Chapter 7- Lymphatic System (Medical Terminology)

Chapter 7 of the Introduction to Medical Terminology Textbook (Second Edition)

Lymph

a colorless or faintly yellow fluid. It leaves the blood capillaries and circulates through a pathway of lymphatic vessels and tissues before returning to the venous circulatory system, or cardiovascular system. Lymph helps remove wastes, toxins, and other harmful substances from the body.

Lymphatic Vessels

include the capillaries and ducts that make up the lymphatic system. Like the veins of the cardiovascular system, lymphatic vessels contain one-way valves that propel lymph in only one direction: away from the body tissues and toward the thoracic cavity

Lymphatic Capillaries

are thin-walled, microscopic tubes that carry lymph to larger vessels and lymphatic tissues throughout the body.

right lymphatic duct

drains lymph from the right arm and the right side of the head and thorax

thoracic duct

situated in the chest, drains lymph from the lower right side and the left side of the body.

lacteals

located in the villi, which are tiny, finger-like projections of the small intestine. The villi enable the small intestine to absorb nutrients from foods and pass these nutrients into the bloodstream. The lacteals remove waste products from the villi and carry these products to the thoracic duct.

Lymph Nodes

small, bean-shaped structures located throughout the body. Lymph nodes filter foreign substances, such as viruses and bacteria, from lymph before lymph is returned to the blood. Lymph nodes also produce lymphocytes.

lymphocytes

cells that perform immune system “surveillance” by detecting and then destroying foreign cells.

tonsils

small masses of lymphatic tissue that form a protective ring in the pharynx (throat) and nasal cavity. protect your body from infection by trapping pathogens that enter through the mouth and nose.

palatine

tonsils on either side of the throat

lingual

tonsils at the base of the tongue

adenoids (pharyngeal)

in the nasopharynx, or the upper part of the throat behind the nose

Thymus

a gland located in the upper mediastinum, or in the area of the chest between the lungs. It grows throughout childhood and begins to atrophy, or diminish in size, after puberty. It secretes thymosin, a hormone that stimulates the bone marrow to manufacture T lymphocytes.

T lymphocytes (T Cells)

mature in the thymus, enter the bloodstream, and defend the body against infectious agents.

Spleen

the largest lymphatic organ in the body. It is located in the upper left side of the abdominal cavity, close to the stomach. It filters the blood by destroying worn-out erythrocytes in a process called hemolysis. produces lymphocytes, stores thrombocytes, and serves as a reservoir for blood, which can be released into circulation when the body has experienced blood loss; the spleen controls the amount of blood in your body

Liver

located in the right upper quadrant of the abdomen and has several important functions. Besides its digestive functions, it filters the blood through hemolysis and serves as a storehouse for healthy erythrocytes.

Peyer’s Patches

small bundles of lymphatic tissue in the walls of the small intestines. Their primary function is to protect the body against harmful invaders that enter through the digestive tract.

immune system

a complex system of cells, tissues, organs, and vessels that work together to defend your body against infection and disease. The primary cells that perform the functions of the immune system are leukocytes

immunity

the ability to resist pathogens and toxins that cause infection or disease

leukocytes

white blood cells. manufactured primarily in the bone marrow. There are two main types of leukocytes: polymorphonuclear leukocytes and mononuclear leukocytes

Polymorphonuclear leukocytes

they have a nucleus made up of multiple segments. Also called granulocytes because their cytoplasm—all the material inside a cell, except for its nucleus—is filled with granules, or tiny particles that contain enzymes for digesting infectious microorganisms.

Mononuclear leukocytes

Have only one nucleus. also called agranulocytes because their cytoplasm does not contain granules.

Neutrophil

cells that destroy harmful pathogens. also called phagocytes because they eat, or swallow, these harmful invaders. The word phagocyte literally means “cell that eats, swallows, or engulfs.”

Eosinophils

granulocytes that secrete chemicals to attack disease-causing parasites. Eosinophils also respond during an allergic reaction.