PMT Organisation Definitions

• Cells


  Make up all living things
• Tissue


  A group of specialised cells with a similar structure and function. They can be made of more than one type of cell
• Tissue examples


  • Muscular tissue
  • Epithelial tissue
• Organ


  Formed from a number of different tissues, working together to produce a specific function
• Organ example


  • Stomach
• Organ system


  Organs working together to perform a certain function
• Organ system example


  • Digestive system
• Organs in the digestive system

  • Glands (salivary glands and pancreas)
  • Stomach
  • Small intestine
  • Liver
  • Gall bladder
  • Large intestine
  • Rectum
  • Anus
• Enzymes


  Biological catalysts (a substance that increases the rate of reaction without being used up)
• Enzymes


  • They can both break up large molecules and join small ones
  • They are protein molecules and the shape of the enzyme is vital to its function
  • Each enzyme has its own uniquely shaped active site where the substrate binds
• Lock and Key Hypothesis

  1. The shape of the substrate is complementary to the shape of the active site, so when they bond it forms an enzyme-substrate complex

  2. Once bound, the reaction takes place and the products are released from the surface of the enzyme
• Optimum pH


  The optimum pH for most enzymes is 7, but some that are produced in acidic conditions, such as the stomach, have a low optimum pH
• Optimum temperature


  The optimum temperature is a range around 37 degrees celsius (body temperature)
• As temperature increases


  The rate of reaction increases up to the optimum temperature, but above this temperature it rapidly decreases and eventually the reaction stops
• Denatured


  When the bonds in the structure of an enzyme break due to extreme temperature or pH, changing the shape of the active site so the substrate can no longer fit in
• Types of enzymes


  • Carbohydrases (convert carbohydrates into simple sugars)
  • Proteases (convert proteins into amino acids)
  • Lipases (convert lipids into fatty acids and glycerol)
• Soluble glucose, amino acids, fatty acids and glycerol pass into the bloodstream to be carried to all the cells around the body
• Tests for biological molecules

  • Benedict's test for sugars (turns brick red)
  • Iodine test for starch (turns blue-black)
  • Biuret test for protein (turns purple)
  • Emulsion test for lipids (add ethanol which results in a cloudy layer if a lipid is present)
  • Sudan III test for lipids (red layer forms on top)
• Bile


  Produced in the liver and stored in the gallbladder, then released into the small intestine. It is alkaline to neutralise the hydrochloric acid from the stomach, and it emulsifies large drops of fat into smaller ones to increase the surface area for lipase to work
• Investigating the effect of pH on an enzyme controlled reaction

  1. Use a water bath or electric heater to warm a solution of amylase, starch and a buffer solution

  2. At regular points, take drops of the solution and place in wells containing iodine

  3. The time for the starch to be completely broken down is recorded and the rate is calculated from the equation 1000/time

  4. Repeat the experiment at different pH values while controlling all other factors
• Rate of enzymatic reactions

  Calculated using the equation: rate = change/time
• Heart


  An organ in the circulatory system that pumps blood around the body in a double circulatory system
• Double circulatory system


  Deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs

  2. Oxygenated blood flows into the left atrium and then into the left ventricle which pumps it around the body
• Structure of the heart

  • Muscular walls to provide a strong heartbeat

  The muscular wall of the left ventricle is thicker

  4 chambers that separate the oxygenated blood from the deoxygenated blood

  Valves to make sure blood does not flow backwards

  Coronary arteries cover the heart to provide its own oxygenated blood supply
• Heartbeat process


  Blood flows into the right atrium and left atrium

  The atria contract forcing the blood into the ventricles

  The ventricles then contract, pushing the blood in the right ventricle into the pulmonary artery and blood in the left ventricle to the aorta

  Valves close to make sure the blood does not flow backwards
• Pacemaker


  A group of cells found in the right atrium that provide stimulation through small electrical impulses which pass as a wave across the heart muscle, causing it to contract
• Artificial pacemaker


  An electrical device that produces a signal causing the heart to beat at a normal speed
• Types of blood vessels

  • Arteries - carry blood away from the heart, have layers of muscle and elastic fibres to withstand high pressure

  Veins - carry blood towards the heart, have a wide lumen and valves to ensure blood flows in the right direction

  Capillaries - allow blood to flow very close to cells, have one cell thick walls for a short diffusion pathway and are permeable
• Rate of blood flow


  Calculated from volume of blood/number of minutes
• Lungs


  Found in the thorax, supply oxygen to the blood and remove carbon dioxide
• Components of the gas exchange system

  • Trachea

  Intercostal muscles

  Bronchi

  Bronchioles

  Alveoli

  Diaphragm
• Ventilation


  The ribcage moves up and out and the diaphragm moves down causing the volume of the chest to increase, resulting in lower pressure so air is drawn in

  The opposite happens when exhaling
• Gas exchange


  Oxygen diffuses down its concentration gradient into the capillary bloodstream

  Carbon dioxide diffuses down its concentration gradient from the blood to the alveoli
• Adaptations of alveoli


  • They are very small and arranged in clusters, creating a large surface area

  The capillaries provide a large blood supply, maintaining the concentration gradient

  The walls of the alveoli are very thin, meaning there is a short diffusion pathway
• Breathing rate


  Calculated by dividing the number of breaths by the number of minutes
• Components of blood


  • Plasma

  Red blood cells

  White blood cells

  Platelets
• Red blood cells


  • They carry oxygen molecules from the lungs to all the cells in the body

  Their biconcave disc shape provides a large surface area

  They have no nucleus allowing more room to carry oxygen

  They contain the red pigment haemoglobin, which binds to oxygen and forms oxyhaemoglobin
• White blood cells


  • They are a part of the immune system, which is the body's defence against pathogens

  They have a nucleus

  There are different types that produce antibodies, engulf pathogens, and coordinate the immune response
• Alveoli


  Very thin, meaning there is a short diffusion pathway
• Calculating breathing rate


  Divide the number of breaths by the number of minutes