Immunology and Neurobiology Unit 3 KA 5 Flashcards
Non-specific body defences
What are Pathogens?
Pathogens are bacteria, viruses or other organisms that can cause disease
What is Immunity?
Immunity is the ability of the body to resist infection by a pathogen or destroy the organism if it succeeds in invading and infecting the body
What are the three lines of defence the body has against invading pathogens?
1) Physical and chemical defences: non- specific - skin, stomach acid, mucus
2) Cellular response: non-specific - Phagocytosis
3) White blood cells: specific - T and B lymphocytes
What is the difference between a Specific and Non-specific response?
A specific response involves white blood cells response to a SPECIFIC pathogen
A non-specific response involves white blood cells response to ANY pathogen
How does the Skin offer physical protection against invading pathogens? (2)
1) Composed of layers of closely packed epithelial cells
2) Sweat and Sebaceous glands in the skin keep the skin ph too low for most microbes to survive
How do Mucus membranes protect the body from invading pathogens?
Line the respiratory and digestive tracts forming a physical barrier by secreting a sticky mucus which traps microbes
How do Tears and Saliva protect the body from invading pathogens?
Tears and saliva contain the enzyme Lysozyme which digests the cell walls of bacteria, destroying them
How does the Stomach protect the body from invading pathogens?
The epithelial lining of the stomach secretes acid which destroys microbes
What happens when the body suffers a physical injury like a cut or an invasion of microbes?
When the body suffers a physical injury it responds by a localised defence mechanism called an inflammatory response at the affected site
Where are Mast cells produced?
Where are they present?
What do they release?
-Mast cells are produced from the same stem cells as white blood cells
-They are present in connective tissue throughout the body
-They release Histamine
What is Histamine?
Histamine is a chemical that causes blood vessels to widen (vasodilation), increasing blood flow and the capillarie permeability
What happens when Mast cells release Histamine?
When Mast cells release Histamine it increases the blood flow making the injured area look red and inflamed, and it swells up due to the stretched capillary walls becoming more permeable causing them to leak fluid into surrounding tissues
Why is an Inflammatory response beneficial? (2)
1) An accumulation of Phagocytes to the damaged tissue
2) Rapid delivery of blood-clotting elements to injured area stopping further blood loss and preventing further infection
What are the five stages of Phagocytosis?
1) Phagocytes recognise surface antigen molecules on pathogen as ‘foreign’ and move towards it
2) Phagocytes engulf pathogen by in-folding of the cell membrane to create a vacuole
3) Lysosomes contain digestive enzymes and are present in the phagocytes cytoplasm, these fuse with the vacuole and release enzymes to digest the engulfed pathogen
4) Breakdown products are adsorbed by the phagocyte
5) Phagocytes release Cytokines which attract more phagocytes to the infected area
What are Cytokines?
Cytokines are protein molecules that act as a signal to specific white blood cells
