10 - Diseases and Immunity

• Comparison of the single & double circulation

  A) gill capillaries

  B) artery

  C) ventricle

  D) atrium

  E) two-chambered heart

  F) single circulation

  G) gill circulatoin

  H) pulmonary artery

  I) right side of the heart

  J) left side of the heart

  K) pulmonary vein

  L) aorta

  M) vena cava

  N) systemic circulation

  O) systemic circulation

  P) pulmonary circulation

  Q) 2

  R) 1

  S) low

  T) high

  U) absent

  V) fish

  W) present

  X) 2

  Y) 4

  Z) reptiles

  [) amphibians

  \) birds

  ]) mammals

  
• Heart diagram (mammal):

  A) inferior vena cava

  B) superior vena cava

  C) aorta

  D) right atrium

  E) right ventricle

  F) pulmonary valve

  G) tricuspid valve

  H) pulmonary artery

  I) pulmonary vein

  J) left atrium

  K) mitral valve

  L) aortic valve

  M) left ventricle

  
• Effect of physical activity on heart rate -

  • heart rate increases from the resting rate and stays high until physical activity slows down or stop 
  • heart rate increases to supply the muscles with more oxygen and glucose a
  • needed to allow the muscles to respire aerobically, so they have sufficient energy to contract
  • after exercise, the heart rate gradually returns to normal
• Coronary artery disease -

  • coronary artery is the artery that transfers blood to the heart
  • coronary heart disease is caused by blockage of the coronary arteries, which supply the heart muscle with oxygen and glucose
  • people get heart attack from lack of oxygen to part of heart
• How blockage is formed -

  • fat deposits form plaque 
  • fat starts to narrow down the lumen 
  • the blood that can go through becomes limited 
  • eventually - causes a difference in pressure that causes the layer, plaque and wall to rupture
  • blood clot + fat blocks off the blood vessel
• Risk factor (poor diet w too much fat):

  • Leads to fatty deposits (atheroma) in arteries, which eventually bloc the blood vessel or allow a blood clot to form
  • Maintaining a healthy, balanced diet will lower the chance of a person becoming obese.
  • Low intake of saturated fats reduces the chances of a build-up of fatty deposits and the formation of blood clots
• risck faactor (obesity):

  Being overweight puts extra strain on the heart and makes it more difficult for the person to exercise
• risk factor (smoking):

  Nicotine damages the heart and blood vessels
• risk factor (stress):

  Tends to increase blood pressure, which can result in fatty materials collecting in the arteries
• risk factor (lack of exercise):

  • The heart muscle loses its tone and becomes less efficient in pumping blood
  • Regular, vigorous exercise reduces the chances of a heart attack. Maybe because it increases muscle tone – not only of skeletal muscle, but also of cardiac muscle.
  • Good heart muscle tone leads to an improved coronary blood flow and the heart requires less effort to keep pumping.
• risk factor (genetic predisposition):

  • Heart disease appears to be passed from one generation to the next in some families
• risk factor (age):

  Risk increases with age
• risk factor (gender):

  Males are more at risk than females
• Treatment for CHD:

  • Stent:
  • is used to expand the blood vessel and allow good flow of blood
  • Bypass surgery:
  • an alternate route is provided for blood to flow
• Blood vessels:

  • blood is pumped away from the heart in arteries and returns to the heart in veins
  • hollow parts of the blood vessels are known as lumen
  • there are three blood vessels:
  • artery
  • vein
  • capillary
• pathogen


  a disease-causing organism
• How pathogens spread -

  • a pathogen is transmitted:
  • by direct contact, including through blood and other body fluids 
  • indirectly, including from contaminated surfaces, food, animals and air (e.g. airborne, vector, contaminated food/water)
  • vector = cannot be transmitted by just being near to the person, it has to make contact with you (e.g being bitten)
  • different pathogens = different mechanisms of transmission
• transmissible disease 


  disease in which the pathogen can be passed from one host to another
• How to control spread of disase - Clean water supply


  On a small scale, drinking water can be boiled to destroy any pathogens.

  On a large scale, drinking water can be protected from sewage contamination, or treated to make it safe. This treatment involves filtration and chlorination
• How to control spread of disease - Hygiene food preparation

  Keeping food-preparation surfaces clean, avoiding the preparation of raw and cooked food on the same surface, cooking food thoroughly to kill any bacteria present
• How to control spread of disease - Good personal hygiene

  Washing hands after using the toilet, moving rubbish or handling raw food; avoiding the handling of money when in contact with unwrapped food
• How to control spread of disease - Waste disposal


  To avoid the development of a breeding ground for pathogens
• How to control spread of disease - Sewage treatment

  To prevent pathogens in faeces from contaminating drinking water and to stop vectors such as flies or rats feeding and transmitting the disease organism
• active immunity


  defence against a pathogen by antibody produciton in the body
• antibodies


  proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destructrion by phagocytes
• active immunity:

  • active immunity is gained after an infection by a pathogen or by vaccination
  • process:

  1. some of the lymphocytes that produced the specific antibodies, as a result of infection by a pathogen, remain in the lymph nodes as memory cells for some time
  2. it can divide rapidly to produce more antibodies to respond to further infections by the same pathogen
  3. this creates immunity to the disease caused by the antigen.
• Vaccination -

  • a weakness or killed form of the diseases is injected into the body (harmless pathogen still has antigens)
  • the body creates antibodies to fight the germs, the specific antigens trigger lymphocytes to product antibodies
  • if the actual disease germs ever attack the body, the antibodies return to destroy them
  • memory cells are produced that give long-term immunity (a rapid immune response if exposed to the same pathogen
• Mechanical barrier


  skin and hairs (e.g. nose hair)
• Chemical barrier


  mucus (can be found in lungs) and stomach acid
• Cellular 


  immune system cells that they interact with (e.g. macrophage, T cell & B cell)
• Antibodies:

  • produced by lymphocytes, formed in lymph nodes in response to the presence of pathogens
  • pathogens have antigens on their surface
  • specific antibodies have complementary shapes which fit specific antigens
  • when pathogen enters a body, its antigens are recognised as foreign and body begins an immune response
  • antibodies lock onto antigens, making bacteria clump together & mark them in preparation for destruction by phagocytes, or neutralise toxins produced by the bacteria
  • once antibodies have been made, they remain in the blood to provide long-term protection (active immunity)
• Vaccination:

  • having people get vaccinated help to control spread of disease
  • (herd immunity)
• Passive immunity


  short-term defence against a pathogen by antibodies acquired from another individual
• Breastfeeding (passive immunity) - 

  • sharing antibody with the child
  • mother has the serum that contains antibodies and passes it onto the baby via ingestion
  • so the child gets temporary immunity from the mother
  • antibodies weakens the virus to a point where own immune system can fight
  • this is when the baby gets the most vaccinations as they are able to handle it
• Cholera


  a disease caused by a bacterium which is transmitted in contaminated water
• Cholera:

  • scholar bacterium produces a toxin that causes the secretion of chloride ions into the small intestine 
  • osmosis = chloride ions will enter the lumen, lumen has a higher concentration and requires more water
  • more water enters lumen via osmosis then exits body as diarrhoea, decreasing the amount of water in the intestine
• Passive immunity does NOT product memory cells
• Phagocytosis:

  1. a phagocyte recognises the antigens on a pathogen
  2. the cytoplasm of the phagocyte moves round the pathogen, engulfing it
  3. a phagocytic vacuole is form which has the pathogen engulfed in it
  4. lysosome fuses itself with the phagocytic vacuole which contains lysosomal enzymes that breaks down the pathogen
  5. to activate the other immune system cells to phagocyte presents the antigens to them