Physiology Flashcards
Define epidemiology
- Study of factors that determine the frequency, distribution and patterns of disease in human populations
- Includes ways to control and eradicate disease
Define pathology
Study of disease and disease process
Define infectious disease
Disease caused by a pathogen
Define communicable disease
Infectious disease which can be passed from human to human
Define contagious disease
Easily communicable disease
Define incidence
Number of new cases of a disease in a defined population for a specific time period
Define prevalence
Number of cases of disease in a given population during a specific time
Define morbidity
State of being diseased
Define mortality
Number of deaths due to a disease in a population
Define sporadic disease
- Occurs occasionally in a geographic distribution
- Usually because disease is well controlled through sanitation or vaccination
Define endemic disease
-Example
- Always present in a population within a certain geographical area
- Often related to health conditions, environmental factor for organism or a biological vector
- Example: Malaria
Define epidemic disease
- Greater than usual number of cases in a particular area over a short period of time
- Can be related to rapid spread due to contamination of food or water source
Define pandemic
-Examples
- Disease in epidemic proportions in several countries
- 1918 Spanish flu
- Current: tuberculosis and AIDS
Define pathogen
Organism capable of causing disease in an otherwise healthy individual
Define virulence
A measure of an organism’s pathogenicity, AKA its ability to cause disease
Define virulence factor
-Examples
- Property of a microbe that creates disease by increasing ability to colonize, derive nutrients or avoid host immunity
- Simply - the weapons with which a pathogen causes disease*
- Examples: pili, capsule, coagulase, hyaluronidase, toxins
Define opportunistic pathogen
- Organism able to cause disease in an immunocompromised host
- Usually lacks virulence factors
- Often normal flora
Define transmission and give examples
- Route of moving from host to host
- Host to host contact
- Inhalation of droplets
- Fecal-oral route
- Blood-blood
- Fomites
- Vector
Define vector
- Carries or transmits pathogen to host
- Biological vectors often arthropods
Define reservoir
- Site from which infectious disease is transmitted
- Shows no sign of disease
- Living or nonliving (fomite)
- Or environmental source such as soil
Define carrier
- Diseased individuals who show no or mild symptoms (subclinical infections) or
- Continue to shed disease post recovery
List the flow of acute disease progression
- Infection
- Incubation period (before disease symptoms begin)
- Prodromal symptoms (fatigue, lethargy, dull ache, headache, etc.)
- Acute phase (species-specific disease symptoms)
- Decline (body’s immune defenses are battling pathogen)
- Convalescence (recovery time)
List the physical & chemical barriers to disease
- Skin
- Mucous membranes
- Normal FLora
- Acidity
- Lysozyme
- Bile
- Interferon
List the portions of the blood involved in the immune system
Aqueous:
- Plasma
- Serum
Cells:
-Erythrocytes
List the WBCs that are granulocytes
- Neutrophils (PMNs)
- Eosinophils
- Basophils
List the WBCs that are agranulocytes
- Monocytes
- Lymphocytes: B cells and T cells
Platelets are…
- fragmented megakaryocytes
- they’re produced from very large bone marrow cells called megakaryocytes
Name another body system that functions in immunity
The lymphatic system
When does non-specific immune response occur?
Once an organism breaches physical and chemical barriers
List the cellular “players” in non-specific immune response
- Neutrophils circulating
- Monocytes circulating (macrophages in tissue)
- Dendritic cells in skin and mucous membranes
- Microglia in CNS
- M cells of GALT
List the stages of phagocytosis
- chemotaxis (ability to move towards a source)
- attachment (of phagocyte to microbe)
- ingestion (of the microbe by the phagocyte)
- digestion (lysozyme with digestive enzymes attaches to phagocyte to form phagolysosome - digests microbe and releases indigestible material)
Explain the respiratory burst associated with phagocytosis
Respiratory burst associated with phagocytosis d/t creation of reactive oxygen species
Describe the inflammatory response
- Response to harmful stimuli, such as pathogens, damaged cells, or irritants
- Protective response involving immune cells, blood vessels, and molecular mediators
The inflammatory response functions to…
Eliminate the initial cause of cell injury, clear necrotic cells and tissue, and to initiate tissue repair
What are the 4 cardinal signs of the inflammatory response?
- Calor – heat
- Dolor – pain
- Rubor – erythema
- Tumor – swelling
What is the first inflammatory cell to arrive?
The neutrophil
-Attracted to infection or tissue injury by soluble chemoattractants AKA chemokines, the acute phase proteins
Give an example of a neutrophil and its function
- E.g. IL-8 produced by damaged host cells attracts and activates neutrophils
- Neutrophils phagocytize particles, secrete cytokines to further attract and activate phagocytes
Which inflammatory cells arrive after the neutrophil? What is the function?
- Macrophages arrive and are activated to phagocytize and digest pathogen
- Macrophage also secrete cytokines which illicit responses such as fever and blood vessel dilation
- Antigen presentation**
Define systemic inflammation
- Uncontrolled systemic inflammation, septic shock, can lead to serious illness and death
- Uncontrolled fever
- BV dilation can lead to massive efflux to tissue resulting in low blood pressure and edema
- Septic shock: gram NEGATIVE organism
Define specific immunity
Activation of lymphocytes which recognize unique invaders
Adaptive immune response is characterized by… (3 parts)
- Specificity for the antigen
- Memory ability to respond more vigorously when re-exposed to the same antigen
- Tolerance ability to discriminate self antigens from non-self antigens
Define antigens (Ag)
- Macromolecules which induce an immune response
- Recognized as foreign i.e. immunogenic
- Molecular size (large enough to be phagocytized)
- Physical form (usually protein in nature)
- Appropriate dose and route
Which phagocytes act as APCs (antigen presenting cells)? What is their function?
- Monocyte
- Macrophage
- Neutrophil
- T helper cells
*Place antigenic determinants on own cell surface and interact and stimulate specific lymphocytes
Explain antigenic determinants
The antibody or T cell receptor (TCR) does not interact with entire Ag, only against a distinct portion of the molecule called an antigenic determinant or epitope.
Therefore antigen presentation by phagocytes is the most important step in initiating the immune response
List the kinds of receptors in antigen presentation
B cell receptor is surface antibody
T Cell Receptor (TCR) = T cell antibody
TCRs bind peptide antigens presented by…
major histocompatibility complex (MHC) proteins.
List the functions of MHC
- MHC proteins serve as a platform for Ag presentation**
- MHC is the chaperone for Ag that are presented to TCRs
- MHC molecules bind to both T cell receptor and CD4/CD8 co-receptors on T lymphocytes to trigger T-cell activation
- It is important to have differing distribution of MHCs
Class I MHC proteins
- where are they found
- what receptor recognizes them
- Found on the surfaces of all nucleated cells
- Recognized by cytotoxic T cell TCR and the CD8 co-receptor
Class I MHC proteins
- function
- comprises
- To address intracellular pathogens, such as viruses and intracellular bacteria (RMSF, gonorrhea, etc.)
- MHC class I comprises HLA-A, HLA-B, and HLA-C molecules
Class II MHC proteins
- where are they found
- what receptor recognizes them
- Found only on the surface of B lymphocytes, macrophages, and dendritic cells, all of which are APCs
- Recognized by helper T cell TCR and CD4 coreceptor
- Further stimulate the immune response by activating T and B cells
Define cell-mediated immunity
- Branch of the immune system mediated by T cells
- Particularly effective against intracellular pathogens i.e. viruses, fungi, protozoa and parasites, cancerous cells and transplanted tissue
Explain Th cells, their markers and activation
- T helper cells
- Bear CD4 markers
- Recognizing MHC II
- Activated by APC**
- Mature and proliferate
- Activate immune response
- 2 subsets
Type I Th cells
- Activate macrophages, CD8+ T cell
- Cellular immune system
- -Maximizes the killing efficacy of the macrophages
- -Proliferation of cytotoxic CD8+ T cells
Type II Th cells
- Activate B lymphocytes, eosinophil, mast cell
- Humoral immune system
- -Stimulates B-cells into proliferation
- -Induce B-cell antibody class switching
- -Increase neutralizing antibody production
Explain Tc cells, their markers and activation
- Cytotoxic T cells
- Bear CD8 marker
- Recognize antigens on virus-infected host cells and tumor cells in conjunction with MHC I*
- Once stimulated circulate and kill Ag bearing cells
- Antigen-specific recognition triggers killing via perforin and granzymes
Explain Ts cells, their markers and activation
- Suppressor or regulatory cells
- A subset bears the CD8 marker
- Serve to inhibit Th cells***
- -Modulates the immune response
- Suppress activation of the immune system and prevent pathological self-reactivity
Explain NK cells
- Natural killer (NK) cells use the same effectors as TC cells to kill virus-infected cells and tumors
- NK cells do not require stimulation, nor do they exhibit memory**
- NK cells respond in the absence of MHC proteins
- There is a subset of T cells called NKT cells which are stimulated outside the MHC requirement
Define humoral immunity
- Branch of the immune system mediated by B lymphocytes
- Activated B cells produce antibody which circulates as the effector of humoral immunity
What kind of immunity is humoral immunity? What is it effective against?
- Antibody-mediated immunity
- Particularly effective against pathogens such as viruses and bacteria in the blood or lymph
- Against soluble pathogen products such as toxins
Immunoglobulin structure
Immunoglobulin (Ig) (antibody) proteins consist of four chains, two heavy and two light
Immunoglobulin G (IgG)
- 80% of circulating Ab
- Appears 2nd in immune response
- Produced by memory cells
- Crosses placenta
Immunoglobulin M (IgM)
- 5-10% circulating Ab
- First to appear in immune response*
- Class switch to IgG occurs due to T cell cytokine
Immunoglobulin A (IgA)
- 10% of circulating Ab
- Found in secretions
- Produced by MALT
Define MALT
- Mucosa-associated lymphatic tissue
- Diffuse system of lymphoid tissue found in various sub-mucosa membrane sites of the body, such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin
Immunoglobulin E (IgE)
- < 1% of circulating Ab
- Binds allergen
- Binds basophils and mast cells
- Allergic response**
Immunoglobulin D (IgD)
- < 0.05% circulating Ab
- Found on immature B cell surface
- B cell then goes to make another Ig molecule
List the Steps to Antibody Production
- First – Ag exposure
- B cell binds Ag via surface Ig (prob. IgD)
- Presents Ag on MHC II to TH via TCR & CD4
- TH secretes cytokines
- B cell stimulated, matures into plasma cell
- Ab secreted (IgM flavor first, then IgG)
- B cells can also be directly stimulated by binding Ag
When is memory B cell found?
- Remains after initial Ag exposure
- Activation requires no T cell interaction
Antigen recognition diversity
- *Billions of Ag recognized, only 300 genes
- DNA recombination of variable and constant regions generates endless combinations
Antibody action
- Antibodies circulate and bind Ag
- Soluble Ag is neutralized
Define opsonization
- You can increase phagocytosis by coating that bacterial cell with antibody.
- Phagocytes can actually bind a portion of the immunoglobulin portion (Fc portion) and helps it phagocytose the organism.
- If you coat that antigen with antibody, it enhances phagocytosis.
- This process is called opsonization.
Explain complement
- If you have antibody there, complement can be stimulated by antibody.
- Antibody is acting as a flag for something else.
- Complement – series of proteins produced by the liver circulating in the blood.
- Only activated to form the hole in the surface of the cell if antibody is there - acts as a guide,
- Hole will be poked in that cell nearby where antibody is stuck to the antigen.
Define Superantigens
- Trigger excessive and aberrant activation of T cells
- Large amounts of cytokine release can cause severe and life-threatening symptoms, including shock and multiple organ failure
- Staphylococcus aureus and Streptococcus pyogenes together produce 19 different superantigens**
- Also Gram negative bacteria, mycoplasma, and viruses
Define natural active immunity
Immune response to antigen – you just getting the exposure
Define natural passive immunity
- Born with certain amount of IgG that can cross the placenta
- Placental transfer of maternal antibody, or breast feeding
Define artificial active immunity
Immune developed after intentional exposure of Ag i.e. vaccination
Define artificial passive immunity
- Injection of preformed Ab
- If you’ve been exposed to Hep A, go get an immunoglobulin shot
Explain inactivated viral vaccines - give examples
- Damaged and not capable of infection
- Salk polio, rabies
Explain attenuated viral vaccines - give examples
- Viable avirulent virus infection
- Varicella, measles, mumps, Sabin (oral)
List the types of bacterial vaccines
- killed
- attenuated
- toxoid
- -denatured toxin
- -e.g. diphtheria, tetanus
Future of vaccines
- Synthetic peptide sequences can be inserted into an engineered virus (Vaccinia) used as a vector to induce immune response
- DNA can be inserted on a plasmid and introduced to cells which translate proteins and induce immune response
