Chapter 10- Protection Against Invaders Flashcards
(17 cards)
Define pathogen and give 2 most common types
Disease- causing organism.
- bacteria
- virus
Define vector
Immediate host of pathogen- eg Mosquitos
How does bacteria reproduce
By mitosis
How do viruses replicate themselves
Viruses infect a cell and use the cells mechanisms to copy their DNA and build virus particles.
What is lysozyme
An enzyme that kills bacteria and viruses
Give 2 examples of bacteria and viruses
BACTERIA: (STI) - chlamydia - syphilis VIRUS: - colds - chicken pox
How are pathogens transferred (6)
- transmission by contact
- transfer of body fluids
- infection by droplets
- ingestion
- airborne transmission
- transmission by vectors
What are the bodies external defences against pathogens- non- specific defence (8)
- skin
- mucous membranes
- hairs
- cilia
- acids
- lysozyme
- cerumen (ear wax)
- flushing action
What are the bodies protective reflexes against disease and pathogens (4)
- sneezing
- coughing
- vomiting
- diarrhoea
What is a phagocyte
Cells that engulf and digest micro- organisms and cell debris
What are leucocytes
White blood cells that are very important to phagocytosis. Destroy bacteria.
What are macrophages ?
LARGE phagocytic cells that develop from some leucocytes. They engulf and destroy micro- organisms- eliminate many pathogens before infection occurs. Some are fixed in place, others wander.
What is the purpose of inflammation?
- repair damaged tissue
- reduce spread of any pathogens
What are 4 signs of inflammation
- redness
- swelling
- heat
- pain
What are the steps of the inflammatory response? (7)
- When stimulated by eg mechanical damage, mast cells release histamine, heparin and other substances into tissue fluid. Mast cells stimulate and coordinate inflammation by releasing chemicals.
- Histamine increases blood flow through the area and causes walls of blood capillaries to become more permeable, so fluid is filtered from blood.
- Heparin prevents clotting in immediate area of injury. Slows spread of pathogens into healthy tissue.
- Chemicals released by mast cells attract phagocytes- leucocytes and macrophages consume micro- organisms
- Pain receptors stimulated by abnormal coordination in tissue. So person feels pain in inflamed area.
- Phagocytes, filled with bacteria, debris and dead cells begin to die. Form pus
- New cells are produced and repair of damaged tissue occurs.
What is the lymphatic system?
Collect some of escaped fluid from blood capillaries and return in to circulatory system. Important in defence against pathogens
How does the lymphatic system assist defence against pathogens?
Lymph entering lymph nodes contains cell debris, foreign particles and potentially pathogenic micro- organisms.
When lymph enters a lymph node, larger particles such as bacteria are then trapped in the mesh work of fibres, or lymphoid tissue. Macrophages ingest particles by phagocytosis
