Organisation

• COPD is a lung disease characterised by irreversible lung damage and an obstructed airway. People suffering from COPD often find it very difficult to breathe.
• Smoking is the primary risk factor associated with COPD and the risk increases with the duration and intensity of smoking.
• 1. Bronchitis - Inflammation of the bronchi and bronchioles, leading to increased mucus production and coughing.
  2. Emphysema - damage to the alveoli walls, leading to fewer larger alveoli, instead of many smaller ones. This reduces the surface area available for gas exchange.
• Risk factor - Something that increases the chance of developing a disease 
• A non-communicable disease is a disease that cannot be spread from person to person 
• bronchitis is the inflammation of airways in the lungs
• A tumour is an abnormal mass of cells that forms when a group of cells undergo uncontrolled growth and division. 
• Two types of tumours - benign and malignant
• A benign tumour is contained within one area, usually within a membrane
• Tumour cells divide by mitosis
• Malignant tumours can invade neighbouring tissues and spread to different parts of the body in the blood
• Ultraviolet radiation is a risk factor for skin cancer.
• The BRCA gene increases the risk factor for

  Ovarian cancer

  Breast cancer
• Risk factors linked to cancer:

  Environmental factors 

  Genetic factors

  Lifestyle factors
• Health can be described as a state of both physical and mental wellbeing. 
• The term 'disease' refers to a group of conditions that can cause ill health.
• The role of the immune system is to detect and destroy pathogens 
• 1. In order to move during exercise, we have to contract and relax our muscles. 
  2. Muscular contraction requires energy though, which has to be released by cellular respiration. 
  3. Most of the time cells carry out aerobic respiration, which is far more efficient but requires oxygen. 
  4. This means that we have to pump oxygen around the body faster when we exercise. 
  5. As a result we increase both our heart rate and our breathing rate.
• Aerobic respiration is more efficient than anaerobic.
• Anaerobic respiration leads to oxygen debt and lactic acid build up.
• The liver removes lactic acid from the blood.
• To measure a persons breathing rate, we can count how many times their chest rises and falls in a given amount of time. 
• The three parts of the circulatory system are the blood, the blood vessels, and the heart.
• On each side of the heart, the atrium and ventricle are separated by a valve, which prevents the blood from flowing backwards.
• The left ventricle has thicker walls because it has to pump blood all the way around the body.
• Body tissues ➔ vena cava ➔ right atrium ➔ right ventricle ➔ pulmonary artery ➔ lungs ➔ pulmonary vein ➔ left atrium ➔ left ventricle ➔ aorta ➔ body tissues
• 1. The walls of the atria contract, pushing blood into the relaxed ventricles.
  2. The walls of the ventricles contract, pushing blood out of the heart. At the same time, more blood will enter the now-relaxed atria.
  3. The cycle repeats.
• Pacemaker cells are found in the right atrium
• The coronary arteries supply the heart muscle with oxygen and nutrients.
• Capillaries carry blood through the body tissues, allowing oxygen, nutrients, and waste products, to be exchanged between tissues and the blood.
• 1. Arteries are large and carry blood at a very high pressure.
  2. Artery walls have a thick middle layer, containing both muscle and elastic tissue.
  3. The muscle tissue provides strength, and allows the arteries to direct blood flow.
  4. The elastic tissue allows the arteries to stretch and recoil.
  5. Compared to their walls, arteries have a relatively narrow lumen, which keeps the blood pressure high.
• • Capillaries are the smallest of the three blood vessels.
  • The role of capillaries is to  nutrients and  products with the tissues.
  • Capillary walls are , meaning substances are able to move through them.
  • Their walls are also only  cell thick which means a short distance for .
  • Capillaries carry blood at a  pressure and have a lower rate of flow than arteries.
• 1. The role of veins is to carry blood from the body (or lungs) back to the heart.
  2. Veins are a similar size to arteries, but they have relatively thin walls and a relatively wide lumen
  3. This is because they carry blood at a much lower pressure.
  4. Veins also contain valves to prevent the blood from flowing backwards.
• Heart ➔ arteries ➔ capillaries ➔ veins ➔ heart