4.1.1 communicable diseases Flashcards
1
Q
Name 4 groups of pathogens that can cause communicable diseases
A
- Bacteria
- Fungi
- Protoctista
- Viruses
2
Q
How does tuberculosis cause disease
A
- Triggers inflammatory response by infecting phagocytes in lungs
- Infected phagocytes are sealed in waxy coated tubercles so bacteria remain dormant
- First infection has no symptoms
- If another factor weakens immune system, bacteria becomes active and destroys lung tissue
3
Q
How does HIV lead to AIDS
A
- Attachment proteins bind to complementary receptors on T helper cells
- HIV particles replicate inside T helper cells, killing or damaging them
- AIDS develops when there are too few T helper cells for the immune system to function
- Individuals cant detroy other pathogens and suffer from secondary diseases/infections
4
Q
How does tobacco mosaic virus cause disease
A
- Affects plants and is mainly transmitted via infected sap
- Causes stunted growth and mottled leaves
5
Q
How is influenza virus transmitted
A
Via troplet infection and contact with mucus containing virus
6
Q
What are symptoms of influenza
A
5-7 days of headache, coughing, sneezing, sore throat, vomiting, fever, muscular/joint pain
7
Q
What causes malaria
A
- Mosquito acts as vector for plasmodium protoctista when it transfers saliva to another organism during feeding
- Parasite reproduces asexually in red blood cells in liver, causing lysis
8
Q
What causes potato/ tomato late blight
A
- Protists
- Transmitted via spores
9
Q
What causes ring rot
A
Bacteria transmitted by planting infected seeds
10
Q
Name 2 fungal infections
A
- Black sigatoka
- Athletes foot
11
Q
How are communicable pathogens transmitted directly
A
- Inhalation (droplet infection)
- Skin to skin contact
- Exchange of fluids
- Penetrate skin actively using enzymes or passively through wounds
12
Q
How are communicable pathogens transmitted indirectly
A
- Comsumption of contaminated food and drink
- Via a vector
- Spores
13
Q
How do living conditions affect disease transmission
A
- Overcrowding increases direct transmission
- Climate determines whuch organisms can survive
- Social factora influence how quickly people are treated
14
Q
Name 4 physical barriers to pathogen entry in plants
A
- Cellulose cell walls
- Lignified layer
- Waxy cuticle
- Old vascular tissue is blocked to prevent pathogens from spreading inside the plant
15
Q
NAme 2 mechanical responses to infection in plants
A
- Guard cells close stomata
- Callose is produced and deposited between cell wall and plasma membrane to limit spread
16
Q
What is necrosis
A
Injury activates intracellular enzymes in plants that kill clees near the site of infection to prevent pathogen from spreading
17
Q
What are the chemical defences plants use against pathogens
A
- Terpenoids
- Phenols
- Alkaloids
- Defensins
- Hydrolytic enzymes
18
Q
Name 4 barriers to infection in animals
A
- Skin is tough keratin layer
- Blood clotting prevents pathogens from entering through breaks in skin
- Hydrochloric acid in stomach kills bacteria
- Mucous membranes trap pathogens and may secrete antimicrobial enzymes
19
Q
What are expulsive reflexes
A
- When the body attempt to force foreign substances out
- e.g. irritation if mucous membranes in nostrils causes sneezing
- e.g. irritation of ciliated epithelium in respiratory tract causes coughing
20
Q
Name 3 ways in which the nonspecific immune system responds to infection
A
- Inflammation
- Phagocytosis
- Digestive action of lysozymes
21
Q
Outline the process of inflammation
A
- Damaged vessels release histamines, causing vasodilation
- Blood flow and permeaility of blood vessels increase
- White blood cells and plasma move into the infected tissue
22
Q
How does blood clotting occur
A
- Blood platelets form plug and release chemicals that enhance clotting
- Fibrinogen changes into insoluble fibrin which covers wound
23
Q
Name 2 types of white blood cell involved in phagocytosis
A
- Neutrophils
- Macrophages
24
Q
How does phagocytosis destroy pathogens
A
- Phagocyte moves towards pathogen which may have been marked by opsionins via chemotaxis
- Phagocyte engulfs pathogen via endocytosis to form a phagosome
- Phagosome fuses with lysosome
- Lysozymes digest pathogens
- Phagocytes absorb the products from pathogen hydrolysis
25
Explain the role of antigen presenting cells
- Macrophage displays antigen from pathogen on its surface (after hydrolysis in phagocytosis
- Enhances recognition by T helper cells which cant directly interface with pathogens/ antigens in body fluid
- Secretes cytokines that are involved in stimulating specific immune response
26
What are lysozymes
- Digestive enzymes found in lysosomes
- Damages bacteria cell walls
27
Outline the process of cell mediated response
- Complementary T helper lymphocytes bind to foreign antigen on APC
- Cell signalling via sectretion of interleukins stimulates:
1. Clonal expansion of complementary T helper cells (rapid mitosis): become memory cells or trigger humoral response
2. Clonal expansion of cytotoxic T cells: secrete enzyme perforin to destroy infected cells
28
Outline the process of the humoral response
- Complementary T helper lymphocytes bind to foreign antigen on antigen presenting T 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 reigon to antigen
29
Describe the function of B lymphocytes
B cells differentiate into plasma cells to secrete antibodies
30
What are the roles of the 3 types of T cells
- T helper: secrete cytokines
- T killer: secrete perforin
- T regulator: suppress other immune cells to prevent autoimmune disease
31
Describe the structure of an antibody
- Quaternary structure: 2 light chains held together by disulphide bridges. 2 longer heavy chains
- Binding sites on variable reigon of light chains have specific tertiary structure complementary to antigen
32
How do antibodies lead to the destruction of a pathogen
- Agglutinins form antigen-antibody complexes to enhance phagocytosis
- Opsonins mark microbes for phagocytes
- Antitoxins make toxins insoluble via neutralisation
33
What are memory cells
- Specialised T helper/ B cells produced from primary immune response
- Remain in low levels in the blood
- Can divide very rapidly by mitosos is organism encounters the same pathogen
34
Contrast the primary and secondary immune response
Secondary response
- Faster rate of antibody production
- Shorter time lag between exposure and antibofy production
- Higher concentration of antibodies
- Antibody levels remai higher after the secondary response
- Pathogen is usually destroyed before any symptoms
35
Give an example of passive natural immunity
antibodies in breast milk and placenta
36
Give an example of passive artificial immunity
anti venom
37
Give an example of active natural immunity
Humoral response to infection
38
Give an example of active artificial immunity
vaccination
39
Define autoimmune disease
The immune system produces antibodies against its own tissues
40
Give 2 examples of autoimmune diseases
- Rheumatoid arthritis: immune system targets joints, causing inflammation
- Lupus: results in inflammation throughout body
41
Explain vaccination
- The vaccine contains dead or inactive form of a pathogen or antigen
- Triggers primary immune response
- Memory cells are produced and remain in the bloodstream so secondary response is rapid and produces higher concentration of antibodies
- Pathogen is destroyed before it causes symptoms
42
Define endemic
Disease occurs routinely in a geographical area
43
Define epidemic
A temporary rapid increase in incidence of disease in a geographical area
44
List some possible natural sources of medicines
- Microorganisms
- Fungi e.g. penicillin
- Plants e.g taxol for chemotherapy
45
what is personalised medicine
Genome sequencing has allowed scientists to predict an individuals response to disease and certain medicines so prescriptions can be targeted
46
What is synthetic biology
Engineering that targets biochemical processes
