HAP lymphatic System

Flashcards on Lymphatic System and Immunity

Lymphatic System

-A second circulatory system

-collects and carries away excess tissue fluid from interstitial spaces, returning it to the blood

- Contains lymphocytes, which help defend the body against disease.

Lymphatic Capillaries

• Tiny, closed-ended tubular vessels

• extend into interstitial spaces, paralleling blood capillaries.

• They receive tissue fluid (lymph) through their thin walls and slits between cells

• are found all over the body except in the central nervous system.

Lymph

Tissue fluid that has entered a lymphatic capillary.

Lymphatic Trunks

Lymphatic trunks drain lymph from lymphatic vessels for the regions they drain into the thoracic or right lymphatic duct.

Collecting Ducts

Either the thoracic or right lymphatic duct which trunks empty into: the right lymphatic duct drains the right side of the head and neck, right arm, and right thorax, and empties into the right subclavian vein, while the thoracic duct drains the rest of the body and empties into the left subclavian vein.

Lymph Nodes

Bean-shaped structures located in groups or chains along lymphatic vessels, containing lymphocytes and macrophages that filter lymph as it flows through.

Thymus

Soft, bi-lobed organ located behind the sternum, anterior to the aorta. It shrinks in size during the lifetime and contains lymphocytes that mature into T cells to provide immunity. It also secretes thymosins, which influence the maturation of T lymphocytes.

Spleen

The largest lymphatic organ in the body, located in the upper left abdominal cavity, and filters the blood to remove damaged blood cells and bacteria.

Pathogens

Disease-causing agents such as bacteria, viruses, fungi, or protozoans.

Innate (nonspecific) defenses

Defense mechanisms that guard against many types of pathogens and respond quickly:

Innate (nonspecific) defenses

Includes species resistance, mechanical barriers, chemical barriers, natural killer cells, inflammation, phagocytosis, and fever.

Adaptive (specific) defenses or immunity

Defenses respond against only a specific type of pathogen and respond more slowly, accomplished by specialized lymphocytes that secrete cytokines or antibodies.

Species Resistance

A species' inherent ability to resist diseases that affect other species due to factors like different chemical environments, incompatible body temperatures, or the absence of necessary receptors.

Mechanical Barriers

Barriers preventing the entry of certain pathogens by providing a physical separation of pathogens and internal tissues, such as unbroken skin and mucous membranes, representing the body’s first line of defense.

Inflammation

A tissue response to injury or infection characterized by redness, swelling, heat, and pain, with the function of stopping the spread of pathogens and infection.

Chemical Barriers

Chemicals that kill many pathogens, including acidic environments and enzymes like pepsin in the stomach and lysozyme in tears.

Natural Killer (NK) Cells

A small group of lymphocytes, other than T cells and B cells, that defend the body against viruses and cancer and secrete substances that enhance inflammation.

Phagocytosis

Engulfment and digestion of pathogens, foreign particles, and debris by phagocytes such as neutrophils and monocytes, which are attracted to the injured area by chemotaxis.

Fever

Occurs when body temperature is re-set to a higher set point, providing a hostile environment for pathogens and causing the liver and spleen to take up iron, reducing its availability for pathogen growth.

Immunity (adaptive immune defenses)

Response by the body against specific pathogens, their toxins or metabolic products, performed by lymphocytes and macrophages that recognize and remember specific foreign molecules on particular pathogens.

Antigens

Molecules that can evoke an immune response, triggering a response against “nonself” molecules, and include proteins, polysaccharides, glycoproteins, or glycolipids.

Immunoglobulin G (IgG)

Antibodies found in tissue fluid and plasma, defending against bacterial cells, viruses, and toxins, and activating complement.

IgA

Antibodies found in exocrine gland secretions (breast milk, saliva, tears, nasal fluid, gastric and intestinal juices, bile, urine).

IgM

Antibodies found in plasma when food antigens or bacteria are present, activating complement, and containing Anti-A and Anti-B, which react with certain red blood cells during transfusions of mismatched blood.

IgD

Found on the surface of most B lymphocytes, and functions in B cell activation.

IgE

Found on surfaces of basophils and mast cells; associated with allergic reactions

Direct attack by antibodies

Agglutination, precipitation, or neutralization of antigens make antigens more susceptible to phagocytosis.

Activation of Complement (antibody action)

Results in opsonization, chemotaxis, inflammation, agglutination, neutralization, alteration, or lysis of antigens or antigen-bearing cells

Hypersensitivity reactions

The body’s excessive immune responses to a normally harmless antigen, that can lead to tissue damage.

Autoimmune disorders

Immune system manufactures autoantibodies, and cytotoxic T cells, against some of its own antigens.