B6.3 Monitoring & Maintaining Health 2

Question 1

How do scabs form?

Answer 1

1. Skin cut and starts to bleed (blood leaks out of body)
2. Platelets change blood protein fibrinogen to fibrin, forming a network of fibres in the cut
3. Red blood cells are trapped in fibres forming a blood clot
4. Clot hardens to form a scab, keeping skin clean + time to heal
   (In time scab falls off)

Question 2

How does the skin prevent microorganisms from entering body?

Answer 2

Physical barrier

• dry, dead outer cells are difficult for microorganisms to penetrate
• sweat glands produce oils that help kill microorganisms

Question 3

How does acid in stomach prevent microorganisms from entering body?

Answer 3

It kills pathogens present in contaminated food or drink

Question 4

How does the cilia and mucus in airways prevent microorganisms from entering body?

Answer 4

• sticky mucus traps microorganisms

- cilia moves mucus up throat to be swallowed

Question 5

How do nasal hairs prevent microorganisms from entering body?

Answer 5

Keep out dust and larger microorganisms

Question 6

How do tears prevent microorganisms from entering body?

Answer 6

Contain lysozymes (enzymes that destroy bacteria)

Question 7

What is the immune system’s main form of defence?

Answer 7

White blood cells

Question 8

What are the two types of white blood cells?

Answer 8

Phagocytes- cells that engulf/ingest microorganisms and then make enzymes that digest the microorganism

Lymphocytes- make antitoxins or antibodies

Question 9

Antibodies

Answer 9

Proteins that bind to antigens on the surface of microorganisms
—> once bound pathogen can be ingested by a phagocyte cell and destroyed

Question 10

Non-specific defence

Answer 10

Defences that prevent entry of all microorganisms

Question 11

Are antibodies specific or non-specific defences + why?

Answer 11

Specific
Each antibody binds to only one type of antigen and therefore only one type of microorganism
(Each time a new type of microorganism enters the body, a different lymphocyte makes a new body to fight it)

Question 12

What happens after a disease has been successfully removed from the body?

Answer 12

• white blood cells are able to make the same antibodies if an infection occurs again
• the body now has immunity to the disease (antibodies destroy pathogen before they can cause illness again)

Question 13

What are hybridomas?

Answer 13

A fusion of myelomas (cancer cells) and lymphocytes

Question 14

What are monoclonal antibodies made from?

Answer 14

Made in a laboratory using hybridomas

Produced by a single clone of cells

Question 15

What do monoclonal antibodies do?

Answer 15

Designed to target a specific toe of cell
—> (like antibodies produced by white blood cells) bind to antigens of target cell = kills cell or prevents it from operating effectively

Question 16

How are hybridomas made?

Answer 16

Genetically modified mice are injected with the required antigen
—> bodies produce immune response, producing antibodies to the specific antigen
—> antibody-producing lymphocyte cells are collected which cannot survive outside of the body and are therefore fused with myeloma cells from the bone marrow which reproduce indefinitely
—> fused cells = hybridomas

Question 17

How are monoclonal antibodies produced from hybridomas?

Answer 17

Hybridomas reproduce to form clones
—> each clone produces required antibody which is harvested
—> the proteins = monoclonal antibodies

Question 18

How are monoclonal antibodies used in pregnancy testing?

Answer 18

When a woman becomes pregnant she produces hormone hCG (human chorionic gonadotrophin) 2 weeks after conception
—> monoclonal antibodies produced to bind to hCG protein causing a colour-change reaction
—> home pregnancy test = short stick with a band of monoclonal antibodies, when using w hCG contacts antibodies a line appears on the stick

Question 19

How are monoclonal antibodies used to detect disease?

Answer 19

Some monoclonal antibodies act as markers; by binding to a specific antigen they confirm its presence
—> monoclonal antibodies developed to bind to antigens of prostate cancer cells in men
—> allows early diagnosis which is crucial for successful treatment

Question 20

How are monoclonal antibodies used in treating cancer?

Answer 20

Monoclonal antibodies target specific cells killing them or preventing them from operating efficiently, as well carrying drugs or radioactive substances directly to a cancer cell
= increases effectiveness of treatment, minimises damage to surrounding tissue

Question 21

Why do we use vaccines?

Answer 21

Some pathogens can make you seriously ill before your immune system has a chance to respond so it’s better not to get infected at all

Question 22

How do vaccines work?

Answer 22

-con again small amounts of weakened or dead versions of a pathogen
—> inserted into body usually by injection
—> causes lymphocytes to produce antibodies to pathogen
—> person is immune (if encounters real pathogen body can respond quicker)

Question 23

Antiseptics

Answer 23

Kill or neutralise all types of pathogen w/o gpdmaging human tissue
—> different antiseptics act on different microorganisms (eg. Bacteria)

Common antiseptics = alcohol, iodine

Question 24

Antivirals

Answer 24

Drugs that destroy viruses (usually by preventing replication)
—> many antivirals are specific and designed to act on one type of virus

Treat infections, eg. HIV, influenza, herpes, hepatitis B

Question 25

What can the activity of an antiviral include?

Answer 25

- blocking virus from entering host cell - preventing virus from releasing genetic material - preventing virus from inserting genetic data into host cell’s DNA

Question 26

Antibiotics

Answer 26

Drugs that kill bacteria w/o damaging human cells, no effect on viruses or fungi -several types of antibiotic, each kills a different range of bacteria

Question 27

How do doctors identify bacteria making person ill?

Answer 27

1. Send stool/blood sample to lab 2. Scientists grow bacteria in samples on agar plate 3. Treat bacteria w different antibiotics to find most effective 4. Person prescribed most effective antibiotic

Question 28

Zone of inhibition

Answer 28

Area on agar plate that bacteria cannot grow | —> measures effectiveness of antibiotic

Question 29

How to measure the zone of inhibition

Answer 29

1. Measure diameter of zone of inhibition 2. Divide diameter by two for radius 3. Use pie r^2 to find area

Question 30

Aseptic technique

Answer 30

An approach to working which prevents cross-contamination from unwanted microorganisms by ensuring apparatus and environment remain sterile (Aseptic = w/o microorganisms)

Question 31

What is done to ensure aseptic technique?

Answer 31

- wash areas with alcohol before + after working - wear gloves if at risk of working with pathogens - autoclave glassware before + after use - work close to Bunsen burner flame

Question 32

How to sterilise a wire loop

Answer 32

1. Heat in Bunsen burner flame until red hot | 2. Cool before use while holding near flame and away from bench

Question 33

How can you identify bacteria?

Answer 33

Grow a colony and characteristics such as shale, colour, edge and surface appearance, and elevation allow you to identify bacteria from sample

Question 34

Technique for isolating bacterial colonies

Answer 34

1. Dip sterilised wire loop into sample of bacteria 2. Make 4/5 streaks across one edge of an agar plate 3. Flame and cool wire loop 4. Make new series of streaks by crossing over first set, picking up some of cells and spreading them across a new section of the plate 5. Repeat steps 3+4 making third set of streaks 6. Repeat steps 3+4 making fourth set of streaks 7. Fix lid with four short lengths of tape 8. Label and incubate plate upside down for several days. Do not open, dispose in disinfectant or sterilise

Question 35

Why is the lid secured using short lengths of tape?

Answer 35

Sealing all the way around wouldn’t allow any air to enter | —> anaerobic conditions often promote growth of pathogenic bacteria

Question 36

Why is agar jelly used?

Answer 36

Nutrients are added to the agar which sets as a jelly = medium for bacteria to grow on

Question 37

How are new drugs discovered?

Answer 37

- plant extracts - made in laboratory - computer modelling (software produces list of compounds that may target a particular condition)

Question 38

Preclinical testing

Answer 38

When finding a potentially useful substance scientists perform laboratory tests to find out how it behaves Eg. testing on live cells, bacteria, tissue cultures BEFORE testing on live organisms (Most drugs fail at this stage as they damage cells or don’t work)

Question 39

Stages of testing a drug must undergo

Answer 39

1. Drug tested on animals (in UK data needed from 2 animal species before it can be used on humans) 2. Clinical trial = drug tested on humans

Question 40

Stages of a clinical trial

Answer 40

1. Tested on healthy volunteers to look for unexpected side effects 2. Tested on small sample of volunteers who suffer from condition to see how effective it is 3. Drug tested on large number of people with condition to se how well it works and check it is safe for everyone

Question 41

If all tests are positive who approved drug (in UK)?

Answer 41

MHRA- the Medicines and Healthcare Products Regulatory Agency

Question 42

Placebo effect

Answer 42

Sometimes people feel better because they expect to feel better when taking medicine

Question 43

How do clinical trials overcome the placebo effect?

Answer 43

Researchers use a double blind trial = Some patients are given drug, others get an exact replica of the drug with no active ingredients —> doctors and patients aren’t told who has received drug until test is over

Question 44

Animal testing, principle of 3 Rs

Answer 44

Reduction - use smaller number of animals possible Refinement- improve experiments to avoid unnecessary suffering and improve way animals are cared for Replacement - where possible replace use of animals with other techniques (eg. using cell cultures or computer models)