Chapter 16 Innate Immunity: Nonspecific Defenses of the Host

Transcription

1 Module 10 Chapter 16 Innate Immunity: Nonspecific Defenses of the Host The concept of immunity Immunity: ability to protect against from microbes and their o Aka, Susceptibility: vulnerability or lack of Two general mechanisms of immunity o immunity: defenses against o immunity: immunity or resistance to a Adaptive Immunity o Involve recognition of o to respond than innate immunity o Has component o Involves Innate Immunity o present and available o Does not involve of a microbe o Acts against in the way o of defense include physical barriers Skin, mucous membranes o Early warning system to prevent FIRST LINE OF DEFENSE: Skin and mucous membranes Physical factors Skin Top layer is dead, continually No space in between skin cells, microbes can t of skin inhibits most growth o In conditions, skin infections common Keratin: protective in skin Most infections of skin are below the skin Mucous membranes Inhibit of many microbes Mucus: slightly fluid composed of o invading microbes o Some pathogens can in mucus Lacrimal apparatus, saliva, urine, secretions o Continual helps wash away microbes Ciliary Escalator Cilia in respiratory tract microbes up and speed up process

2 Defecation and vomiting microbes FIRST LINE OF DEFENSE: Chemical Factors Sebum substance in skin produced by in skin Forms film over skin Contains acids the growth of some Lower Some bacteria can sebum à Lysozyme that breaks down cell wall Found in, tears,, and tissue fluids Low ph Skin ( ) Gastric Juice ( ) Vaginal Secretions ( ) Normal Microbiota Normal microbiota protect via Normal microbiota with pathogens for SECOND LINE OF DEFENSE If microbes first layer, begins Second line of defense to invasion include defensive cells, inflammation, fever, antimicrobial substances Formed elements in blood Formed elements: in blood o Leukocytes: (WBC) Different WBC, Types of white blood cells Neutrophils o Highly against o Active in stages of infection o Can leave bloodstream and move into to fight infection Basophils o Release, important in Eosinophils o Produce toxins against, such as helminths o Can, move into tissue

3 Dendritic cells o Destroy microbes by o Activate immune response Monocytes o Not phagocytic in o Can move into tissue, mature into Highly phagocytic Lymphocytes o Natural killer (NK) cells Kill cells, cells Any cell that displays plasma membrane proteins o T cells, B cells o Play central role in Diiferential White Blood Cell Count of each type of in a sample Leukocytosis: increase in o Can double, triple, quadruple Leukopenia: in WBC count o Due to impairment of white blood cell, Differential white blood cell count can help type of or Phagocytosis Phago: from Greek, meaning Cyte: from Greek, meaning Ingestion of or particles by a : cells that perform phagocytosis o,, dendritic cells During infection, and migrate to infected area increase in initial stages of infection dominate in initial stages of bacterial infection o bacteria As infection progresses, dominate o Clear up cell In and infections, macrophages always dominate Mechanism of phagocytosis Chemotaxis: chemical of phagocytes to microbes o Attracted to microbial products, damaged tissue cells, various chemicals Adherence: of phagocyte to microbe Ingestion: of microbe o Projections called o Microbe internalized in vesicle called

4 Digestion: of microbe o Phagosome fuses with lysosome à, destroys microbe o material expelled from cell Microbial evasion of phagocytosis Inhibit Kill phagocytes phagosome Prevent fusion Survive inside Inflammation response to infection Characterized by, pain,,swelling Acute inflammation:, intense o Cause of inflammation removed Chronic inflammation: lasting, less intense o Cause of inflammation Functions: o To the injurious agent o To limit the effects on body by injurious agent o or replace damaged tissue Stages of inflammation Vasodilation and increased permeability of blood vessels Vasodilation: (increase in diameter) of blood vessels o Increases to area o Responsible for (redness), Vasodilation also results in increased o Allows, chemicals to pass from to injured area o Responsible for (swelling) Phagocyte migration and phagocytosis Blood flow eventually brings to site of infection o invading microorganisms In response to bacteria, neutrophils first, followed by monocytes often die after killing many cells; contribute to release from cells, results in vasodilation, permeability Blood clots around injury prevents Localized collection of pus called an Tissue repair Replacement of or cells Speed of repair depends on tissue o Skin heals fast, cardiac (heart) muscle heals slow

5 Fever temperature response to infection Most commonly caused by, infections Certain chemicals trigger a of body thermostat to a higher body temperature o LPS Chill: response to body temperature Crisis: response to body temperature Fever is up to certain degree o Helps increase production, repair Complications include: o : rapid heart rate, may compromise weak hearted o Increased o in young children o Delirium o Coma o C ( F) = death Antimicrobial substances Complement system: defensive system consisting of in blood Destroy microbes by: o ( ) of bacteria o Triggering o Helping with Evading complement system Some capsules prevent complement Some gram- negative bacteria can lengthen surface glycolipids to prevent o - resistant Some gram- positive cocci release that complement proteins Interferons produced by cells that with viral Effective against many different types of viruses Protect cells by causing them to produce (AVP) o that inhibit of viral particles Effective for are toxic to heart, liver, kidneys, bone marrow Antimicrobial peptides Newly discovered, may be most important component of immunity Small à amino acids Bind to causing cell lysis Produced by,