Cardiovascular system consists of the heart, blood and blood vessels. Oxygenation takes place in the lungs. Stroke volume is the volume, per heart beat, of blood pumped. Cardiac output is the amount of blood pumped by the heart in one minute. The three types of blood vessels are arteries, veins and capillaries The main work of the capillaries is gaseous exchange. Blood consists of plasma, white and red cells and platelets. Haemoglobin is found in the red blood cells. The main work of red blood cells is to carry oxygen. Blood pressure is the force of blood against artery walls.
Air leaves the trachea and passes through the bronchi. The tiny sacs in the lungs are called alveoli. In the alveoli carbon dioxide passes out of the blood. When we exhale, pressure in the chest increases. Respiration is the release of energy from glucose in the muscles. During exercise working muscles need more oxygen. Insufficient oxygen supplies are available during strenuous exercise. During anaerobic exercise there is a build up lactic acid. Gaseous exchange takes place in the lungs in the alveoli. The percentage of oxygen in exhaled air is about 16%
The skeleton, bones and joints
The skeleton protects vital organs. The floating bone at the knee is called the patella. The large flat bones at the top of the back are called scapula. The vertebrae which the ribs are attached to are called thoracic. Vertebrae which allow some side movement are called thoracic. The synovial hip joint is an example of a ball and socket joint. Synovial fluid lubricates the joint. The bones of embryos are made largely of cartilage. To create bone the process of ossification uses calcium. The humerus is a long bone.
Muscles and movement
Cardiac muscle is unique to the heart. Muscle fibres which use oxygen well are called slow twitch. Muscle contractions which cause movement are isotonic. Chest muscles used in the tennis forehand are the pectorals. There is no movement from contraction which is isometric. A pair of muscles working together would be biceps and triceps. For eccentric contraction the muscle lengthens as the fibres contract. Growth of muscles is called hypertrophy. Good muscle tone reduces the risk of injury. When muscles hypertrophy they gain greater size, strength and endurance.
Health and Fitness
Physical activity to improve health and fitness is called exercise. Our distribution of muscle and fat is known as body shape. The ability to keep going for a long time is called cardiovascular fitness. The range of movement at a joint is called flexibility. Flexibility is vital for gymnastics. How well a task is completed is called performance. The ability to change our body position quickly is agility. Power is the ability to use strength at speed. Reaction time takes place between stimulus and movement. All sprinters need very good reaction time.
Principles and methods of training
A successful training programme will meet individual needs. In the FITT training principles F stands for frequency. Deciding how hard to train refers to training intensity. In aerobic training muscles have sufficient oxygen. Speed and muscular endurance can be improved by interval training. The maximum heart rate is calculated by subtracting age from 220. Warm up should prepare muscles by stretching. Warm down should include light exercises. Lactic acid is a waste product of anaerobic exercise. Carbon dioxide is removed from the body through the lungs.
Effects of exercise and training
When first exercising muscles contract more.With regular training bone density increases. With regular training muscles hypertrophy. With regular training muscular endurance improves. When first exercising blood vessels near the skin open. With regular training cardiac output increases. When first exercising depth of breathing increases. With regular training the strength of the intercostals increases. With regular training the number of alveoli increases.The amount of air breathed in and out in one breath is called tidal volume.
Quick release energy is provided by carbohydrates. Fats in the diet provide slow release energy. To maintain fluid levels the body needs water. Cheese and oils provide considerable supplies of fat. The number of kilojoules you need to stay alive each day is called your basic metabolic rate. If you consume more energy than you use you will put on weight. People who eat insufficiently for their activity level will lack energy. It is possible to group different body shapes by using a system called somatotyping. Mesomorphs have a wedge shaped body and are more likely to be suited to sprinting. Endomorphs have a pear shaped body and are more likely to be suited to weight lifting.
Drugs in sport
Narcotic analgesics may mask pain. Injecting blood that has previously been removed from the body is known as blood doping. Keeping heart rate low is a benefit of beta blockers. Anabolic steroids can cause increased aggression. Diuretics can cause dehydration. Excessive alcohol consumption may cause liver damage. Cannabis can reduce concentration.Dangers caused by cigarettes and canabis include heart disease. Amphetamines are examples of stimulants. One banned social drug is cannabis.