B2 - Cell Organisation

• Mouth


  Chewing food is an example of mechanical digestion. An enzyme in saliva called amylase helps digest starch into sugars (chemical digestion).
• Stomach


  An enzyme called protease helps digest protein into amino acids. Hydrochloric acid helps to kill bacteria.
• Small intestine


  Where fat is digested. Fat is broken down by the enzyme lipase to make fatty acids and glycerol. Nutrients are absorbed into the blood through the villi.
• Large intestine


  Where most water is absorbed
• Liver


  Makes an alkaline substance called bile, it is released into the small intestine to help digest fat by emulsifying (breaking up) fat molecules to increase the surface area. Bile also helps neutralise the pH to stop the enzyme lipase from denaturing. Stored in gall bladder
• Pancreas


  A gland that makes all three digestive enzymes (lipase, protease, amylase)
• Amylase


  Starch into glucose (sugars)
• Protease


  Protein (chain of amino acids) into amino acids
• Lipase


  Fat into glycerol and fatty acids
• Enzyme


  A biological catalyst, made of protein, speeds up chemical reactions
• Active site


  The site on an enzyme where the substrate binds and the reaction occurs, specific in shape(complimentary)
• Denatured


  When the active site changed shape and the substrate can no longer bind
• Optimum conditions for enzymes

  - Neutral pH

  - 37 temperature (body temp)
• Trachea


  Our largest airway

  
• Lungs


  Spongy organs that fill with air when we inhale

  
• Bronchi


  The trachea branches into these, one carries air to each lung

  
• Bronchioles


  Smaller airways that carry air into the alveoli

  
• Alveoli


  Small sacks where gas exchange occurs

  
• Diaphragm


  Layer of muscle that separates the chest cavity from the abdominal cavity

  
• Heart structure

  
• Valve


  To make sure blood only goes in one direction
• Blood component: plasma


  - 55%

  - Straw coloured liquid

  - Transports carbon dioxide from organs to lungs, urea from liver to kidneys, water, hormones and digested food ( e.g glucose)
• Blood component: red blood cells

  - 45%

  - Transport oxygen from lungs to organs

  - Have a biconcave shape (large surface area)

  - No nucleus (more room for oxygen)

  - Packed with a red protein called haemoglobin
• Blood component: white blood cells


  - less that 1%

  - Have a nucleus

  - Kill pathogens by engulfing them or producing antibodies
• Blood component: platelets


  - Small protein fragments

  - Involved in formation of scabs/ clots

  - Help blood to clot at the site of a wound
• Artery


  - Muscle layer outside

  - Thicker walls (blood is pumped at higher pressure)

  - Smaller lumen (hole in pipe)

  - Don't need valves

  - Elastic layer inside

  
• Vein


  - Muscle layer outside

  - Blood flows at lower pressure

  - Large lumen

  - Have valves to prevent back- flow of blood

  - Thinner muscle layer

  
• Capillary


  - Wall made of a single layer of cell

  - Blood travels single file

  - Short diffusion pathway

  - Very small lumen (need to diffuse quickly)

  - Low pressure for nutrients

  
• Artificial pacemakers


  A wire passed from a vein to the right atrium. Sends electrical impulses to heart to control rhythm.

  
  

  + Not very risky

  - Immune system can reject it

  - May malfunction
• Heart transplant


  An operation to replace damaged or failing heart with a healthy one from a donor who has just died.

  
  

  + Better quality of life

  + Improved chance of longer life

  - Major surgery

  - Anti- rejection drugs for life

  - Shortage of donors
• Bypass surgery

  Transplants a vein from the leg to divert blood around narrow/clogged arteries.

  
  

  + No rejection risks

  + Effective

  - Major surgery
• Statins


  Drugs to lower cholesterol.

  
  

  + Reduce cholesterol

  - Possible side effects
• Artificial valves


  Device to replace a faulty valve.

  
  

  + No rejection

  - Need to take anti-clotting drugs
• Biological valves

  Made from tissue from cows' hearts or actual pigs' valves.

  
  

  + Improves oxygen levels, pumping efficiency

  - Rejection can be fatal
• Stents


  Short wire mesh/ plastic tube that opens up an artery when inserted (balloon to blow up/ open).

  
  

  + Small operation

  + Increased blood flow

  - Damage may occur to artery

  - Allergic reaction to drugs
• Causes of cancer

  - Red meat - Smoking

  - Viruses - Lack of exercise

  - Viral infection - UV

  - Age

  - Obesity

  - Stress

  - Alcohol

  - Genetics
• Benign tumour


  - Cells are not cancerous so will not spread

  - Inside membrane

  - Don't invade other parts of the body

  - Can cause problems depending on where they are

  - Form from abnormal cell division causing the DNA to change
• Malignant tumour


  - Cells are cancerous and can spread to other tissues and organs

  - Form secondary tumours

  - Form from abnormal cell division causing the DNA to change
• Upper epidermis


  Prevents infection, bacteria and fungi getting into the leaf
• Lower epidermis


  Single layer of cells