Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Chapter 4 Inflammation and Infection

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Defense Mechanisms Three lines of defense protect body against foreign invasion: –Physical or surface barriers –Inflammation –Immune response

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammation Non-specific cellular and vascular reaction to tissue Repels and destroys invader –Cleans up debris to promote healing Requires blood supply

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammatory Process Signs and symptoms: –Redness –Heat –Edema –Pain

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Types of Inflammation Acute –Lasts less than 10 days Chronic –Lasts two weeks or longer

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammatory Exudates Appearance and amount of exudate (blood fluid) reveals acute or chronic condition Serous exudate –Clear, serum-like fluid –Acute state of inflammation –E.g., skin blisters, cold sores

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammatory Exudates Fibrinous exudate –Indicates larger injury with severe inflammation –Also known as scab –E.g., strep throat, bacterial pneumonia forming mesh-like lesion

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammatory Exudates Purulent exudate –Pus Abscess –Collection of pus Empyema –Accumulation of pus in body cavity

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Inflammatory Lesions Due to physical or pathologic injury Inflammatory lesions include: –Abscesses –Ulcers –Cellulitis

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tissue Repair and Healing Ongoing process Tissue repair: –Regeneration Leads to normal function –Fibrous connective tissue repair Does not lead to normal function –Scar formation

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tissue Healing Primary union (first intention) –Involves approximating edges of wound –Steps of primary healing: Forms scab After one to two days, new capillaries begin to bridge gap between wound edges

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tissue Healing Primary union (first intention) –Steps of primary healing: Fibroblast grows across deeper wound layers –Forming granulation tissue Scar forms E.g., surgical incision

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tissue Healing Secondary union (secondary intention) –Involves larger, deeper wounds with more inflammation than primary union –Needs more capillaries, fibroblasts, and collagen

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tissue Healing Secondary union (secondary intention) –Steps of secondary healing: After one week, new soft red tissue produced –Granulation tissue Scar tissue formed Healing time dependent on size of wound

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Animation Click Here to Play Tissue Repair Animation

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Delayed Wound Healing Debridement –May be necessary to wash or cut away necrotic tissue and foreign material Factors affecting healing time: –Age –Size of wound

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Delayed Wound Healing Factors affecting healing time: –Location –Nutrition –Circulation –Organism virulence –Steroids

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Complications of Wound Healing Poor or excessive scar formation Dehiscence –Separation of tissue margins

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Complications of Wound Healing Keloid –Hard, raised scar Adhesions –Fibrous bands of tissue that attach to surfaces of adjacent organs as scar tissue develops

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Keloid Photo courtesy Mark L. Kuss

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Infection Invasion of microorganisms causing cell or tissue injury Pathogenic –Microorganisms causing disease Opportunistic –Normal flora become pathogenic under certain conditions

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Infection Conditions for flora to become pathogenic: –Microorganisms gain access to body through portal of entry –Pathogen resistant to defenses of host –High number of invading microorganisms –Vulnerable condition of individual or host

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Infectious diseases –Leading cause of death worldwide –Crucial to identify and track Centers for Disease Control and Prevention (CDC) provide these services in United States

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Bacteria –Primary or secondary disease –Staphylococcus Bacterium on skin –Streptococcus Bacterium that live on skin and in throat

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Bacteria –Common enteric bacteria: Escherichia coli (E. coli), klebsiella, pseudomonas, shigella, and salmonella

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Viruses –Smallest infective organism Must be visualized by electron microscope –Cannot reproduce or live outside cell –Not easily treated –Not killed by antibiotics But antibiotics help prevent secondary infections

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Viruses –Immunizations effective in preventing E.g., measles, mumps, rubella, smallpox –Latent viruses lay dormant in cells and replicate Causing symptoms during times of stress

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Fungi –Microscopic plant-like organisms larger than bacteria –Only few are pathogenic –Types of infections: Tinea –Skin Candida –Superficial infection of skin and mucous membranes

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Fungi –Treated with antibiotics and antifungal medications –Often difficult to cure –May require long-term therapy

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Rickettsiae –Microscopic organisms that are intermediate between bacteria and viruses –Must live in host cell Like virus –Spread by fleas, ticks, mites, and lice –Rocky Mountain spotted fever Most common

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Protozoa –Single-celled microscopic organisms –Found in soil Live on dead or decaying material –Infection through bite of infected insect or ingestion of spores –Malaria Most common

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Frequency and Types of Infection Helminths –Roundworms or flatworms –Pinworms and tapeworms Most common Pinworms cause anal itching Tapeworms cause intestinal disease due to inadequately cooked meat

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Testing for Infection Blood Culture and sensitivity Skin