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Is our body resistant to most plan and animal pathogens?
Yes, the physiological proccesses of humans are incompatible with those pathogens. The correct chemical receptors are not present on human cells.
what are examples are extracelluar pathogens?
- Bacteria, parasites, fungi
- -Pneumonia, Tetanus, sleeping sickness
What are examples of intracellular pathogens?
- Bacteria, parasites
- (TB, Malaria, Leprosy, Leishmaniasis)
- -Viruses (smallpox, flu, chickenpox)
What are examples of parasitic worms?
What is nonspecific mechanisms?
What are characteritics of innate immunity?
Rapid response (hours), Fixed, limited number of specificities, and constant during a response
What is a specific mechanism?
What are the characteristics ofadaptive/acquired immunity?
Slow response, variable, numerous hlighly selective specificities, and improve during response (memory)
What are the body's first line of defense?
Structures, chemicals, and processes that work to prevent pathogens from entering the body: Skin and mucous membranes of the respiratory, digestive, urinary, and reproductive systems.
What are the two layers in the skin?
- -epidermis: mulitple layers of tightly packed cells, few pathogens can penetrate these layers, shedding of dead skin cells removes microogranisms, epidermal dendritic cells phagocytize pathogens
- -dermis: collagen fibers help skin resist abrasions taht could introduce microorganisms.
What is the role of skin in innate immunity?
- -Chemicals that defend against pathogens
- -Perspiration by sweat glands-salt inhibits growth of pathogens
- -Animicrobial peptides act against microorganims
- -Sebum by sebaceous glands help keep the skin pliable and less likely to break/tear, lowers skin ph to a levl inhibitory to may bacteria
What is the role of mucous membrane in innate immunity?
-Line all body cavities
What are the layers of the mucous membrane?
- -Epithelium: Line, outer covering of membranes, living cells, tightly packed to prevent entry of pathogens, shedding of cells carry away pathogens
- -deep connective layer: supports epitelium
What is the role of the lacrimal apparatus?
- -Produces and drains tears
- -Blinking spreads tears and washes surface of eye
- -Lysozyme in tears destroys Gram (+) bacteria
What is the role of normal microbiota in innate immunity?
- Normal microbiota compete with potentioal pathogens- microbial antagonism
- -They make it hard for pathogens by consuming nutrients, create an unfavorable enviroment, stimulate body's 2nd line of defense, and provide vitamins
What are other first-line defenses?
- -Antimicrobial peptides: present in skin, mucous membranes, neutrophils, act against a variety of microbes
- -Inducing holes in bacteria membrane and intracellular killing
- -Other processes and chemicals: many organs secrete chemicals with antimicrobial properties
What is the body's 2nd line of defense?
- -Operates when pathogens penetrate the skin or mucous membranes
- -composed of cells, antimcrobial chemicals
What are examples are the body's 2nd line of defense?
- -Phagocyic cells (blood and tissue, neutrophils, basophils, eosinophils)
- -Nonspecific chemical defenses against pathogens
- 1. complement proteins (serum)
- 2. Antimicrobial peptides (all body secretions)-act against pathogen
- 3. Interferons-increase resistance of cells to viral infection
- Inflammation-increase capillary permeability and blood flow to allow WBC to move
- Fever- (Local or systemic)- Mobilizes defense, inhibits pathogens.
What are the components of blood?
- -Plasma (46-63%): mostly water, electroyltes, gases, nutrients, and proteins
- -Serum: remaining when clotting factors are removed:Complement proteins, antiboides, iron-binding compounds.
What are formed elements:
- -Cells and cell fragments in the plasma.
- 1. RBC (erythrocytes) Carrying O2 and CO2 (99% of formed elements)
- 2. Platelets: involved in blood clotting
- 3. WBC (leukocytes): Defding the body against invaders, divided into granulocytes and agranulocytes
What is hematopoiesis?
-Refers to the formation and development of the cells in the bood.
What is a cytokine?
A communciation between the cells
What is the name of the cell that starts development of a blood cell?
-Stem cell, then common myeloid stem cell, common lymphoid (makes lymocytes) and erythroid (makes RBC).
What are basophils?
- -Stain blue with basic dye methylene blue
What are eosinophils?
- -Stain red/orange with acidic dye eosin
- -Phagocytize and capable of diapedesis (chemotaxis)
What are neutrophils?
- -Stain liliac with mix of acidic and basic dyes
- -Phagocytize pathogens, capable of chemotaxis
What are lymphocytes?
- -Most invovled in adaptive immunity
What are monocytes?
- -Leave the blood and mature into macrophages
- -house-shoe shape
Increased eosinophils indicate?
-allergies or parasitic worm infection
increased leukocytes and neutrophils show?
Viral infections show an increase in what WBC?
What is phagocytosis?
- -Cells that can do this are called phagocytes
- six stages:
- 1. Chemotaxis
- 2. Adherence
- 3. Ingestion (in phagosome)
- 4. Fusion with lysosome
- 5. Killing
- 6. Elmination
What are opsonins?
- -A molecule that promotes phagocytosis by binding to the surgace of a microbe.
- -Complement: Helps the cell adhere better to the pathogen so it can eat it up -Inactive protein, until stimulated by pathogen
What is killing by eosinophils?
- -Attack parasitic helminths (worms) by attaching to their surface
- -secrete toxins that weaken or kill
What is eosinophilia?
-An elevated amt of eosinophils, seen with ahelminth infestation. (in periperal)
What is killing by Nk lymphocytes?
- -Always there, not adaptive
- -Secrete toxins on surface of virally infected cells and tumors
- -Differentiate normal body cells because they have membrane proteins similar to NK cells
What are Toll-like receptors (TLR)?
- -Proteins in cell membranes taht recognize pathogens
- -Integral membrane proteins produced by pahagocytic cells
- -Bind pathogen-associated molecular patterns (PAMPS)
- -Initiate defensive responses
- -Apoptosis (program cell death), secretion of inflammatory mediators, production of stimulatns of adaptive immune respone
What are interferons?
- Protein molecultes released by hose cells to nonspecifically inhibit the spread of viral infections.
- -Causes many symptoms with viral infections.
- -Type 1 and 2
What are type 1 interferons?
- -non-immune interferon
- -Alpha and beta
- -Any cell
What are type two interferons?
- -Only immune cells- leukocytes
What are characterisitics of Alpha interferon?
- -epithelium, leukocytes
- -inducing agent: virsues
- Action: Stimulates production of aniviral proteins
- -Aka Leukocyte-IFN
What are characterisitics of Beta interferons?
- -Fibroblasts (CT)
- -Inducing agent: virus
- -Action: stimulats production of antiviral proteins
- aka: fibroblast-IFN
What is the action of alpha and beta interferons?
-Interferons are released goes to neighboring cells and stops the RNA/protein of the cell because a virus cannot infect a "sick cell", then it breaks up the virus RNA
What is complement?
- -Set of serum proteins designated numerically according to their order of discover. 1-9 (Does not mean they happen in this order)
- -Activation results in lysis of the foreign cell
- -can be activated in three ways: classical, alternate, lectin
What is the classical pathway in complement?
-Activated by antibody molecues coating the microbes (Adaptive)
What is the alternate pathway in complement?
-Activated by surface components of microbes directly
What is the MAC attack?
-membrane attack complexes- hole in cell
What happens after the 1st line in complement is activated
-The rest will follow and end result is MAC Attack
What is c3b?
an opsonin for phagocytosis. A split product of c3, which can bind to cell membranes and then an opsonin for neutrophils and macrophages
How does the classical pathway work?
-Antigen and antibody with proteins from immunoglobins (1, 2,4), then activation (this is the complement) by C3 splitting into c3a and c3b for opsonization and inflammation. Then C5 splits into c5a and c5b for inflammation and it is followed by MAC Attack
How does the alternative pathway work?
c3b the opsinon is on the cell, then activation (this is the complement) by C3 splitting into c3a and c3b for opsonization and inflammation. Then C5 splits into c5a and c5b for inflammation and it is followed by MAC Attack.
What is c3a and c5a?
- -Anaphylatoxins (allergies)
- -Smooth muscle contraction, histamine realease from mast cells, enhanced vascular permeability (vasodilation) for inflammation.
What is c5a?
-A chemotactic agent for neutrophils (PMN) and macrophages. It signals for help-need vasodilation
What is C56789?
MAC attack: induces holes in membrane of pathogen
What is the inactivation of complement?
- -Body's own cels withstand complement cascade (inhibitors)
- -Proteins on many cells bind and break down activated complement proteins
What is inflmmation?
- -Nonspecific response to tissue damage from various caues
- -Redness, heat, swelling, pain, and loss of function
- -local or systemic
- two types: Acute and chronic
What is acute inflammation?
- -develops quickly and is short lived
- -Typically beneficial
- -2nd line of defense
- 1. Vascular events
- 2. Cellular events
- 3. Tissue Repair
What are vascular events in inflammation?
- -Leading to dilation and increased permeability of the blood vessels
- -prostaglandins and leukotrienes (produced by damaged cell)
- -Histamine (mast cells and blood basophil release)
- -Anaphylotoxins (c3a, c5a complement)
What are cellular events in inflmmation?
- -leading to the migration of phagocytes to the site of injury is mediated by:
- Release of chemotacitc factors
- -c5a: complement cascade
- -interleukin (il-8): released by macrophages
- -antibody IgG is an opsonin
What is the stimulation of inflammation by complement?
-c3b and c5a fragments of complement cause mast cells realse inflammatory mediators cause vasodiatation of capillaries
What is a fever?
- - Body temp over 37 C
- -Results when pyrogens trigger the hypothalamus to increase the body's core temp
- Various types of pyrogens: Bacterial toxins, cytoplasmic contents of bacteria by lysis, antibody-antien complexes: signal for interluekin by macrophages.
- -pathogens do not like higher heat.
- -heat makes cells more aware