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Bio: Cells > Cell Recognition + The Immune System > Flashcards

Cell Recognition + The Immune System Flashcards

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1
Q

What are the two types of defence systems? What do they mean?

A

Non-specific: generic defences that are immediate and respond in the same way to each pathogen.
Specific: slower defences that are specific to each pathogen.

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2
Q

What are examples of non-specific defence systems?

A
  • Physical and chemical barriers (e.g. skin)
  • Phagocytosis
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3
Q

What are examples of specific defence systems?

A
  • Cell-mediated response
  • Humoral response
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4
Q

Swelling/inflammation is known as the non-specific inflammatory response. How does this work and help the body?

A

Histamine is secreted and vasodilation increases the blood supply. This increases the supply of phagocytic cells to the area.

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5
Q

What term describes a body’s own cells?

A

‘Self’

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6
Q

What term describes foreign cells?

A

‘Non-self’

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7
Q

What are examples of physical barriers?

A
  • Skin
  • Scabs
  • Tears
  • Eyelashes
  • Stomach acid
  • Nasal hair
  • Cilia
  • Goblet cells (secrete mucus)
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8
Q

What are the two types of phagocytes?

A

Neutrophils and macrophages.

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9
Q

Describe the features of a neutrophil.

A

It is made in the bone marrow, travels via the blood and squeezed out into tissue fluid. It is short lived and has a multi-lobed nucleus.

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10
Q

Describe the features of a macrophage.

A

It is made in the bone marrow, travels via the blood as a monocyte. They are longer lasting and can become antigen presenting cells (APC).

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11
Q

Describe phagocytosis.

A

Phagocyte engulfs pathogen, and places it into a vesicle called a phagosome. The phagosome fuses with lysosomes to form a phagolysosome. The lysosome releases lysozymes which hydrolyse the pathogen.
If the phagocyte is a neutrophil, it will collect as pus. If it is a macrophage, it will present the antigen from the pathogen on its cell surface membrane once the pathogen has been hydrolysed (becomes an APC).

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12
Q

What types of cells do T lymphocytes respond to?

A
  • Cells transplanted from a donor
  • Cancer cells
  • Antigen presenting phagocytes/cells (weaker answer, only sometimes accepted)
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13
Q

What triggers the cell mediated response?

A

Antigen presenting cells (e.g. macrophages)

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14
Q

Where are T cells produced and where do they mature?

A

They are produced in the bone marrow.
They mature in the thymus.

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15
Q

Where are B cells produced and where do they mature?

A

They are produced in the bone marrow.
They mature in the bone marrow.

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16
Q

Describe the cell mediated response.

A

T helper cells have receptors on their surface which bind to antigen on APC. This activates T helper cells to divide by mitosis and make a large number of clones (clonal expansion). The cloned helper T cells are then able to differentiate.

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17
Q

What do the cloned T helper cells differentiate into?

A
  • Memory cells for long term immunity
  • Stimulate phagocytes to engulf pathogen
  • Remain T helper cells and stimulate specific B cells to divide and secrete antibodies
  • Activate cytotoxic T cells (killer T cells)
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18
Q

How are cytotoxic T cells activated?

A

By T helper cells, which release chemicals called cytokines.

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19
Q

How do cytotoxic T cells work?

A

They release a protein called perforin, which makes holes in the membrane of the target cell and makes it freely permeable and causes the cell to be destroyed.

20
Q

Describe the humoral response.

A

The pathogen’s antigen enters the B cell via endocytosis, this antigen is then presented on the surface membrane. A T helper binds to this antigen/receptor complex. The T helper cell stimulates the B cells to divide via mitosis. These B cells then differentiate into plasma cells, which produce monoclonal antibodies or B memory cells.

21
Q

What is an antigen?

A

A protein which stimulates a specific immune response.

22
Q

What is an antibody?

A

An immunoglobulin, which is complementary to a specific antigen.

23
Q

Describe the structure of an antibody.

A

A Y shaped protein (called an immunoglobulin) made up of 4 polypeptide chains (quaternary structure) ~ 2 heavy chains, 2 light chains. It has a variable region and a constant region. The antigen binding sites are in the variable region, which is specific to a particular antigen due to it being different sequences of amino acids for different antibodies. It is held together by disulfide bridges. It has a hinge region, which gives the molecule flexibility.

24
Q

What is agglutination and why does it occur?

A

Antibodies have at least 2 binding sites, which leads to agglutination. It causes the pathogens carrying antigen-antibody complexes to clump together, preventing pathogens spreading and making it easier for phagocytes to engulf a number of pathogens at the same time.

25
Q

Other than binding to antigens, what else can antibodies do?

A

Bind to toxins produced by pathogens, making them harmless.

26
Q

Describe the primary immune response.

A

There is a slight delay due to antigen presentation, selection of complimentary T and B cells and mitosis. The cloned plasma cells produce antibodies and eventually die off, which is when the antibody concentration declines. Memory cells remain in circulation and stored in lymph nodes.

27
Q

Describe the secondary immune response.

A

There is a rapid increase in antibody concentration due to immediate activation of memory T and B cells. Many cloned plasma cells produce very large quantities of antibodies in a short period of time. As plasma cells die off, antibody concentration declines. Memory cells remain in circulation and stored in lymph nodes.

28
Q

Why may we suffer from the same disease twice?

A

Antigen variability - where gene mutation changes the antigen on the surface of the pathogen (e.g. cold virus or influenza). Antigens are no longer complimentary to the surface receptors of memory cells so no longer secondary response.

29
Q

What are the two different categories of immunity?

A
  • Passive or active
  • Natural or artificial
30
Q

What is active natural immunity?

A
  • An individual becoming infected with a disease
  • Body / plasma cells produce own antibodies
  • B memory cells formed
31
Q

What is passive natural immunity?

A
  • Baby becomes immune due to the antibodies received from mother through placenta or breast milk
  • Short lived
  • No memory cells
32
Q

What is active artificial immunity?

A
  • Vaccination
  • Memory cells formed
33
Q

What is passive artificial immunity?

A
  • Become immune after being injected with antibodies from someone else
  • E.g. antivenom (antibody, venom = antigen)
  • Short lived
  • No memory cells
34
Q

What are the features of active immunity?

A
  • Requires exposure to antigen
  • Takes a while for production of antibodies to develop
  • Memory cells are produced
  • Long term protection
35
Q

What are the features of passive immunity?

A
  • Does not require exposure to antigen
  • Protection is immediate
  • Memory cells are not produced
  • Short term production ~ antibodies are broken down
36
Q

What is a vaccination?

A

When a small amount of an inactive form of a pathogen (disease causing microorganism) into the body.

37
Q

How does the body respond to the vaccine?

A

The same as the humoral response, where B lymphocytes are activated and divide via mitosis. They differentiate into memory cells or plasma cells. Plasma cells produce monoclonal antibodies. B memory cells provide long term immunity from the live pathogen.

38
Q

What is antibiotic resistance?

A

Where a certain strain of bacteria can no longer be killed by antibiotics.

39
Q

What causes antibiotic resistance?

A
  • Doctors overprescribing antibiotics
  • Patients not finishing their courses of antibiotics
40
Q

What are the features of a successful vaccination program?

A
  • Economically available in sufficient quantities
  • Few side effects
  • Vaccinating vast majority of the vulnerable population (herd immunity)
  • Being able to produce, store and transport the vaccine
41
Q

What is herd immunity?

A

When a significant proportion of the population are vaccinated, which makes it difficult for a pathogen to spread.

42
Q

What are monoclonal antibodies?

A

One type of antibody produced from a clone of plasma cells.

43
Q

What are the uses of monoclonal antibodies?

A
  • For diagnosis
  • In labs, to measure levels of hormones/chemicals in the blood, or to detect pathogens
  • To treat certain diseases by binding them to radioactive substances or toxic drugs
  • In research to locate or identify specific molecules in a cell or tissue by binding them to a fluorescent dye
44
Q

What is direct MAB therapy?

A

When the MAB attaches to a specific antigen and blocks chemical signals that stimulate uncontrolled cell division.

45
Q

What is indirect MAB therapy?

A

When a therapeutic drug is attached to the MAB to target a specific cell type, e.g. the magic bullet.

46
Q

What are the advantages of direct MAB therapy?

A
  • Antibodies are non toxic
  • Antibodies are highly specific
  • Fewer side effects than other forms of therapy
47
Q

What are the advantages of indirect MAB therapy?

A
  • Small doses required - cheaper + reduces side effects
  • Target specific sites
  • Doesn’t damage healthy cells

Bio: Cells (7 decks)

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