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Human Biology > Immune System > Flashcards

Immune System Flashcards

How does the body defend itself from infection?

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1
Q

External Defences

What are the protective reflexes?

A

Sneezing, Coughing, Vomiting, Diarrhoea

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2
Q

Non-specific Defences

Sneezing

A

the forceful expulsion of air from lungs.

  • stimulated by irritation of nasal cavity such as fumes + dust particles + foreign substances + pathogens
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3
Q

Non-specific Defences

Coughing

A

irritation of lower respiratory tract (the bronchi and bronchioles)

  • air is forced from lungs which induces sneezing
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4
Q

Non-specific Defences

Vomiting

A

abdomen and diaphragm contract to expel stomach contents (with toxins from bacteria)

  • induced psychologically, stretching of stomach
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5
Q

Non-specific Defences

Diarrhoea

A

irritation of small/large intestines by bacteria, virus or protozoans.

  • increases contractions of intestinal muscles so irritant is removed quickly
  • no time for absorption to happen
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6
Q

Response to Infecion: Prevention

What are the two types of antibiotics?

A

bactericidal: change structure of cell wall/membrane or disrupt the enzymes

bacteriostatic: stop bacteria from reproducing by [disrupting protein synthesis]

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7
Q

Response to Infecion: Prevention

How can we prevent antibiotic resistance in bacteria?

Antibiotics are resistant from improper and widespread use.

A
  • prevent misuse
  • develop a new class of antibiotics
  • genetically engineer bacteria to disable the resistance
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8
Q

Non-specific Defences

Can you explain the process of phagocytosis?

A
  1. The** phagocyte** moves into the invading bacterium
  2. Phagocyte changes shape so it completely encloses bacterium
  3. Lysosomes contain destructive enzymes
  4. Enzymes are released and destroy the bacterium
  5. Harmless particles are released from phagocyte

IELEH (invade, enclose, lysosome, enzyme, harmless)

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9
Q

How do antivirals prevent the reproduction of viruses

A

Aimed at identifying viral proteins that can be disabled after genetic sequences of virus.

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10
Q

Pathogens

Differences between bacteria and viruses

A

Bacteria:
* unicellular, prokaryotic organisms that use binary fission to replicate
* reproduce without a host cell
* very small, bigger than virus
* not all bacteria are pathogenic

Virus:
* non-living organisms that need a host to replicate
* they are not cells but **genetic material **surrounded by a capsid.
* very small, even smaller than bacteria
* all viruses are pathogenic

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11
Q

Non-specific Defences

Can you describe the process of inflammation?

A
  1. Mast cells: stimulated by mechanical damage or local chemical changes, which releases heparin and histamine.
  2. The chemicals that mast cell’s produce attract phagocytes which attack invading pathogens + foreign objects and eats remaining debris of infection
  3. Stimulates nociceptors in the area
  4. Dead phagocytes with debris or bacteris form pus
  5. New cells made by mitosis + damaged tissue is repaired.

MANDN acronym

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12
Q

Non-specific Defences

Can you explain the process of fever?

A
  1. Due to infection, the body’s thermostat is set at an abnormaly high rate (38.5> is considered a fever)
  2. The body responds through shivering and vasoconstriction.
  3. The body temperature continues to rise
  4. Crisis point is reached and the fever breaks with sweating and vasodilation on skin.
  5. Body falls to its normal temp.

Crisis point is when the thermostat resets and resets back to normal

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13
Q

Non-specific Defences

What is the lymphatic system?

A
  • A network of lymph capillaries joined to larger lymph vessels
  • lymph node, located at some lymph vessels.
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14
Q

Non-specific Defences

What is the function of the lymphatic system

A
  1. Collect fluid from escaping blood capillaries + return to circulatory system
  2. Internal defence of micro-organisms
    a. lymph nodes contain network of lymph vessels containing macrophages and kill micro-organisms quickly
    b. lymphocyte formulation increases when infection occurs · swollen + sore lymph nodes.
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15
Q

Immune Response

What does antibody-mediated immune response involve?

A

It involves B-cells and eliminate extracellular antigens.

This is also called humoral.

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16
Q

Immune Response

What does cell-mediated immune response involve?

A

It involves T-cells and eliminates intracellular antigens

This is also called cellular.

17
Q

Immune Response

What does a humoral immune response work against?

A
  • Works against bacteria, toxins and viruses before they enter the body’s cells.
  • Also works against the eryhtrocytes of different blood groups

Note: think of “Bacteria, virus and blood group entering? Funny!”

18
Q

Immune Response

Explain the process of humoral immune response.

A
  1. Foreign antigens reaches the lymphoid tissue
  2. Certain B-cells stimulate to undergo rapid cell division
  3. Most new B-cells become plasma cells to produce + release antibodies.
  4. Antibodies combine with antigent to incactivate/ destroy
  5. Some new B-cells form memory cells
19
Q

What does cellular immune response work against?

A
  • Work against cells infected by viruses, bacteria, fungi and parasites.
  • Also, cancer cells, transplanted tissues and organs.
20
Q

Can you explain the process of cellular immune response

A
  1. Foreign antigens reaches lymphoid tissue
  2. Certain T-cells stimulate to undergo** rapid cell division**
  3. Most new T-cells become killer T-cells or helper T-cells which migrate to site of infection
  4. Killer T-cells destroy antigen, helper T-cell promote phagocytosis
  5. Some sensitised T-cells form memory cells.

T-cells ARE CELLULAR

21
Q

What is the role of histamine?

A

increases blood flow by** vasodilation** + makes blood vessel walls more permeable to allow more fluid to move into tissues.

22
Q

What is the role of heparin?

A

prevents clotting in immediate area so clots form around damage instead, preventing the spread of pathogens.

23
Q

The difference between enveloped and non-enveloped viruses?

A
  • Enveloped viruses have an extra layer of protein molecules that surround the DNA/RNA
  • Non-enveloped viruses do not have this lipid layer.
24
Q

What is the advantage of an enveloped virus.

A
  • The lipid layer they use is a replica of the host cell.
  • Harder for the body to detect it as a threat
  • Escape lysis with envelope
25
Q

How do antibodies work?

A
  • Precipitation: bind soluble antigens to become insoluble
  • Lysis: dissolve organisms
  • Agglutination: grouping the bacteria/virus/foreign objects.
  • Neutralisation: binds to viral binding sites/bacterial antigens to prevent entry. Combine with foreign enzymes/toxins to** inhibit the reactions**.
  • Coat: to cover the face of the bacteria.

PLAN C!

26
Q

Killer T-cells

A
  • Migrate to the site of infection
  • Attach to invading pathogen and secrete a substance that kills infected cells
  • Goes searching for more
27
Q

Helper T-cells

A

Secrete cytokines that
* attract lymphocytes to sensitise and intensify response
* attract macrophages and increase their phagocytic activity
* promoting activity of Killer T-cells

ALAMP

28
Q

Suppressor T-cells

A
  • acts when the infection is finished OR reaction is too intense
  • Releases substances to inhibit B/T cells
29
Q

What are non-specific defence mechanisms and give some examples.

A
  • makes up the innate immune syste and work against all pathogens
  • external defences, inflammation, fever, phagocytosis and the lymphatic system
30
Q

What are specific defence mechanisms and give some examples.

A
  • make up the adaptive/acquired immune system and are directed to a specific pathogen.
  • humoral/antibody mediated and cell mediate responses
31
Q

What are the external defences?

A
  • flushing action: helps to cleanse pathogens. Flush pathogens through urination, crying, sweating and salivating.
  • cerumen: ear wax is slightly acidic and has lysozyme
  • hairs and cilia: hairs in ears + nose traps particles. Cilia move mucus towards the throat so it can be coughed up
  • acids: secreted in the stomach, vagina and sweat to kill/reduce bacterial growth.
  • lysozyme: enzymes that kill bacteria found in tears, sweat, nasal secretions and tissue fluid
  • mucous membranes: the exterior body cavities which secrete mucus to inhibit microbial growth
  • skin: an impervious barrier that prevents pathogens from entering. Sebum and sweat prevent microbial growth

F CHALMS

32
Q

Can you define what inflammation is and what is it’s purpose?

A

response to any damage to tissues. Occurs as a series of integrated steps.

  • Reduce spread of pathogens, to destroy them and to prevent entry of additional pathogens.
    Remove damaged tissues/cell debris
    Begin repair of damaged tissue.

Four signs of inflammation: redness, swelling, heat and pain.

33
Q

Can you run me down what an antibody is and its functions?

A
  • ** Y-shaped specialised proteins** (immunoglobulins) produced in response to a non-self antigen by plasma cells.
  • Antibodies combine with the antigen, for which they are specific to, to form an antigen-antibody complex – similar to lock-and-key.
  • Each antibody can only combine with one particular antigen.
  • The shape of the antibody is the same as the shape of the B-cell receptor which detects/becomes activated by the antigen. (See antibody-mediated

Human Biology (7 decks)

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