Lymphatic System and Immunity Chapter 16

The lymphatic system is closely associated with the cardiovascular system It includes a network of vessels that circulate body fluids

Figure 16.5 page 427 Lymphatic Capillaries Microscopic, closed- ended tubes that assist in the transport of fluids

Lymph The fluid inside a lymphatic capillary

Lymphatic Vessels Formed by the merging of lymphatic capillaries They have valves that help prevent backflow of lymph

Lymph Nodes Formed by the merging of lymphatic vessels Lymphatic Trunk Drain lymph

Collecting & Thoracic Ducts Receive and get rid of lymph ******************

TISSUE FLUID & LYMPH Tissue fluid originates from blood plasma and is composed of water and dissolved substances

FUNCTION OF LYMPH *Carries protein molecules that leak out of the blood capillaries, back to the bloodstream

*Transports foreign particles (bacterial cells & viruses) that may have entered the tissue fluids, to the lymph nodes ******************

LYMPH NODES Lymphocyte A type of white blood cell that is important to immunity

Hilum The indented region of a lymph node through which the blood vessels and nerves connect with the structure

Nodule Dense mass of lymphocytes

Lymph Sinuses Spaces within the node through which lymph circulates ******************

THYMUS & SPLEEN Thymus A glandular organ located in the mediastinum behind the sternum and between the lungs

It secretes a hormone called thymosin which is thought to stimulate the maturation of certain T lymphocytes

Spleen A large, glandular organ located in the upper left region of the abdomen ******************

BODY DEFENSES AGAINST INFECTION Infection Invasion of microorganisms into the tissue; leads to inflammation

Pathogens Agents that cause disease Immunity The condition that permits natural or acquired resistance to disease

NONSPECIFIC IMMUNITY Species Resistance Mechanical Barriers Against the entrance of infectious agents: skin, mucous membranes

Chemical Barriers Also prevent the entrance of disease: enzymes in various body fluids (tears, stomach acid)

Inflammation A response that occurs in the blood vessels and tissues in response to an injury or irritation (White blood cells group here)

SPECIFIC TYPES OF IMMUNITY Naturally acquired active immunity occurs when a person who has been exposed to a live pathogen…

…develops a disease and becomes resistant to that pathogen as a result of a primary immune response

Vaccine A substance that contains antigens and is used to stimulate the production of antibodies

Vaccines usually contain bacteria or viruses that have been killed or weakened so they cannot cause serious infection

This is considered Artificially acquired active immunity

ALLERGIC REACTIONS Involve antigens combining with antibodies

Likely to be excessive or violent and may cause tissue damage A delayed-reaction allergy results from repeated exposure to antigenic substances

Allergen A foreign substance capable of stimulating an allergic reaction

Allergic reactions may damage certain cells, which, in turn, release various chemicals

The released chemicals can cause hives, hay fever, asthma, eczema, or gastric disturbances

TRANSPLANTATION & TISSUE REJECTION If transplanted tissue is recognized/matched it will be accepted by the recipient’s cells ***********************

If the recipient’s cells see the tissue as foreign, the tissue will act against it and reject it