| OCR Specifications 2000. Module 1. Section A: Anatomy and Physiology. |
| AS Level PE - Anatomy & Physiology |
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| Contains course notes, worksheets, revision questions and answers and relevant links to useful web sites. |
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| 2001 - S J Bettinson at www.physed.co.uk All comments to [email protected] |
| Define: agonists �.............................�������������������� anatagonists..................���������������������� fixators ���������������������������� synergists .....................���������������������� isometric... ����....................������������������ isokinetic ���..................�������������������� isotonic ���������������������������� concentric ...�������������������������� eccentric......��������������������������. Action: 1. Draw a limb and describe the action that it is performing, e.g. the arm bending at the elbow. 2. Label the bones, joints and muscles involved in the action. 3. Name an exercise that could be used to develop the agonist muscle that you have drawn e.g. bicep curls using free weights to develop the biceps brachii. Action/ Exercise Movement Agonist Antagonist Example:bicep curls using free weights flexion at the elbow joint biceps brachii contracts concentrically on upward phase triceps brachii relaxes/ works eccentrically SECTION 2 Movement Analysis Hitting a hockey ball. This when the subject transfers momentum from their body to the ball in order for great force to act on the ball causing it to travel along distance. The force should be applied to the COG of the ball so that linear motion occurs.. Backswing and transfer of movement backwards. During the backswing the body weight is transferred on to the right leg. There is slight internal rotation of the left leg and slight flexion of the right knee ( a hinge joint) .Whilst the body moves backwards the arms move backwards. There is rotation at the spine as the arms move, the right arms abducts laterally and there is adduction of the left arm. at the ball and socket joint of the shoulder. Contact with the ball. The body weight transfers forwards, the right knee flexes slightly more and then the left leg as the arms move in for the stick to hit the ball. There is adduction at the shoulder joint from both arms. The left hand extends after slight flexion at the wrist joint (condyloid) whilst the backswing occurred. There is transfer of momentum from the body to the stick and then to the ball as they come in to contact. The long length of the hockey stick amplifies the force due to it acting like along lever. The centre back point of the ball must be hit or otherwise the ball will not travel in the same direction of the force. The harder the ball is struck the faster it will accelerate (Newton�s 2nd law). Follow through. Rotation continues at the spine to the left, the left arm begins to adduct as the right arm continues to adduct, the left leg extends and as the right leg extends there is slight internal rotation at the hip Movement Analysis: � describe the skill and its purpose � evaluate the action in terms of the joint action, muscle action and function and the applied mechanics � correct any faults Using this example, choose a sport of your own choice and describe the different phases of an action that is part of that sport. Make reference to the following: joint types, type of movement, muscle function, mechanics. SECTION 3: Motion and Action � classes of levers � lever length � angle of pull � force size A lever is a rigid bar that rotates around a fixed point, a fulcrum. It is used to apply force / effort against a resistance. A lever has two functions: 1. to overcome a larger resistance than the effort applied i.e. provide strength. 2. to increase the distance a resistance can be moved by using an effort greater than the resistance i.e. to improve range of movement. The function depends on the position of the insertion ( where effort is applied) relative to the joint it moves ( the fulcrum). Classes of Levers. 1st order: see-saw e.g. flexion and extension at the neck. 2nd order: wheelbarrow e.g. plantar flexion of the ankle, where the effort is where the Achilles inserts onto the calcaneus and the resistance is the ankle joint supporting the body�s weight. 3rd order: most common lever in the body. It is inefficient in terms of strength but allows range of movement and speed. Angle of Pull This is the position of the insertion relative to the joint, measured in degrees. The angle of pull alters throughout a movement and affects the pulling force. In the resting position the angle of pull for most muscles is quite small and does not exceed 90 degrees throughout the movement. Structures within joints can act as pulleys to increase the angle of pull and efficiency of the muscle, e.g. the patella. A muscle works most effectively as it nears an angle of pull of 90 degrees and where it is not advantageous the only solution is to increase the strength of the muscle. Length of Lever The longer the lever the greater the change in momentum and consequently change in velocity, that can be imparted on an object, e.g a ball can be hit harder when the arm is fully extended, rackets lengthen the lever further. Force Size. Forces can: � stop something move � make something move � prevent something from moving � be internal or external The magnitude of a force is measured in Newtons. Weight is a product if mass an gravity. The force from a muscle is determined by the size and number of the fibres within any one muscle. If a single force is applied to a body throughout its COG the body will move in the same direction as the force. The position of application of the force is important as applying the force slightly off centre will produce angular motion. In sport the athlete has to vary the forces they use and this may be in either open or closed skill situations. SECTION 4: Motion and Action � linear � angular � Newtons laws � gravity � static and dynamic c.o.g. � balance � rotation Motion can only occur if a force is applied. It may be linear (straight line)or angular ( around an axis). Newton�s 1st Law: Law of Inertia This states that: � a body continues in its state of rest or of uniform motion unless a force acts upon it�. The greater the mass of the body the greater force to overcome its state of inertia. Newton�s 2nd Law: Law of Acceleration. �the acceleration of an object is directly proportional to the force causing it and is inversely proportional to the mass of the object.� Momentum = velocity X mass Momentum can be built up and passed from one body part on to another. Newton's 3rd Law:Law of Reaction �for every action there is an equal and opposite reaction� e.g. sprint starts and moving arms to cause rotations in dives. Centre of Gravity/ Point of Balance This alters as the body position alters and the performer moves from being balanced to off balanced. Balance has a static and dynamic dimension. The centre of gravity is dependent upon the distribution of mass within a body. Males COG is usually higher than females. Balance. In a balanced position the COG is over the base. For amore stable position you need a larger base or a lower COG. Off balance positions are also important e.g. the fall of the sprint start and eccentric force for forward somersaults when the COG is in front of the feet. SECTION 5: Structure and Function of the Heart � internal � external � cardiac muscle � chambers � valves � vessels � wall and pericardium � sequences � conduction system The heart lies within the pericardial cavity, which forms part of the mediastinum, part of the thoracic cavity. The heart is surrounded by a closed sac known as the pericardium and is bathed within pericardial fluid, reducing friction from the action of the heart. Heart wall: � endocardium inner layer, smooth tissue, allows uninterrupted blood flow. � myocardium middle layer, cardiac muscle tissue (has a nucleus. Many mitochondria, interconnected by intercalated discs to allow a co-ordinated wave of contraction.) � epicardium outer layer, inner layer of pericardium ,strong fibrous tissue for protection. Inferior and superior vena cavae bring deoxygenated blood from the body to the right atrium Four pulmonary veins bring oxygenated blood from the lungs to the left tarium Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs Aorta carries deoxygenated blood from the left ventricle round the body Coronary artery off the aorta provide the heart with blood from extensive capillaries. Deoxygenated blood leaves via the coronary sinus. The septum separates the two sides of the heart. The atria have thinner walls than the ventricles. The wall of the right ventricle exerts a pressure of about 25mmHg and the left about 120mmHg. Valves. The blood flows in one direction through the heart. The valves between the atria and ventricles are atrioventricular valves, on the right is the tricuspid and on the left is the bicuspid. The flow of blood pushes the valves open and they are closed by thin connectives tissue called the chordae tendinae. They are attached to the papillary muscles, which are attached to the walls of the ventricle. When the ventricles contract so do the papillary muscles, causing the chordae tendinae to tighten and prevent the valves from collapsing inwards. The aortic valve is between the left ventricle and the aorta and the pulmonary valve is between the right ventricle and the pulmonary artery. Theses are both semilunar valves. Blood flowing from the ventricles forces the valves open, these valves also only operate in one direction. The atria contact to force blood into the ventricles which have relaxed. The ventricles contact to force blood onwards and then they relax to let the semilunar valves close again preventing backflow. This is the cardiac cycle and at rest takes place about every 0.8seconds. The contraction phase is known as systole and takes about 0.3seconds and the relaxation phase, diastole takes place every 0.5 seconds. These terms are usually used to describe the action of the ventricles. The muscular pump of the heart needs a stimulus to make it contract. The muscle needs a wave like contraction so that the atria contract before the ventricles. Another problem is the upwards flow of blood to leave via the aorta and pulmonary artery. The wave of contraction is initiated by a special node in the wall of the right atrium called the sinuatrial node or pacemaker. The SA node is controlled by the autonomic nervous system. The nerve impulse spreads like a wave as all the muscle fibres are interconnected. This causes the atria to contract. The impulse then spreads from the ventricles at the apex of the heart under the control of the atrioventricular node sited in the atrioventricular septum.. The impulse travels across the atria to the AV node and then down a specialised bundle of nerve tissue in the septum, the Bundle of His, The nerve impulse is carried to the apex of the heart where the specialised fibres branch out into smaller bundles called purkinje fibres. These extend upwards and across the ventricles causing the ventricles to contract and push blood up and out of the heart. Once the ventricles have completely relaxed another impulse is initiated at the SA node and the cycle is repeated. SECTIO 6: � diastole and systole of cardiac cycle � 2 phase timing � ECG traces � cardiac output � stroke volume � heart rate (rest and exercise) � regulation of rate (neural, hormonal, intrinsic) The Electrocardiogram The electrical activity of the conduction system can be measured by electrodes on the skin of the chest and is recorded in the form of a trace. The P wave occurs just before the atria contract, the QRS complex occurs just before the ventricles contract and the T wave corresponds to repolarisation of the ventricles before ventricular diastole. Cardiac Output This is the blood the heart pumps out per minute (Q).. It is a product of the amount of blood ejected ( the stroke volume) and the heart rate. Q = SV X HR Stroke volume is measured in ml of blood per beat Heart rate beats per minute Cardiac output litres per minute At rest the average SV is 70ml, HR = 72 bpm and Q = 5lites/min. The resting HR of each individual varies greatly. As the heart is exercised it gets bigger and stronger and the end diastolic volume of the ventricles increases. Maximum HR = 220- age. The maximum SV varies from 110-120 ml for an untrained to 150-170ml for a trained athlete. More oxygen can be delivered to the tissue enabling them to work harder and longer. During exercise 85% of blood is channelled to the working muscles. The flow of blood to the brain is maintained but is decreases to the liver, kidneys and gastrointestinal tract. Control of Heart Rate 1. neural 2. hormonal 3. intrinsic. Neural The sympathetic cardiac accelerator nerve speeds up the HR and the parasympathetic vagus nerve slows it down. These nerves stimulate the SA node , the pacemaker. Control of the nerves is co-ordinated by the cardiac control centre which is stimulated by: � muscle receptors in the muscles and joints that stimulate the cardiac control � chemoreceptors in the muscle that respond to changes in muscle chemistry e.g. rise in lactic acid � excitement � changes in blood pressure, detected by baroreceptors in the aorta and carotid arteries, a decrease in blood pressure results in an increase in HR and SV � chemoreceptors in the aorta and carotid arteries that respond to changes in O2, CO2 and pH levels. Hormonal Adrenaline is secreted from the adrenal glands into the blood and stimulates the SA node, increasing the HR. It also increases the strength of contraction produced by the myocardium. Intrinsic When a muscle warms up the conduction system speeds up. The heart rate of a warm heart increases. During exercise the amount of blood returning to the heart is increased, stretching the cardiac muscle more than usual. This stimulates the SA node and increases the HR and force of contraction. This relationship between SV and venous return is Starlings Law. Exercise. The HR increases during exercise for the increased demands of o2 an to remove waste products. Before exercising your HR increases, the anticipatory rise is caused by adrenaline. The heart rate rises rapidly as exercise commences due to a nerve reflex response, initiated by muscle receptors stimulating the cardiac control centre. Chemoreceptors in the muscles react to chemical changes and send messages to the cardiac control centre to increase HR. The heart warms up and the rate increases further. When you stop the muscle receptors stop stimulating the cardiac control centre and the heart rate begins to fall quite rapidly. The activity of the chemoreceptors also reduces this, combined with the reduced levels of adrenaline, the drop in venous return and in temperature. SECTION 7: The Heart � neural, hormonal and intrinsic factors � HR, stroke volume and cardiac output � sub maximal and maximal exercise � recovery � graphs of HR varying with load and recovery The HR increases with an increase in load. Initially cardiac output increases as a result of both the HR and the SV increasing, but maximum SV is achieved during sub maximal work and any increase in cardiac output during maximal exercise is solely due to an increase in HR. As the load increases the Hr steadily rises until a maximum HR is reached. By this stage most of the energy is being produced anaerobically and you will have to stop exercising because of fatigue. If you are working submaximally your HR will usually rise until you reach a point where the o2 delivered to the working muscles is sufficient to release enough energy aerobically to cope with the demands of the exercise. The HR will then reach a plateau, this is steady state exercise. After exercising it takes a few minutes for your heart rate to return to resting levels. This is because you need to maintain an elevated rate of aerobic respiration in order to replenish some of the energy stores you have used during the exercise and also to remove some of the waste products that have accumulated. The Heart Myogenic: generates its won pulse P atria contract QRS ventricles contract T ventricles relax Bradycardia HR < 60 bpm Venous return muscle pump and respiratory pump from ventilation action Regulation of HR Hormonal adrenaline Intrinsic warmer Neural muscle receptors that stimulate the cardiac control centre sat the onset of exercise chemoreceptors in muscles, lactic acid response excitement baroreceptors chemoreceptors in aorta and carotid arteries, respond to gas and pH levels Task: Resting HR sitting , carotid Resting HR lying, carotid Resting HR sitting, radial 3 min step test, HR after exercise HR after 1 min HR after 2 mins HR after 3 mins 3 min faster rate step test HR after exercise HR after 1 min HR after 2 mins HR after 3 mins SECTION 8: Structure and Type of Vessel � arteries � arterioles � capillaries � veins � venules � systemic and pulmonary circulation Arteries and Arterioles. Arteries carry oxygenated blood from the heart to the tissues. Arteries branch off the aorta to form arterioles. They consist of three layers of tissue � outer fibrous layer, tunica adventitia/ externa � thick middle layer, tunica media � thin lining of cells to the inside, the endothelium, tunica intima. Tunica media is made up of elastic tissue and smooth muscle. Arteries have more elastic tissue but less smooth muscle than arterioles. Vasoconstriction and dilation can therefore occur which helps regulate blood pressure and ensures tissues are receiving sufficient blood e.g. during exercise. They have 3 functions: 1. carry and control blood flow 2. cushion the pulsatile flow of blood from the heart 3. help control blood pressure Veins and Venules. These return blood to the heart. They have less smooth muscle and elastic tissues than arteries. They join to form the vena cavae before entering the heart. They have thinner walls which allows them to distend and for blood to pool. Veins also have pocket valves to prevent back flow and so up to 70% of blood volume can be found in the venous system. Capillaries. They are composed of a single layer of endothelial cells. The capillary network is very extensive. Distribution of blood through the capillaries is controlled by pre capillary sphincters. Pulmonary circulation is when blood leaves the heart to go to the lungs to pick up oxygen. Systemic circulation is blood pumped around the rest of the body. SECTION 9: Vascular System � venous return � vasometer centre � vascular shunting � blood flow and velocity � blood pressure and exercise effects |
| Section 1: Muscle Function |
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