Lecture 15 &16- Intro To Human Immunity Flashcards
What is Immunity?
The body’s ability to defend itself against
- Infectious agents
- foreign cells
- Abnormal body cells eg cancer
What are the two broad types of immune defenses?
- Innate immunity (nonspecific)
- adaptive/acquired immunity (specific)
Which type of immunity retains memory?
Adaptive immunity
Give examples of External defenses? (Barriers to entry)
- Intact skin- cannot be penetrated except if tiny cuts are present
- Mucous membranes lining digestive, respiratory, and genitourinary tracts - some of these cells produce mucus
- washing action of saliva, tears, urine constantly bathe surfaces of exposed tissue
- Secretions of skin and mucous membranes chemicals kill or weaken bacteria
Sebaceous glands and sweat glands PH 3-5, acidic enough to prevent colonization
- Ciliated cells in upper respiratory tract, sweep mucus and trapped particles, to be swallowed or coughed out
- Acidic pH of stomach destroys most pathogens before entry to intestine
- Flora (harmless bacteria) in intestine and other areas prevents colonization of pathogens
Describe the process of inflammatory reaction, and under which circumstance does it occur?
When tissue are damaged
- Damaged tissue and Mast cells(tissue equivalent to Basophils) release inflammatory chemicals (histamine kinin) that dilate capillaries bringing blood to injures site causing redness & heat
- ↑ permeability allows proteins, fluids, and phagocytes(Macrophages) to enter swelling site
- Swollen area and kinins stimulate free nerve endings –> pain
- Phagocytes kill microbes
Describe mechanism of phagocytosis
- Phagocytes attach to microbes and engulf them by Endocytosis , forming a vacuole
- vacuole fuses with lysosome
- lysosome kills microbes by producing toxic compounds (nitric oxide & free radicals)
- lysozyme degrades them to small fragments
- Degraded products secreted by exocytosis
Describe how Natural Killer cells work and where they derive from?
Derive from Lymphoid stem cells
- NK cells patrol the body and attack virus infected cells and cancer cells
- when a cell is infected or becomes cancerous various stress-induced molecules are produced and are put on the surface of the cell
- NK cell receptor, called killer activating receptor, recognizes these stress induced molecules
- This interaction creates a + signal, enables NK cell to kill the cell bound to it
Give examples of protective proteins (internal innate defense) and their function
- Lysozymes present in (saliva, tears, mucous secretions) can destroy bacteria as they enter the upper respiratory tracts or openings of the eyes
- Interferons (α &β) produced by cells infected with viruses and protect non infected cells present in antiviral drugs such as Hepatitis C
- Complement proteins- present in plasma ≈30 and activated by bacterial infections
C5a- participate in inflammatory response by attracting phagocytes to the site of inflammation
C3b- bind to the surface of pathogens and help in phagocytosisby macrophages and neutrophils
C5-C9- form a membrane attack complex that make holes in cell walls & plasma membrane of bacteria
Which type of cells activate NK killer cells?
viral infected or cancer cells
Which type of cells send α& β interferons?
Viral infected cells
What type of WBC’s are responsible for acquired immunity?
Lymphocytes
What are antigens and what type of molecules are they?
a foreign molecule recognized by lymphocytes that elicit a response
thsy are large molecules (mainly proteins & polysaccharides)
helps to differenciate between ‘self’ and ‘non-self’
Explain humoral immunity
it is a type of acquired immunity
B lymphocytes with the antigen receptor recognize antigen, and are activated undergo proliferation, differenciate to either memory cells or plasma cells
plasma cells (short lived)secrete antibodies, protect against extracellular pathogens
Memory cells(long lived) differenciate to plasma cells and other memory cells when antigen is recognized in future
What are antibodies?
- glycoproteins that have a complimentary shape to antigen , bind by non covalent factors
- Are also known as immunoglobulin (Igs)
- Y shaped with 2 arms- each with heavy & light chains and constant and variable regions
- bind in a lock and key manner to form antigen antibody complexes
How are antigens recognized by lymphocytes?
lock and key mechanism
Lymphocytes in general (not a single one) have millions of different receptors
State the different ways that antibodies can function
- neutralize viruses and bacteria
- Agllutinate (clump) bacteria
- Inactivate toxins and soluble antigens , neutralizing the effect
- Facilitate uptake of the pathogen and soluble antigens by phagocytic cells
- Activate protein compliment system to kill pathogen
What is Cell Mediated immunity and how does it work?
A type of specific defense involving T lymphocytes:
Helper T cells, cytotoxic T cells, memory T cells
- T cells recognize antigen in surface of APC’s (antigen presenting cells eg; Macrophages) through T receptors in association with self proteins (major histocompatibility complex) molecules
- helper T cells activated and secrete cytokines. Stimulating …
- [proliferation of B cells to plasma cells–> secrete antibodies, and memory cells
- cytotoxic T cells to proliferate and kill virus infected cells & cancer cells
- macrophages and neutrophils to kill intracellularly pathogens]
Give examples of diseases treated by active immunity and its method of intake
- Diphtheria,Pertussis, and Tetanus intramuscular
- BCG(treats TB) intradermal
↑bacterial
viral are
- Hepatitis B intramuscular
- Polio oral
- Measles,Mumps,Rubella -subcutaneous
- Vitamin A oral (not actual antigen or pathogen- helps immunity)
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