communicable disease

• what is a pathogen?

  microorganisms that cause disease
• what type of pathogens are there?


  bacteria

  fungi

  virus

  Protoctista
• what are characteristics of TB and what causes it?


  disease that kills cells and tissues, the lungs are more often affected

  caused by : bacteria
• what are characteristics of bacterial meningitis and what causes it?


  infection of membranes that surround brain and spinal cord, membranes become swollen which may cause damage to brain and spinal cord

  caused by : bacteria
• what are characteristics of HIV/AIDS and what is it caused by?


  attacks cells in immune system and compromises immune system
• what are characteristics of influenza and what is it caused by?


  attacks respiratory system and causes muscle pains and headaches

  caused by : virus
• what are the characteristics of ringworm and what is it caused by?


  Growth of fungus in skin with spore cases erupting through skin to cause rash

  Caused by fungus
• what are characteristics of athletes foot and what is it caused by?


  Growth under skin or feet, particularly between the toes

  caused by fungus
• what does a life-cycle of a pathogen involve?


  Travel from one host to another

  entering the host tissues

  reproducing

  leaving the host tissues
• what is direct transmission?

  Direct transmission refers to the transfer of a pathogen from one host to another through physical contact or close proximity.
• what is indirect transmission?


  Pathogens are transmitted via a vector
• how can a pathogen be transmitted?

  Direct physical touch

  faecal

  droplet infection

  spores
• How does hygiene affect transmission of pathogens?

  Hygiene affects transmission of pathogens by reducing the likelihood of contact with contaminated surfaces or individuals.
• What are other factors that affect transmission?

  Social factors such ;

  as overcrowding

  poor ventilation,

  poor health,

  poor diet

  homelessness

  living or working with people who have migrate from areas where disease more common
• how can a plant be infected with a pathogen?


  1)In soil by entering the roots

  2)spores as means of sexual and asexual reproduction these sports can be carried by wind (airborne)

  3)once pathogen side plant may affect or vascular tissues pathogen leaves are distributed when the leaves are shed and carry the pasture back to the soil where it can grow an infection of the plant

  4) indirect transmission of a plant pathogen often occurs as a result of an insect attack
• how does disease and climate affect transmission of pathogens?

  Protists bacteria and fungi can grow and reproduce more rapidly and warm moist conditions therefore they tend to be more common in warmer climates in cooler climate. These patterns may be damaged or even killed by cold winter weather.

  as a result, there is a greater variety of disease to be found in warmer climates and animals or plants living in these regions are more likely to be infected
• what is a passive defence?


  These are defensive present before an infection and their role is to prevent entry and spread of the pathogen

  passive defences include physical barriers and chemicals
• what are the physical defences of a plant?


  Cell wall - acts a physical barrier but complete contains chemical defences that can be activated

  lignin thickening - of cell wall waterproof and indigestible

  waxy cuticles - prevent water collecting on cell surfaces

  Bark - Contains chemical defences that work against pathogenic organisms

  stomatal closure - stomata are possible points of entry for pathogens, when a pathogen is detected the Guard will close
• what is an active defence?


  When specific chemicals are released to kill a pathogen
• Chemicals in active defences

  • Terpenoids
  • Phenols
  • Alkaloids
  • Defensive proteins
  • Hydrolytic enzymes
• Terpenoids

  Essential oils that have antibacterial and anti-fungal properties
• Phenols


  Have antibiotic anti-fungal properties, they bind to slavery proteins and digestive enzymes, insects that ingest a high amount of these enzymes will not grow and eventually die
• Alkaloids


  Not shrink containing compounds that give bitter taste, inhibit herbivores feeding (some acids inhibit protein synthesis)
• Defensive proteins


  Small cysteine rich proteins that act upon molecules in plasma membrane of pathogen, possibly inhibiting the action of ion transport channels
• Hydrolytic enzymes


  Found in spaces between cells, they include chitinases which breakdown the chain found in fungal cell wall and eliza enzymes which are capable of degrading bacterial cell walls
• what is necrosis?


  Deliberate self suicide a few cells are sacrificed to save the rest of the plant by killing cells surrounding the infection. The plant can limit the pathogens access to water nutrients and therefore can stop it from spreading further around the plant.
• what is a non-specific primary defence?


  The mechanisms that have evolved to prevent entry of pathogenic organisms they are non-specific as they will prevent the entry of any pathogen
• how does the skin act as a primary defence?

  It is a physical barrier and the outer layer of skin is called epidermis and it consist of layers of skin keratinocytes that migrate out of the surface of the skin and dry out so by the time they reach the surface they are dead (keratinasised)
• how do Lysozymes act as a primary defence?


  eyes are protected by antibodies and enzymes in the tear fluid
• how do hair and mucus actors a primary defence


  Noses contain hair and mucus which filter out larger pathogens containing particles
• how do cillia and mucus act as a primary defence?

  They have goblet cells that make mucus

  mucus traps pathogens cilia water layer of mucus along the back of the throat.
• how does hydrochloric acid act as a primary defence?


  Most pathogens in digestive system are killed by activity of the stomach which can be pH 1-2 this denatures the pathogens enzymes
• how do you explosive reflexes act as a primary defence?

  Coughing sneezing and vomiting

  they respond in irritation and caused by presence of microorganisms or toxins that they release
• how does blood clotting work?


  1)Damaged blood vessel releases protein called thromboplastin

  2) calcium ions and thromboplastin convert prothrombin protein to enzyme thrombin

  3) thrombin catalyses conversion of soluble protein fibroisogen to insoluble protein fibrin

  4) Fibrin fibres mesh together trapping platelets and red blood cells. This forms a blood clot.
• what is a secondary defence?

  Used to combat pathogens that have entered the body when a pathogen invades the body is recognised as a foreign by the chemical makers on its outer membrane. These markers are called antigens.
• what is inflammation?


  local immune response to tissue injury or infection
• what are the symptoms of information?


  Heat

  redness

  adima

  pain

  loss of function
• what is the process of inflammation?

  1)vasoconstriction of blood vessels occurs to reduce blood loss and formation of clots

  2)Vasoactive chemicals are released from cell which are histamine and prostaglandins these chemicals increase blood flow and dilate blood vessels

  3) capillaries become more permeable and can be described as leaky. This is so fluids and proteins can leak into the surrounding tissue. (neutrophils)

  4) neutrophils find sites of injury as they squeeze through end edis site and follow toxins released by bacteria (chemotactic gradient)
• what is phagocytosis?


  Digestion of pathogens
• what is the process of phagocytosis?

  1)Neutrophil binds to opsonin attached to antigen of the path

  2) pathogen is engulfed by endocytosis forming a phagosome

  3) Lysosomes fuse to the phagosome and release lytic enzymes into it (phagosome becomes a phagolysosome)

  4) after digestion harmless products can be absorbed into cell