Function of the Lymphatic System
-Return interstitial fluid back to the bloodstream
-Transport lipids and lipid-soluble vitamins into the bloodstream
-Production and maturation of lymphocytes
-Generates an immune response against antigens in the interstitial fluid
Lymph is comprised of: (3)
1. Interstitial fluid
2. Solutes
3. Foreign materials
Define Lymphatic Capillaries
Lymphatic capillaries are closed-ended tubes that are found interspersed among most blood capillary beds.
-They resemble blood capillaries but they have overlapping endothelial cells that act as one way valves allowing interstitial fluid a one-way entranc
What are lacteals?
The gastrointestinal tract contains specialized lymph capillaries that collect not only interstitial fluid but also collect lipids and lipid-soluble vitamins
What is chyle?
The lymph collected from the gastrointestinal system has a milky color due to the lipid absorption
Lymphatic capillaries merge to form ___.
Lymphatic capillaries merge to form LYMPHATIC VESSELS.
(Afferent/Efferent) lymphatic vessels bring lymph to a lymph node.
Afferent
(Afferent/Efferent) lymphatic vessels transport filtered lymph away from the lymph node.
Efferent
Left and right ___ are formed from merging lymphatic vessels.
Lymphatic trunks
Each trunk drains lymph from a specific region of the body:
Jugular trunks - head and neck
Subclavian trunks - upper limbs, breasts and superficial thoracic wall
Bronchiomediastinal trunks - deep thoracic structures
Intestinal trunks - most abdominal structures
Lumbar trunks - lower limbs, abdominopelvic wall and
The right lymphatic duct is located:
The right lymphatic duct is located deep to the right clavicle and returns lymph at the junction of the right subclavian and internal jugular veins.
-The right lymphatic duct returns lymph from the right side of the head and neck, right upper limb and the
The ___ is the largest lymphatic vessel. It begins just inferior to the diaphragm as a rounded saclike structure called the ___.
thoracic duct, cisterna chyli
The thoracic duct passes through:
The thoracic duct passes through the aortic opening of the diaphragm and returns lymph into the junction between the left subclavian and internal jugular veins
-The thoracic duct collects lymph from most of the body (excluding the right lymphatic duct dra
Name the lymphatic cells that are located in the lymphatic and circulatory systems.
-Macrophages
-Nurse cells: Found in thymus, secrete thymic hormones.
-Dendritic cells: Found in lymph nodules, antigen presenting cells.
-Lymphocytes
The body contains three types of lymphocytes:
T-lymphocytes (T-cells), B-lymphocytes (B-cells), NK cells
___ is the process of lymphocyte development.
Lymphopoiesis
The final result of lymphopoiesis is that the lymphocyte becomes ___, meaning the cell can participate in the immune response.
immunocompetent
All lymphocytes originate in the ___ but their maturation sites differ.
red bone marrow
Define Lymphatic Nodules
Lymphatic Nodules are oval clusters of lymphatic cells with some extracellular matrix but NOT surrounded by a connective tissue capsule.
MALT (Mucosa-Associated Lymphatic Tissue)
-Lymphatic nodules located in the mucosa of the gastrointestinal, respiratory, genital and urinary tracts
-These nodules monitor and respond to antigens that may enter these tracts
Pharyngeal tonsils (adenoids)
located in the posterosuperior wall of the nasopharynx
Palatine tonsils
located in the posterolateral wall of the oral cavity
Lingual tonsils
located along the posterior one-third of the tongue
___ consist of lymphatic cells and extracellular matrix and is completely surrounded by a connective tissue capsule.
Lymphatic Organs
Thymus
Bilobed organ located superficial to the heart
Function of Thymus
-Site of T-lymphocyte differentiation and maturation
-In adulthood, T-lymphocytes can only be produced by cell division and not by the maturation of new cells in the thymus
Small, round or oval structures located along the pathway of lymph vessels
Lymph Nodes
The primary function of a lymph node
Filter antigens from the lymph and initiate an immune response
Most apparent lymph node clusters occur as:
Axillary lymph nodes, Inguinal lymph nodes, Cervical lymph nodes
Internal extensions of the capsule, ___, project into the node
trabeculae
Lymph exits nodes via efferent vessels at an indentation of the node called the ___.
hilum
Functions of the Spleen
-Initiates an immune response when antigens are found in blood (white pulp function)
-Serves as a reservoir for erythrocytes and platelets (red pulp function)
-Phagocytizes old, defective erythrocytes and platelets (red pulp function)
-Phagocytizes bacter
Largest lymphatic organ in body just lateral to left kidney
Spleen