Defence against Pathogens -Humans

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  • Created by: Om4r
  • Created on: 16-06-19 16:59
What is the acronym for physical defences against pathogens in humans?
SIMWEB
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What does SIMWEB stand for?
Skin, Inflammation, Mucous membranes, Wound repair, Expulsive reflexes and Blood clotting?
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How does Skin act as a physical defence against pathogens?
Its a physical barrier which blocks pathogens from entering the body. Also a chemical barrier as it can produce chemicals that are antimicrobial which lower PH inhibiting pathogen growth
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How does Inflammation act as a physical defence against pathogens?
Leaking blood vessels isolate pathogens that may have entered the damaged tissues and causes vasodilation which increases blood flow to the infected area so more white blood cells arrive to fight any present pathogens
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What are the Signs of inflammation?
Swelling, pain, heat, redness
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What is inflammation triggered by and what is the mechanism?
Tissue damage. Damaged tissues release molecules which increase permeability of blood vessels causing them to leak (isolatingPs) Molecules also cause vasodilation which increases blood flow to area and more white blood cells arrive to fight pathogens
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How does a mucous membrane act as a physical defence against pathogens?
Protects body openings that are exposed to the environment e.g. nostrils,anus, ears. Some release mucous which is a sticky substance trapping pathogens
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How does Wound repair act as a physical defence against pathogens?
Skin is able to repair itself reforming barrier against pathogens.
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How does skin repair itself?
outer layer of skin divides and migrates to the edges of the wound. Tissue below wound contracts which brings the edges closer together. Repaired using collagen fibres-too many= scar forms
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How do Expulsive reflexes act as a physical defence against pathogens?
E.g. coughing and sneezing. They attempt to expel foreign objects including pathogens.
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How do blood clots act as a physical defence and how do they form?
A blood clot is a mesh of protein fibres. They plug wounds to prevent pathogen entry and blood loss. Form when platelets are exposed to damaged blood vessels- by a series of reaction
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What are Opsonins?
Protein molecules that bind to the antigen on the surface of a pathogen. They enhance the ability of phagocytic cells to bind and engulf the pathogen
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What are Cytokines?
Hormone-like molecules that are used in cell signalling to stimulate the immune response
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What is a neutrophil?
A type of white blood cell that engulfs foreign matter and traps it in large vacuole (phagosome)which fuses with lysosomes to digest the foreign matter
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What is the First line of secondary defence?
Phagocytosis
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How are neutrophils recognised?
By their multi-lobed nucleus.
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Where are neutrophils manufactured?
In the bone marrow
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What is present in large numbers in neutrophils?
Lysosomes which are digestive enzymes
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What is pus formed from?
Dead neutrophils which collect in an area of infection
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What are the steps in Phagocytosis?
Neutrophil binds to the opsonin attached to the antigen of the pathogen. Pathogen is engulfed by endocytosis forming a phagosome, lysosomes fuse to phagosome and release digestive enzymes , digested bacterium released out of phagocyte by exocytosis
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What is the role of macrophages?
To engulf pathogen (not digest) and present antigen on cell surface becoming an antigen presenting cell (APC),
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What are the 2 main types of Lymphocytes?
T lymphocytes and B lymphocytes
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What activates T-lymphocytes?
Phagocytes
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What activates B- lymphocytes?
T-lymphocytes
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What is on the surface of T-lymphocytes?
Receptors
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How do Phagocytes activate T-lymphocytes (TL)?
Receptors on TL binds to antigen on APC. All TLs have different receptors. TL bind to complementary antigen which activates the TL- process called clonal selection. TL undergo clonal expansion.
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What is clonal expansion and what happens after this occurs?
When T-lymphocytes divide to produce clones of itself. Different types of TL carry out different functions
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What are the 3 different types of T-lymphocyte?
T-helper, T-Killer, T-regulatory
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What is the function of T-helper cells?
To release substances to activate B-lymphocytes and T killer cells
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What is the function of T-Killer cells?
Attach to and kill cells infected with a virus
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What is the function of T-regulatory cells?
They suppress the immune system from other white blood cells which helps stop the immune system cells from mistakenly attaching to hosts body cells
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What is the function of T-memory cells?
They remain in the blood for a long time providing long-term immunity
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What are Interleukins?
Signalling molecules that are used to communicate between different white blood cells
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What is active immunity?
Where the immune system is activate and manufactures its own antibodies
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What is artificial immunity?
Immunity that is achieved as a result of medical intervention
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What is an Epidemic?
A rapid spread of disease through a high proportion of the population
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What is natural immunity?
Immunity achieved through normal life processes
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What is passive immunity?
Immunity achieved when antibodies are passed to the individual through breast feeding or injection
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What is vaccination?
A way of stimulating an immune response so that immunity is achieved
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What forms can antigenic material that's used in vaccines?
Whole living organisms that have similar antigens but aren't as harmful as those that cause the real disease. Dead pathogen, or a weakened version of the pathogenic organism
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What are the 2 types of vaccination?
Herd and ring vaccination
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What is herd vaccination?
When all or most of the population are vaccinated preventing the spread of the disease
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What is Ring vaccination?
Vaccinating people in the immediate vicinity of the new case of disease
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How do T-lymphocytes activate B-lymphocytes (BL)?
BL covered with proteins called antibodies( different BL different antibody)these bind to antigens to form antigen anti-body complexes. Antibody on surface of BL binds to complementary antigen which activates it. Activated BL divides by mitosis
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What do B-lymphocytes divide into by mitosis?
Plasma and memory cells.
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Card 2

Front

What does SIMWEB stand for?

Back

Skin, Inflammation, Mucous membranes, Wound repair, Expulsive reflexes and Blood clotting?

Card 3

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How does Skin act as a physical defence against pathogens?

Back

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Card 4

Front

How does Inflammation act as a physical defence against pathogens?

Back

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Card 5

Front

What are the Signs of inflammation?

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