Year 11Achievement Standard 1.2

The Respiratory System The lungs, mouth, throat and nose make up the respiratory system One of the major functions of the respiratory system is to bring oxygen into the body and remove carbon dioxide. Oxygen is inhaled down through the bronchi and into the alveoli of the lungs. From there it is transferred into the blood. Carbon dioxide and other wastes (metabolites) are transferred from the blood through the lungs and out of the body. When exercising, breathing occurs faster and more deeply, allowing more oxygen to be inhaled and transferred to the blood and muscles where the oxygen is used to help fuel exercise.

Figure 1: The Respiratory System Bronchus Lung Ribs Diaphragm Trachea (wind pipe) Bronchioles Alveoli Intercostal muscles

The Heart The heart is a muscle that contains four chambers. The upper two chambers are called atria and the bottom two are called ventricles. The heart’s job is to pump blood around the body. It does this by squeezing the blood out of the ventricles. The blood leaves the heart through a large vessel called the aorta; from there it goes out to the muscles and organs where they take oxygen out of the blood. The blood then returns to the heart and lungs to be re- oxygenated During exercise, muscles require more oxygen. This means that during exercise the heart has to work faster by beating more times in a minute and harder by pumping more blood out with each beat.

Figure 2: The Human Heart Right ventricle Septum (dividing wall) Tricuspid valve Vena cavae Aorta Right atrium Semilunar valves Pulmonary artery Pulmonary veins Left atrium Bicuspid valve Left ventricle Cardiac muscle

The Circulatory System In effect there are two different circulations of blood within the body: Pulmonary circulation: circulation of blood between the heart and lungs – ensures deoxygenated blood from the body is ‘refuelled’ with oxygen from the lungs. Systemic circulation: circulation of blood between the heart and body – ensures ‘refuelled’ blood is distributed to the muscles of the body.

The Circulatory System – Part II There are three main types of blood vessel in the human body: Arteries – thick-walled vessels that carry blood away from the heart at a high pressure. Capillaries – thin-walled vessels that oxygen and nutrients can move into from cells. Veins – thin-walled vessels which carry blood towards the heart at low pressure after the oxygen and other materials have been taken out. This series of vessels relies on gravity and contracting muscles to transport the blood. Valves which are located in the vessel walls keep the blood going in one direction (preventing the blood from moving backwards).

Figure 3: The Circulatory System

Cardiovascular Fitness Cardiovascular (heart, lungs and blood vessels) Cardiovascular fitness is a measure of the body’s ability to utilise oxygen. In other words, it is an indicator of how fast somebody is able to breathe in oxygen into the lungs, transport it through the body to the muscles and use it to provide energy for the exercise that the person is doing. As cardiovascular fitness improves, the heart gets larger and stronger and is able to pump more blood and with it more oxygen to the muscles. The muscles can also take more oxygen from the blood and become better at using oxygen to produce energy.

Physiological responses to exercise Short-term: or acute responses to exercise – what actually happens to the body while a person is exercising. -e.g. Increase in heart rate, perspiration. Long-term: or chronic responses to exercise – what happens to the body as a result of regular exercise. -e.g. The heart gets stronger and larger, resting and exercise heart rate decrease

Energy Systems Three pathways provide energy for physical activity - Two are anaerobic (without oxygen), and the other aerobic (with oxygen). - These three energy systems overlap and sometimes combine to power all human movement. - The type of energy pathway that is used is dependent on the type of activity being performed.

Energy Systems – Part II Aerobic system - Energy is supplied to the body through the consumption of oxygen. This combines with lactic acid to produce water, therefore there is no effect on performance. Activities that use this energy system include running, swimming and cycling long distances Anaerobic lactic system - The anaerobic lactic system is used for shorter-duration, high-intensity activity typically lasting between seconds. Energy is supplied through the consumption of carbohydrate. This causes the build up of lactic acid, which eventually causes performance to decrease. At this point the person either lowers their intensity or allows the aerobic system to continue fuelling the exercise, or they stop exercising completely. Activities that use this energy system include rugby, netball or soccer, where high- intensity activity is performed for short periods of time. Anaerobic CP system -The anaerobic CP system is used for very short duration, high-intensity activity typically lasting up to 30 seconds. Energy is supplied to the body through the consumption of creatine phosphate. There are no by products with this energy system and it keeps going until all the stored energy is used up. This energy pathway replenishes after 2-3 minutes. Activities that use this energy system include jumping, short sprints or striking actions.

Figure 4: Energy Systems