General Circulation & Lymphatics Of The Body Flashcards
The Circulatory System
Function: Transports blood and lymph to and form the tissues of the body; these fluids carry cells, nutrients, waste products, hormones, & antibodies.
Structures: Includes the heart, blood vessels, and lymphatic vessels.
The cardiovascular system
-circulates blood
-oxygen, nutrients diffuse across the arterial capillary walls and enter interstitial fluid, which carries oxygen and nutrients to the target cells; carbon dioxide and wastes diffuse across the venous capillary walls (to be carried to the lungs to be exhaled)
The lymphatic system
-circulates lymph
-collects fluid directly from tissues
-carries excess fluid (lymph) back to venous system
-movement of the lymph relies heavily on the massaging motion of surrounding tissues (muscle contraction)
-the lymphatic system serves as an adjunct to the venous part of the circulation
Lymphatic System: Cisterna Chyli
Efferent
-think “exit”, conveying away from a center
Afferent
-conveying toward a center
Thymus
Function: training and development of T lymphocytes; produces thymosins (hormones that stimulate the development of antibodies)
-the thymus is larger in younger animals
Lymphoepithelial Structures
-No capsule, close to moist epithelial surface, at origin of lymphatic drainage pathway
-tonsils
-diffuse lymphatic tissue / lymphatic nodules
-MALT (mucosa-associated lymphatic tissue)
Spleen
Functions: blood storage, removal of particular matter from circulation, destruction of worn-out erythrocytes, production of lymphocytes
Lymph nodes and hemal nodes
-encapsulated, with subscapular sinus
-cortex includes germinal centers where lymphocytes are continually produced
-reticular framework contains phagocytic cells
-hemal nodes - most familiar in sheep; darkly colored from blood; found below the roof of the abdomen and thorax
Arterioles
Supply blood to tissues from the heart
Veins
Return blood from tissues to the heart
Capillaries
Exchange vessels within tissues
What are similarities of blood vessels?
-endothelium (Simple squamous epithelium derived from mesoderm)
-tunica adventitia
-transmits a fluid in a single direction with little or no back flow permitted
What are differences between lymph vessels and blood vessels?
-lymph vessels generally have no tunica media with smooth muscle
-one or two layers of smooth muscle and elastic fibers may be present in larger vessels
-transmit lymph, not blood
-all lymph vessels have valves while only some veins, and no arteries in most animals, have valves
-these valves allow flow in only one direction
