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Topic 6: microbiology and pathogens > 6.7 response to infection > Flashcards

6.7 response to infection Flashcards

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Biology 101 flashcards
1
Q

what act as antigens?

A

glycoproteins on the surface of the cells

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2
Q

what is an antigen?

A

any substance which stimulates an immune response in the body

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3
Q

what are three physical barriers to infection?

A
  • skin
  • stomach acid
  • gut and skin flora
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4
Q

What are examples of non-specific responses to infection?

A
  • inflammation
  • fevers
  • phagocytosis
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5
Q

what is the process of inflammation?

A

1- mast cells, found in connective tissue below the skin and around blood vessels, and basophils release chemicals called histamines
2- these cause the blood vessels in the area to dialate leading to local heat and redness
3- they also cause capiliaries to become permeable as cells seperate and plasma leaks out with leucocytes and antibodies

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6
Q

what is the reason we have fevers?

A
  • hypothalamus that regulates temperature resets to a higher temperature when a pathogen is detected as a higher temperature reduces reproduction of the pathogens
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7
Q

what is phagocytosis?

A

a process in which white blood cells engulf pathogens

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8
Q

what are the two main groups of leucocytes (white blood cells)?

A
  • granulocytes (can be stained)
  • agranulocytes
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9
Q

what are the two types of phagocyte?

A
  • neutrophils
  • macrophages
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10
Q

what are neutrophils?

A
  • granulocytes
  • can only ingest a few pathogens before it dies as it cannot renew it’s lysosomes
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11
Q

what are macrophages?

A
  • agranulocytes
  • have a large capacity for ingesting pathogens becuase they can renew their lysosomes
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12
Q

what is the process of phagocytosis?

A

1- pathogen attaches to phagocyte by antibodies and surface receptors (pathogen recognisable by opsonins)
2- the pathogen is engulfed by infolding of phagocyte membrane (a vesicle called a phagosome)
3- phagosome fuses with lysosome
4- lysosome enzymes break pathogen down
5- once engulfed, the pathogen produces cytokines in the surrounding tissues which send a signal to other phagocytes that there is an infection, raises body temperature and triggers the specific immune response

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13
Q

what are the two types of specific response to infection?

A
  • the humoral immune response
  • cell-mediated immune response
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14
Q

what are lymphocytes?

A

type of white blood cells involved in the specific immune response that travel around the body in the blood and the lymph

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15
Q

what are the two kinds of lymphocytes?

A
  • B cells
  • T cells
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16
Q

what are B cells?

A
  • produced in the Bone marrow
  • involved with humoral immunity (liquids: blood,plasma)
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17
Q

what are the three types of B cell that develop when it binds to an antigen?

A
  • B effector cells: divide to form plasma cell clones
  • Plasma cells: produce antibodies to particular antigens
  • B memory cells: provide immunological memory to a specific antigen allowing the body to respond very quickly if infected with the same pathogen
18
Q

what are T cells?

A
  • mature in the Thymus
  • involved with cell-mediated response
  • display thousands of identical T receptors that bind to antigens on infected body cells
19
Q

what are the three types of T cell that are produced from this?

A
  • T killer cells: produce chemicals to destroy infected body cells
  • T helper cells: activate the plasma cells to produce antibodies against the antigens on a particular pathogen and also create opsonins to ‘label’ pathogens for phagocytosis
  • T memory cells: very long-lived cells that make up part of immunological memory
20
Q

what are MHCs?

A

Major Histocompatibility Complex proteins that display antigens on their cell surface membrane

21
Q

what is the humoral response?

A

reacts to antigens found outside the body cells including antigens on pathogens such as bacteria and fungi, and to antigen-presenting body cells

21
Q

what are the two stages of the humoral response?

A
  • T helper activation stage
  • effector stage
21
Q

T helper activation

A
  • when a pathogen enters the body, chemicals are produced that attract the phagocytes, including the macrophages and neutrophils
  • a macrophage engulfs the pathogen and seperates off the antigens from the digested pathogen and combines them with the major histocompatibility complex.
  • the macrophage then becomes an antigen presenting cell
  • this then binds to receptors on a T helper cell
  • once the T helper cell is activated, it divides to form T memory cells and active T helper cells
21
Q

The effector stage

A
  • an antigen of pathogen binds to the complimentary receptor on a B cell
  • B cell engulfs the pathogen and broken down by enzymes and antigens are presented on the major histocompatibility complexes and becomes an APC
  • an activated T helper cell binds to the APC and releases cytokines which stimulate the B cell to divide to produce B memory and B effector cells
  • B effector clones differentiate into plasma cells and produce antibodies which are specific to the antigen
21
Q

what are the three ways that antibodies cause destruction?

A
  • agglutination
  • opsonisation
  • neutralisation
22
Q

what is agglutination?

A

when antibodies bind to the antigens on pathogens, the microorganisms agglutinate and clump together which helps them stop spreading around the body and makes it easier for engulfing

23
Q

what is opsonisation?

A

the antibody acts as an opsonin, a chemical which makes an antigen or pathogen more easily recognised by phagocytes

24
Q

what is neutralisation?

A

antibodies neutralise the effects of bacterial toxins by binding to them

25
Q

when does the cell-mediated response occur?

A

what a pathogen/virus invades a host cell

26
Q

the cell-mediated response

A

1- when a body cell is infected, some of the pathogen is digested and the antigens are presented on MHCs and becomes a APC
2- a T killer cell with a wide range of complimentary receptors binds to the APC and T helper cells release cytokines which stimulate the cell to divide
3- the T killer cell divides to form many active T killer cell clones and T killer memory cell clones
4- the active T killer cells bind to the APC and release enzymes that make small pores
5- these pores in the APC allow water and minerals in and cause lysis
6- any undamaged pathogens released are marked with antibodies and destroyed

27
Q

which cells are longer lasting in the bloodstream and create a secondary immune response upon second contact with pathogen?

A
  • B memory cells (produce antibodies)
  • T memory cells (produce T killer cells)
28
Q

what is natural active immunity?

A
  • when your body comes into contact with a foreign antigen, your immune system is activated
  • it makes the antibodies needed against the antigens on th pathogen and the pathogen is destroyed
    (your body makes the antibodies)
29
Q

what is natural passive immunity?

A
  • when a mammal like a human is pregnant, pre-formed antibodies are passed from mother to baby through the placenta
  • after birth the baby receives additional protection from mother’s milk (colostrum)
    (passive because the body doesn’t make the antibodies and antibodies are not replaced)
30
Q

what is artificial passive immunity?

A
  • antibodies found in one individual are extracted and injected into another individual
  • short-lived but very effective
    (the body does not make the antibodies and is not naturally done)
31
Q

what is artificial active immunity?

A
  • small doses of a safe form of pathogen are used to produce immunity
    (body produces it’s own antibodies but from an artificial trigger)
32
Q

How do we eradicate disease?

A

vaccination programmes (have eradicated smallpox and almost polio)

33
Q

why is it hard to eradicate diseases?

A
  • certain pathogens can mutate quickly and some survive in soil and water
34
Q

why does herd immunity play a part in vaccination?

A

because if a significant enough proportion of the population is vaccinated, it makes it very hard for the disease to spread and it protects people who cannot be vaccinated

35
Q

what are the pros of vaccination?

A
  • the child, and the adult they grow into are protected from disease that could kill them
  • society benefits as the potential pool of infection is reduced through heard immunity and protects those who cannot have it
  • the cost for treating these serious diseases decreases
36
Q

what are the cons of vaccination?

A
  • some live vaccines are grown in eggs and children with egg alergies can have severe allergic reactions
  • minority of children become severely ill after a vaccine due to extreme immune response
  • some scientists suggest mass vaccination programmes are linked to the recent rise in childhood asthma and allergies

Topic 6: microbiology and pathogens (7 decks)

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