Human disease

• The immune system is made up of cells, tissues, organs, and proteins that work together to defend the body against infection.
• Innate immunity provides an immediate response to pathogens through physical barriers such as skin and mucous membranes, chemical defenses like acidic pH and enzymes, and cellular responses including phagocytosis by neutrophils and macrophages.
• Cardiovascular diseases


  Diseases of the heart and blood vessels
• Cardiovascular diseases are non-communicable, meaning they cannot be passed from person to person
• Coronary heart disease


  Layers of fatty material build up inside the coronary arteries, causing them to narrow and reduce blood flow to the heart muscle
• Effects of reduced blood flow in coronary heart disease

  1. Lack of oxygen for the heart muscle

  2. Can result in a heart attack where the heart is starved of oxygen
• Adaptive immunity involves specific recognition of antigens by lymphocytes (B-cells and T-cells) and memory B-cells, leading to antibody production and activation of cytotoxic T-cells.
• Statins


  Drugs that reduce the level of cholesterol in the blood, slowing down the buildup of fatty materials in the arteries
• Statins


  • Effective in reducing the risk of coronary heart disease
  • Can cause unwanted side effects like liver problems
• Stent


  A tube inserted into a coronary artery to keep it open and allow normal blood flow, but does not treat the underlying causes
• Antigens are foreign substances or molecules that trigger an immune response.
• Heart valve issues


  Valves may not fully open or may be leaky, causing the heart to work harder and leading to heart enlargement or feelings of weakness and fatigue
• Mechanical heart valves


  Made of metal, can last a lifetime but increase the risk of blood clots, requiring patients to take anti-clotting drugs
• Biological heart valves


  Valves from animals, do not last as long and may need to be replaced, but patients do not need to take drugs
• Heart failure


  The heart cannot pump enough blood around the body
• Immunity refers to the ability of the body's defense mechanisms to protect it from pathogens.
• Heart transplant


  Patients must take drugs to stop the donated heart from being rejected by the body's immune system
• Artificial heart


  A temporary solution to allow a damaged heart to rest or while waiting for a transplant, but increases the risk of blood clotting and is not a long-term solution
• Active immunity involves exposure to antigenic material through vaccination or natural infection, resulting in long-lasting protection.
• Memory cells are long-lived and allow rapid recall responses upon subsequent exposure to the same pathogen.
• Antibodies produced by plasma cells can neutralize viruses and bacteria, while cytotoxic T cells directly kill infected cells.
• Antibodies bind to antigen on the surface of microbes or infected cells, marking them for destruction by other immune system components.
• Cytotoxic T-cells directly kill infected cells.
• Innate immunity is the first line of defense against infection, involving physical barriers such as skin and mucous membranes, chemical defenses like stomach acid, and cellular responses including phagocytosis by white blood cells (WBC).
• Benign tumor


  Growth of abnormal cells which are found in one area, contained within a membrane, do not invade or spread to other parts of the body
• Malignant tumor


  Malignant cells invade neighboring tissues, move into the bloodstream, spread to different parts of the body and form new tumors (secondary tumors)
• Malignant tumor cells are classed as a cancer
• Risk factors for developing cancer

  • Genetic (e.g. certain types of breast cancer, prostate cancer, cancer of the large intestine)
  • Lifestyle (e.g. lung cancer linked to smoking, skin cancer linked to UV exposure, mouth and throat cancer linked to alcohol)
  • Environmental (e.g. radon, a radioactive gas that increases risk of lung cancer)
• The immune system has two main types of defenses: innate (non-specific) and adaptive (acquired).
• Barrier defences include physical barriers such as the skin and mucous membranes, and chemical barriers like stomach acidity and lysozymes in tears and saliva.
• Many diseases are non-communicable, meaning they are not spread from person to person, but are instead caused by risk factors
• Epidemiology


  Studying the patterns of disease to determine risk factors
• As the number of cigarettes smoked per day increases


  The risk of developing lung cancer also increases
• Causal mechanism


  The scientific explanation for how a risk factor can cause a disease
• Cigarette smoke contains chemicals called carcinogens that damage DNA and increase the risk of cancer
• Sampling


  Investigating a group of people to draw conclusions about the whole population
• To avoid bias, we need to take as large and random a sample as possible
• We cannot draw conclusions from a small or non-random sample
• Non-communicable diseases cannot be passed from person to person and they're not caused by pathogens
• Adaptive immunity involves specific recognition of antigens through B lymphocytes producing antibodies and T lymphocytes recognizing infected cells and activating other immune cells.