Organisation

• Cells are the basic building blocks of all organisms

  A tissue is a group of cells with a similar structure and function

  Organs are a cluster of tissues performing specific functions

  Organs are organised into organ systems

  Organ systems work together to form organisms
• When cells differentiate they:

  • change shape
  • develop different sub-cellular structures to let it carry out a specific function
• Sperm cells:

  • Tail - propels sperm to fertilise egg
  • Mitochondria near head - site for respiration, provides energy for journey
  • Nucleus - contains genetic material
  • Acrosome - contains enzymes to penetrate outer layer off egg
• Muscle cell:

  • protein fibres that contact
  • Mitochondria to give energy
• In plants, root hair cells, xylem and phloem cells are all specialised cells.
• Xylem cells :

  • end walls break down to form hollow tubes
  • cell wall is strengthened by lignin
• Phloem cells:

  • End walls allow sugars through but support the tubes
  • aranged end to end in tubes
• Root hair cell:

  • Lots of mitochondria for active transport of minerals
  • Long projection to increase the surface area to absorb water and minerals
• Enzymes are biological catalysts that speed up chemical reactions in living organisms
• Properties of enzymes :

  • All large proteins
  • Space within the protein molecule called active site
  • Each enzyme catalyses a specific reaction
  • The work best at an optimum temperature and pH
• Lock and key theory : The substrate (key) fits into the enzymes active site (lock)
• Enzymes that experience high temps or pH out of their optimum will change shape. This is called denaturing.
• Denatured enzymes can't function as they have lost their shape so cannot fit the substrate into the active site
• Digestive enzymes are produced by specialised cells in glands and lining of the gut:

  The enzymes pass out of the cells into the digestive system

  They come into contact with food molecules

  They catalyse the breakdown of large insoluble food molecules into smaller soluble molecules
• Amylase:

  • Produced in the salivary glands and the pancreas
  • Is a carbohydrase that breaks down starch into sugar
• Protease:

  • Produced in stomach, pancreas and small intestine
  • Breaks down proteins into amino acids
• Lipase:

  • Is produced in the pancreas and small intestine
  • breaks down lipids (fats) into fatty acids and glycerol
• Bile:

  • Made in liver, Stored in gallbladder
  • Alkaline to neutralise hydrochloride acid from the stomach
  • Emulsifies fats to increase surface area for enzymes
  • Alkaline conditions and large surface area increase the rate at wich fat is broken down by lipase
• Blood is a tissue that is made up of a liquid called plasma, Plasma contains:

  • red blood cells
  • white blood cells
  • platelets
• Plasma transports chemical substances around the body such as hormones, glucose, oxygen, carbon dioxide
• Red blood cells:

  • contain haemoglobin, this binds to oxygen to transport it from the lungs to cells and tissues for respiration
  • do not have a nucleus, this is so there is more room for haemoglobin
  • Are small so they can fit through tiny capillaries
  • are shaped like biconcave disc, this gives them a large surface area that oxygen can quickly diffuse over
• White blood cells:

  • help protect body against infection
  • can change shape, to squeeze out blood vessels into the tissues or surround and engulf microorganisms
• Platelets:

  • fragments of cells that collect at wounds and trigger blood clotting.
• The heart pumps blood around the body in a double circulatory system
• There are four chambers in the heart:

  • Right Atrium
  • Right ventricle
  • Left Atrium
  • Left Ventricle

  (THE HEART RIGHT IS YOUR LEFT AND THE HEART LEFT IS YOUR RIGHT, ITS FLIPPED DUE TO IT BEING THE PATIENTS HEART)
• The heart contains a :

  Vena carva (connected to right atrium)

  Pulmonary artery (connected to semi lunar valve RIGHT)

  Aorta (connected to semi lunar valve LEFT)

  Pulmonary vein (connect to left atrium)
• Blood enters heart through atria.

  Atria contracts forcing blood through ventricles

  Ventricles contact forcing blood out of the heart

  Valves prevent backflow
• Natural pacemaker is controlled by a group of cells in the right atrium
• Artificial pacemakers are used to treat heart failure and irregular heartbeats
• Gaseous Exchange:

  1. Blood is sent to lungs via pulmonary artery
  2. Air obtained by breathing reaches lungs through trachea (has rings of cartilage to prevent collapsing)
  3. Trachea divides into two tubes - the bronchi
  4. Bronchi divide to form bronchioles
  5. Bronchioles divide into tiny air sacs called alveoli
  6. Alveoli exhange carbon dioxide and oxygen
  7. Blood taken back to heart through pulmonary vein
• Alveoli:

  • Have a large, moist surface area
  • Have a rich blood supply
  • Close to blood capillaries so distance for gases to diffuse is small
• Arteries:

  • Take blood from heart to organs
  • Thick walks made from muscle and elastic fibre
• Veins:

  • Take blood from organs to heart
  • Thinner walls and valves to prevent backflow
• Capillaries

  • allow substances needed by cells to pass out of the blood
  • Allows substances produced by cells to move into blood
  • Narrow thin walled blood (good for diffusion)
• Non-communicable diseases - can’t spread between organisms

  Communicable diseases - can spread between organisms
• Risk factors:

  • aspects of a persons lifestyle
  • Substances in a persons body or environment
• Cardiovascular disease - Lack of exercise/smoking

  Type 2 diabetes - Obesity

  Liver and brain damage - Excessive alcohol intake

  Lung diseases - Smoking

  Skin cancer - Ionising radiation

  Brain damage in babies - excessive alcohol intake during pregnancy
• Coronary heart disease - Layers of fatty material build up inside coronary arteries and narrow them
• Treatment for Coronary heart disease :

  • Stents - Keep coronary arteries open
  • Statins - reduce blood cholesterol levels and slow down rate fatty material builds up
• Faulty valves can be replaced by biological or mechanical valves