Why are muscles described as being antagonistic?
Muscles can only pull, they cannot push, so at least two muscles are needed to move a bone to and fro. A pair of muscles that work in this way are described as antagonistic.
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What is an extensor?
A muscles that contracts to cause extension of a joint is called an extensor.
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What is a flexor?
A flexor is the corresponding muscles that contracts to reverse the movement.
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Is your bicep an extensor or flexor?
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Is your tricep an extensor or flexor?
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Give three examples of synovial joints.
The hip, knee and ankle joints are examples of synovial joints.
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What is a synovial joint?
A synovial joint is when the muscles that articulate (move) in the joint are separated by a cavity filled with synovial fluid, which enables them to move freely.
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What does a ligament do?
Joins bone to bone.
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Describe the properties of a ligament.
Ligaments are strong and flexible.
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What does a tendon do?
Joins muscle to bone.
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What does cartilage do?
It protects bones within joints, absorbs synovial fluid and acts as a shock absorber.
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What properties of ligaments make them effective at holding the bones in place at a joint?
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What reduces the wear and tear due to friction in a mobile synovial joint?
Synovial fluid, cartilage
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What properties must tendons have to make them effective at enabling movement?
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What is muscle made up of?
Muscle is made up of bundles of muscle fibres. Each fibre is a single cell.
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What is different about muscle cells compared to other body cells?
Muscle cells are multinucleate.
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Why do muscle cells have to be multinucleate?
A single nucleus could not effectively control the metabolism of such a long cell.
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How does the elongated muscle fibre form?
During prenatal development, several cells fuse together to from an elongated muscle fibre.
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What is the contractile unit of a myofibril called?
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What are the names of the protein molecules that make up a sarcomere?
Actin and Myosin
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What is the name of the thick protein filament in the sarcomere?
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What is the name of the thin protein filament in the sarcomere?
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How are contractions of muscles brought about?
Contractions are brought about by coordinated sliding of myosin and actin filaments within the muscle cell sarcomeres.
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Why do muscle fibres have a striped (striated) appearance?
The proteins (actin and myosin) overlap and give the muscles fibre its characteristic striped appearance under the microscope.
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What two other protein molecules is actin associated with?
Troponin and Tropomyosin
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What are myosin molecules shaped like?
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What is the sarcoplasmic reticulum?
This is a specialised type of endoplasmic reticulum; a system of membrane bound sacs around the myofibrils. It is a store for calcium ions.
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What happens once calcium binds to a troponin molecule?
When a calcium ion binds to the troponin molecule it causes it to move. As a result, the tropomyosin shifts its position as well.
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Once the tropomyosin shifts in its position what is exposed?
Myosin binding sites on the actin filament are exposed.
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What happens once myosin heads bind with the myosin binding sites on the actin filaments?
ADP and Pi are released. The myosin changes shape causing the myosin head to nod forward. This results in the relative movement of the filaments.
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What happens when an ATP molecule binds to the myosin head?
This causes the myosin head to detach and an ATPase on the myosin head hydrolyses the ATP, forming ADP and Pi. The myosin head returns to its original position and the cycle can start again.
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What happens when a muscle relaxes?
The muscle is no longer being stimulated by nerve impulses. Calcium ions are actively pumped out of the muscle sarcoplasm, using ATP. The troponin and tropomyosin move back once again blocking the myosin binding sites on the actin.
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What happens to muscles in the absence of ATP?
In the absence of ATP, the cross-bridges remain attached. This is what happens in Rigor Mortis. Any contracted muscles become rigid.
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What does BMR stand for?
Basal Metabolic Rate.
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What is BMR a measure of?
BMR is a measure of the minimum energy requirement of the body at rest to fuel basic metabolic processes.
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How is BMR measured?
It is measure by recording oxygen consumption under strict conditions; no food is consumed for 12 hours before measurement, with the body totally at rest in a thermostatically controlled room.
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Why would a single nucleus be unable to control the metabolism of a long cell like a muscle fibre?
It would take too long to move proteins synthesised from mRNA from a single nucleus and to reach the furthest parts of the cell
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Women generally have a higher percentage of body fat than men. Why might this account for the fact that women generally have lower BMRs?
Better insulation reduces heat loss; so less energy is used to maintain core body temperature.
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What is the source of energy for all animal activity?
Food. The energy sources for most people are carbohydrates and fats, which have either just been absorbed from the gut or have been stored around the body.
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What series of enzyme controlled reactions is linked to the synthesis of ATP?
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What is ATP created from?
ADP and inorganic phosphate.
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How do phosphate ions exist in solution?
They are hydrated, i.e. water molecules are bound to them.
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In order to make ATP what must happen to the phosphates in solution?
Phosphate must be separated from these water molecules. This reaction requires energy.
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What is higher in energy, ATP in water or ADP and Pi in water?
ATP - this is why it is a way of storing chemical potential energy.
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Why does the hydrolysis of ATP provide energy?
It require little energy to break a phosphate off an ATP molecule. Once removed the phosphate group becomes hydrates and a lot of energy is released as the bonds between water and phosphate form.
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What is the initial stage of carbohydrate breakdown known as?
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What does glycolysis literally mean?
'Splitting of sugar'
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Where are stores of glycogen found?
In muscle or liver cells.
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What is glycogen?
A polymer of glucose.
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Why does glycolysis require an input of energy?
Glucose is stable and unreactive so enery in the form of ATP needs to be supplied in order to get things started.
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How do you increase the reactivity of glucose in glycolysis?
Two phosphate groups are added to the glucose from two ATP molecules, and this increases the reactivity of the glucose.
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What happens to the glucose once the phosphates have been added to it?
It can now be split to form two intermediate compounds, each with three carbons.
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How is pyruvate formed?
The intermediate compounds are oxidised, producing pyruvate (3C). Two hydrogen atoms are removed during the reaction and taken up by the coenzyme NAD.
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What is a coenzyme?
Coenzymes are small, organic, non-protein molecules that carry chemical groups between enzymes.
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Why are the glycolysis reactions described as anaerobic?
No oxygen is used.
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What happens to pyruvate if oxygen is available?
If oxygen is available pyruvate passes into the mitochondria. There it is completely oxidised, forming carbon dioxide and water.
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What happens to pyruvate during the link reaction?
Pyruvate is decarboxylated and dehydrogenated.
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What is decarboxylation ?
When carbon dioxide is released as a waster product.
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What is dehydrogenation?
When hydrogens are removed (2) and taken up by the coenzyme NAD.
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What is formed at the end of the link reaction?
Acetyl CoA (2C)
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What does Acetyl CoA combine with in the first part of the Krebs cycle?
It combines with a 4 carbon molecule forming a 6 carbon molecule.
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What happens to the 6 carbon molecule in the Krebs cycle?
Carbon dioxide is removed and 2H are removed to form a 5 carbon molecule. The 2H are used to reduce the coenzyme NAD.
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What happens to the 5 carbon molecule in the Krebs cycle?
Carbon dioxide is removed and 3 x 2H are removed, causing 2 NAD's to be reduced and one FAD to be reduced. The four carbon molecule is recreated.
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What is the role of the reduced coenzymes in aerobic respiration?
The reduced coenzyme shuttles the hydrogen atoms to the electron transport chain on the mitochondrial inner membrane. Each hydrogen atom's proton and electron separate, with the electrons passing along a chain of electron carriers - e transport chain
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What is substrate level phosphorylation?
The energy for the formation of ATP comes from the substrates.
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Why is the synthesis of ATP via the electron transport chain termed 'oxidative phosphorylation'?
Oxidation/reduction reactions occur as the electrons pass along the electron transport chain; the final electron acceptor is oxygen; phosphate is added to ADP to form ATP.
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Energy released as -e pass along transport chain; this energy used to move H+ from matrix to intermem.space; this creates elec.chem gradient (intermem. space >+ than matrix); H+ diffuse through protein channels; ATPase on protein - ADP+Pi->ATP
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What happens to H+ in the matrix?
The H+ and -e recombine to form hydrogen atoms. These combine with oxygen to form water. The oxygen, acting as the final carrier in the electron transport chain is thus reduced.
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What equipment do you use to measure the rate of respiration?
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Why is KOH or soda lime put in the bottom of the test tube with the respiring organism?
To absorb the carbon dioxide released.
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What is the advantage of having a system of enzyme-controlled reactions to transfer energy from food fuels?
It prevents the cell overheating and allows the controlled release of energy in small useful quantities.
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What happens to pyruvate in anaerobic respiration?
Pyruvate is reduced to form lactate and the oxidised NAD is regenerated.
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What is the effect of lactate build up?
H+ from the lactic acid accumulates in the cytoplasm and neutralises any negatively charged groups in the enzymes active site. The attraction between the charged groups in the active site and the enzyme will be affected - may no longer bind together.
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How do we get rid of lactate?
Most of the lactate is converted back into pyruvate, and is oxidised directly to from CO2 and H2O in the Krebs cycle. As a result oxygen uptake is greater than normal in the recovery period - oxygen debt or post-exercise oxygen consumption.
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Why are athletes in training advised not to simply stop or lie down after strenuous exercise, but rather to aim for active recovery through gentle exercise?
To maintain rapid blood flow through the muscles to supply oxygen and to remove lactate.
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What molecule is used for the instant regeneration of ATP?
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What is creatine phosphate?
This is a substance stored in muscles that can be hydrolysed to release energy. This energy can be used to regenerate ATP from ADP and phosphate, the phosphate being provided by the creatine phosphate itself.
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When does creatine phosphate breakdown begin?
It begins as soon as exercise starts, triggered by the formation of ADP.
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Can creatine phosphate stores be regenerated?
Yes, they are regenerated from ATP when the body is at rest.
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What are the three energy systems?
ATP/PC, aerobic respiration and anaerobic respiration.
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What is aerobic capacity?
The ability to take in, transport and use oxygen.
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What is cardiac output?
Volume of blood pumped by the heart in a minute.
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How do you maintain adequate oxygen supply when running?
Increasing cardiac output, faster rate of breathing and deeper breathing.
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What is stroke volume?
The volume of blood ejected from the left ventricle each time it contracts.
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How do you measure cardiac output?
cardiac output = stroke volume x heart rate
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What is the stroke volume for most adults at rest?
50-90 cm cubed
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What is venous return?
The blood returning to the heart.
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Why does stroke volume and cardiac output increase with exercise?
In diastole, during exercise, the heart fills with a larger volume of blood. The heart muscle is stretched to a greater extent, causing it to contract with greater force, and so more blood is expelled.
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Why does stroke volume specifically increase during exercise?
When the body is at rest, the ventricles do not completely empty with each beat; approximately 40% of the blood volume remains in the ventricles after contraction. During exercise stronger contractions occur, ejecting more of the blood from the heart
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What is the artery at your wrist called?
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What is the artery at your neck called?
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What is the average heart rate for males and females?
Males - 70 bpm; Females - 72 bpm
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What are some factors that cause differences in heart rate?
Our hearts differ in size, owing to differences in body size and genetic factors.
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Why does a larger heart result in a lower resting heart rate?
It will expel more blood with each beat and so, other things being equal, does not have to beat as frequently to circulate the same volume of blood around the body.
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Why is the heart described as being myogenic?
It can contract without external nervous stimulation.
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Where does depolarisation of the heart start?
At the sinoatrial node (SAN)
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What is the sinoatrial node also known as?
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What causes the atria to contract?
The SAN generates an electrical impulse; this spreads across the right and left atria, causing them to contract at the same time.
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Following atrial systole, where does the impulse generated by the SAN travel to?
The atrioventricular node (AVN)
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The impulse is delayed at the AVN, for how long and why is this important?
0.13s; The delay ensures that the atria have finished contracting, and that the ventricles have filled with blood before they contract.
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Following the delay at the AVN, where does the impluse go?
The signal reaches the Purkyne fibres. These are large, specialised muscles fibres that conduct impulses rapidly to the apex of the ventricles.
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Where is the apex of the ventricles?
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There are left and right bundles of fibre, what are they collectively called?
Bundle of His.
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Why does contraction of the ventricles begin at the tip?
The first ventricular cells to be depolarised are at the apex of the heart, so that contraction begins at this point and travels upwards towards the atria.
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How can the electrical activity of the heart be detected and displayed?
Using an electrocardiogram (ECG)
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How is an ECG carried out?
Electrodes are attached to the persons chest and limbs to record the electrical produced during the cardiac cycle. When there is a change in polarisation of the cardiac muscle, a small electrical current can be detected - this is measured by an ECG.
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What is the P wave on an ECG?
Depolarisation of the atria, leading to atrial contraction (atrial systole)
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What is the PR interval on an ECG?
The time taken for the impulses to be conducted from the SAN across the atria to the ventricles, thought the AVN.
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What is the QRS complex on an ECG?
The wave of depolarisation resulting in contraction of the ventricles (ventricular systole)
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What does the T wave show on an ECG?
Repolarisation (recovery) of the ventricles during the heart's relaxation phase (diastole).
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Why does an ECG not show atrial repolarisation?
The signals generated are small and are hidden by the QRS complex.
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What is bradycardia?
A heart rate of less that 60 bpm; common in fit athletes at rest by can also be a symptom of heart problems. Possible causes include hypothermia , heart disease or use of medicines or drugs.
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What is tachycardia?
A heart rate greater than 100 bpm; normally the result of anxiety, fear, fever or exercise. It can also be a symptom of coronary heart disease, heart failure, use of medicine or drugs, fluid loss or anaemia.
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What happens during a period of ischaemia?
The heart muscle does not receive blood due to atherosclerosis causing a blockage of coronary arteries. The normal electrical activity of the heart and rhythm of the heart are disturbed, and arrhythmias can affect a larger area of heart muscle.
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What can an ECG provide information about?
Abnormal heartbeats, areas of damage, and inadequate blood flow.
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What controls your heart rate?
Heart rate is under the control of the cardiovascular control centre located in the medulla of the brain.
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What are the names of the two nerves going form the cardiovascular control centre to the heart?
Accelerator (sympathetic nerve) and Vagus nerve (parasympathetic) (decelerator)
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What does stimulation of the SAN by the sympathetic nerve cause?
An increased heart rate
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What does stimulation of the SAN by the vagus nerve cause?
A decreased heart rate
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What does the cardiovascular control centre detect?
Accumulation of carbon dioxide and lactate in the blood, reduction of oxygen and increased temperature.
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What happens to blood pressure as you increase cardiac output?
It rises; to prevent it rising too far, pressure receptors in the aorta and the carotid artery send nerve impulses back to the cardiovascular control centre. Inhibitory nerve impulses are then sent to the SAN - negative feedback.
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What does stimulation of sympathetic nerves do?
Prepares the body for action
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What does stimulation of parasympathetic nerves do?
Controls the body's systems when resting and digesting
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What causes the release of adrenaline?
Fear, excitement and shock.
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What is adrenalines effect on heart rate?
Has a direct effect on the SAN , increasing the heart rate to prepare the body for any likely physical demands.
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How does adrenaline maximise blood flow to active muscles?
It causes the dilation of the arterioles supplying skeletal muscles, and constriction of the arterioles going to the digestive system and other non-essential organs; this maximises blood flow to the active muscles.
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Why does pressing on your carotid artery reduce pulse rate, thereby giving a false reading?
If pressing on the neck causes increased blood pressure in the carotid artery, blood pressure receptors in the carotid artery would signal to the cardiovascular control centre which in turn would stimulate the vagus nerve-reducing heart rate/pulse
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Where could you take your pulse more reliably?
The wrist or the groin
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What is tidal volume?
The volume of air we breathe in and out at each breath
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What is vital capacity?
The maximum volume of air we can inhale and exhale
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How can lung volumes, including tidal volume and vital capacity, be measured?
Using a spirometer
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What is minute ventilation?
The volume of air taken into the lungs in one minute
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What controls breathing?
The ventilation centre in the medulla oblongata of the brain
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How do we inhale?
Ventilation centre send impulse every 2-3secs to external intercostal muscles and diaphragm muscles. Both sets of muscles contract, causing inhalation.
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What happens during deep inhalation?
During deep inhalation, not only are the external intercostal muscles and diaphragm muscles stimulated, but the neck and upper chest muscles are also brought into play.
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How do we stop inhaling?
As the lungs inflate stretch receptors in the bronchioles are stimulated. The stretch receptors send inhibitory impulses to the ventilation centre. Impulses to the muscles stop, the muscles relax stopping inhalation and allowing exhalation.
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How do we exhale?
Exhalation is caused by the elastic recoil of the lungs and by gravity helping to lower the ribs. Not all the air in our lungs is exhaled with each breath; the residual air and air inhaled mix with each breath.
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When do internal intercostal muscles contract?
The internal intercostal muscles only contract during deep exhalation. For example, during vigorous exercise a larger volume of air is exhaled, leaving less residual air in the lungs.
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What is the most important stimulus in controlling the breathing rate and depth of breathing?
Concentration of dissolved carbon dioxide in arterial blood - its effect on pH
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How does an increase in blood carbon dioxide concentration causes an increase in ventilation?
CO2 dissolves in plasma-makes carbonic acid -> increases the acidity of blood (H+)-Chemoreceptors sensitive to H+ located in the ventilation centre(VC) of the medulla-they detect rise in H+ conc. Impulse sent to other parts of VC-breathing stimulated
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Why are there chemoreceptors in the carotid artery and aorta?
These are stimulated by changes in pH resulting from changes in carbon dioxide concentration. These chemoreceptors monitor the blood before it reaches the brain, and send impulses to the ventilation centre.
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How is carbon dioxide removed from the alveolar air?
More frequent and deeper breaths maintain a steep conc. gradient of CO2 between alveolar air and blood- this in turn ensures efficient removal of CO2 and uptake of O2.
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What is the region of the brain that controls movement?
The motor cortex
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What does the motor cortex do once you start exercising?
It sends impulses to the ventilation centre in the medulla, increasing ventilation sharply.
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During vigorous exercise, the concentration of oxygen in the lungs is higher than when at rest. Suggest the reasons for, and the advantage of, this elevated oxygen level.
The depth and rate of breathing increase so there is a greater volume of air inhaled and mixed with the residual air in the lungs-conc. of O2 increases-steeper diffusion gradient-increased speed of gas exchange-advantage is raised metabolic rate.
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Suggest why it is beneficial that stimulation of stretch receptors in the muscles increases ventilation.
Stretch receptors signal the start of movement, allowing ventilation to increase before there is a build-up of the waste products of respiration.
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When a person breathes air containing 80% oxygen, the minute ventilation is reduced by 20%. Explain how this occurs.
The increased concentration of oxygen in the blood is detected by the chemoreceptors that slow down the breathing rate and decrease the depth of breathing.
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What is aerobic capacity dependent on?
Uptake and transport of oxygen to the muscles as well as the efficiency of use once it reaches the muscle fibres.
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What are the two different muscle fibres called?
Slow twitch and fast twitch.
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What are slow twitch fibres?
Fibres specialised for slower, sustained contraction, and can cope with long periods of exercise. They need to carry out large amounts of aerobic respiration to do this.
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What are the key features of slow twitch fibres?
Contain large amounts of the dark red pigment myoglobin; they have many mitochondria and high concentrations of respiratory enzymes; they are associated with numerous capillaries to ensure a good oxygen supply.
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What is myoglobin and what does it do?
It is a protein similar to haemoglobin. It has a high affinity for oxygen, and only releases it when the concentration of oxygen in the cell falls very low; it therefore acts as an oxygen store within muscle cells.
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What are fast twitch fibres?
Fibres specialised to produce rapid, intense contractions. The ATP used in these contractions is produced almost entirely from anaerobic glycolysis.
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What are the key features of fast twitch fibres?
They have few mitochondria. They also have very little myoglobin, so have few oxygen reserves; only a few associated capillaries. They fatigue easily due to rapid build up of lactate.
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What is the optimal temperature range for human cells?
37-38 degrees Celsius
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What will happen to metabolic reactions if body temperature falls below or rises above the normal range?
Low temperatures lead to low metabolic rates as enzyme controlled reactions are slow; high temperatures increase the rate of metabolic reactions initially, but then it declines as enzymes denature at higher temperatures.
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What is homeostasis?
The maintenance of a stable internal environment.
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What is negative feedback?
A deviation in from the norm results in a change in the opposite direction back to the norm. This process is known as negative feedback.
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What is thermoregulation?
The control of body temperature.
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How is temperature maintained in humans?
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What is the hypothalamus?
The hypothalamus is the control mechanism and acts as a thermostat, turning on the effectors necessary to return the temperature to the norm.
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What can the hypothalamus do to cool the body down?
Stimulate sweat glands to secret sweat; inhibit contraction of the arterioles in skin(capillaries dilate - vasodilation), hair erector muscles(hairs lie flat), liver(reduce metabolic rate) and skeletal muscles(no shivering).
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What can the hypothalamus do to heat the body up?
Stimulates arterioles in the skin to constrict, hair erector muscles to contract, liver to raise metabolic rate and skeletal muscles to contract in shviering. Inhibits sweat glands.
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What effectors are activated when the body temperature falls below the norm?
Hair erector muscles; muscles in the walls of the arterioles in the skin; skeletal muscles; liver cells.
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How does arteriole vasoconstriction reduce energy loss?
It decreases the blood flow to skin which reduces the energy lost by radiation, conduction and convection.
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How does arteriole vasodilation increase energy loss?
It increases the blood flow to the skin which increase the energy lost by radiation, conduction and convection.
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What are the 4 methods of energy transfer?
Radiation, conduction, convection and evaporation.
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Why does high humidity make marathon running more dangerous?
Less energy is lost by evaporation which makes it harder for athletes to keep their body temperatures down to a safe level.
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What are URTIs?
Upper Respiratory Tract Infections
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How does moderate exercise affect the immune system?
Moderate exercise increases the number and activity of a type of lymphocyte called natural killer cells.
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Where are natural killer cells found?
In the blood and lymph
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Why are natural killer cells called natural killer cells?
It was once thought that they did not require activation to destroy damaged cells.
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How are natural killer cells activated?
They are activated in several ways, for example by cytokines and interferon.
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How do natural killer cells function?
How natural killer cells work in not yet thoroughly understood, but they seem to target cells that are not displaying 'self' markers. They release the protein perforin which makes pores in the targeted cell membrane - leads to apoptosis.
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Why is cell apoptosis likely to have a better outcome than cell lysis in the case of cells infected by a virus, such as one that causes URTI?
Apoptosis is likely to destroy the infected cell and any virus inside it; cell lysis would split open the cell releasing any viruses inside.
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What is the effect of vigorous exercise on the immune system?
Research shows that, during recovery after vigorous exercise, the number and activity of some cells in the immune system falls (natural killer cells, phagocytes, B-cells, T-helper cells). The specific immune system is depressed as a result of this.
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How will the action of killer T cells be affected by the decrease in T helper cell numbers?
Few T-helper cells so less cytokines produced; T-killer cells will not be activated by the cytokines.
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What does treatment of joint damage normally consist of?
RICE - rest, ice, compression, elevation; anti-inflammatory painkillers and, if necessary, surgery.
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What joint in particular is susceptible to damage?
The knee joint.
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What happens when the articular cartilage covering the surfaces of the bones wears away?
The bones may actually grind against each other, causing damage that can lead to inflammation and a form of arthritis.
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What is patellar tendonitis (jumper's knee)?
It occurs when the kneecap (patella) does not glide smoothly across the femur due to damage of the articular cartilage on the femur.
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What is bursitis?
The bursae (fluid sacs) that cushion the points of contat between bones, tendons and ligaments can swell up with extra fluid. As a result, the
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What can sudden twisting or abrupt movement of the knee joint result in?
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What problems can large incisions during surgery cause?
These large incisions can cause a great deal of bleeding, a lot of pain, increased risk of infection, and prolonged recovery after the operation.
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What is keyhole surgery on joints called?
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How would a surgeon carry out an arthroscopic procedure?
The surgeon makes one or two small incisions (4mm), a small camera and light source are inserted, allowing the inside of the joint to be seen, and a diagnosis can be made or confirmed. If surgery required, miniature instruments are inserted in cut.
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What type of damage to the knee joint can be tackled particularly effectively by keyhole surgery?
Damaged cruciate ligament.
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What type of joint is the knee and how many ligaments is it held by?
Hinge joint; held by 4 ligaments, 2 of which are cruciate ligaments.
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What does the posterior cruciate ligament do?
Prevents the knee from bending back too far; damage to this usually occurs when you fall onto a bent knee.
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What does the anterior cruciate ligament do?
Prevents the knee form being bent forward too much; damage to this usually occurs by sudden turning, pivoting, or cutting manoeuvres.
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Describe the normal role of a tendon?
Tendons connect muscle to bone.
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Suggest 2 reasons why the tendon used to repair a ligament is taken from the same injured joint?
Only one operation is required; there should be no immune response to a tendon from the same person whereas a tendon from someone else could be rejected.
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Ligaments are more elastic than tendons. Suggest what advice a footballer who has had a torn ligament in her knee replaced with one of her tendons might be given to help her get fit again?
The tendons will be less elastic than a ligament, so she is likely to be advised to exercise her knee gently to stretch the tendon so that she regains full movement in her joint; she must avoid overstretching and damaging the tendon.
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You might think removing a tendon to use as a ligament would just cause a different problem for the athlete. Suggest why it doesn't?
Muscles usually have more than one attachment to bones (tricep has 3), so that removal of one tendon will still leave other tendons attaching muscle to bone; the remaining tendons may grow stronger with use so missing tendon doesn't cause weakness.
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What is a prosthesis?
An artificial body part used by someone with a disability to enable him or her to regain some degree of normal function or appearance.
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What is a particularly successful use prosthetics?
Replacing hip and knee joints with artificial joints.
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Name some advantages of physical activity?
Lowers blood pressure (more vasodilation); increases level of blood HDLs; helps to maintain a healthy weight; improves mental wellbeing; reduces risk of some cancers; reduces likelihood of developing type 2 diabetes.
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What are hormones?
Hormones are chemical messengers, released directly into the blood from endocrine glands.
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Why are many hormones produced in their inactive form or packaged in secretory vesicles by the golgi apparatus?
So that the cells in the endocrine glands that make the hormone are not themselves affected by their products.
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Which hormones does the pituitary gland release
Growth hormone (stimulates growth); FSH (controls testes and ovaries); ADH (causes reabsorption of water in kidneys)
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What hormone does the thyroid gland release?
Thyroxine (raises basal metabolic rate)
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What hormone does the adrenal gland release?
Adrenaline (raises basal metabolic rate, dilates blood vessels, prepares the body for action)
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What hormone does the pancreas release?
Insulin (lowers blood glucose concentration)
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What hormone does the ovary release?
Oestrogen (promotes development of ovaries and female secondary sexual characteristics)
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What hormone does the testis release?
Testosterone (promotes development of male secondary sexual characteristics)
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How are hormones carried around they body?
They are carried in the bloodstream.
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Why can steroid hormones pass through the cell membrane?
They are lipid based and so dissolve.
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Most hormones travel all around the body in the blood, and will come into contact with many cells. Why do hormones only produce a response within cells of their target organs?
The hormone binds to a complementary receptor to bring about a response; only the target cells have the complementary receptors.
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What does EPO stand for?
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What type of hormone is EPO?
It is a peptide hormone.
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Explain how taking EPO would increase the performance of an endurance athlete.
It would increase the number of red blood cells and hence the amount of haemoglobin; improving the blood's oxygen-carrying capacity; enhancing oxygen delivery to the muscle tissue and hence improving aerobic capacity.
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Suggest how EPO might stimulate formation of new blood cells.
Unspecialised stem cells in the bone marrow divide and differentiate to form red blood cells; EPO binds to receptors on target cells in the bone marrow; altering gene expression that will lead to formation of the red blood cells inc. haemoglobin.
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What are the health risks associated with EPO?
If EPO levels are too high, the body will produce too many red blood cells, which can increase the risk of thrombosis, possibly leading to heart attack and stroke.
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What is meant by thrombosis?
Blood clots in arteries or veins.
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Explain why EPO is not taken by sprint athletes?
Sprint athletes rely on anaerobic respiration so performance is not dependent on the athlete's aerobic capacity.
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Why would it be important to distinguish between natural and synthetic EPO?
To help determine if athletes are taking EPO as a performance-enhancing drug.
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What type of hormone is testosterone?
It is a steroid hormone.
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What is testosterone made of?
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What receptor does testosterone bind to?
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What does testosterone do?
It binds to androgen receptors on target cells. They modify gene expression to alter the development of the cell; for example they will increase anabolic reactions such as protein synthesis in muscle cells, increasing the size and strength of muscle.
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Why is injecting testosterone not an effective way of building muscle, and how has this problem been overcome?
The testosterone is quickly broken down; to overcome this problem synthetic anabolic steroids such as nandrolone have been manufactured by chemical modification of testosterone.
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What are the dangers of using and overusing anabolic steroids?
Can cause high blood pressure, liver damage, changes in menstrual cycle in women, decreased sperm production and impotence in men, kidney failure and heart disease. They can increase aggression in both women and men.
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What were anabolic steroids originally developed for?
The treatment of muscle-wasting diseases.
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What are anabolic steroids classed as?
Class C drugs.
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How can you detect the use of anabolic steroids?
Anabolic steroids and their by-products can be identified relatively easily in urine samples by the technique of mass spectrometry.
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What happens to the ration of testosterone to epitestosterone when you take anabolic steroids?
The ration increases; if the ratio is above 4:1 you are guilty of doping.
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Name a performance enhancing substance that is not banned.
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What is creatine considered to be?
A nutritional supplement.
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Where is creatine naturally found?
In meat and fish. It is also synthesised in the body from the amino acids glycine and arginine.
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Why would creatine considered to be performance-enhancing?
It is reported to increase the amount of creatine phosphate in muscles; this should improve performance in short-duration, repeated, high-intensity exercises.
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What are some of the adverse effects of taking creatine?
Diarrhoea, nausea, vomiting, high blood pressure, kidney damage and muscle cramps.
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Why are the International Olympic Committee and other sporting bodies against the use of performance-enhancing substances?
They consider them to be unhealthy and against the ethics of the sport.
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Why would some people consider the use of performance-enhancing substances ethically acceptable?
Athletes have the right to decide whether to take the drug or not, deciding for themselves if the benefit is worth the health risk. There is already inequality of competition due to differences in time available to train and resources available.
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Other cards in this set
What is an extensor?
A muscles that contracts to cause extension of a joint is called an extensor.
What is a flexor?
Is your bicep an extensor or flexor?
Is your tricep an extensor or flexor?