MMG Nonspecific Lines of Defense

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What is the first line of defense in the body?: -skin and mucous membranes or respiratory, digestive, urinary, and reproductive systems
What are the second line of defense in the body?: -phagocytosis, complement, interferon, inflammation, fever
What is the third line of defense in the body?: -lymphocytes, antibodies
How are microbes removed from the skin?: -everytime movement occurs, thousands of dead skin cells are removed along with microorganisms
What cells can phagocytize pathogens on the epidermis?: -Langerhans cells (dendritic cells)
What is collagen for?: -found in the dermis
-gives skin strength and pliability to resist abrasions that could introduce microorganisms
How do the sweat glands play a role in nonspecific cases?: -perspiration released
-salt inhibits growth of pathogen by drawing water from their cells
-lysozyme destroys cell wall of bacteria
How do the oil glands play a role in nonspecific cases?: -sebum secreted by sebaceous (iol) glands
-helps keep skin pliable and less likely to break or tear
-lowers the pH of the skin to a level inhibitory to many bacteria
What is microbial antagonism?: -competing of normal flora with potential pathogens making it difficult for them to prosper
What are some various activities of normal flora that interupts pathogens?: -secrete antimicrobial substances limiting pathogen growth
-consumption of nutrients
-changes environment pH
-helps stimulate body's second line of defense
-promote overall health by providing vitamins to host
Where are some body areas that produce antimicrobial secretions?: -stomach acid
-bile
-urine
-saliva
How is the eye protected?: -lacrimal glands secrete tears that bathe the eye
What are involved in blood defenses?: -cells (phagocytosis)
-antimicrobial chemicals (interferons)
-processes (inflammation, fever)
Does plasma or serum contain clotting proteins?: -plasma (serum is liquid only)
What cells exist in blood?: -formed elements: erythrocytes, platelets, and leukocytes
What are two types of macrophages?: -wandering macrophages
-fixed macrophages
What are wandering macrophages?: -leave the blood via diapedesis and phagocytize throughout the body
What are fixed macrophages?: -do not move throughout the body and often phagocytize within a specific organ
*Langerhans cells, alveolar macrophages, microglia, Kupffer cells
What is included in the reticuloendothelial system?: -all macrophages, plus monocytes attached to endothelial cells
*AKA mononuclear phagocytic system
What are components of "innate immunity"?: -phagocytosis
-extracellular killing by leukocytes (complement and interferons)
-inflammation
-fever
What are the five stages of phagocytosis?: 1) chemotaxis of phagocyte to microbe
2) adherence
3) ingestion of microbe by phagocytes
4) digestion of microbe by enzymes
5) elimination (exocytosis)
What blood cells are involved in extracellular killing?: -eosinophils
-natural killer lymphocytes
Describe eosinophils.: -mainly attack parasitic helminths (worms) by attaching to their surface
-secrete toxins that weaken or kill the helminth
-high levels indicative of helminth infection
Describe Natural killer cells.: -secrete toxins onto surface of virally infected cells and tumors
-differentiate normal body cells because of similar membrane proteins to NK cells
What are two ways to activate the complement system?: -classical pathway; augments antibodies
-alternate pathway; before antibodies are made
What happens during complement activation?: -forms membrane attack complex (MAC), which forms holes in membranes leading to lysis of pathogen
What makes up the complement system?: -serum proteins
-numbered acording to their discovery
What are the three end results of the complement cascade?: -opsonization
-inflammation
-membrane attack complex and cell lysis
What are the steps of the complement system (not last step though)?: 1) C1 activates when binding to antibody-antigen complexes
2) enzyme C1 splits C2 and C4
3) C2 and C4 fragments combine forming enzyme which splits C3 into C3a and C3b
4) C3b combines with remaining C2 and C4 to form another enzyme that cleaves C5 into C5a and C5b
What is the last step of the complement system?: 5) C5b combines with C6, C7, and several C9 molecules to form a MAC. This drills circular holes in the pathogens cytoplasmic membrane leading to hypotonic lysis of cell
What does C3a do?: -causes chemotoxis and inflammation
What does C3b do (besides combining with other fragments)?: -acts as opsonin
What does C5a do?: -causes chemotaxis and inflammation
What are interferons?: -protein molecules released by host cells to nonspecifically inhibit the spread of viral infections, particularly viruses with RNA genomes
What are the three types of interferons?: IFN-alpha
IFN-beta
IFN-gamma (y)
When are IFN-y present?: -appears later in the course of infection
When are IFN-a and IFN-B present?: -present early in the infection
What is interferon therapy?: -it was thought that this might be a good antiviral treatment
What is the problem with the interferon therapy?: -many viral infections don't respond to interferon therapy at all
-only a slight effect is seen with those viral infections that do respond
Describe how interferons work.: -virus infects cell
-cell produces interferon to neighboring cells and bind to receptors which triggers AVP
-AVP remains inactive in neighboring cell, but activates when double-stranded RNA enters and then attacks the RNA
*original cell dead, but saved second cell
What are the characteristics of inflammation?: -redness
-heat
-swelling
-pain
What is the effect of acute inflammation?: -beneficial and short-lived
-dilation and increased permeability of blood vessel
-migration of phagocytes
What is the effect of chronic inflammation?: -develops slowly and lasts a long time
-can cause damage to tissues
How does inflammation occur (list up to blood clot)?: -cut/injury
-damaged cells release histamine, protstaglandins, and leukotrienes
-vessels more permeable, histidine causes vasodilation
-macrophages and neutrophils squeeze through wall
-blood clot forms
Once a blood clot forms during inflammation, what happens next?: -more phagocytes migrate to site
-accumulation of damaged tissue forms pus
-undifferentiated stem cells repair damaged tissue
-blood clot absorbed or falls off as scab
What does increased permeability do during inflammation?: -allows antimicrobial chemicals and clottin gproteins to seep into damaged tissue but also results in swelling, pressure on nerve endings, and pain
What are pyrogens?: -chemicals that trigger hypothalamus to increase the body's core temperature over 37 degrees
What are the different types of pyrogens?: -bacterial toxins
-antibody-antigen complexes
-Interleukin-I (IL-1)
What are the benefits of fever?: -enhances effects of interferons
-inhibits growth of some microorganims
-may enhance performance of pahocytes, cells of specific immunity, and the process of tissue repair
What does IL-1 cause?: -causes hypothalamus to secrete prostaglandins that reset the hypothalamic "thermostat"
How does IL-1 work?: -travels to hypothalamus
-hypo secretes prostaglandin which resets hypothalamic thermostat
-nerve impulses cause shivering, high met rate, sweating inhib, and vasocon.
-increased body temp to point set by hypothalamic thermostat
What are chills associated to fever due to?: -reduced blood flow of constricted vessels
What does a decrease in IL-1 cuase?: -return of normal temperature of body

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