Understanding the Body's Defense Mechanisms: Inflammation and Immunity

1. Chapter 13 Inflammation, Infection, and Immunity

2. Skin and Mucous Membranes The body’s first line of defense Protective covering; secretes substances that inhibit the growth of microorganisms Sweat glands secrete lysozyme, an antimicrobial enzyme Sebaceous glands secrete sebum, which has antimicrobial and antifungal properties Acidic secretions from skin and mucosa of GI and GU systems inhibit growth of many pathogenic organisms Secretions from mammary glands and the respiratory and GI tracts contain immunoglobulin; also clean up phagocytes

3. Skin and Mucous Membranes Surfaces colonized by “normal” bacterial flora: prevent pathogens (disease-causing organisms) from entering the body Cilia in respiratory tract, motility of the GI tract, and sloughing of dead skin distribute and remove microorganisms, preventing their overgrowth and invasion

4. Phagocytosis and Inflammation The second line of defense Helps rid body of invading microorganisms White blood cells (leukocytes): colorless cells that are able to phagocytose (ingest) bacteria that can cause infection when they invade the body Measuring the number of these cells indicates severity of infection

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6. The Inflammatory Process A series of cellular changes that signal the body’s response to injury or infection May be caused by Physical agents Excessive sunlight, x-rays Chemical stimuli Insect venom, other chemicals Biologic agents Bacteria, viruses

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8. The Inflammatory Process Inflammation: literally “the fire within” This descriptive phrase illustrates the four classic manifestations of inflammation Rubor (redness) Calor (heat) Tumor (swelling) Dolor (pain)

9. Actions in the Inflammatory Process Hemodynamic changes Dilation of the capillary bed Increases blood flow to the area Warmth and redness at the site of inflammation

10. Actions in the Inflammatory Process Increased capillary permeability Chemical mediators cause leukocytes to line the small blood vessel walls near the inflammatory site Cells pass through the walls; inhabit inflamed area Ingest and carry away bacteria and other foreign substances Permeability of these vessels causes protein-rich fluid to flow through vessel walls into the interstitial space Collection of fluid is responsible for the swelling

11. Chemical Mediators The hemodynamic changes and vascular permeability occur with the help of several chemical mediators Prostaglandins, histamine, and leukotrienes Powerful substances found in various body tissues; liberated during the inflammatory process Cytokines and eicosanoids Cause blood and blood vessel changes

12. Kinin System Produces bradykinin, which also mediates blood vessel dilation and permeability Produces pain, another classic sign of inflammation

13. Complement System Especially important in immunologically mediated reactions involving antigen-antibody complexes Causes massive release of histamine and other substances that produce marked vasodilation, vascular permeability, and smooth muscle contraction These cellular changes produce classic signs of anaphylactic shock: hypotension, swelling, and bronchoconstriction

14. Anti-Inflammation Cortisol Hormone produced by the adrenal cortex Anti-inflammatory substance that slows the release of histamine, stabilizes lysosomal membranes, and prevents the influx of leukocytes Result is to impede the inflammatory process Protects body from excessive or prolonged inflammation Drugs (such as corticosteroids) that mimic cortisol often used to treat inflammatory conditions

15. Signs and Symptoms of Inflammation Local inflammation Produces the classic signs of heat, swelling, redness, and pain, all of which result in loss of function Systemic inflammation Fever, headache, muscle aches, chills, sweating, and leukocytosis

16. Wound Healing Tissue repair and regeneration set in motion from the beginning of the inflammatory process Process speed depends on type of tissue injured, severity of the wound, presence of infection, and health of the host Macrophage cells are produced to clean up inflammatory debris Fibroblasts begin repair process by laying down elastin and collagen at the edges of the wound These substances gradually migrate to the base, forming granulation tissue

17. Wound Healing Epithelial cells migrate over the wound and under the scab (usually formed of dried blood and fibroblasts) The scab falls off Damaged cells are replaced by new cells of their own composition by process of regeneration Some tissue regenerates well, other must undergo repair; may involve replacing injured cells with connective tissue that will eventually create a scar

18. Wound Healing Occasionally wound becomes infected or ulcerated, resulting in tissue loss Granulation tissue and capillary buds form at wound margins; wound eventually filled with granulation tissue Delayed primary closure Sometimes the wound bed is too large for the granulation tissue to fill Wound is cleaned and débrided to enhance healing When infection is no longer present, wound is sutured closed

19. Infection Invasion by microorganisms, multiplication of invading organisms, and resulting tissue damage Inflammation: nonspecific body reaction to tissue injury; infection: a specific process that causes tissue injury Infection always results in inflammation, but inflammation may be caused by other processes Inflammation precedes infection Usually the result of the invasion by organisms Caused by a wide variety of microorganisms

20. Bacteria One-celled microorganisms capable of multiplying rapidly within a susceptible host Classified as gram positive or gram negative Classified according to shape Round bacteria: cocci Groups of two: diplococci Clusters: staphylococci Chains: streptococci Rod-shaped organisms Fusiform (with tapered ends) Spirochetes (spirals)

21. Bacteria Classified according to their ability to grow in the presence of oxygen Aerobes Will grow in the presence of oxygen Anaerobes Will not grow in the presence of oxygen Each classification highlights a characteristic of a microorganism that is considered in the design of an antimicrobial drug to kill or retard the growth of the organism

22. Viruses Very small microorganisms that cause significant morbidity (disease) in humans Illnesses range from the common cold to acquired immunodeficiency syndrome (AIDS); childhood illnesses (measles, chickenpox); and several forms of hepatitis Visible only with electron microscopy Contain strand of genetic material and surrounded by a protein capsule, but have no cell wall Cannot replicate on their own; depend on the resources of the host cell

23. Viruses Damage by stimulating antigen-antibody response in tissues that causes inflammation and cell destruction Because of replication of the virus within the host cell, seldom possible to kill virus without harming the host cell Explains why relatively few antiviral drugs available Current antiviral drugs suppress viral reproduction or growth so that they decrease the severity or duration of the infection, but they are not curative Prevention (immunizations, hygiene) is still the best way to combat viral illness

24. Fungi Vegetable-like organisms that exist by feeding on organic matter Many of these infections are superficial skin infections that rarely produce serious illness Systemic fungal infections caused by Cryptococcus and Aspergillus species; can be life-threatening Patients with compromised immune systems (e.g., HIV) are at especially high risk of acquiring opportunistic fungal infections Fungal infections are called mycoses

25. Protozoa Make up a large group of one-celled organisms Those that produce disease in humans include the Plasmodium species (malaria), Entamoeba histolytica (amoebic dysentery), Giardia lamblia (giardiasis, characterized by diarrhea), and Trypanosomagambiense (sleeping sickness) Infections often spread by food or water contaminated by human or animal feces

26. Rickettsiae Between bacteria and viruses in size Rods, cocci, or pleomorphic (varied) shapes Multiply in cells of animal hosts (e.g., rats and squirrels); transmitted to humans through flea and tick bites Rocky Mountain spotted fever and typhus Diseases caused by rickettsiae tend to be more prevalent in areas in which sanitation is poor and rodent and insect populations are not well controlled

27. Helminths Parasites (worms) are found in soil and water and are generally transmitted from hand to mouth Infections occur commonly in the gastrointestinal tract and may produce mild abdominal pain and bloating, or they may be asymptomatic Examples: pinworms, tapeworms, and hookworms

28. Mycoplasmas Gram-negative, multishaped organisms without cell walls that are responsible for several infections in humans Responsible for primary atypical pneumonia and have been linked to Reiter’s syndrome Infections usually found in the upper respiratory tract and most often affect children and young adults Respond well to erythromycin

29. Transmission of Infection Chain of Infection Infection possible only when factors occur in sequence 1. Causative agent 2. Reservoir 3. Portal of exit 4. Mode of transfer 5. Portal of entry 6. Susceptible host

30. Signs and Symptoms of Infection Localized infections Redness, pain, warmth, swelling, and pus Generalized infections May not show all signs apparent in localized infections Pain may be mild to severe depending on its location Warmth is generally expressed as fever Malaise Anorexia Prostration

31. Types of Infection Community-acquired infection Acquired in day-to-day contact with the public Childhood illnesses, tuberculosis, HIV/AIDS, food-borne illness, sexually transmitted infections Prevention and control Immunizations, educating food handlers, screening and early treatment, isolation of infected person, control vectors, personal measures (condom use, proper hygiene, especially hand washing)

32. Types of Infection Hospital-acquired (nosocomial) infection Occur within a health care facility; may affect patient as well as health care worker Strains of bacteria in hospital usually more virulent and often resistant to antibiotics Some pathogenic bacteria that are no longer susceptible to previously effective antibiotics are found in hospital patients

33. Medical Asepsis Limit spread of microorganisms Often called clean technique Change bed linen, sanitize bedpans, use individual medication cups for each patient and for each administration, frequent hand washing Hand washing Most effective method to prevent cross-contamination Soiled hands main transmission of nosocomial infections

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35. Surgical Asepsis, or Sterile Technique Eliminate microorganisms from any object that comes into contact with the patient Includes care techniques that prevent unsterile surfaces from coming into contact with the patient, such as during dressing changes

36. Standard Precautions Infection control guidelines for hospitals and other health care agencies from Hospital Infection Control Practices Advisory Committee (HICPAC) and CDC For all patients in hospitals regardless of their isolation status Use when you will have contact with a patient’s blood, bodily fluids, secretions (except sweat), excretions, broken skin, and mucous membranes Use when you have contact with materials that are soiled or contaminated with bodily fluids or blood

37. Transmission-Based (Isolation) Precautions Airborne precautions Used with diseases that are spread through the air Droplet precautions Used with infections that are spread by droplets or dust particles containing the infectious agent Contact precautions Used when caring for patients who are infected by microorganisms that are transmitted by direct (skin-to-skin) or indirect contact with contaminated equipment

38. Bioterrorism The intentional use of microorganisms to cause death or disease

39. Immunocompromised Patients Decreased immunity to infection; are at increased risk for bacterial, fungal, parasitic, and viral infections

40. Nursing Care of Patients with Infections Urge the patient to consume adequate fluids Encourage to consume high-protein, high-vitamin diet Isolation, if required Laboratory tests White blood cell count with differential; erythrocyte sedimentation rate; iron level; cultures of urine, blood, wound, sputum, and throat Administer antibiotic drug therapy Hyperbaric oxygen therapy

41. Immunity Provides resistance to invading organisms; enables body to fight off invaders once they have gained access Antigen Any substance capable of stimulating a response from the immune system Usually foreign; body recognizes it because it’s different Antibodies Also known as immunoglobulins Proteins are created in response to specific antigens

42. Immunity Innate (natural) immunity Present at birth; not dependent on a specific immune response or previous contact with an infectious agent Acquired immunity Develops after birth as a result of the body’s natural immune responses to antigens Depends on the proper development and functioning of B and T lymphocytes Developed after direct contact with an antigen through illness or vaccination

43. Immunity Leukocytes (white blood cells) Key role in immune responses to infectious organisms and other antigens Granulocytes and nongranulocytes Thymus and bone marrow Participate in the formation and maturation of immune system cells

44. Immunity Lymph nodes Attack antigens and debris in the interstitial fluid and produce and circulate lymphocytes Spleen Filter dead cells, debris, and foreign molecules from blood Liver Filters blood and plays a part in the production of specific immunoglobulins and other chemicals involved in the immune response

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46. Nonspecific Defenses Against Infection Innate (natural) immunity Present at birth; physical and chemical barriers to invasion of the body as well as substances that protect and repair tissues and stimulate the body to fight off disease Physical and chemical barriers, inflammation, and phagocytosis are nonspecific defenses against infection

47. Specific Defenses Against Infection—The Immune Response Antibody-mediated immunity First-line defense: B lymphocytes and the production of antibodies in response to specific antigens Humoral immune response initiated when an antigen binds to a special receptor on a B lymphocyte Results in antibodies that seek out and “stick to” specific antigens in the body Forms antigen-antibody complexes, which are then targeted for cleanup by neutrophils and macrophages Formation of these complexes activates complement and intensifies T-lymphocyte activity

48. Specific Defenses Against Infection—The Immune Response Cell-mediated immunity A delayed response to injury or infection because of time needed for migration of T cells and production of substances that enhance the immune response and influence the destruction of antigens Fights most viral or bacterial infections and hinders the growth of malignant cells This process also launches an attack on transplanted tissue or organs in the body

49. Immunodeficiency Etiology and risk factors Body unable to launch an adequate immune response and is at great risk for infection Can be congenital or, more commonly, acquired Medical treatment Congenital immunodeficiency treated with replacement therapy of the immune component Acquired immunodeficiency is treated by correcting the underlying condition

50. Immunodeficiency Nursing care Prevent infection Encourage adequate nutritional intake Perform good skin, mouth, perineal, wound, and IV site care; assess for signs of infection Encourage patients to turn, cough, and breathe deeply Protective (compromised host) isolation may be necessary Patient education on risks and signs of infection