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N Biology A Level > Topic 6.7 Response To Infection > Flashcards

Topic 6.7 Response To Infection Flashcards

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1
Q

What does innate mean

A

Non-specific

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2
Q

What are three main ways pathogens can enter our tissues?

A

Via our
- skin
- lungs
- intestines

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3
Q

How does the skin protect the body against pathogens?

A
  • sebum contains fatty acids, toxic to microbes
  • keratin stops bacterial growth
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4
Q

How do lungs / respiratory system protect the body against pathogens?

A
  • mucus made by goblet cells : trap pathogens/microorganisms (bcs sticky)
  • cilia, woft mucus, either spat out or destroy in stomach
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5
Q

What is the non-specific inflammatory response?

A
  • innate, same response whatever the pathogen
  • localised response of tissues to damage
    1. Triggered when mast cells release histamine and prostaglandins
  • histamine causes dilation of venules or arterioles,diapedesis
  • more tissue fluids (with phagocytes) go towards injured site, so phagocytes can engulf
  • prostaglandins increase blood flow
    2. Sensory neurons become more sensitive
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6
Q

Why is prostaglandins useful in the innate response?

A

Increase blood pressure and flow
So more tissue fluids (including phagocytes) coming to the area

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7
Q

What is diapedesis?

A

capillaries become more permeable

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8
Q

What is an erythrocyte

A

Red blood cell

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9
Q

How do you know it’s a neutrophil?

A

It has a multi-lobe nucleus

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10
Q

What shape nucleus do macrophages have

A

Kidney shaped

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11
Q

What do lymphocytes usually look like (their nucleus shape)

A

Round nucleus

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12
Q

2 types of phagocytes

A

Neutrophils
Macrophages

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13
Q

What’s the difference between neutrophils and macrophages?

A
  • N come out of capillaries, engulf pathogens
  • N dominate infected simple early / M at later stages
  • M does that, and adds another step
    • live longer , larger
    • can present antigenic fragments to T lymphocytes after engulfing
  • N has multi-lobe nucleus / M is big and kidney shaped nucleus
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14
Q

What is MHC

A

Proteins every cell has them - markers
Diff tissues have varying MHCs
Help cells identify it’s a self cell, not foreign (so won’t attack)

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15
Q

What’s an antigen presenting cell

A

Antigen fragments bounded to MHC

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16
Q

What are cytokines

A

Cell signaling protein to recruit other cells

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17
Q

What does chemokines do

A

Induce chemitaxis
Recruit other phagocytes (macrophages)

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18
Q

What are the 2 types of lymphocytes

A

B or T

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19
Q

What do B and T lymphocytes have

A

Antigen-receptor molecules
Complementary to antigens
Each lymphocyte has only 1 type of antigen receptor (unique to cell types)

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20
Q

What is the difference between B and T lymphocytes?

A

B can release antigen receptor (aka antibodies) (also stays, does both) (become plasma cells)
T cannot, they only stay on cell

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21
Q

What is the humoral response 1?

A
  • macrophage and B lymphocytes engulf pathogen
  • present their antigens on MHC to become APCs
  • T helpers activated when binding with macrophage antigen-MHC complex, producing more T helpers and memory
  • more T helpers bind with B-lymphs, secrete cytokines and activate
  • mitose and produce B effector cells > differentiate into either B memory or plasma
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22
Q

How do intestines / digestive system protect the body against pathogens?

A
  • stomach acids
  • enzymes found in saliva, lysozymes
  • gut microbiomes (flora) outcompete pathogens
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23
Q

What does histamine do?

A

histamine causes dilation of venules or arterioles: diapedesis (capillaries become more permeable)
more tissue fluids (with phagocytes) go towards injured site, so phagocytes can engulf

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24
Q

What do prostaglandins do?

A

Increase blood flow to injured site

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25
Q

Why would prostaglandins cause oedema?

A

Because more tissue fluids are transported (?) to the injured site

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26
Q

What are 2 things that mast cells release?

A
  • histamines
  • prostaglandins
27
Q

What are 2 types of phagocytes?

A

Macrophages and neutrophils

28
Q

What turns into an Antigen presenting cell (APC) in humoral 1?

A

Macrophages and B-cell

29
Q

What can release antigen receptors

A

B lymphocytes

30
Q

What activates the B cell in humoral 1?

A

T helper cells using cytokines

31
Q

What happens with B cells after activation with T cells

A

Divide (via mitosis)
Into B-memory cells
OR effector cells that further differentiate into plasma cells, that can release antigen receptors

32
Q

What does MHC stand for and made of?

A

Major Histocompatibility Complex
Glycoproteins within phospholipids bilayer, highly variable

33
Q

What are complement proteins?

A

In plasma, activated by presence of pathogens
Happens at the same time as phagocytosis happens (before humoral, during inflammation)
- attract more phagocytes (like cytokines)
- opsonins binds to surface of membrane of foreign cells, water enters pores via osmosis, lyse
- aid attachment of phagocytes

34
Q

What is the process of phagocytosis? (7 steps)

A
  1. Chemotaxis and adherence of microbe to phagocyte
  2. Ingestion of microbe by phagocyte
  3. Formation of phagosome
  4. Fusion: Phagosome + lysosome = phagolysosome
  5. Digestion of ingested microbe by lysozyme
  6. Formation of residual body containing indigestible material
  7. Discharge of waste materials
35
Q

Where are B and T lymphocytes made and mature?

A

B- made, stay and mature in bone marrows (B-B)
T- made in bone marrows, mature in Thymus (T-T)

36
Q

Can T lymphocytes bind directly to pathogens?

A

No
Can only bind to antigen presenting cells (APCs)

37
Q

What’s the point of antibodies?

A
  • enhance phagocytosis (opsonisation)
  • activate more complement proteins (so more lysis)
  • can bind to toxins and neutralise them
  • reduces number of infectious units to be dealt with (Agglutination) (GLUE things tgt)
38
Q

What are 2 types of toxins by bacteria

A

Endotoxin
and exotoxin

39
Q

What’s opsonisation

A

Enhance phagocytosis

40
Q

What is humor in humoral?

A

Body fluids
Since Antibodies released to body fluids
B lymphocytes only involved

41
Q

Humoral response cannot take place when…

A

Virus has already injected itself into host cell

42
Q

Change in MHC of a self cell is considered a ….
How does it happen

A

An APC
Due to mutation or replicating antigens in protein synthesis (?)

43
Q

What does T lymphocytes divide into in cell mediated immune response?

A

T killer (cytotoxic cell)
T memory
More t helper

44
Q

What are T helper cell receptors called

A

CD4 receptors

45
Q

What is the cell mediated immune response?

A

When pathogens are inside host cells , antibodies aren’t effective
T-helper cells bind to APC and become activated + release cytokines
Divide into 3 types of cells (T-killer, T-helper, T-memory)

46
Q

How do T-killer cells destroy body cells infected by viruses (APC)?

A

Destroy cells changed by mutation to form cancer cells or cells transplanted organ using perforin

47
Q

Unnecessary usage of antibiotics is a …

A

A selection pressure

48
Q

Explain why agglutination could take longer at low and at high concentrations of sperm cells? (2 marks)

A
  • Bcs at low conc the collision between antibody and antigen is less frequent
  • bcs at high concs there may be insufficient antibodies
49
Q

If mention of antibodies, immediately think…

A

Humoral response

50
Q

Compare and contrast cell mediated vs humoral response

A
  • both use T cells
  • both produce memory cells
  • both involve cytokines
  • both are ACTIVE forms of immunity
  • T killer involved in cell mediated / not h
  • antibodies invoked in H / not c
  • antigen presentation in H by B cells / infected host cell present antigens in C (only when host cell is infected)
51
Q

Why are cytokines released in cell mediated response?

A

To recruit T killer cells

52
Q

How are monoclonal antibodies made?

A
  • inject antigen into mouse
  • trigger humoral response of mouse
  • extract plasma cells (that release complementary antibodies)
  • fuse with myeloma cells
  • hybridoma cells produced > divide and secrete antibodies
  • purify antibodies
53
Q

What are uses of monoclonal antibodies?

A
  • cancer treatments
  • vaccine
  • tests (covid, pregnancy)
  • identify cancerous cells or blood clots (PET scans)
54
Q

What are the issues with using monoclonal antibodies made by mice plasma cells (B-lymphocytes)?

A
  • foreign proteins to humans (attack w humoral!)
55
Q

What is humanising antibodies and why is it beneficial?

A

Put specific antigen binding sites of mice onto human antibodies
- less foreign so less likely to reject
- complementary to target antigens so only attached to them
- have less side effects

56
Q

What is monoclonal antibody therapy?

A

Using monoclonal antibodies (mAb) to bind to specific cells or proteins
Stimulate patients’ immune system to attack those cells

57
Q

What can you put in vaccines?

A
  • antigens
  • inactivated pathogens
  • antibodies
  • mRNA (so protein synthesis, produce antigen after cell mediated response, present antigen on MHC, host cell becoming APC)
58
Q

Outline the process of cell mediated response.

A
  • complementary T helper lymphocytes bind to foreign antigen on APC
  • rapid mitosis takes place, become memory cells or trigger humoral
  • T killer cells produced, secrete perforin to destroy infected cells
59
Q

What are antibodies?

A

Proteins secreted by plasma cells
complementary Antigen receptors

60
Q

Types of vaccine?

A
  • inactivated pathogens
  • live attenuated (chemically modified, so doesn’t cause disease)
  • toxoids (modified toxins)
  • genetically modified DNA/mRNA
  • administered either by injection or orally
61
Q

Why is genetically modified DNA/mRNA vaccines trigger cell mediated response, not humoral?

A

Because it has DNA and mRNA has to be transcribed and reached host cell
Cell mediated tackles host cells that have been injected by pathogens

62
Q

What response is specific

A

Humoral
Cell mediated

63
Q

What response is nonspecific?

A

Inflammatory

64
Q

how does a macrophage become an antigen presenting cell? (2 marks)

A
  • antigen on surface of macrophage
  • binding of antigen to receptor on T helper cell

N Biology A Level (18 decks)

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