Disease And Immunity Flashcards

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1
Q

Define disease

A

Condition that impairs normal functioning of an organism

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2
Q

What organism causes disease?

A

Pathogen

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3
Q

Types of disease causing pathogens

A
  • Bacteria
  • Viruses
  • Fungi
  • Protoctists
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4
Q

Define communicable disease

A

A disease that can spread between organisms

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5
Q

Name some disease caused by bacterium

A
  • Tuberculosis
  • Bacterial meningitis
  • Ring rot
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6
Q

Name some diseases caused by viruses

A
  • HIV/AIDS
  • Influenza
  • Tobacco mosaic virus
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7
Q

Name some diseases caused by fungus

A
  • Black Sigatoka
  • Ringworm
  • Athletes foot
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8
Q

Name some diseases caused by Protoctists

A
  • Potato/tomato late blight

- Malaria

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9
Q

What are the two types of transmission?

A
  • Direct transmission

- Indirect transmission

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10
Q

Describe direct transmission

A

When a disease is transmitted directly from one organism to another

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11
Q

How can direct transmission occur?

A
  • Droplet infection
  • Sexual intercourse
  • Directly touching an infected organism
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12
Q

Describe indirect transmission

A

When a disease is transmitted from one organism to another via an intermediate

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13
Q

Through what intermediates can disease be transmitted?

A
  • Air
  • Water
  • Food
  • Vector
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14
Q

What factors can impact/affect transmission

A
  • Living conditions
  • Social factors
  • Climate
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15
Q

How can living conditions affect transmission?

A

Overcrowded living conditions can increase the transmission of many communicable diseases

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16
Q

How can social factors affect transmission?

A

Worse social conditions can lead to increased likelihood of disease; income, occupation, area a person lives in.
-People with limited access to good resources, education and health care may suffer more

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17
Q

How can climate affect transmission?

A

Provides optimum conditions for breeding of vector or growth of pathogen

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18
Q

What animal defences against pathogens are there?

A
  • The skin
  • Mucous membranes
  • Blood clotting
  • Inflammation
  • Wound repair
  • Expulsive reflexes
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19
Q

How does the skin protect against pathogens?

A
  • Acts as a physical barrier, blocking pathogens from entering the body
  • Acts as a chemical barrier, producing anti microbial chemicals that kill or slow down MO and can lower pH to inhibit pathogen growth
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20
Q

How do mucous membranes protect an organism from pathogens?

A
  • Protect body openings exposed to environment

- Secrete mucus that traps pathogens and contains antimicrobial enzymes

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21
Q

How does blood clotting help defend against pathogens?

A
  • Blood clots plug wounds to prevent pathogen entry and blood loss
  • Formed by a series of chemical reactions that take place when platelets are exposed to damaged blood vessels
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22
Q

What is a blood clot?

A

A mesh of protein fibres

23
Q

How does inflammation help prevent disease

A
  • Isolate and defend against pathogens
  • Damaged tissues release molecules that increase the permeability of blood vessels so they start leaking fluid into surrounding areas
  • This causes swelling and helps isolate pathogen that may have entered damaged tissue
  • Molecules cause vasodilation, increasing blood flow and bringing white blood cells to the area to help fight pathogens
24
Q

What is the first line of secondary defence in non-specific defences?

A

Phagocytosis

25
Q

Define antigen

A
  • Chemical marker on the plasma membrane of cells

- Protein or glycoprotein

26
Q

Define opsonins

A

Proteins that bind to the antigen of pathogens and then allow phagocytes to bind

  • Type of antibody
  • Some are not very specific so will bind to many phagocytic cells
  • Role is to enhance ability of phagocytic cells to bind and engulf pathogen
27
Q

Types of phagocytes

A
  • Neutrophil

- Macrophage

28
Q

Describe a neutrophil

A
  • Most common phagocyte
  • Multi lobed nucleus
  • Manufactured in bone marrow
  • Travel in blood and can move into tissue fluid
  • Short lived but will released in large numbers as a result of infection
  • Contain a large number of lysosomes
  • Engulf and digest pathogens
  • Usually die soon after digesting a few pathogens
  • Dead neutrophils may collect in an area of infection; form pus
29
Q

Describe the process of a neutrophil

A
  • Neutrophil binds to the opsonin attached to antigen of pathogen
  • Pathogen is engulfed by endocytosis forming a phagosome
  • Lysosomes fuse to the phagosome and release lytic enzymes into it
  • After digestion, the harmless products can be absorbed into the cell
30
Q

What parts of phagosomes are specialised for function

A
  • Receptors on plasma membrane that can bind to opsonin or specific antigen
  • Lobed nucleus that allows cell to squeeze through narrow gap
  • Well-developed cytoskeleton that helps the cell to change shape to engulf pathogen and to move lysosomes and vacuoles around cell
  • Many lysosomes consisting of lysin
  • Many mitochondria to release energy from glucose
  • Lots of ribosomes to synthesise enzymes involved
31
Q

Describe a macrophage

A
  • Larger cells manufactured in bone marrow
  • Travel in blood as monocytes before settling in body tissue
  • Many found in lymph nodes where they mature into macrophages
32
Q

Dendritic cells

A
  • A type of macrophage

- Found in the more peripheral tissue

33
Q

What is the role of a macrophage

A

Role in initiating the specific response to invading pathogens

  • When a macrophage engulfs a pathogen it doesn’t fully digest it
  • Antigens from surface of pathogen is saved and moved to special protein complex on surface of cell
  • Cell now becomes antigen presenting cell
34
Q

Describe an antigen presenting cell

A
  • A cell that exposes the antigen of a pathogen on its surface so that other cells in the immune system can recognise it
  • Special protein complex ensures that the antigen presenting cell is not mistaken for a foreign cell and attached by phagocytes
35
Q

What does the antigen-presenting cell do when it moves around the whole body

A
  • Comes into contact with specific cells that can activate the full immune response
  • Presents to T and B lymphocytes
36
Q

Role of antigen-presenting cell

A

To increase the chance of the antigen coming into contact with a B or T lymphocyte that will activate the full immune response - only a certain B or T will have the correct recognition site for the antigen

37
Q

Clonal selection

A

Selection of a specific B or T that is specific to an antigen - the activation of B or T lymphocyte

38
Q

Antibodies

A

Specific proteins released by plasma cells that can attach to pathogenic antigens

39
Q

B memory cells

A

Cells that remain in the blood for a long time providing long term immunity

40
Q

Clonal expansion

A

An increase in the number of cells by mitotic cell division

41
Q

Interleukins

A

Signalling molecules that are used to communicate between different white blood cells

42
Q

Plasma cells

A

Derived from B lymphocytes- cells that manufacture antibodies

43
Q

T-helper cells

A

Cells that release signalling molecules to stimulate the immune response

44
Q

T killer cells

A

Cells that attack and destroy our own body cells that are infected with a pathogen

45
Q

T memory cells

A

Cells that remain in the blood for a long time providing long term immunity

46
Q

T regulator cells

A

Cells that are involved with inhibiting or ending the immune response

47
Q

Describe the structure of B lymphocytes and T lymphocytes

A
  • White blood cells with large nucleus

- Specialised receptors on plasma membrane

48
Q

What do antibodies do

A

-Neutralise the foreign antigens

49
Q

What cells do T lymphocytes differentiate into

A
  • T helper cells
  • T killer cells
  • T memory cells
  • T regulator cells
50
Q

Role of T helper cell

A

-To release cytokines that stimulate B cells to develop and stimulate phagocytosis by the phagocytes

51
Q

Role of T killer cells

A

-Attack and kill host body cells that display the foreign antigens

52
Q

Role T memory cells

A

Provide long term immunity

53
Q

Role of T regulator

A
  • Shut down the immune response after the pathogen has been successful removed
  • They are also involved in preventing autoimmunity
54
Q

What types of cells can B lymphocytes develop into

A
  • Plasma cells

- B memory cells