2. Organisation

• A tissue is a group of cells with a similar structure and function
• An organ is a group of tissues performing similar functions
• An organ system is a group of organs which work together
• Digestive enzymes are biological catalysts, made of proteins, which are coded for in our DNA.
• Enzymes are secreted by glands and break down food in small soluble molecules
• Amylase

  Produced by - salivary glands, small intestine, pancreas

  Converts carbohydrates into sugar/ starch
• Lipase

  Produced by - small intestine, pancreas

  converts fats into glycerol + fatty acids
• Protease

  Produced by - Stomach, small intestine, pancreas

  Converts proteins into amino acids
• Enzymes have a specific shape called the active site. If the active site changes shape, it no longer works- this is called denatured.
• High temperatures and extreme pH can cause an enzyme to denature
• The purpose of the digestive system is to break down large ingested food down into smaller molecules so it can be absorbed into the blood.
• Bile is made in the liver, stored in the gall bladder, then secreted into the small intestine.
• Sugar

  Indicator - Benedict's reagent (MUST BE BOILED TO WORK)

  Negative test - colour blue
• Starch

  Indicator - Iodine

  Negative test - colour Yellow

  Positive test - Blue/Black
• Protein

  Indicator - Biuret

  Negative test - colour Blue

  Positive test - colour Pink-Purple
• Lipids

  Indicator - Sudan III or Ethanol

  Negative test - No layers

  Positive test - Red layer or White layer
• The heart is an organ that pumps blood round the body ins a double circulatory system.
• Blood is a tissue consisting of plasma, cells, and platelets.
• The right ventricle pumps blood to the lungs where gas exchange takes place (Pulmonary artery).
• The left ventricle pumps blood around the rest of the body
• The vena cava brings deoxygenated blood from the body to the right atrium
• The pulmonary artery takes blood from the left ventricle to the lungs
• The pulmonary vein carries oxygenated blood from the lungs to the left atrium
• The aorta takes blood from the left ventricle to the body
• The blood flows in one direction and valves in the heart prevent back flow
• The trachea is a tube which allows air to flow into the lungs.
• The trachea divides into two bronchi
• Each bronchus divides into bronchioles
• At the end of each bronchiole is an alveolus
• Each alveoli is surrounded by a network of capillaries
• Artery - carry blood away from the body

  Thick muscular walls

  Small lumen

  Can carry blood under high pressure

  Carries oxygenated blood (NOT THE PULMONARY ARTERY)
• Vein - carries blood to the heart

  Thin walls

  Large lumen

  Cary blood under low pressure

  Has valves to stop back flow

  Veins carry deoxygenated blood (NOT THE PULMONARY VEIN)
• Capillary - connects arteries and veins

  One cell thick to allow diffusion

  Carry blood under very low pressure
• Satins are drugs that lower blood cholesterol levels and are used to treat high cholesterol.
• Stent - a metal tube that opens up a blocked blood vessel
• Pacemaker - regulates and controls heart rate and rhythm.
• Valve replacement - damaged valves are removed and either plastic or animal valves are inserted
• Heart transplant - a donor is needed, risk of organ rejection and lack of donors
• Coronary heart disease (CHD) is a condition resulting from blockages in the coronary arteries
• The main symptoms of CHD are heart attack and heart failure.