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A-Level Biology > Cell Recognition and the Immune System > Flashcards

Cell Recognition and the Immune System Flashcards

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1
Q

Immunity

A

The body’s ability to identify and protect itself against disease

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2
Q

Immune System

A
  • The system in the body responsible for maintaining homeostasis
  • Does this by recognising organisms from non-harmful organisms and produces a response
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3
Q

Pathogens

A

Any organism that causes disease/an immune response to its host

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4
Q

2 Main types of Defence Mechanisms

A
  • Specific Defence Mechanisms
  • Non-Specific Defence Mechanisms
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5
Q

Non-Specific Defence Mechanisms

A
  • Doesn’t distinguish between one pathogen and another
  • Responds to all pathogens in the same way
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6
Q

2 Types of Non-Specific Defence Mechanisms

A
  • Barriers to entry
  • Phagocytosis
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7
Q

Barriers to entry

A
  • Skin
  • Saliva and Tears
  • HCL Stomach Acid
  • Mucus and Cilia Cells
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8
Q

How does the Skin act as a Barrier to Entry?

A
  • It covers the entire body and acts as a physical barrier
  • It secretes antimicrobial substances
  • When the skin is cut, platelets clot and dry out to form a scab at the site of the wound
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9
Q

How do Saliva and Tears act as a Barrier to Entry?

A
  • Saliva and Tears contain lysozymes
  • These lysozymes are able to destroy bacteria cells by hydrolysing their cell walls
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10
Q

How do Mucus and Cilia Cells act as a Barrier to Entry?

A
  • Goblet cells (found in the trachea) produce mucus, which is able to trap pathogens
  • The mucus is wafted up the trachea by cilia cells in the trachea towards the throat
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11
Q

How does the Nose act as a Barrier to Entry?

A
  • Nose hairs act as a physical barrier to pathogens
  • Cells in the nose produce mucus which traps pathogens
  • When you blow your nose, the pathogens are removed with the mucus
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12
Q

How does HCL Acid in the Stomach act as a Barrier to Entry?

A

HCL Acid lows the pH of the stomach which kills microbes

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13
Q

Phagocytosis

A
  • Chemotaxis (phagocytes (neutrophils) detect chemokines released by the pathogen and move towards it)
  • Phagocyte attaches to to the surface of the pathogen
  • Phagocytes engulfs the pathogen to form a phagosome (phagocytic vesicle)
  • Lysosomes move to the pathogen, fuse with it and release lysozymes into it
  • Lysozymes hydrolyse the pathogen
  • The breakdown products are absorbed by the phagocyte or leave it
  • The neutrophils die (accumulation of pus signals dead neutrophils
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14
Q

Antigen

A

Foreign protein on the surface of an organism that stimulates an immune response

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15
Q

Specific Defence Mechanisms

A
  • Does distinguish between different pathogens
  • Creates long lasting immunity
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16
Q

2 Types of Specific Defence Mechanisms

A
  • Cell-Mediated Responses (involve T-lymphocytes)
  • Humoral Responses (involve B-lymphocytes)
17
Q

Cell Mediated Response

A
  • Macrophage engulfs pathogen and presents itself on it’s surface (macrophage is an antigen presenting cell now)
  • T-cell receptors on the T-helper cell attach to the pathogen and activate the T-helper so it undergoes mitosis
  • Interleukins are produced (they trigger more phagocytes to increase phagocytosis rate and stimulate B-cells to divide by mitosis)
  • Interleukins trigger division of T-killer cells (release perforin which destroys pathogen cell membrane making it free-permeable and unable to survive)
18
Q

Humoral Immunity

A
  • B-cell engulfs pathogen and presents it on its cell surface
  • T-helper attaches to the B-cell to activate it
  • Stimulates plasma cells to divide (produce and secrete antibodies that attach to the antigen of the pathogen and destroy it)
  • Stimulates memory cells to divide (respond to future infection by the same pathogen
19
Q

Antibodies

A
  • Proteins made by B-lymphocytes in response to the presence of a specific antigen
  • Complementary to a specific antigen
20
Q

Structure of Antibodies

A
  • 4 polypeptide chains (2 heavy chains (long) and 2 light chains (short) )
  • ## Specific antigen binding site that antigens bind to and form antigen-antibody complex

A-Level Biology (8 decks)

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