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FertileNaïveArt45

Uploaded by FertileNaïveArt45

School of Nursing

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microbiology host-microbe interactions infectious diseases immunology

Summary

This document provides an overview of host-microbe interactions, covering topics such as why we don't get sick all the time, the role of the immune system, different types of infectious disease, and the stages of infectious disease. It features diagrams and explanations of various concepts related to the subject.

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Host microbe interactions Why don’t we get sick all the time? The immune system protect us from infections Non-specific and specific host defences Host Defences – or why we don’t get sick all the time! Host Defences – or why we don’t get sick all the time! Clostridium tetani from nail i...

Host microbe interactions Why don’t we get sick all the time? The immune system protect us from infections Non-specific and specific host defences Host Defences – or why we don’t get sick all the time! Host Defences – or why we don’t get sick all the time! Clostridium tetani from nail infect foot -> produce exotoxin (tetanus toxin) Host Defences – or why we don’t get sick all the time! Host Defences – or why we don’t get sick all the time! Nothing happens! IMMUNE! Host Defences – or why we don’t get sick all the time! IMMUNE RESPONSE Is ill, but then recovers: and is now IMMUNE Host Defences – or why we don’t get sick all the time! Immune response not effective enough…….. INTERVENTION: GIVE TETANUS ANTI- TOXIN to counteract tetanus toxin Host Defences – how do they work? Overview of Nonspecific Host Defences: ◼ What is the difference between Nonspecific and Specific Host Defences? ◼ Nonspecific Defences (INNATE DEFENCES) lack specificity! -1st line of defence -are rapid ◼ Specific Defences (ADAPTIVE DEFENCES) respond to specific invaders! -take longer to respond (2nd line of defence!) -have “memory” Immunological memory is defined as the ability of immune cells to specifically ‘remember’ the first encounter with a given antigen and to mount a secondary response that is faster and greater in magnitude than the primary response. Physical (Anatomical) Defences ◼ The skin – Physical barrier Fig. 19-1 The skin forms a physical barrier to infection Physical (Anatomical) Defences ◼ The Mucous Membranes ◼ Provide physical defence for the respiratory, digestive, and urogenital systems Fig. 19-2 Mucous Membranes also ◼ Mucous forms a physical barrier to infection Physical (Anatomical) Defences ◼ Flushing actions: urine, sweat, tears, saliva ◼ Respiratory Tract -Cilia Fig. 19-3 Defences at the eye -Coughing & Sneezing Biochemical Defence Tactics ◼ At the skin: -low pH, high salt -sebum: -lower pH -fatty acids -sweat: -lower pH -lysozyme (sweat, Fig. 19-1 The skin also has some other tears, saliva) strategies to prevent infection! -cleaves NAM-NAG linkages Biochemical Defence Tactics ◼ At the Gastrointestinal Tract: -Gastric acid → low pH ◼ In the blood: -Transferrins (iron- binding proteins) Fig. 22-11: The stomach has strategies too Our “Normal Microflora” ◼ How do they help???? ◼ Competition for Space! ◼ competition for nutrients ◼ Antagonism – bacteriocins Figure 14-3: locations of resident normal microflora in the human body Specific immunity_ antibodies Terminology you should know Reading Host Microbe Relationships continued….. Infectious disease terminology Stages of Infectious disease infectious disease terminology: a starter! ◼ Infectious Disease vs noninfectious disease! ◼ Infectious Disease: caused by infectious agents ◼ Noninfectious Diseases: caused by anything else! Communicable vs noncommunicable infectious disease ◼ Communicable Infectious Diseases: can be spread from one host to another – Contagious: easily spread between hosts – Ex) chickenpox ◼ Noncommunicable Infectious Diseases: are not spread from one host to another! – Alternate routes: – Ex) botulism: ingestion of botulism toxin made by Clostridium botulinum – Tooth decay, acne, tetanus Signs, symptoms, & sequelae ◼ Signs: -characteristics of a disease that can be observed by examining a patient ◼ Symptoms: -disease characteristics felt only by the patient ◼ Sequelae: -after effects, present after recovery Types of infectious disease: Acute, Chronic, Subacute & Latent: ◼ Acute: rapid! -rapid development; over quickly ex) colds! ◼ Chronic: slow development, persists over long time period ex) tuberculosis, leprosy ◼ Subacute: inbetween! ex) gingivitis ◼ Latent: periods of inactivity (before and/or between attacks) ex) herpes simplex virus (HSV) Types of infectious disease: Local vs Systemic Infections ◼ Local Infection: -limited to a small area of the body ex) boils, bladder infection ◼ Systemic infection: -widely distributed through the body ex) measles, typhoid fever Types of infectious disease Primary vs secondary infections ◼ Primary infection: ◼ Superinfection: -initial infection -secondary infection ◼ Secondary due to destruction infection: of normal -follows primary microflora infection --can be ◼ Subclinical opportunistic; Infection: -few (or no) signs & symptoms Stages of infectious disease ◼ Incubation period: infected, but no signs or symptoms Figure 14.9 Stages of infectious disease: ◼ Incubation periods: vary between different microbes Figure 14.10 Incubation periods of selected infectious diseases Stages of infectious disease ◼ Incubation period ◼ Prodromal phase: initial symptoms ◼ Invasive phase: intense illness Acme = highest intensity ◼ Decline phase: subsiding signs & symptoms Figure 14.9 ◼ Convalescence period: recovery Stages of infectious disease ◼ Incubation period ◼ Prodromal phase: initial symptoms ◼ Invasive phase: intense illness Acme = highest intensity ◼ Decline phase: subsiding signs & symptoms Figure 14.9 ◼ Convalescence period: recovery

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