Biology__Topic 6__T6L6 Flashcards
What is the immune response?
Several mechanisms in the body act to destroy the invading pathogen. This task is performed by the immune system.
What two types of (immune) responses are there?
Non-specific responses help to destroy any invading pathogen, Specific immunity is always directed at a specific pathogen
What are the 4 types of non specific responses?
Lysozyme
Inflammation
Interferon
Phagocytosis
How does the Lysozyme non-specific response work?
If dirt lands in eye, you cry.
Tears helps to wash out foreign material and attacks bacteria on the surface of the eye.
Lysozyme is an enzyme which kills bacteria by breaking down their cell walls - found in saliva, tears and nasal secretions.
How does the inflammatory non-specific immune response occur?
Damaged white blood cells and mast cells release chemicals, e.g. histamine.
Chemicals cause arterioles to dilate, increasing blood flow in the capillaries at infected site.
Histamines increase permeability of the capillaries so the vessels leak.
Plasma fluid, white blood cells and antibodies leak from the blood into the tissue causing oedema.
Infecting microbes can be attacked by these intact white cells
How does phagocytosis work as a non-specific immune response?
Phagocytes are white blood cells that engulf bacteria and other foreign matter, found in the blood and tissues.
They extend their cell surface membranes and engulf pathogens in phagocytic vacuoles.
Lysosomes fuse with vacuole membrane, releasing digestive enzymes by exocytosis which break down the pathogen.
Phagocytes include both neutrophils and macrophages.
What first occurs when a site in the body is infected?
Chemicals released by bacteria and the cells damaged at the site of infection attract phagocytic white cells.
Neutrophils engulf between 5-20 bacteria (phagocytosis) before they become inactive and die.
Then macrophages destroy as many as 100 bacteria by phagocytosis, they also ingest debris from damaged cells, and foreign matter (e.g. dust).
The ingested material is enclosed within a vacuole.
Lysosomes containing digestive enzymes fuse with the vacuole, the enzymes are released, and they destroy the bacteria.
What is pus?
Dead phagocytic and bacterial cells, mainly neutrophils, which form a thick fluid called pus
How do Neutrophils and macrophages engulf bacteria?
Bacterium with antigens on surface is engulfed by neutrophil or macrophage
Then enclosed in vacuole
Lysosomes fuse with vacuole,
Releasing digestive enzymes that
Destroy foreign material.
How are bacteria able to spread within the body?
by the blood or in the lymph
What is the spread of bacteria through the body hindered by?
Macrophages in the lymph nodes, spleen and liver. THE LYMPHATIC SYSTEM.
What happens when the lymphatic system fails?
Widespread infection known as septic shock or ‘blood poisoning’.
How does the non-specific immune response interferon occur?
Interferon provides non-specific defence against viruses, and some bacteria and protozoa.
Microbe-infected cells produce this (antimicrobial) protein;
it diffuses to the surrounding cells where it binds to receptors,
Preventing the viruses entering the cell and preventing microbes replicating.
It inhibits microbial protein synthesis and in this way limits the formation of new microbe particles.
How are materials cycled through the blood and lymphatic system?
O2, glucose and ions diffuse from blood vessels into the tissue fluid, before draining through the lymphatic vessels.
