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Biology 3 > Immune defences > Flashcards

Immune defences Flashcards

1
Q

What are the three defence mechanisms of the body that are used to protect itself from pathogens and foreign matter?

A
  • Natural barriers
  • innate immune response
  • adaptive immune responses
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2
Q

What are the three types of natural barriers?

Provide examples.

A
  • chemical: acids, enzymes (in saliva or tears), mucus, sebum, swear,
  • mechanical: intact skin, mucous membranes, cilia, nasal hairs
  • microbiological: gut flora
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3
Q

How can the body distinguish from self and non-self cells?

A

Self-cells contain molecules present on the surface of their cell membranes that identify themselves as belonging to the body while non-self cells contain surface molecules (antigens) that the body recognises as not belonging to the body.

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4
Q

Why does the body need to distinguish between self and non-self cells?

A

White blood cells play a vital role in the non-specific and specific defence. It is important that when defending the body against pathogens white blood cells are able to distinguish foreign cells from those of our own body.
This….

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5
Q

What is the difference between class 1 MHC markers and class 2 MHC markers?

A

MHC 1 markers are located on the surface of all human cells with a nucleus whereas MHC 2 markers are only located on antigen presenting cells.
These markers are treated in a different manner by white blood cells.

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6
Q

Where are blood cells produced?

A

Produced in the bone marrow of long bones.

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7
Q

Which type of blood cell leaves the bone marrow in an immature state?

A 
T cells (T lymphocytes).
The migrate to the thymus gland which is their site of maturation.
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8
Q

Do all blood cells look the same?

A

No, all blood cells take on different looks as they have different roles.

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9
Q

What is the first line of defence?

A

The body’s natural barriers.
- part of the defence against pathogens provided by the mechanical, chemical and microbiological barriers of the innate immune system that prevent entry of pathogens into the body.

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10
Q

What is the second line of defence?

A

Involves innate responses to the presence of foreign particles.

  • consists of the actions of immune cells and soluble proteins mounting a rapid but non-specific attack against pathogens that gain entry to the body.
  • cannot distinguish one type of microorganism from another
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11
Q

What is a phagocyte? (4)

A
  • a white blood cell which engulfs pathogen via phagocytosis
  • formed in bone marrow and flow through lymphatic and circulatory system
  • the lysosomes present in the phagocyte destroys the pathogen with enzymes
  • includes macrophages, dendritic cells and neutrophils
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12
Q

What are the cells of the second line of defence?

Use the acronym!

A

Please bring home no more pathogens.

  • Phagocyte
  • Basophil
  • Histomine
  • Neutophil
  • Macrophage
  • platelets
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13
Q

What are complement proteins?

Provide 2 examples.

A

A group of proteins that assist phagocytes in recognising the presence of pathogens
eg antibodies, interferons

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14
Q

What is an interferon?

State the cause and effect.

A
  • A chemical (cytokine) that is secreted by viral infected cells.
  • The release of interferon makes adjacent uninfected cells more resistant to the virus (reducing chance of infection).
  • It triggers cells to make enzymes which prevent the virus from making more copies of itself.
  • successful against viruses that do not travel far.
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15
Q

What is inflammation?

What is released?

A

A reaction to infection whereby histamines (from mast cell) causes local arterioles to expand, drawing more blood into the area.
Histamine causes capillaries to become highly permeable allowing macrophages and neutrophils to pass out of the bloodstream to the infected area.

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16
Q

What is the temperature response?

A

When macrophages recognise a foreign cell they release the cytokine; interleukin 1.
This causes the hypothalamus to reset, resulting in a fever.
The high body temp is an unfavourable condition for the pathogen (limits reproduction) hence providing WBC a better chance to defend.

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17
Q

What is the lymphatic system?

A

A system of vessels and lymph nodes which plays a vital role in defending the body against the myriad of pathogens.

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18
Q

Is the lymphatic system a one-way system?

A

No, the system contains valves which prevent the backflow of fluid. The system relies on muscle contranctions to circulate the lymoh fuid around the body.

19
Q

What are lymph nodes?

A

Sections filled with WBC which filter lymph passing through the body. Antigens will pass though here and meet lymohcytes.
They swell during infection as lymphocytes are multiplying rapidly in order to overcome invader.

20
Q

What are the primary lymphoid organs?

A

Generate lymphocytes from immature progenitor cells.

  • bone marrow
  • thymus
21
Q

What are the secondary lymphoid organs?

A

Sites where mature B and T cells are activated by meeting complementary antigens, developing into effector cells.

  • lymph nodes
  • the spleen
22
Q

What is the third line of defence?

A

A form of specific immunity in which people produce their own antibodies to a particular antigen.
Involves action of b cells and t cells.

23
Q

What is the primary response of the adpative immune system?

A

Occurs after first contact with pathogen

  1. Mactrophage captures pathogen and displays fragmnets of its antigen on an MCH2 marker.
  2. Macrophage binds with a t-helper cell and M releases interleukin one which activate T helper cell
  3. T helper cell releases interleukin 2, activating other lymphocytes
24
Q

What is the cell-mediated response?

A

Involves action of T cells on intracellular pathogens

  1. the T helper cell directly binds to the MCH 2 marker on M and becomes activated when M releases interleukin 1
  2. the activated T cell releases interleukin 2, stimulating other helper T cells, cytotoxic t cells and b cells that are specific to that disease to become activated. Clonal selection
  3. Helper t cells will differentiate into t memory cells which remain in the lymph nodes
  4. the cytotoxic t cells will attack infected cells. they use their t cell receptors to recognise MCH1 markers on cells, they bind to marker and secrete perforin proteins.
  5. these proteins punch holes in the membrane of infected cells and stimulate cell to undergo apoptosis
  6. suppressor t cells then turn off immune response once infection has been eradicated
25
Q

What are the actions of supressor t cells? (3)

A
  • directly kill immune cells
  • inhibit secretion of immune cells
  • secrete proteins that alter cellular functions
26
Q

What is hummoral immunity?

A

Involves the resistance to disease via the production of antibodies that bind to specific antigens.

27
Q

What is the definition of an antigen?

A

Defined as a group of compounds present on the cell surface that bind to specific immune receptor and elicit an immune response.

28
Q

What is an antibody?

A

A protein molecule designed to attach to only one specific type of antigen.
Produced by B cells.

29
Q

What is the structure of an antibody?

A

Comprised of 4 chains:
- 2 light
- 2 heavy
Has 2 antigen binding sites

30
Q

What is the definition of a pathogen?

A

An infectious agent that causes disease in its host.

Eg. virus, prion, bacterium, fungus, parasite.

31
Q

What are the 5 types of antibodies?

GAMED

A
  • igG
  • igA: passive immunity
  • igM
  • igE: allergic reaction
  • igM
32
Q

What is the role of antibodies?

A

Control extracellular pathogens because they bind with its antigen to form an antibody complex.

33
Q

What is the hummoral response?

A
  1. antigen engulfed by macrophage and presented on MHC 2 marker.
  2. M will travel to lymph node and with the aid of a helper T cell, a B cell with complementary antibody receptor will be selected. Clonal selection.
  3. Due to complementary relationship, B cell is stimulated to rapidly divide (clonal expansion)
  4. clones are differentiated into plasma b cells and memory b cells.
  5. Plasma be cells become antibody-producing factories
  6. memory b cells with specific antibody remain in the body for decades
34
Q

What are the ways in which an antibody may function?

CANO!

A
  • neutralisation: coat pathogen to prevent them attaching to host cells
  • agglutination: exposes pathogens to be engulfed
  • opsonisation: enhances engulfments
  • complement proteins: activate them so they attach to pathogen and flag them, attracting other immune cells
35
Q

What is the secondary immune response?

A

Occurs after a second exposure to the same pathogen.

Due to the presence of memory b and t cells, the immune response will be immediate, faster and greater.

36
Q

Which immune components are involved in inflammation?

A

Basophil, mast cell and neutrophil

37
Q

What is a basophil?

A

Phagocytic and release of histamine and other molecules as part of inflammatory response; play a role in allergic reactions.

38
Q

Which immune cells are found in the tissue in an inactive state?
DMM

A
  • macrophage
  • dendritic cells
  • mast cells
39
Q

Which immune cells are granulocytes?

BENNM

A
  • basophils
  • eosinophils
  • neutrophils
  • NK cells
  • mast cells
40
Q

One of the similarities between the defence mechanisms of a plant and an animal includes the..?

A

Use of an epidermal layer to inhibit the invasion of pathogens.

41
Q

Name one feature of plants that inhibits the entry of infective organisms.

A
  • waxy layers on outside surface
  • intact or thick cuticle
  • chemicals that repel potential pathogens.
42
Q

Briefly explain the role that phagocytes have in the immune response to infection.

A
  • recognise, engulf and destroy foreign material (such as pathogens)
  • engulf antibody–antigen complex
  • display the antigens of ingested pathogens to trigger an immune response.
43
Q

Name one feature of humans that inhibits the entry of infective organisms. (6)

A
  • intact skin
  • enzymes in tears of eyes
  • enzymes in saliva
  • mucus in nose, respiratory system and intestine
  • pH of digestive system
  • digestive enzymes in digestive system.

Biology 3 (10 decks)

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