Biology

• How the body prevents pathogens entering


  1. Spin barrier

  2. Nose produces mucus

  3. Airway passages produce mucus

  4. Stomach produces hydrochloric acid

  5. Immune system responds to pathogens that have entered the body
• Antibodies


  Attach to invading cells, destroy/kill invading cells, make them clump together so phagocytes can engulf more pathogens
• Memory cells


  Provide faster immune response upon later exposure to the same pathogen
• Veins


  • Carry blood into the heart
  • Have thin walls and large lumen
  • Have valves to prevent backflow of blood
  • Blood travels slowly at low pressure
• Capillaries


  • Connect arteries to veins
  • Have permeable walls to allow diffusion of substances
• Eukaryotic cells


  Have a cell membrane, cytoplasm and nucleus
• Prokaryotic cells


  Don't have a nucleus, genetic material is not enclosed in a nucleus, have a single DNA and small rings of DNA called plasmids
• Diffusion


  Process of particles spreading from an area of high concentration to an area of low concentration
• Factors that increase rate of diffusion


  • Increasing concentration gradient
  • Increasing kinetic energy of particles
  • Increasing surface area
• Diffusion examples


  • Oxygen diffusing into cells
  • Water diffusing out of cells when a bee is removed
• Osmosis


  Process where water molecules move from an area of high water concentration to an area of low water concentration across a partially permeable membrane
• Factors that increase osmosis

  • Increasing temperature
• Osmosis examples


  • Root hairs absorbing water from soil
• Active transport


  The net movement of substances from an area of lower concentration to an area of higher concentration, using energy
• Active transport examples


  • Root cells absorbing minerals from soil
  • Nutrients being absorbed into bloodstream in human gut
• Preclinical trials


  1. Drugs first undergo tests on human cells

  2. Tested on whole animals

  3. Tested for efficacy and toxicity and dosage
• Clinical trials (humans)


  1. Healthy volunteers given first to receive the drug to check for side effects

  2. Dose is gradually increased and tested

  3. Patients in 2 groups, 1 group gets a placebo

  4. Trials are blind so patient doesn't know

  5. Some trials are double blind meaning neither patient and doctor know who receives the drug
• Peer review


  Other scientists conduct results to ensure the validity and reliability of trial outcomes before publication
• Pulmonary


  Related to the lungs
• Heart


  The organ that pumps blood around the body
• Aorta


  The main artery that carries oxygenated blood from the left ventricle of the heart to the rest of the body
• Pulmonary artery


  The artery that carries deoxygenated blood from the right ventricle of the heart to the lungs
• Vena cava


  The large veins that carry deoxygenated blood from the body into the right atrium of the heart
• Vein


  A blood vessel that carries deoxygenated blood towards the heart
• Atrium


  The upper chambers of the heart that receive blood flowing into the heart
• Ventricle


  The lower chambers of the heart that pump blood out of the heart
• Valves


  Structures in the heart that ensure one-way flow of blood
• Blood flow through the heart

  1. Blood enters from vena cava and pulmonary vein

  2. Vena cava brings deoxygenated blood into the right atrium

  3. Pulmonary vein brings oxygenated blood from the lungs to the left atrium

  4. The atria contract, pushing blood into the ventricles

  5. The ventricles contract to send blood out of the heart via pulmonary artery and aorta
• Double circulatory system


  • Two circuits working together, one pumps to the lungs, one pumps to the rest of the body
• The heart receives oxygen-rich blood through its own network of coronary arteries, ensuring it has the oxygen it needs to function effectively
• Pacemaker


  A group of cells in the heart that regulate the heartbeat by generating electrical impulses causing the heart muscles to contract
• Coronary arteries can become narrowed by a build-up of fatty deposits, leading to heart attacks, chest pain, and shortness of breath
• Stents keep coronary arteries open to allow adequate blood flow
• Statins are drugs that lower blood cholesterol, reducing the risk of heart attack
• Vaccinations


  Confer and eradicate diseases
• Vaccinations


  • Smallpox (eradicated)
  • Polio (nearly eradicated)
• Herd immunity

  When a large population are vaccinated, the unvaccinated are protected
• Vaccinations do not always guarantee immunity, booster shots may be needed
• Painkillers


  Drugs that manage symptoms like pain and fever but do not target the underlying cause
• Antibiotics


  Work on a deeper level, by either killing the bacteria or preventing their reproduction