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Defence against infectious disease (VI. 3) - Coggle Diagram
Defence against infectious disease (VI. 3)
The skin
Mucous membranes produce mucus, made of glycoproteins, that trap pathogens and digests them (enzyme lysozyme)
Sebaceous glands produce sebum that lowers the pH (not optimal for bacteria)
The outermost layer acts as a physical barrier
Primary defence against pathogens
Clots
Thrombin mediates the conversion of fibrinogen into fibrin
The fibrin forms a mesh in cuts that traps more
platelets and also blood cells
This results in the production of thrombin
Platelets aggregate around the cut plugging it, they also release clotting factors
When a cut occurs, blood clotting occurs very quickly to prevent blood loss and pressure drops
Immune cells
Phagocytes
When wounds become infected, many phagocytes are drawn, resulting in pus
They engulf pathogens by endocytosis
and digest them with enzymes
Phagocytes squeeze out through pores in the walls of capillaries and move to sites of infection
Antibody production
Antigens stimulate cell division in the small group of lymphocytes that produce that specific antibody
Large clones called plasma cells are produce and they secrete enough antibodies to destroy the pathogens
Antibodies are produced by lymphocytes, and each lymphocyte produces only one type of antibody
Antibodies make a pathogen more recognisable to phagocytes
Antigens present on the pathogen are recognised as foreign by the body
They also prevent viruses from entering their host cells
Even after the infection, some plasma cells persist as memory cells, so that in the next infection they will quickly divide
Antibiotics
Antibiotics are useless against viruses
Antibiotics resistance occurs when bacteria mutate, making them immune to the antibiotic
Many antibiotics are produced by fungi, used to compete against bacteria for resources
They target bacterial DNA replication,transcription, translation, ribosome function and cell wall formation
Antibiotics are substances that inhibit the growth of prokaryotes, without affecting eukaryotics cells