Chapter 12- Communicable Dieseas

Skin covers the body and prevents entry of pathogens Lined with mucous membranes, that seceret sticky mucus Lysosomes in tears and urine

If you cut yourself, the skin is breached and pathogens can enter the boy. Blood clots rapidly to seal the wound. When platelets come into contact with collagen in skin or wall of damaged blood vessel, that adhere and begin to secrete several substances.

Localised response to pathogens resulting in inflammation at the site of wound Mast cells are activated in damaged tissue and release chemicals in histamines and cytokines Histamines make the blood vessels dilate and vessels more leaky Cytokines attract white blood cells

Fevers Phagocytosis

Specialised white cells that engulf and destroy pathogens. There are two main types of phagocytes- neutrophils and macrophages.

• Pathogens produce chemicals that attract phagocytes • Phagocytes recognise non human proteins on the pathogen • The phagocyte engulfs the pathogen and encloses it im a vacuole known as a phagosome. • The phagosome combines with a lysosome to form a phagolysosome • Enzymes from the lysosome digest and destroy the pathogen

Chemicals that bind to a pathogen and tag them so they can be more easily recognised

Bone marrow

Thymus gland

Cell receptors on their cell surface membrane . They produce interleukins which stimulate the activity of B cells, which increases antibody production.

Destroy the pathogen carrying antigen. They produce a chemical called perforin, which kills the pathogen by making holes in its membrane.

These live for a long time and are part of the immunological memory. If they meet a antigen the second time they divide rapidly to form a huge number of T killer cells

Cells suppress the immune system acting to control and regulate it.

Plasma cells B effector cells B memory cells

These produce antibodies to a particular antigen and release them into the circulation.

Divide to form plasma cell clones

These live for a long time and provide the immunological memory

Interleukins produced by activated T helper cells The activated B cells divide by mitosis to give clones of plasma cells and B memory cells Cloned plasma cells produce antibodies that disable the antigens , known as primary immune response Some cloned B cells can develop into b memory cells. Perform part of secondary immune response

Natural is where you meet a pathogen for the first time, your immune system is activated and antibodies are formed, which results in the destruction of the antigen Artificial is where the disease is killed before their immune system makes the antibodies they need.

Gives temporary immunity is where antibodies are formed in one individual, extracted and then injected into the bloodstream of another individual

The immune system of the body is stimulated to make its own antibodies to a safe form of an antigen, which is injected into the bloodstream

Opsonins-tag pathogens for better recognition Agglutinins-stick pathogens together for better recognition Antitoxins-neutralize toxins released by pathogens