1. RESPIRATORY SYSTEM By Arturo Cruzat

2. Glossary 1. The Lungs 2. Breathing 3. Gas Exchange 4. Smoking and disease

3. The Lungs Larynx - Air passes through here during breathing. When breathing out, the vocal cords can be made to vibrate. The sounds preduced make up our speech Trachea - Tube that carries air towards the lungs. Rings of cartilage prevent the trachea collapsing during inhalation. Bronchus - First branch from the trachea. There is 1 bronchus to each lung. Bronchioles - Final, very fine branch leading into the alveolus. Alveoli - These are lined by the membranes where gas exchange takes place. The surface is moist, thin and has an enormous area. The lung is the essential respiration organ in many air- breathing animals, the two lungs are located near the backbone on either side of the heart. It's main parts are: Branch of pulmonary artery - delivers deoxygenated blood at high pressure from the right ventricle of the heart. Branch of pulmonary vein - returns oxygenated blood to the heart for pumping out to the tissues.

4. Breathing Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and removes carbon dioxide.The medical term for normal relaxed breathing is eupnea. Breathing is brought about by: -The action of two groups of muscles – the intercostal muscles and the diaphragm. -The properties of the pleural membranes that sorround the lungs The intercostal muscles (“intercostal” means “between the ribs”) and the diaphragm work together to alter the volume of the chest cavity. Changing the volume of the chest cavity will automatically change the pressure of air inside it. (it is a law of physics that pressure x volume is a constant, in other words, if pressure increases then volume must decrease, and vice versa.

5. Gas Exchange Glucose + oxygen → energy + CO 2 + (energy) Gas exchange is a process in biology where gases contained in an organism and atmosphere transfer or exchange. In human gas-exchange, gases contained in the blood of human bodies exchange with gases contained in the atmosphere. Human gas-exchange occurs in the lungs.. The gas exchange system in humans is shown opposite and is made up of: -A respiratory surface: membranes lining the alveoli in the lungs. -A set of tubes to allow air from the outside to reach the respiratory surface. This set of tubes has many branches, and is sometimes called the “bronchial tree”. -A blood supply (carried by the pulmonary artery and pulmonary vein) to carry dissolved gases to and from the respiratory surface. -A ventilation system (the intercostal muscles and the diaphragm) to keep a good flow of air over the respiratory surface.

6. Smoking and disease (1) How si smoking harmful? Smoking is inhaling the smoke from burning tobacco (and paper). This smoke can harm the lungs and respiratory passages for a number of reasons: - it is hot - It has a drying effect - It contains many harmful chemicals The heat and dryness irritate the lungs, but the main dangers of smoking come from the chemicals in the burning tobacco. There are over 100 known chemicals in tobacco. These includes tars, carbon monoxide, sulphur dioxide, nicotine and even small quantities of arsenic and plutonium. Lung cancer is 10 times more likely in a smoker than a non-smoker. The tumour invades other tissues. This causes pain and loss of function of other tissues, often resulting in death.

7. Smoking and disease (2) Nicotine - is the chemical that causes addiction. It is also a stimulant which makes the heart beat faster and at the same time makes blood vessels narrow. Together these two effects raise blood pressure. The increased heart rate increases the demand for oxygen, but carbon monoxide reduces oxygen avaibility, so heart muscle is more likely to be damaged. Tar causes cancer which is uncontrolled division of cells. These cells, usually those lining the lower part of the bronchus, grow through the basement membrane and invade other tissues. It also an irritant which makes coughing more likely. Cilia are destroyed which means that mucus accumulates in the respiratory tubes. Dust and microbes, trapped in the mucus, slide down towards the lungs making the person cough. This causes bronchitis. Carbon monoxide reduces the oxygen supply, it reduces oxyhaemoglobin formation because it binds very tightly to heamoglobin. Carbon monoxide poisoning is especially likely when car engines are allowed to run in enclosed spaces and when atmosphere is smogged. Cancer of the mouth and larynx called Laryngitis causes a husky voice, and makes speaking difficult and paintful. Emphysema results when the walls of the air sacs are destroyed. This happens because smoke affects white blood cells which then destroy lung tissue. There is less surface for gas exchange and breathing becomes difficult