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immunity Flashcards

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Biology 101 flashcards
1
Q

define pathogen

A

disease causing organisms

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2
Q

what are bacteria

A

single celled organisms

found all over the body, particularly skin and alimentary canal

classified by cell shape

e.g. anthrax, gastroenteritis, pneumonia

treated by antibiotics

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3
Q

what are viruses

A

Distinctive structures containing DNA or RNA surrounded by a protein coat and lipid envelope

Infect cells by introducing its own DNA, so cells manufacture virus particles

e.g. HIV, chickenpox, influenzas, measles, COVID-19

Some drugs can control infections (anti-virals), no drugs known can kill them

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4
Q

define bacteriophage

A

bacteria infected by a virus

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5
Q

what are fungi and parasites

A

Disease causing organisms

Fungi examples: e.g. ringworm, tinea

Parasite examples: malaria, lice, tapeworms, ticks

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6
Q

list the 6 different methods of transmitting pathogens

A

contact

droplets

body fluids

ingestion

airborne

vectors

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7
Q

explain the transmission of pathogens by contact

A

Direct contact: touching an infected person (skin infections and some sexually transmitted diseases)

Indirect contact: touching an object that has been touched by an infected person (drinking from the same cup)

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8
Q

explain the transmission of pathogens by droplets

A

Tiny droplets of moisture may contain pathogenic organisms. These are emitted when you breath, talk, sneeze or cough.

Droplets may be breathed in by another person or settle on food and then ingested.

e.g. Cold and flu are spread by droplets.

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9
Q

explain the transmission of pathogens by body fluids

A

Blood or other body fluids from an infected person come into contact with another person

E.g. being pricked by an infected needle –> hepatitis B and C

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10
Q

explain the transmission of pathogens by ingestion

A

Contaminated food or drink may results in disease

e.g. Food poisoning and typhoid

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11
Q

explain the transmission of pathogens by airborne transmission

A

When airborne moisture evaporates, some bacteria and viruses are able to survive as spores

These can be inhaled and can cause infection (Anthrax spores, COVID-19)

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12
Q

explain the transmission of pathogens by vectors

A

Host of a pathogen, transfer of pathogens by other animals

e.g. Insects, ticks, mites, mosquitoes (malaria) and flies (spread pathogens to food which is then ingested)

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13
Q

what are the body’s non-specific defences against disease

A

external defences - prevents pathogens entering the body

protective reflexes

defence cells

inflammatory response

fever

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14
Q

list the body’s external defences

A

ear: cerumen inhabits bacterial growth

trachea and bronchi: mucous layer traps microorganisms

stomach: acidic juices kill microorganisms
vagina: acidic secretions inhibit bacterial growth
eyes: cleansed by tears containing chemicals inhibiting bacterial growth

nasal cavity: mucous and hairs trapping microorganisms

mouth cavity: mucous membrane trapping microorganisms and saliva cleansing mouth

skin: impervious barrier
urethra: urine flow prevents bacterial growth
anus: mucous membrane traps microorganisms.

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15
Q

what are the body’s protective reflexes?

A

A reflex is a rapid, stereotyped, involuntary response to a stimulus

Sneezing – forceful expulsion of air from the lungs to eject air, mucous, foreign particles or irritating gases. Stimulus is irritation of nasal cavity walls.

Coughing – caused by irritation to bronchi and bronchioles. Air and mucous is forced from the lungs out via the mouth

Vomiting – response to excess stretching of the stomach or bacterial toxins. Results in contraction of abdominal muscles and diaphragm to expel stomach contents.

Diarrhoea – caused by irritation of intestines, resulting in increased muscle contractions of intestinal walls. Swiftness of contents moving through large intestine doesn’t allow for water to be absorbed.

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16
Q

explain defensive cells in the body’s non specific response to diseases

A

Phagocytes: cells that engulf and digest micro-organisms and cell debris

  1. Macrophages: large cells that engulf, digest or release chemicals to destroy other cells
  2. Leucocytes: white blood cells that engulf, digest or release chemicals to destroy other cells
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17
Q

what is the purpose of the body’s inflammatory response

A

Reduced spread of pathogens

Destroys pathogens

Remove and repair damaged tissues and cells

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18
Q

explain what happens during the body’s inflammatory response

A

Inflammation involves damaged tissue, stretch receptors (causing pain), redness (more blood brought to area), swelling (vasodilation of capillaries)

Damage to cells causes mast cells to release histamine and heparin
- Histamine increases blood flow (redness) and
permeability/vasodilation of capillaries (swelling
and heat)
- Heparin prevents clotting (to keep bringing white
blood cells to the area)
- These abnormal conditions cause pain

These chemicals attract phagocytes to consume debris and microorganisms
- Shape-shifting phagocytes move through permeable
capillary walls into tissue fluid to consume pathogens
- The microorganisms and phagocytes die and form pus

New cells are produced through mitosis

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19
Q

explain what occurs in the body during a fever

A

Benefits: inhibit growth of some bacteria and viruses, and speeds up chemical reactions in the body, promoting cell repair

During infection (inflammatory process) the white blood cells release pyrogens

Hypothalamus responds to the pyrogens to reset the body’s thermostat (ideal body temp increases)

The body ‘feels’ cold and responds by shivering and vasoconstriction of arterioles in the skin

Body temp rises

Macrophages are drawn to the area and engulf the pathogen

Macrophage stimulated to release cytokines

cytokines enhance the pyrogens

Eventually fever breaks, with sweating and vasodilation and body temp returns to normal.

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20
Q

what are the 2 parts of immune response in specific responses to infection

A

humoral response (antibody-mediates): involves production of antibodies, which circulate around body and attack invading pathogens

cell mediated response: formation pf lymphocytes that destroy invading pathogens

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21
Q

explain what antigens are

A

Definition: any substance capable of causing a specific immune response

Antigens can be:
 Large molecules
 Proteins, carbohydrates, lipids of nucleic acids
 A whole microorganism, e.g. bacteria cell
 Part of a bacterium e.g. cell wall or capsule
 Toxins produced by bacteria
 Contained within tissues transplanted from another person, such as blood cells of a foreign blood group

22
Q

describe what antibodies are

A

Definition: a specialised protein that is produced in a response to a non-self antigen

Can combine with that antigen to form an antigen-antibody complex

have specific active sites where the antibody can combine

23
Q

what are the benefits of antibody-mediated immunity (humoral) /what’s it’s purpose?

A

Provides resistance to viruses, bacteria and bacterial toxins before the micro-organisms/substances enter the body’s cells (while it is still in tissue fluid

24
Q

explain the process of antibody-mediated immunity

A
  1. Pathogen invades body
  2. An antigen is detected by a macrophage
  3. Macrophage engulfs pathogen and becomes an APC (antigen-presenting cell) by displaying the antigen on its membrane
  4. APC presents antigen to B cells
  5. Antigen activates B cells, they enlarge and divide into a group of cells called a clone
  6. Most of the clones become plasma cells which secrete the specific antibody capable of binding to the active site of the antigen
  7. The antibodies circulate in the blood, lymph and extracellular fluid to reach the site of invasion of foreign material
  8. The B cells of the clone that didn’t differentiate into plasma cells become memory cells
  9. These cells spread to all body tissues to allow the response to occur more rapidly if the antigen enters the body again
25
Q

how do antibodies provide resistance to infection?

A

Combine pathogen with foreign enzymes or bacterial toxins, or inactivate them by inhibiting reaction with other cells/compounds

Bind them to the surface of viruses and prevent the virus from entering cells

coat bacteria so they’re more easily consumed by phagocytes

Cause foreign particles to clump together - agglutination

Dissolving them

React with soluble substances to make them insoluble and more easily consumed by phagocytes

26
Q

what is the ‘primary response’

A

the immune reaction’s response upon encountering a new foreign antigen for the first time

27
Q

what is the immune response slower in the primary response than the secondary response to an antigen

A

It may take several days to build up large amounts of antibodies

It takes time for the B cells to multiple/differentiate into plasma cells

However, the primary response leaves the immune system with a memory of that particular antigen

With a second exposure to the same antigen the response is much faster because of the memory cells

With this secondary response plasma cells are able to form very quickly, with antibody levels in plasma rising rapidly

Often the antigen has little opportunity to exert symptoms on the body

28
Q

what is the purpose of cell-mediated immunity

A

Provides resistance to the intracellular phase of bacterial and viral infections

Important in providing resistance to fungi parasites

rejects transplants of foreign tissue

Also important in fighting cancer cells

29
Q

explain the process of cell-mediated immunity

A

T lymphocytes are responsible for cellular immunity, but the cells start the same way as antibody mediated

A macrophage or B cell encounters the foreign antigen, travels to the nearest lymph node and presents it to the T cells

The antigen activates one particular type of T cell to become sensitized

It enlarges and divides, forming a clone

Some cells of the clone remain in the lymphoid tissue as memory cells

If infection with the same antigen should occur again, these memory cells can initiate a much faster response in the second infection

30
Q

what are the 3 different types of T cells

A

(T cells that don’t become memory cells develop further into 3 different types of cells)

killer T cells

helper T cells

suppressor T cells

31
Q

what are killer T cells

A

migrate to site of infection and deal with invading antigen

They attach themselves to invading cells and secrete and inject a substance that will destroy the antigen, then go of in search of more antigens

32
Q

what are helper T cells

A

Bring more lymphocytes at the infected site to become sensitized, thus intensifying the response

Attract macrophages to the place of infection so macrophages can destroy pathogens by phagocytosis

Intensify phagocytic activity of macrophages

33
Q

what are suppressor T cells

A

Act when immune activity becomes excessive of when infection has been successfully dealt with

Release substances that inhibit B and T cell activity, slowing down immune response

34
Q

what is natural active immunity

A

The person naturally acquires the antigen in normal everyday life, and the body responds by creating antibodies

e.g. being exposed to a cold

35
Q

what is natural passive immunity

A

The person naturally acquires the antibodies through normal life actions

e.g. antibodies transferred to a baby through the placenta or breast milk

36
Q

what is artificial active immunity

A

Someone artificially acquires the antigen, and the body responds by creating antibodies

e.g. COVID vaccinations

37
Q

what is artificial passive immunity

A

Artificially acquiring the antibodies

e.g. vaccination

38
Q

what is herd immunity

A

Vaccinating a large enough proportion of the population to stop the transmission of a pathogen

It stops the chain of transmission and does not give the pathogen a host so it can die out

39
Q

what are live attenuated vaccines

A

These contain weakened micro-organisms (reduced virulence – ability to produce disease symptoms)

40
Q

what are toxic vaccines

A

If a bacteria or virus produces a toxin, the toxin can be filtered and used as the antigen in a vaccine to initiate an immune response

41
Q

what are subunit vaccines

A

Instead of using the whole pathogen, a fragment of the micro-organism is used to provoke and immune response

42
Q

what are biosynthetic vaccines

A

Using recombinant DNA - bacterial or viral DNA can be manipulated to become harmless

43
Q

list the 3 different types of vaccine delivery

A
  • Injections: using a syringe into the body
  • Oral: a syrup that is swallowed
  • Aerosol spray: nasal spray
44
Q

what are some common vaccine side effects

A 
redness
swelling
heat
pain
fevers
45
Q

what are some vaccine risks

A

Allergic reaction: generally not from the vaccine but the medium they are cultured in (e.g. egg-white)

Cross species disease: not from the vaccine but the medium that are cultured in (e.g. animal tissues)

Use of chemical preservatives: concerns about health risks of chemicals, also misinformation

46
Q

explain the ethical concern of manufacturing in therms of vaccines

A

As viruses reproduce in living cells, vaccines require a host to be developed. Chicken embryos or mice use used to culture vaccines – animal welfare is an ethical consideration

Sometimes human tissue needs to be used, so cells created in the IVF process are used – ethically, many people are unhappy with the origin of these cells

47
Q

explain the ethical concern of testing in therms of vaccines

A

People who volunteer for drug trials need to be well informed of the risks. Often volunteers come from poorly developed nations with less education, so there is concern that they may not understand the risks adequately

Before clinical trials, drugs are tested on animals

48
Q

explain the ethical concern of decisions in therms of vaccines

A

Parents are making decisions on behalf of their children – but a risk of a side effect may affect a child for life?

Is it the responsibility of the healthy majority to become immunized to protect the vulnerable?

49
Q

explain what antibiotics are

A

A substance that kills or inhibits the growth of bacteria
E.g. penicillin, streptomycin, cephalosporin

Can be broad spectrum (kills a wide range of bacteria)

Can be narrow spectrum (targets specific types of bacteria)

Bacteriostatic antibiotics inhibit growth of bacteria by interfering with protein synthesis

Bactericidal antibiotics destroy bacterial pathogens by targeting cell walls, cell membranes or metabolic pathways/action of enzymes found inside bacteria

50
Q

what are antivirals

A

Scientists are attempting to find viral proteins that can be disabled

Any drug that interferes with the replication process is likely to be toxic to the host cell

There are many antiviral drugs available and more being developed

Human bio (16 decks)

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