Lympatic System 1 Flashcards
Components of the Lymphatic System?
Lymph fluid, Lymph vessels, Lymphatic tissue & organs & red bone marrow
Functions of Lymph vessels?
transport lymph & absent in avascular tissue, R bone marrow, NS and spleen
Functions of Lymphatic tissue & organs?
Contain lymphocytes for immune response
What is lymph?
Reabsorbed interstitial fluid in lymphatic capillaries
Where is red bone marrow found?
Ends of long bones and flat bones
What are the 3 functions of the Lymphatic system?
Drain excess interstitial fluid to maintain BP, BV, Transport and absorb dietary fats, aid immune responses
Where are lymphatic capillaries located?
Lymphatic capillaries are more fenestrated than systemic capillaries and interwoven between systemic capillaries and have valves for one-way entry and movement
How is lymph formed?
As hydrostatic pressure drives blood through system capillaries to nourish cells, some of the interstitial fluid is absorbed by the cells, while some are reabsorbed into the system by osmotic pressure due to the high osmolarity of blood proteins that cannot exit the system capillaries and the rest are collected by lymphatic capillaries to produce lymph which are drained by the lymphatic system and returned to the circulatory system
How much lymph is formed daily?
3 L
What happens if fluid is not drained?
Causes tissue swelling and edema
How are lymphatic capillaries different from systemic capillaries?
Lymph capillaries have larger diameters, closed ends that prevent the backward movement of fluid, and lined with overlapping endothelium cells (valves) that open during pressure changes.
How does interstitial fluid enter lymph capillaries?
During internal lymph capillary low pressure, the interstitial follows the pressure gradient into the capillaries through the endothelium openings
What happens when internal lymphatic vessel pressure increases?
The valves close and the lymph continues circulation deeper into the system after which pressure decreases again
What are lacteals?
Special capillaries in the folds of the gut membrane of small intestines contain villi that are highly vascularized and absorb fats after digestion producing a creamy, white lymph fluid called chyle.
How do lymph flow?
Lymphatic capillaries join together to form progressively larger lymphatic vessels with nodes along intervals that join together to form trunks that drain into lymphatic ducts
How is lymph driven up to the heart?
Driven towards the heart by skeletal or muscle pumps like venous return.
What are lymph trunks?
Converged lymph vessels that collect fluid from certain locations of the body and finally drain into lymph ducts
What is the left thoracic duct?
Primary channel responsible for lymph collection from left side and lower half of the body, and drainage into the heart by left subclavian vein.
What is the right lymphatic duct?
Lymphatic duct that collects lymph from the right and upper halves of the body and drains through the junction between the right jugular veins and right subclavian vein to the superior vena cava
What are the primary organs of the lymphatic system?
Red bone marrow and Thymus produce lymphocytes
What are the secondary organs?
Tonsils, lymph nodes & nodules, spleen which provide sites for immune responses
What are the functions of red bone marrow?
Synthesize hematopoietic stem cells that produce platelets, RBCs, and WBC such as immunocompetent B and pre-competent T cells
What is the thymus gland?
Bilobed organ located in the mediastinum between the sternum and aorta, above the heart.
Structure of thymus?
Encased by connective tissue layer, and two parts separated by connective capsule which contain internal protruding extensions called trabeculae that divide the thymus into lobes
What are the two parts of thymic lobes?
Heavily stained outer cortex, lighter stained inner medulla
What is the function of the outer cortex?
Mature & educate Pre-T cells and produce thymic hormones
What are the functions of the inner medulla?
Contain congregated epithelial layer that degenerates and gets filled with keratin granules called Hassall’s Corpuscles or thymic corpuscles as sites of T-cell death
What happens to the functional portion of the thymus with age?
Functional portion at peak during childhood and reduces in size and gets replaced with fat at adulthood
What are lymph nodes?
Bean-shaped structures located in intervals along lymphatic vessels that filter lymph
How many lymph nodes does the body have?
600 nodes
Where are the biggest clusters of nodes located?
Cervical, mamillary, axillary and groin areas
Where are the biggest clusters located of lymph nodes found?
Cervical, mamillary, axillary and groin areas
What is the functions of lymph nodes?
Filter lymph fluid and provide adequate immune responses to pathogens
How does lymph enter lymph nodes?
Through many afferent vessels
How does lymph exit nodes?
Through few efferent vessels
What is the structure of nodes?
Encased by dense connective tissue capsule which exhibit internal protruding extensions that divide the node into lobules each of which act to provide one-way flow deeper into the node as checkpoints for filtering the lymph and constitute of a stoma framework made of reticular fibers
What do the node lobules contain?
Pathways called sinuses that house a range of B-cells, T-cells, macrophages, lymphocytes and dendritic cells that identify possible threats to produce immune responses.
How does lymph flow in nodes?
Afferent, subcapsular sinus, trabecular sinus, medullary sinus, Efferent
What are lymph nodules?
Egg-shaped masses of lymphatic tissue that are not encased by a connective tissue capsule
Where are lymph nodules located?
MALT - mucus-associated lymphoid tissue are found in mucosa membranes of digestive, respiratory, urinary and reproductive tracts in areas that are frequently exposed to bacteria.
What do nodule clusters form?
Tonsils and Peyer’s Patches.
What are Peyers Patches?
Lymphatic follicles located in the ileum or mucosa membrane of the small intestine.
What are the 5 tonsils?
1 Pharyngeal, 2 palatines, 2 lingual tonsils
Where are the functions of the tonsils?
Formed like a ring in junction around the opening of the respiratory tract and filter the incoming substances for pathogens.
Where is the Pharyngeal (Adenoid) tonsil located?
The back wall of the nasopharynx
Where is the Palatine tonsils located?
Each side of the oral cavity
Where are the lingual tonsils located?
Base of the tongue
Where is the spleen located?
Between the stomach and diaphragm in the left side of the abdominal cavity inferior to the diaphragm.
Spleen structure?
Encased by connective tissue capsule and similar framework to lymph nodes and contain trabecular extensions that pierce deep into the spleen.
What are the functions of the white pulp?
Consists of lymphatic tissue heavily concentrated with lymphocytes and macrophages, and its B and T-cells produces immune responses, and the macrophages engulf blood-borne pathogens
What are the functions of the red pulp?
Consists of venous sinuses filled with blood and splenic cords that are filled with RBCs, lymphocytes and macrophages, and removes impaired or damaged BCs and platelets, store 1/3 of body’s platelets and produces hemopoieses in fetus.
