Protection against disease Flashcards
List non-specific defence mechanism?
Skin
Tears
Saliva
Mucus
Cilia
Phagocytosis
How does skin work against pathogens?
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
How does tears and saliva work against pathogens?
Contain lysozyme breaking cell wall of bacteria
How does mucus work against pathogens?
Secreted by epithelial cells
Traps bacteria and dust entering air passages
It contains lysozyme and other antibacterial substances
How does cilia work against epithelial cells?
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
How does cilia work against epithelial cells?
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
Describe phagocytosis?
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
What is 2 main specififc defence system?
Humoral response
Cellural response
What is immune system?
Defense mechanism activating lymphocytes against antigens
What is antigens?
Protein or glycoprotein that is (or seems) foreign to organism
Stimulates antibody production
Present on:
-surface of cell
-Free molecule such as toxin
What is structure of antibodies?
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
What is constant region in antibodies?
Has sequence of amino acids is same in all molecules of the same type of antibody
What is variable region in antibodies?
Has amino acid sequence different in different molecules of the same type of antibody
What is 5 types of antibodies?
IgG, IgM, IgA, IgD and IgE
What is agglutination and how it happens?
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
How is phagocytosis stimulated by antibodies?
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
What is precipitation in antibodies conetxt?
Molecular level agglutination
Antibodies (precipitins) attach to toxin (antigen) causing them to group together
It neutralise toxin action and gets them destroyed later
How does antibodies prevent attachment of pathogens?
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
Describe humoral response using antibodies?
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
What is T cell structure?
They have protein receptors on cell mambrane which recognise specific antigens that respond to a single specific antigen
Describe cellular response?
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
List and describe different types of T cells?
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
What is 2 type of active immunity and describe them?
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
What is natural passive immunity?
Antibodies are obtained through placenta or breast milk feeding, providing short term protection, as body is not stimulated to produce their memory cells
What is artificial passive immunity?
Injection of specific antibodies following exposure to virulent antigens(e.g. rabies, venom)
Short term protection
List and explain how rejection chance of trasplant is lowered?
Tissue typing - ensuring genetically similar
Irradiation - used on bone marrow to reduce T-lymphocytes
Immunosupressive drugs - cyclosporin for exp, reduces T-lymphocytes
What is problem with rehusus factor?
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
