Protection against disease Flashcards

1
Q

List non-specific defence mechanism?

A

Skin

Tears

Saliva

Mucus

Cilia

Phagocytosis

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2
Q

How does skin work against pathogens?

A

Made of indigestible keratin

Secretion of sebaceous glands at hair follice have antiseptic properties agains some bacteria

Commensal bacteria competes with pathogens for nutrients on skin reducing number of pathogens

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3
Q

How does tears and saliva work against pathogens?

A

Contain lysozyme breaking cell wall of bacteria

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4
Q

How does mucus work against pathogens?

A

Secreted by epithelial cells

Traps bacteria and dust entering air passages

It contains lysozyme and other antibacterial substances

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5
Q

How does cilia work against epithelial cells?

A

Hairs on epithelial cells on upper parts of respiratory teact

Create current moving mucus and traped matterial to pharynx

Swallowing carries them to stomach where it gets killed

Coughing and sneezing also removes them

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6
Q

How does cilia work against epithelial cells?

A

Hairs on epithelial cells on upper parts of respiratory teact

Create current moving mucus and traped matterial to pharynx

Swallowing carries them to stomach where it gets killed

Coughing and sneezing also removes them

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7
Q

Describe phagocytosis?

A

Phagocyte detects pathogens and extends pseudopodia
around it

Then engulfs it forming phagosome

Lysosome fuse with vacuole causing hydrolysis of pathogens

Insoluble parts gets exocytosis and soluble parts gets absorbed

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8
Q

What is 2 main specififc defence system?

A

Humoral response

Cellural response

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9
Q

What is immune system?

A

Defense mechanism activating lymphocytes against antigens

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10
Q

What is antigens?

A

Protein or glycoprotein that is (or seems) foreign to organism

Stimulates antibody production

Present on:
-surface of cell
-Free molecule such as toxin

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11
Q

What is structure of antibodies?

A

Globular protein

Has 4 polypeptide chains - 2 heavy and 2 light joined via disulfide bonds

Each chain consisit of constant region and variable region

Variable regions form 2 antigens binding site
This allows binding to 2 different antigens
Allows also formation of lattice like antibody-antigen complex

These have specific tertiary structure complementary to antigens

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12
Q

What is constant region in antibodies?

A

Has sequence of amino acids is same in all molecules of the same type of antibody

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13
Q

What is variable region in antibodies?

A

Has amino acid sequence different in different molecules of the same type of antibody

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14
Q

What is 5 types of antibodies?

A

IgG, IgM, IgA, IgD and IgE

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15
Q

What is agglutination and how it happens?

A

Clumping cells having antigen(agglutinogen) against with specific antibodies(agglutinins) react

Antibody can attach to same antigens of same cells

This joins cells together, linking more form an agglutinated mass that can be all destroyed

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16
Q

How is phagocytosis stimulated by antibodies?

A

Some antibodies(opsonins) can label foreign cells for phagocytosis

These antibodies attach to antigens on surface of microorganism

Phagocytes have receptors on cell surface membrane which match with opsonins

17
Q

What is precipitation in antibodies conetxt?

A

Molecular level agglutination

Antibodies (precipitins) attach to toxin (antigen) causing them to group together

It neutralise toxin action and gets them destroyed later

18
Q

How does antibodies prevent attachment of pathogens?

A

Antibodies specifically produced agains antigens on cell surface can prevent it to attach to cell membrane

These antigens, usually glycoprotein, aids pathogens to enter host cell normally

19
Q

Describe humoral response using antibodies?

A

B lymphocytes can secrete small amounts of antibodies from cell membrane

Macrophage can display antigen phagocyted on membrane that is presented to B lymphocytes

Specific antigen attaches to complementary antibody on B lymphocytes

Antibodies bind to antigens forming an antibody antigen complex

T helper cell would also bind to B cell activating mitosis division

This stimulates B cell to divide by mitosis, producing identical plasma cells (clonal selection)

Following exprosure to antigens some B lymphocytes develop into memory B which can divide and evelop into plasma cells

These plasma cell produce more antibodies quicker if secondary response happens than when primary response

20
Q

What is T cell structure?

A

They have protein receptors on cell mambrane which recognise specific antigens that respond to a single specific antigen

21
Q

Describe cellular response?

A

Each different types of T cell respond to a different antigens

Antigen is, often, presented to T cell by an antigen presenting cell

T cells is stimulated dividing by mitosis and form identical T cells all with same reseptor

These can develop into different types of T cells

Can also stimulate phagocytosis of phagocytes

22
Q

List and describe different types of T cells?

A

Cytotoxic T cells - uses its surface receptors to attach the antigen and secrete chemical destryoing the cell

Helper T cells - stimulate B lymphocytes to divide and produce antibodies

Memory T cells - produced during primary response, remain in blood after infection cleared and produce quicler respose in case of reinfection with same antigen

23
Q

What is 2 type of active immunity and describe them?

A

Natural active immunity - Results of natural exposure to antigen, as someone gets infected and remain with memory cells after recovery

Artificial active immunity - vaccination, antigen in vaccine stimulates immune response, producting memory B cells and T cells

Sometimes booster injection is provided to ensure a more effective response to long, life term immunity

24
Q

What is natural passive immunity?

A

Antibodies are obtained through placenta or breast milk feeding, providing short term protection, as body is not stimulated to produce their memory cells

25
Q

What is artificial passive immunity?

A

Injection of specific antibodies following exposure to virulent antigens(e.g. rabies, venom)

Short term protection

26
Q

List and explain how rejection chance of trasplant is lowered?

A

Tissue typing - ensuring genetically similar

Irradiation - used on bone marrow to reduce T-lymphocytes

Immunosupressive drugs - cyclosporin for exp, reduces T-lymphocytes

27
Q

What is problem with rehusus factor?

A

Rhesus positive has antigen, while negative do not

Rhesus antibodies are not produced unless rhesus negative receive rhesus positive blood

Antibodies causes agglutination and lysis of foreign red blood cells

This happens id its second time of receiving blood