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3.2 Cells > 3.2.4 Cell recognition and the immune system > Flashcards

3.2.4 Cell recognition and the immune system Flashcards

(41 cards)

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1
Q

Antigens

What type of molecules may these be

A

Proteins

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2
Q

Antigens

What they enable the immune system to identify

A
  • pathogens
  • cells from other organisms of the same species
  • abnormal body cells
  • toxins
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3
Q

Pathogen

Definition

A

-microorganism that causes disease

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4
Q

Pathogen

ways in which it may cause disease when it has entered the body

A
  • produces toxins

- damages/kills cells

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5
Q

Toxin

Definition

A

-poisons (molecules, not cells)

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6
Q

Types of defence mechanisms

A
  • non-specific

- specific

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7
Q

Non-specific defence mechanisms

A
  • immediate response

- same for all pathogens

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8
Q

Non-specific defence mechanisms

Examples

A

Physical barrier
└e.g. skin, mucus, saliva
Phagocytosis
└engulfing of large particles

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9
Q

Specific defence mechanisms

A
  • slower response

- specific to each pathogen

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10
Q

Specific defence mechanisms

Examples

A

-cell mediated response
└T lymphocytes
-humoral response
└B lymphocytes

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11
Q

Lymphocytes

Where produced

A
  • bone marrow

- as stem cells

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12
Q

B lymphocyte (B cells)

A

-mature in bone marrow
-associate with humoral immunity
└involving antibodies present in body fluids such as blood plasma
-act by infections in blood

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13
Q

T lymphocyte (T cells)

A

-mature in thymus gland
-associated with cell-mediated immunity
└immunity involving body cells
-act in response to infected cells

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14
Q

Antigen

Definition

A

-a protein that causes an immune response

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15
Q

Antigen

Location

A

-cell surface membranes/cell walls of invading cells

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16
Q

Antigenic variation

A

-pathogens can change their surface antigens due to change in their genes

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17
Q

Antigenic variation effect

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A
  • have to do primary response as memory cells for secondary response won’t recognise new antigens
  • difficult to develop vaccines
18
Q

Disease

Definition

Study These Flashcards
A

-collection of symptoms

└not organisms

19
Q

Phagocytosis of pathogens

Process

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A
  • phagocyte recognises antigens on the pathogen as foreign
  • it is attracted to the pathogen by chemicals
  • the pathogen is then engulfed
  • and enclosed in a vesicle
  • the vesicle fuses with a lysosome
  • which contains hydrolytic enzymes
  • which hydrolyse/digest the pathogen
20
Q

Phagocyte

Location

Study These Flashcards
A
  • some travel in blood

- some leave and migrate to the site of the infection

21
Q

EQ: structures a bacterial cell may have that a white blood cell does not have

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A
  • Cell wall
  • Capsule / slime layer
  • Circular DNA
  • Naked DNA / DNA without histones
  • Flagellum
  • Plasmid
  • Pilus
  • 70s / smaller ribosomes
  • Mesosome
22
Q

Neutrophil structure

Study These Flashcards
A

-lobed nucleus

23
Q

Neutrophil/phagocyte function

Study These Flashcards
A

-phagocytosis/engulfing

24
Q

Lymphocyte structure

Study These Flashcards
A

-large nucleus

25
Lymphocyte function
-produce antibodies
26
T cell and B cell | Similarities
- both are types of white blood cell | - both are produced from stem cells
27
T cell and B cell | Differences
- b cells = bone marrow - t cells = thymus gland - t cells are involved in cell-mediated immunity - b cells are involved in humeral immunity
28
The cellular response
The response of T lymphocytes to a foreign antigen
29
Antigen presenting cells | Definition
cells displaying foreign antigens on their cell-surface membrane
30
Antigen presenting cells | Process
-phagocyte recognises antigens on the pathogen as foreign -it is attracted to the pathogen by chemicals -the pathogen is then engulfed -and enclosed in a vesicle -the vesicle fuses with a lysosome -which contains hydrolytic enzymes -which hydrolyse/digest the pathogen -PAGOCYTE PRESENTS PATHOGENS ANTIGENS ON SURFACE CAN ACTIVATE OTHER IMMUNE SYSTEM CELLS
31
T cells | what they respond to
-organism's own cells that have been infected by non-self material -cells from another individual of the same species that are genetically different └e.g. transplanted material └as have different antigens on their cell-surface membrane from the antigens on the organism's own cells
32
T cells | How they distinguish between self and non self cells
- phagocytes present some antigens of the pathogen they have engulfed and hydrolysed on own cell-surface membrane (antigen presenting cells) - body cells invaded by a virus present some viral antigens on own cell-surface membrane - transplanted cells from individuals of the same species have different antigens on their cell-surface membrane - cancer cells are different from normal body cells and present antigens on their cell-surface membrane
33
The cellular response | Stages
-pathogens invade body cells └phagocytes engulf pathogens -phagocyte presents antigens from pathogen on cell-surface membrane= antigen presenting cell -receptors on a specific helper T cell (Th) └fit exactly onto these antigens -= activates T cell to divide rapidly by mitosis and form clone cells (genetically identical) -cloned T cells: └form memory cells └enable rapid response to further infections by the same pathogen └stimulate phagocytosis └phagocytes to engulf pathogens └stimulate B cells to divide and produce their antibody └activate cytotoxic T cells (Tc cells)
34
T cells
- type of white blood cell | - receptor proteins on its surface that can bind to complimentary antigens presented by phagocytes = activates T cell
35
TH cells
Release chemical signals to activate and stimulate phagocytes, TC cells and B cells
36
cytotoxic T cells (TC cells) | what they kill
- abnormal cells | - body cells that are infected by pathogens
37
cytotoxic T cells (TC cells) | how they kill
-produce protein called perforin └makes holes in the cell-surface membrane └=membrane becomes freely permeable to all substances └=cell dies
38
Why is it an issue that T cells are most effective against virus replicating inside cells
-viruses use living cells to replicate | └so sacrifice body cells prevents viruses multiplying and infecting more cells
39
The cellular response | B cells
- can be activated by Th cells | - secrete antibodies
40
The cellular response | phagocytes
- can be activated by Th cells | - phagocytosis
41
EQ: Explain the increase in specific plasma cells and antibody in people infected with the Ebola virus.
- the antigen on Ebola binds to and stimulates a specific B cell - which causes replication/cloning of the B cell - B cells produce antibodies

3.2 Cells (8 decks)

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