Defense Mechanisms  Three lines of defense protect the body against foreign invasion: Physical or surface barriers Inflammation Immune response Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.2

Inflammation  Non-specific cellular and vascular reaction to tissue  Repels and destroys invader; cleans up debris to promote healing  Requires blood supply Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.3

Inflammatory Process  Signs and symptoms: Redness Heat Edema Pain Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.4

Chronic Inflammation  Last two weeks or longer  Acute inflammation lasts less than 10 days Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.5

Inflammatory Exudates  Appearance and amount of exudate (blood fluid) reveals acute or chronic condition  Serous exudate is clear serum-like fluid Acute state of inflammation Skin blisters and cold sores Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.6

Inflammatory Exudates  Fibrinous exudate Indicates larger injury with severe inflammation Commonly called scab Strep throat or bacterial pneumonia forming a mesh-like lesion Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.7

Inflammatory Exudates  Purulent exudate called “pus”  Collection of pus is an abscess  Accumulation of pus in body cavity is empyema Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.8

Inflammatory Lesions  Due to physical or pathologic injury  Inflammatory lesions include: Abscesses Ulcers Cellulitis Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.9

Tissue Repair and Healing  Ongoing process  Tissue repair: Regeneration Fibrous connective tissue repair Scar formation Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.10

Tissue Repair and Healing  Regeneration leads to normal function  Fibrous connective tissue repair does not Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.11

Tissue Healing  Primary Union (First Intention) Involves approximating edges of wound Steps of primary healing: ○ Forms scab ○ 1 to 2 days, new capillaries begin to bridge gap between wound edges Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.12

Tissue Healing  Primary Union (First Intention) Steps of primary healing: ○ Fibroblast grows across deeper wound layers forming granulation tissue ○ Scar forms ○ Example of primary healing is surgical incision Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.13

Tissue Healing  Secondary Union (Secondary Intention) Larger, deeper wounds with more inflammation than primary union Need more capillaries, fibroblasts, and collagen Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.14

Tissue Healing  Secondary Union (Secondary Intention) After a week, new soft red tissue called granulation tissue is produced Scar tissue is formed Healing time is dependent on size of wound Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.15

Delayed Wound Healing  Debridement (washing or cutting away necrotic tissue and foreign material) may be necessary Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.16

Delayed Wound Healing  Factors affecting healing time: Age Size of wound Location Nutrition Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.17

Delayed Wound Healing  Factors affecting healing time: Circulation Organism virulence Steroids Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.18

Complications of Wound Healing  Poor or excessive scar formation  Dehiscence - separation of tissue margins  Keloid - hard, raised scar  Adhesions - fibrous bands of tissue that attach to surfaces of adjacent organs as scar tissue develops Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.19

Infection  Invasion of microorganisms causing cell or tissue injury  Pathogenic - microorganisms causing disease  Opportunistic - normal flora become pathogenic under certain conditions Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.20

Infection  Conditions for flora to become pathogenic Microorganisms gain access to body through portal of entry Pathogen is resistant to defenses of host Number of invading microorganisms Condition of individual or host Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.21

Frequency and Type of Infection  Infectious diseases leading cause of death in the world  Identifying and tracking infectious diseases is crucial Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.22

Frequency and Type of Infection  CDC - Centers for Disease Control and Prevention provide these services in the United States Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.23

Frequency and Types of Infection  Bacteria Primary or secondary disease Staphylococcus is bacterium on skin Streptococcus live on skin and in throat Escherichia coli, Kelbsiella, Pseudomonas, Shigella, and Salmonella are common enteric bacteria Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.24

Frequency and Types of Infection  Viruses Smallest infective organism Must be visualized by electron microscope Cannot reproduce or live outside cell Viral infections are not easily treated Antibiotics do not kill a virus but help prevent secondary infections Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.25

Frequency and Types of Infections  Viruses Immunizations are effective in preventing many viral diseases such as measles, mumps, rubella, and smallpox Latent viruses lay dormant in cells and replicate and cause symptoms during times of stress Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.26

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 © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.27

Frequency and Types of Infections  Fungi Treated with antibiotics and antifungal medications Often difficult to cure May require long-term therapy Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.28

Frequency and Types of Infections  Rickettsiae Microscopic organisms that are intermediate between bacteria and viruses Must live in host cell like a virus Spread by fleas, ticks, mites, and lice Most common infection: Rocky Mountain Spotted Fever Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.29

Frequency and Types of Infections  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 is most common disease Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.30

Frequency and Types of Infections  Helminths Roundworms or flatworms Pinworms and tapeworms are most common Pinworms cause anal itching Tapeworms cause intestinal disease due to inadequately cooked meat Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.31