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Exercise Physiology Circulatory System What is the Human Circulatory System ? • The main organ of the circulatory system is the Human Heart. • The Functions of the Circulatory System ? • To transport blood around the body. The blood itself also carries numerous other substances which the body requires to function. Circulatory System • The main substance being Oxygen, carried by a protein called haemoglobin, found inside red blood cells. • Blood also carries waste products, such as Carbon Dioxide away from muscles and organs in order to be dispelled by the lungs. Circulatory System Circulatory System DID YOU KNOW!!?? 1. It takes 20 seconds for blood to circulate the entire body. Oxygenated blood leaves the aorta about1 mile an hour. 2. The power output of the heart ranges from 1-5 watts per minute. Which is the equivalent to the usage of a 60 watt bulb. It has been said that enough energy is produced a day to drive a truck 20 miles. Circulatory System 3. Human blood is colourless, it is the hemoglobin that makes it red. 4. Due to the heart having its own electrical impulse, it will continue to beat even when removed from the body as long as it has an adequate supply of oxygen. 5. On average, the human body has about 5 liters (almost 9 pints) of blood continually traveling through it by way of the circulatory system. A kitchen tap would need to be turned on all the way for at least 45 years to equal the amount of blood pumped by the heart in an average lifetime. Circulatory System Terminology • Heart rate is simply the number of heart beats per minute. • Stroke volume is the volume of blood, in millilitres (mL), pumped out of the heart with each beat. • Cardiac output: is the volume of blood pumped by the heart per minute (mL blood/min). Cardiac output is a function of heart rate and stroke volume. Cardiac Output in mL/min = heart rate (beats/min) X stroke volume (mL/beat) Circulatory System • An average person has a resting heart rate of 70 beats/minute and a resting stroke volume of 70 mL/beat. The cardiac output for this person at rest is: • Cardiac Output = 70 (beats/min) X 70 (mL/beat) = 4900 mL/minute. • The total volume of blood in the circulatory system of an average person is about 5 litres (5000 mL). During vigorous exercise, the cardiac output can increase up to 35 litres/minute Respiratory System Function of the Respiratory System • The function of the human respiratory system is to transport air into the lungs and to facilitate the diffusion of Oxygen into the blood stream. Its also receives waste Carbon Dioxide from the blood and exhales it. Respiratory System Terminology • Respiratory Volumes: is the amount of air inhaled, exhaled and stored within the lungs at any given time • Tidal Volume: the amount of air which enters the lungs during normal inhalation at rest. The average tidal volume is 500ml. The same amount leaves the lungs during exhalation. • Total Lung Capacity: This is the total amount of air the lungs can hold. The average total lung capacity is 6000ml, although this varies with age, height, sex and health. Respiratory System DID YOU KNOW!!?? 1. Due to the heart being located on the left- hand side of most humans – the right lung is slightly larger than the left. 2. The highest speed at which expelled particles from a sneeze have been measured to travel is 103.6 mph (167 km/h). Guiness book of records 2004 3. We lose half a litre of water a day through breathing. ENERGY SYSTEMS Muscle Contraction causes Movement, but requires ENERGY to do so!!! The ATP Molecule a. Adenosine Tri-phosphate (ATP) Adenosine P P P ATP Molecule • ATP replenishes with the use of Oxygen (Aerobic) • Wastes products are expired and breathed out • Unfortunately there is only enough ATP in the muscles to last for 2 seconds. • The body has 3 other systems to replenish ATP to ensure we can keep exercising. ATP Production during Exercise 3 Systems used to replenish ATP •ATP-CP System •Anaerobic (Lactic Acid) Glycolysis •Aerobic Glycolysis The ATP-CP System • Duration: 1-15 seconds • When: Sudden increase in intensity (whilst oxygen supply catches up), or short intense movements • This system breaks down stored Creatine Phosphate (CP) in the muscle; it requires no oxygen (anaerobic) • Limitations: by amount of CP the body can store. • What sports predominantly use this energy system? ATP-CP Energy System • Replenishes ATP rapidly by breaking down Creatine Phosphate releasing energy to reform ATP • Active at the beginning of all forms of activities • Especially important in high intensity exercises like weight lifting that require short bursts of energy. • Only a small quantity of PC can be stored. Athletes do try to load up with supplements The Anaerobic Lactic System • Duration: Up to 3 minutes • When: Sudden increase in intensity (whilst oxygen supply catches up) • Provides energy for moderate to high intensity exercise. The system uses energy from the breakdown of carbohydrates (glucose) and requires no oxygen. • Limitations: Production of lactic acid. • What Sports? Anaerobic (Lactic Acid) Glycolysis • Breakdown of carbohydrates (glycolysis) for fuel when without oxygen eg beginning of exercise or high intensity workout >85% of HRmax • Results in formation of lactic acid, which causes muscle fatigue Aerobic System • Duration: Unlimited • Predominant energy supplier for low to moderate intensity exercise <85% HR MAX • The system breaks down both carbohydrates and fats for energy and requires oxygen (aerobic). • What Sports? Aerobic Glycolysis • Replenishes ATP with the use of oxygen • System works at rest and during very low intensity exercise Energy System Interplay • The interplay of energy systems refers to the dominant energy system at any given time during an event. • All energy systems make ATP from the start of physical activity. However, one is more dominant than the others at particular times, depending on the intensity & duration of the activity. Short Term Effects of Exercise • When we begin to exercise the body has to respond to the change in activity level Short Term Effects of Exercise Circulatory System • The release of adrenaline (often before exercise even begins) causes the heart rate to rise • Increase in Cardiac Output • Increases in Lactic Acid (produced during the early anaerobic phase of exercise), Carbon Dioxide (due to increased rates of energy production) and temperature all act as stimuli to the cardiac control centre which responds by further increasing the heart rate • Blood pressure increases, thus increasing flow rate and the speed of delivery of O2 and nutrients to the working muscles Short Term Effects of Exercise Respiratory System • Changes in the concentration of CO2 and O2 in the blood are detected by the respiratory centre which increases the rate of breathing • The diaphragm and surrounding muscles work harder to further increase the expansion during inhalation, to draw in more air. Short Term Effects of Exercise Muscles • The higher rate of muscle contraction depletes energy stores • Myoglobin (protein that carries and stores oxygen in muscle cells) releases its stored Oxygen to use in aerobic respiration. O2 can now be diffused into the muscle from the capillaries more quickly due to the decreased O2 concentration in the muscle Short Term Effects of Exercise When you begin to exercise your body must immediately adjust to the change in activity level. Energy production must increase to meet demand with changes to the predominant energy system and fuel source occuring throughout the exercise in order to maintain the required level of performance. Short Term Effects of Exercise Responses to Anaerobic Exercise • In order to immediately meet the sudden higher energy demand, stored ATP is the first energy source. This lasts for approximately 2 seconds. • When stored ATP is used up the ATP-PC system kicks in but it can only last 8-10 seconds before PC stores are depleted. • The lactic acid system (Anaerobic glycolysis) must then take over as the predominant source of energy production. High intensity (but sub-maximal) exercise can last for between 3 and 5 minutes using this system • If the exercise continues at a high intensity, and Oxygen is not available at a fast enough it interferes with muscular function. This is called the Lactate threshold. Short Term Effects of Exercise Responses to Aerobic Exercise • Due to the necessity of Oxygen being present for aerobic metabolism, the first few minutes of low to moderate intensity exercise are powered by anaerobic metabolism. • Continued low to moderate intensity exercise is then fuelled by carbohydrate and fat stores using aerobic metabolism. Long Term Effects of Exercise • Regular exercise results in adaptations to the circulatory, respiratory and muscular systems in order to help them perform better under additional stress. Long Term Effects of Exercise • Circulatory System • The cardiac muscle surrounding the heart gets bigger, resulting in thicker, stronger walls and therefore increases in heart volumes. The more blood pumped around the body per minute, the faster Oxygen is delivered to the working muscles. • The number of red blood cells increases, improving the bodies ability to transport Oxygen to the muscles for aerobic energy production. • The resting heart rate decreases in trained individuals due to the more efficient circulatory system. • The accumulation of lactic acid is much lower during highlevels activity, due to the circulatory system providing more Oxygen and removing waste products faster. Long Term Effects of Exercise • Respiratory System and Exercise • The respiratory muscles (Diaphragm/intercostals) increase in strength. • This results in larger respiratory volumes, which allows more Oxygen to be diffused into the blood flow Long Term Effects of Exercise Muscles • The muscles, bones and ligaments become stronger to cope with the additional stresses and impact put through them. • The amount of myoglobin within skeletal muscle increases, which allows more Oxygen to be stored within the muscles and a larger amount of glycogen can be stored for energy. Training for Volleyball • If you were to start a 6 month training programme for Volleyball what methods of training might you use? • What effect would these have? Methods of Training You may use the following if training for Volleyball: • • • • Weight Training (focused on power) Plyometrics (focused on power) Interval Training (ATP-CP) Circuit (Power and Agility based)