Chapter 34 Part 1

Chapter 34 Part 1

Immunologic Disorders

Anatomic Structures and Components

-Bone marrow--spongy center of the bones where the white blood cells (WBCs) are made.

-Stem cells: cells with the potential to develop into many different types of cells in the body

-White blood cells (leukocytes)--Early in life certain WBCs, called lymphocytes, migrate from the bone marrow where they are produced to the thymus where they mature into T lymphocytes, or T cells.

-Cytokines: Cytokines are hormones secreted by cells to signal other cells.

Anatomic Structures and Components

˜Eicosanoids-class of fatty acids that regulate blood vessel vasodilation, temperature elevation, WBC activation, and other physiologic processes involved in immunity.

--Thymus

--Lymph, lymphatics, and lymph nodes

--Liver

--Spleen

Physiologic Functions:

Innate Immunity

˜Operational at all times, whether or not a pathogen is present

˜Are immediately functional at birth

˜Include anatomic and physiologic barriers, inflammatory response, and the ability of certain cells to phagocytose foreign invaders

Physiologic Functions: Barriers

˜Skin and mucous membranes: a protective covering; secretes substances that inhibit pathogen growth

-Sweat glands secrete lysozyme, antimicrobial enzyme

-Acidic gastrointestinal (GI) and genitourinary (GU) systems inhibit growth of pathogenic organisms

Physiologic Functions: Barriers

-Secretions from the respiratory and gastrointestinal tracts contain the antibody IgA, as well as phagocytes

-Surfaces colonized by normal bacterial flora; prevents pathogens from attaching/gaining access to the body

-Coughing and sneezing, peristalsis in the GI tract, emptying the bladder, and sloughing of dead skin cells: remove microorganisms from the body, thus preventing their invasion and overgrowth

Physiologic Functions: Inflammation

˜Body initially responds to an injury or infection by dilating the capillary bed and increasing the capillary permeability of the affected area

˜Brings white blood cells to the site; allows them to enter the tissue to attack microorganisms

˜This multistep process is called inflammation and is recognized by rubor (redness), tumor (swelling), calor (heat), and dolor (pain) at the site of injury or infection

Physiologic Functions: Phagocytosis

˜The process of ingesting and digesting invading pathogens, dead cells, and cellular debris

Physiologic Functions:

Acquired Immunity

˜Specific to particular pathogen: activated only when needed

˜Antibody-mediated

--Initiated when IgM immunoglobulins on B lymphocytes detect a foreign antigen

--Active: person synthesizes own antibodies in response to pathogen

--Passive: antibody produced by person or animal is transferred to another person

Physiologic Functions: Acquired Immunity (cont.)

˜Cell-mediated

--Aimed at intracellular defects caused by viruses and cancer

--Responsible for delayed hypersensitivity reactions and rejection of transplanted tissue

Physiologic Functions: Tolerance

˜Immune system must recognize its own proteins

˜Autoimmune diseases occur when there is a breakdown of tolerance; immune system identifies its own proteins as foreign and mounts a response to destroy these self-proteins

˜Examples: idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), acute rheumatic fever, type 1 diabetes mellitus, systemic lupus erythematosus, rheumatoid arthritis, Graves’ disease, and Hashimoto’s thyroiditis

Age-Related Changes

˜Bone marrow becomes less productive

˜Lymphatic tissue shrinks, resulting in fewer and smaller lymph nodes

˜Immunologic function not affected unless a person is unusually stressed by trauma, a chronic infection, or treatment for cancer

Multiple Choice

Which of the following is a true statement?

• A.Lymphocytes are produced in the thymus.

• A.Mature T lymphocytes are released into circulation after they have matured.

• A.The thymus continues to grow until age 50.

• A.The thymus is a lymphoid organ located above the spleen.

Multiple Choice

Which of the following statements are true about white blood cells?

• A.When neutrophils enter tissue, they are called macrophages.

• A.Macrophages can ingest many foreign antigens and survive months to years.

• A.Monocytes combat parasitic infections.

• A.Eosinophils can initiate a massive inflammatory response that quickly brings other white blood cells to the site of infection.

Multiple Choice

When there is a breakdown of tolerance, what types of diseases occur?

• autoimmune

• viral

• bacterial

• cancer

Multiple Choice

The body's first line of defense is:

• inflammation

• phagocytosis

• antibodies and antigens

• skin and mucous membranes

Multiple Choice

The body's defense network against infection is the:

• cardiovascular system

• respiratory system

• immune system

• circulatory system