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Biology > Disease and the immune system > Flashcards

Disease and the immune system Flashcards

1
Q

Name 4 groups of pathogen that can cause disease?

A
  • bacteria
  • fungi
  • protoctista
  • viruses
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2
Q

How does myobacterium tuberculosis cause disease?

A
  • triggers inflammatory response by infecting phagocytes in the lungs
  • infected phagocytes are sealed in waxy-coated tubercules so bacteria remains dormant (first infection is symptomless)
  • if another factor weakens immune system bacteria becomes active and destroys lung tissue
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3
Q

How does HIV result in the symptoms of AIDS?

A
  • attachment proteins bind to complementary CD4 receptors on TH cells
  • HIV particles replicate in TH cells killing/ damaging
  • AIDS develop when there are few TH cells for the immune systems function
  • individuals can’t destroy other pathogens and suffer from secondary infections/ diseases
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4
Q

How does tobacco mosaic virus cause disease?

A
  • affects plants (transmitted via infected cell sap)
  • contains ssRNA which is transcribed by host cells to assemble new virions
  • virions enter other cells through plasmodesmata then enter xylem + phloem
  • causes stunted growth and mottled leaves
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5
Q

What causes malaria?

A
  • female mosquitoes act as a vector for plasmodium protoctista
  • parasite produces asexually in RBC in the liver causing lysis
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6
Q

What causes potato/ tomato blight and ring rot?

A

Blight = protoctista mainly transmitted via spores

Ring rot = protoctista mainly transmitted by planting infected seeds

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7
Q

How are communicable pathogens transmitted directly?

A
  • inhalation (droplet infection)
  • skin to skin contact/ fluid exchange
  • penetrating of skin through enzymes and wounds
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8
Q

How are communicable pathogens transmitted indirectly?

A
  • contaminated food and drink
  • via a vector
  • spores
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9
Q

How do living conditions affect disease transmission?

A
  • overcrowding increases direct transmission
  • climate determines which organisms can survive
  • social factors influencing how quickly people are treated
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10
Q

Name 4 physical barriers the pathogen entry in plants?

A
  • cellulose cell walls

-lignified layers

  • waxy upper cuticle
  • old vascular tissue blocking spread within the plant
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11
Q

Describe 2 mechanical responses to infection in plants?

A
  • guard cells close stomata
  • thick polysaccharide callose is produced and deposited between the cell wall and plasma membrane limiting spread
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12
Q

Name 5 barriers to animal infections?

A
  • tough keratin skin layer
  • blood clotting preventing pathogen entering body
  • hydrochloric acid in stomach killing bacteria
  • gut and skin bacteria compete with pathogen
  • mucus membranes trap pathogen and secrete enzymes
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13
Q

What are expulsive reflexes?

A

Body’s attempt to force foreign substances out

  • sneezing due to irritation of mucous membranes in nostrils
  • coughing due to irritation ciliated epithelium in respiratory tract
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14
Q

Name 4 ways the non specific immune system responds to infection?

A
  • inflammation
  • phagocytosis
  • digestive action of lysosomes
  • production of antiviral agent
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15
Q

Outline the process of inflammation?

A

1) damaged vessels release histamine causing vasodilation

2) blood flow and permeability of blood vessels increases

3) WBC and plasma move into infected tissue

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16
Q

How does blood clotting occur?

A

1) blood platelets plug and release chemicals that enhance clotting (thromboplastin)

2) prothrombin changes into thrombin (it’s active form)

3) fibrinogen changes into insoluble fibrin which covers the wound

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17
Q

Name two types of WBC involved in phagocytosis?

A
  • neutrophil
  • macrophages
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18
Q

How does phagocytosis destroy a pathogen?

A
  • phagocyte moves towards pathogen which may have been marked by opsonins
  • phagocyte engulfs pathogen via endocytosis to form a phagosome
  • phagosome fuses with lysosome (phagolysosome)
  • lysozyme digests pathogen
  • phagocyte absorb the products from pathogen hydrolysis
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19
Q

Explain the role of antigen-presenting cells?

A
  • macrophage displays antigen from pathogen on it’s surface
  • enhances recognition by Th cells which can’t directly interface with pathogens/ antigens in body fluid
  • secrete cytokines involved in stimulating specific immune response
20
Q

What are lysozymes?

A

Digestive enzymes found in lysosomes as well as many secretions. Damage bacteria cell walls causing osmotic lysis

21
Q

Name the 2 types of specific immune responce?

A
  • cell mediated
  • humoral
22
Q

Outline the process of cell mediated responce?

A
  • complementary Th lymphocytes bind to foreign antigens on APC
  • cell signalling via secretion of interleukins stimulates…

a) clonal expansion of complementary Th cells (rapid mitosis) becoming memory cells or triggering humeral responce

b) clonal expansion of cytotoxic T cells secreting perforin enzyme to destroy infected cells

23
Q

Outline the process of humeral responce?

A
  • complementary Th lymphocytes bind to foreign antigen on antigen presenting cells
  • release cytokines that stimulate clonal expansion (rapid mitosis) of complementary B lymphocytes
  • B cells differentiate into plasma cells
  • plasma cells secrete antibodies with complementary variable region to antigen
24
Q

Describe the structure and function of B lymphocytes?

A
  • differentiate into plasma cells to secrete antibodies to destroy the pathogen
  • remain in barrow until mature
25
Q

Describe the structure and function of T lymphocytes?

A

T helper = secrete cytokine

T killer = secrete perforin

T regulator = suppress other immune cells to prevent autoimmune disease

26
Q

What is an antibody?

A

a protein secreted by plasma cells

27
Q

Describe the structure of an antibody?

A

Quaternary structure = 2 ‘light chains’ held by disulfide bridges with 2 ‘longer’ heavy chains

Binding sites = on variable regions of light chains have specific tertiary structure complementary to antigen

Constant region = rest of antibody

28
Q

How do antibodies lead to the destruction of pathogens?

A
  • agglutinins form antigen antibody complexes to enhance phagocytosis
  • activation of complement
  • opsonins mark microbes for phagocytes
  • antitoxins make toxins insoluble via precipitation/ neutralisation
29
Q

What are memory cells?

A
  • specialised Th/B cells produced from primary immune response
  • remain in low levels in the blood

can divide very rapidly by mitosis if organism encounters the same pathogen again

30
Q

Contrast the primary and secondary responce?

A
  • secondary responce has faster rate of antibody production than primary
  • secondary responce has a shorter time lag between exposure and antibody production than primary
  • secondary responce has higher antibody concentration than primary
  • antibody levels remain higher after secondary responce than primary
  • pathogen usually destroyed before any symptoms in secondary responce not primary
31
Q

What is passive immunity?

A

immunity required through transfer of antibodies from one individual to another

32
Q

What is active immunity?

A

immunity required through production of antibodies in responce to infection or through vaccination

33
Q

What is the difference between active and passive immunity?

A
  • both involve antibodies and can be natural and artificial
  • passive is immediate whereas active’s a time lag
  • passive has antibodies from an external source whereas active is from lymphocytes (antibody)
  • passive has no direct contact with an antigen whereas active needs direct contact
  • passive has no memory cells and is short term whereas active has memory cells and is long term
34
Q

What is natural immunity?

A

natural immunity develops after an infection resulting from body’s responce to an antigen

35
Q

What is artificial immunity?

A

when the body is given immunity to a disease by vaccination

36
Q

What are examples of passive and active immunity?

A

Passive natural = antibodies in breast milk

Passive artificial = anti venom needle injection

Active natural = humoral responce to infection

Active artificial = vaccination

37
Q

What is an autoimmune disease?

A

Immune system produces antibodies against it’s own tissue

38
Q

Give 2 examples of autoimmune diseases?

A

Rheumatoid arthritis = immune system targets synovial lined joints causing inflammation

Lupus = results in inflammation throughout the body

39
Q

Define endemic?

A

disease occurring routinely in a geographical area

39
Q

Explain the principle of vaccination?

A
  • vaccine contains dead/ inactive for of pathogen
  • triggers primary immune responce
  • memory cells are produced and remain in the bloodstream so secondary responce is rapid producing higher antibody concentrations
  • pathogen is destroyed before causing symptoms
40
Q

Define pandemic?

A

temporary rapid increase in incidence of disease in a geographical area

41
Q

What role do vaccines play in preventing endemics?

A
  • vaccinating 80-90% of population reduces available carriers of pathogen (herd immunity)
  • vaccinating close contacts of infected individuals limits spread
42
Q

What are possible natural sources of medicine?

A
  • microorganisms
  • fungi (e.g penecillin)
  • plants (e.g foxglove)
43
Q

What are the benefits of using antibodies to treat bacterial infections?

A
  • reduces population of bacteria colony
  • inhibit formation of nucleic acids (growth)
  • prevent formation of peptidoglycan cross-links (osmotic lysis)
44
Q

What are the risks of using antibiotics to treat bacterial infections?

A
  • overuse increasing resistant strains of bacteria
  • difficult to treat antibiotic resistant strains of bacteria

Biology (22 decks)

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