chapter 10 bacteria and viruses. section 10c-2 defense against infectious disease a. structural...

Chapter 10 Chapter 10 Bacteria and Bacteria and

VirusesViruses

Section 10C-2Section 10C-2Defense against infectious diseaseDefense against infectious disease

A. Structural defense – “First line of A. Structural defense – “First line of defense” keep pathogens out!defense” keep pathogens out!1.1. Skin and mucous membranes lining Skin and mucous membranes lining

respiratory, digestive and urinary tractsrespiratory, digestive and urinary tracts2.2. Mucus traps microbes and disposes of themMucus traps microbes and disposes of them3.3. Stomach acid kills swallowed pathogensStomach acid kills swallowed pathogens4.4. Intestinal flora (good bacteria living in Intestinal flora (good bacteria living in

intestines) competes against bad bacteriaintestines) competes against bad bacteria5.5. Tear glands make lysozyme, which kills Tear glands make lysozyme, which kills

bacteria entering eyesbacteria entering eyes


B. Nonspecific defenses - “Second line of B. Nonspecific defenses - “Second line of defense”defense” Inflammatory response, phagocytic Inflammatory response, phagocytic cells, lymphatic system, fevercells, lymphatic system, fever

– InflammationInflammation – increases blood flow in – increases blood flow in response to chemicals released by infected cellsresponse to chemicals released by infected cells

– PhagocyticPhagocytic cells – white blood cells arrive due cells – white blood cells arrive due to increased blood flow, recognize invaders, to increased blood flow, recognize invaders, form a barrierform a barrier

Pus: fluid, WBC and dead pathogensPus: fluid, WBC and dead pathogens


B. Nonspecific defenses (cont.) B. Nonspecific defenses (cont.) – Lymphatic system Lymphatic system – helps clean body of – helps clean body of

pathogens and toxins, phagocytizes pathogens and toxins, phagocytizes pathogenspathogens

– Fever – Raised body temperature, makes Fever – Raised body temperature, makes environment less favorable for many environment less favorable for many pathogens & accelerates reactions that pathogens & accelerates reactions that activate defenses (if fever is too high, may activate defenses (if fever is too high, may cause damage to body tissues)cause damage to body tissues)


C. Specific defenses – “Third line of C. Specific defenses – “Third line of defense” – immune system (Ch. 22)defense” – immune system (Ch. 22)

– Antibodies – proteins made by specific cells Antibodies – proteins made by specific cells in the blood that combat specific pathogens in the blood that combat specific pathogens or their toxinsor their toxins

– Other special cells with particular duties Other special cells with particular duties have “chemical memory” of pathogenhave “chemical memory” of pathogen


D. Medical control- “chemical warfare”D. Medical control- “chemical warfare”– Chemotherapy Chemotherapy – use of chemical agents to treat or – use of chemical agents to treat or

prevent disease. Meant to injure the pathogen without prevent disease. Meant to injure the pathogen without harming host’s body but may have side effects.harming host’s body but may have side effects.

– Antibiotics: Antibiotics: CChemicals produced by living thingshemicals produced by living things

Work by interfering with enzymes and metabolic pathways that Work by interfering with enzymes and metabolic pathways that bacteria have (& humans don’t have), like cell wall synthesisbacteria have (& humans don’t have), like cell wall synthesis

Are nonspecific (kill many kinds of bacteria), but don’t kill virusAre nonspecific (kill many kinds of bacteria), but don’t kill virus

Types: Types: Bactericidal-Bactericidal- kill bacteria, kill bacteria, Bacteriostatic-Bacteriostatic- inhibit inhibit growth of bacteriagrowth of bacteria

Example: Example: PenicillinPenicillin – The first antibiotic, a mold, discovered – The first antibiotic, a mold, discovered by Sir Alexander Flemming, by Sir Alexander Flemming,

10C-3 Disorders: diseases not 10C-3 Disorders: diseases not caused by a pathogencaused by a pathogen

1.1. Inherited disorders – due to a gene or inherited Inherited disorders – due to a gene or inherited tendency (ex. diabeties)tendency (ex. diabeties)

2.2. Injuries – broken bone, burns, etc.Injuries – broken bone, burns, etc.3.3. Deficiency disease – lack of a vitamin/mineralDeficiency disease – lack of a vitamin/mineral4.4. Chemical poisoning or radiation sickness – due Chemical poisoning or radiation sickness – due

to exposure to environmental factorsto exposure to environmental factors5.5. Other organic disorders like stroke, kidney Other organic disorders like stroke, kidney

stones, etc. caused by unknown or partially stones, etc. caused by unknown or partially understood causesunderstood causes

10C-3 Disorders (cont.)10C-3 Disorders (cont.)

• Benign tumors – abnormal growth of cellsBenign tumors – abnormal growth of cells• Biopsy – take tissue sampleBiopsy – take tissue sample• Pathologist – tissue specialist, analyzes tissue Pathologist – tissue specialist, analyzes tissue

from biopsy to determine benign or malignant from biopsy to determine benign or malignant (benign tumors usually surgically removed)(benign tumors usually surgically removed)

• Cancer – malignant tumor (rapid cell Cancer – malignant tumor (rapid cell growth)growth)• May May metastasize metastasize (separate from parent tumor (separate from parent tumor

and spread to other parts of the body)and spread to other parts of the body)


• CancerCancer1.1. Initiation: 1Initiation: 1stst step to developing cancer, step to developing cancer,

cells become partially cancerous, happens cells become partially cancerous, happens in 1 of 3 waysin 1 of 3 waysA.A. Carcinogenic chemicals – cause cancer Carcinogenic chemicals – cause cancer

(ex. tobacco products)(ex. tobacco products)B.B. Radiation – ultraviolet or x-rays can cause Radiation – ultraviolet or x-rays can cause

(ex. skin cancer)(ex. skin cancer)C.C. Viruses – some viruses linked to some Viruses – some viruses linked to some

cancers (ex. HPV cancers (ex. HPV cervical cancer) cervical cancer)


• CancerCancer2.2. Promotion: once cell has become Promotion: once cell has become

potentially cancerous, diet/general potentially cancerous, diet/general health/genetic makeup help promote health/genetic makeup help promote conversionconversion of initiated cells to cancer of initiated cells to cancer cells (tumor forms)cells (tumor forms)– see p. 292 for steps to reduce cancer risksee p. 292 for steps to reduce cancer risk


• Cancer TreatmentsCancer Treatments1.1. Surgery – leading method, remove cancer cellsSurgery – leading method, remove cancer cells2.2. Radiation – x-rays or radioactive isotope Radiation – x-rays or radioactive isotope

emission to destroy cancer cells, side effects emission to destroy cancer cells, side effects harsh, can cause new tumorsharsh, can cause new tumors

3.3. Chemotherapy – chemicals aimed at Chemotherapy – chemicals aimed at destroying cancer cells, side effects harm other destroying cancer cells, side effects harm other cells in the bodycells in the body

Facet: clinical death – absence of brain waves Facet: clinical death – absence of brain waves for 24-48 hoursfor 24-48 hours

chapter 10 bacteria and viruses. section 10c-2 defense against infectious disease a. structural...

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