2.5 b

Question 1

What are non-specific immune responses of mammals?

Answer 1

• physical barriers
• chemical secretions
• inflammatory response
• phagocytes
• natural killer cells

Question 2

What are examples of physical barriers?

Answer 2

skin epithelial tissue, tears, earwax, mucus/mucosal membranes

Question 3

What are examples of chemical barriers?

Answer 3

hyrolytic enzymes in mucus, lyzozyme in tears, hydrochloric acid in stomach, urine (acdic), interferon - signal proteins made by hosts cells in response to viruses (blocks transcription of viral proteins)

Question 4

What can saliva and tears do?

Answer 4

destory bacteria cell walls

Question 5

What doe low pH environs do?

Answer 5

areas such as stomach, vagina and sweat glands denature cellular proteins of pathogens

Question 6

What do injured cells release?

Answer 6

signalling molecules which result in enhanced blood flow to the site and bring antimicrobial proteins and phagocytes

Question 7

What is the inflammatory response?

Answer 7

• chemicals incl. histamine and prostaglandins (cytokines) released causing blood vessels to leak fluid into tissues, causing swelling
• helps isolate foreign substance from further contact with body tissues
• chemicals also attract phagocytes

Question 8

What is phagocytosis?

Answer 8

white blood cells carry out non-specific process, uses powerful enzymes contained in lysosomes, engulfs them and store inside vacuole, detect chemicals released by bacteria and move towards it, lysosomes within phagocyte fuse with and digest bacterial cell

Question 9

Describe natural killer cells (NK)

Answer 9

• lymphocytes (white blood cell) identify abnormal cells (virus infected/cancerous)
• normal cells have major hisotcompatibility class I (MHC I) molecules on their surface
• abnormal cells MHC I molecules have latered expressions so target for NK cells
• NK’s identify and attach to cells virally infected, releasing chemicals leading to cell death by inducing apoptosis

Question 10

What are lymphocytes?

Answer 10

white blood cells, mammals contain different ones, each receptor on surface which could recognise parasite antigen

Question 11

What causes lymphocyte to divide?

Answer 11

antigen binding to receptor, creates clonal population

Question 12

What do lymphocytes do?

Answer 12

some produce antibodies other induce apoptosis

Question 13

What gives antibodies antigen specificity?

Answer 13

antibodies possess regions where amino acid sequence varies according to antigen

Question 14

What are antigens?

Answer 14

proteins on all cells surface, if they don;t belong to host they are considered foreign
- includes molecules belonging to bacteria, viruses, fungi, parasitic worms and cells from transplanted tissues

Question 15

What happens when antigen binds to antibody binding site?

Answer 15

antigen-antibody complex can result in parasite inactivation, rendering it susceptible to phagocytes or stimulating cell lysis

Question 16

Why are memory cells important?

Answer 16

when they recognise an antigen, if it enters the body again, they produce many copies of the cell and quickly produce plasma cells which secrete antibody to destroy foreign antigens

Question 17

What does initial antigen exposure do?

Answer 17

produces memory lymphocyte cells specific to it so secondary response is produced in the future

Question 18

How is antibody production enhanced in secondary respone?

Answer 18

in terms of production speed, concentration in blood and duration in blood.

Question 19

What does antigenic variation do for parasite?

Answer 19

allows change between different antigens during course of host infection, may also allow reinfection of same host with new variant

Question 20

How can viruses escape immune surveillance?

Answer 20

by integrating their genome into host genomes, existing in an inactive state known as latency
- virus then activates again when favourable conditions arise

Question 21

what is epidemiology?

Answer 21

the study of outbreak and pattern of infectious disease to determine spread factors

Question 22

What are some disease spread factors?

Answer 22

• spread quicker through dense populations/areas of overcrowding
• some individuals genetically immune due to genetic variation
• resistant individuals present barrier to transmission, if high enough number of resistant individuals, an epidemic may be avoided

Question 23

Explain herd immunity…

Answer 23

when resistant individuals ultimately provide a level of protection to non-immune population
- the threshold is density of resistant hosts
- number of resistant individuals may be increased by vaccinations

Question 24

What does the herd immunity threshold depend upon?

Answer 24

• the disease
• the efficacy of the vaccine
• the contact parameters for the population

Question 25

What are pros and cons of herd immunity and vaccination?

Answer 25

Pros
- protects vulnerable and un-vaccinated
- reducing spread of disease

Cons
- developing world: vaccination not possible due to malnutrition/poverty
- developed world: percentage of population rejects vaccine

Question 26

How do vaccine work?

Answer 26

• contain antigens that elicit immune response
• contain a microorganism or virus in a weakened, live or killed state, or proteins/toxins from the organisms

Question 27

What are challenges in vaccine treatment?

Answer 27

• some parasites difficult to culture in lab making vaccine design difficult
• rapid antigen change has to be reflected in vaccine design
• antigenic variation must be reflected
• similarities between host and parasite metabolism makes it difficult to fin drug compounds that only target the parasite

Question 28

What conditions make coordinated treatment/control programs difficult to achieve?

Answer 28

overcrowding can occur in refugee camps due to war or natural disaster or rapidly growing cities in less economically developed countries (LEDCs)

Question 29

What cans sometimes be the only practical control strategies?

Answer 29

civil engineering projects to improve sanitation combine with coordinated vector control

Question 30

What are the benefits of improved parasite conrol?

Answer 30

reduce child mortality and result in population-wide improvements in child development and intelligence as individuals have more resources for growth and development