the control system of homeostasis is...?
The effector triggers a response which is fed back to the stimulus to return the variable to normal/maintain homeostasis.
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The afferent pathway is the...?
Sensory pathway
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The efferent pathway is the...?
Motor pathway
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Homeostasis increases heat loss by...?
Widening the blood vessels, to loose heat through radiation.
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Homeostasis decreases heat loss by...?
Contracting the blood vessels, to reduce the radiation of heat/heat loss through radiation.
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Homeostasis also increases heat loss through...?
Causing the body to sweat, which looses heat through evaporation.
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Homeostasis increases body temperature through...?
The uncoordinated shivering of the skeletal muscles, which increaes respiration and heat production.
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What are Ectotherms?
Organisms which do not regulate their own body temperature (cold blooded).
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What are Endotherms?
Organisms which do regulate their own body temperature (warm blooded).
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What is the first stage in controlling blood glucose levels, when the levels of blood glucose are too high?
High blood glucose levels are detected. (Stimulus)
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What is the second stage in controlling blood glucose levels, when the levels of blood glucose are too high?
The stimulus triggers an action potential which is sent to the CNS. This then triggers the release of insulin. (Effector)
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What is the thrid stage in controlling blood glucose levels, when the levels of blood glucose are too high?
β Glucose receptors in the pancreas detect the levels of gluocse and triggers the production of insulin.
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What is the fourth stage in controlling blood glucose levels, when the levels of blood glucose are too high?
The inuslin bonds with insulin receptors on the liver, and trigger the formation of glygogen from glucose through glycogenesis. This lowers the blood glucose levels.
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Glycogenesis is...?
The formation of glycogen from glucose.
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Gluconeogenesis is...?
The formation of new glucose from amino acids and glycerol.
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Glycogenolysis is...?
The break down of glycogen into glucose.
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What is the first stage in controlling blood glucose levels, when the blood glucose levels are too low?
Low blood glucose levels are detected. (Stimulus)
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What is the second stage in controlling blood glucose levels, when the blood glucose levels are too low?
α Glucose receptors in the pancreas detect the low levels of glucose and trigger the production of glucagon.
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What is the third stage in controlling blood glucose levels, when the blood glucose levels are too low?
Glucagon receptors on the liver trigger the break down of glygogen into glucose through glycogenolysis. This increases blood glucose levels.
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If blood glucose levels are still too low, what happens?
Gluconeogenesis occurs, where amino acids and glycerol are converted into glucose.
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Which hormone also monitors and controls blood glucose levels?
Adrenaline
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Adrenaline is a --- hormone.
Non-lipid-soluble
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Adrenaline binds to specific receptor proteins on the cell membranes of which organ?
Liver cell membranes.
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The binding of adrenaline triggers an associate --- to change shape.
Transmembrane Protein
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The change in shape of the transmembrane protein triggers...?
The activation of the enzyme Adenylate Cyclase.
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Adenylate Cyclase causes the conversion of ATP into...?
Cyclic AMP
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Cyclic AMP activates which protein?
Protein Kinase A
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Protein Kinase A, activates another enzyme, whcih triggers the conversion of...?
Glycogen into glucose, resulting in an increase in blood glucose levels.
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What is Type One Diabetes?
When the body doesnt produce insulin.
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What are the warning signs for Type One Diabetes?
Increased thirst and urination, constant hunger, extreme tiredness, weight loss and blurred vision.
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What is Type One Diabetes caused by?
Genetics, environmental factors and auto-immune factors.
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How can Type One Diabetes be managed?
Through insulin injections, oral medication, diet and exercise and blood glucose monitoring.
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What is Type Two Diabetes?
Where either the body doesnt produce enough insulin, or the body no-longer responds to insulin.
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What are the warning signs for Type Two Diabetes?
Fatigue, wounds healing slowly and pain or numbness in the hands or feet (extremities).
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What can Type Two Diabetes be caused by?
Lifestyle/Lifestlye choices, genetics and aging.
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How can Type Two Diabetes be managed?
Through diet and exercise, blood glucose monitoring and in some cases, insulin injections or oral medication.
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What is Hypoglycaemia?
Low blood glucose levels.
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What is Hyperglycaemia?
High blood glucose levels.
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What are the five stages of Osmoregulation?
1. Ultrafiltration, 2. Selective Reabsorption, 3. The Loop of Henle, 4. The Regulation of Ions, 5. The Collecting Tubule.
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What happens in Ultrafiltration?
High hydrostatic pressure forces small particles out of the blood in the Glomerulus into the Bowman's Capsule. These small particles rae called the filtrate.
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What is in the filtrate produced in the Glomerulus/Bowman's Capsule?
Water, Urea, Salt and Glucose.
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Through which blood vessel does the blood move into the glomerulus?
The afferent arteriole
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What happens in Selective Reabsorption?
Glucose is reabsorbed into the blood in the proximal convoluted tubule through facilitated diffusion and active transport. Some water is also reasorbed into the blood through osmosis, moving along the ψ gradient.
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Na+ is pumped out of the proximal convoluted tubule through active transport. Cl-, glucose and amino acids also leave here, but through...?
Co-Transport
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How much (as a percentage) filtrate is reabsorbed is in selective reabsorption?
85%
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What happens in the Loop of Henle?
The Loop of Henle increases water reabsorption through osmosis, due to the tissue surrounding the Loop of Henle becoming gradually more salty (thus having a lower ψ).
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The longer the Loop of Henle...?
The more water that is absorbed.
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Desert animals such as hamsters have very long Loops of Henle, in order to...?
Preserve as much water as possible.
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The descending limb of the Loop of Henle is ---, whilst the ascending limb is ---?
Permeable to water, impermeable to water.
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Na+ ions are pumped out of the ---, lowering the water potential and allowing water from the --- to fill the gap in the middle of the Loop of Henle.
Ascending limb, descending limb.
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As water is removed, the concentration of the filtrate...?
Increases
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If osmoreceptors in the blood detect low levels of water, then an action potential triggers the release of --- from the ---.
ADH, Pituitary Gland
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ADH stands for...?
Anti-Diuretic Hormone
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ADH triggers the cells in the collecting tubule to open more --- in the membrane.
Aquaporins
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More aquaporins allows for a greater concentration of --- to move into the blood and out of the ---.
Water, Collecting Tubule
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The reabsorption of water in the collecting tubule results in...?
The concentration of the filtrate becoming even greater.
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This results in a ...?
Low volume, high concentration urine.
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Card 2

Front

What is the gap between two nerves called?

Back

Synapse

Card 3

Front

What opens after an action potential arrives at the synapse (the neuromuscular junction)?

Back

Preview of the front of card 3

Card 4

Front

The opening of the calcium channels in the neuromuscular junction causes...?

Back

Preview of the front of card 4

Card 5

Front

What is the name of the transmitter in the neuromuscular junction/synapse?

Back

Preview of the front of card 5
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