Organisation

• Cells

  The basic building blocks of all living organisms
• Tissue

  A group of cells with a similar structure and function
• Organ


  Aggregations of tissues performing specific functions
• Organ system


  Organs organised to work together to form organisms
• Enzyme

  Catalyses specific reactions in living organisms due to the shape of their active site
• Enzymes and their functions

  • Carbohydrases (break down carbohydrates to simple sugars)
  • Proteases (break down proteins to amino acids)
  • Lipases (break down lipids (fats) to glycerol and fatty acids)
• The products of digestion are used to build new carbohydrates, lipids and proteins. Some glucose is used in respiration.
• Bile

  Made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
• Heart

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

  A group of cells located in the right atrium that control the natural resting heart rate
• Artificial pacemaker


  Electrical device used to correct irregularities in the heart rate
• Types of blood vessels

  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Have thick walls (and narrow lumen) with muscle tissue and elastic tissue to handle high blood pressure from the heart
• Veins

  • Have valves to prevent blood from flowing backward (and wider lumen), as they transport blood at low pressures back to the heart
• Capillaries

  • Have thin walls and are permeable to allow for efficient exchange of substances with cells
• Blood


  A tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended
• Red blood cells

  • Essential for delivering oxygen to our tissues through the use of hemoglobin. Their unique shape and lack of a nucleus allow for more space and efficient oxygen absorption.
• White blood cells

  • Play a crucial role in our immune system by defending against pathogens. They can engulf microorganisms, produce antibodies, and neutralize toxins. Unlike red blood cells, they have a nucleus.
• Platelets

  • Small fragments of cells that assist in clotting to prevent excessive bleeding. They act like a glue, patching up wounds and preventing microorganisms from entering.
• Plasma

  The liquid component of blood and makes up the majority of its volume. It carries various components, including red and white blood cells, platelets, nutrients, waste products, hormones, proteins, and antibodies.
• In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.
• Stents

  Used to keep the coronary arteries open
• Statins


  Widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit
• Faulty heart valves

  Can be replaced using biological or mechanical valves
• Heart transplant

  A donor heart, or heart and lungs can be transplanted in the case of heart failure
• Artificial heart

  Occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
• Factors affecting health

  • Diseases (communicable and non-communicable)
  • Diet
  • Stress
  • Life situations
• Defects in the immune system

  Individual is more likely to suffer from infectious diseases
• Viruses living in cells

  Can be the trigger for cancers
• Immune reactions initially caused by a pathogen

  Can trigger allergies such as skin rashes and asthma
• Severe physical ill health

  Can lead to depression and other mental illness
• Risk factors

  Aspects of a person's lifestyle or substances in the person's body or environment that are linked to an increased rate of a disease
• Examples of risk factors

  • Diet
  • Smoking
  • Exercise
  • Obesity
  • Alcohol
  • Carcinogens
  • Ionising radiation
• Many diseases are caused by the interaction of a number of factors
• Cancer

  The result of changes in cells that lead to uncontrolled growth and division
• Benign tumour

  Growths of abnormal cells which are contained in one area, usually within a membrane. They do not invade other parts of the body.
• Malignant tumour

  Cancer cells that invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours
• Leaf

  A plant organ
• Plant tissues

  • Epidermal tissues
  • Palisade mesophyll
  • Spongy mesophyll
  • Xylem and phloem
  • Meristem tissue found at the growing tips of shoots and roots

  
• Xylem

  A tissue which transports water and minerals from the roots up the plant stem and into the leaves