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62 terms

Chap 20 Lymphatic System

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What are the two most important functions of the lymphatic system?
-Maintain fluid balance in the internal environment
-Promote body's immunity
What act as "drains" to collect excess tissue fluid and return it to the venous blood just before it returns to the heart?
Lymph vessels
What is the specialized component of the circulatory system; made up of lymph, lymphatic vessels, and isolated structures containing lymphoid tissue: lymph nodes, aggregated lymphoid nodules (e.g., Peyer's patches), tonsils, thymus, spleen, and bone marrow?
Lymphatic system
What transports tissue fluid, proteins, fats, and other substances to the general circulation?
Lymphatic system
What begin blindly in the intercellular spaces of the soft tissues; and do not form a closed circuit?
Lymphatic vessels
What is the complex, organized fluid that fills the spaces between the cells and is part of the ECM and resembles blood plasma in composition with a lower percentage of protein?
Interstitial fluid (IF)
What is the clear, watery-appearing fluid found in the lymphatic vessels?
Lymph (lymphatic fluid)
What closely resembles blood plasma in composition but has a lower percentage of protein; and is isotonic?
Lymph (lymphatic fluid)
What are the microscopic blind-end vessels where lymphatic vessels originate; their wall consists of a single layer of flattened endothelial cells; networks branch and anastomose freely?
Lymphatic capillaries
Lymph from right upper quadrant empties into what?
Right lymphatic duct and then into right subclavian vein
Lymph from rest of the body (minus upper right quad) empties into what?
Thoracic duct, which then drains into left subclavian vein;
What does the thoracic duct originate as?
Cisterna chyli (chyle cistern)
Lymph that flows through reenters the general circulation at what rate/day?
3 liters/day
Lymphatic capillary wall is formed by what?
Single layer of thin, flat endothelial cells
As the diameter of lymphatic vessels increases from capillary size what happens to the walls of the vessel?
The walls become thicker and have three layers
What are present every few millimeters in large lymphatics and even more frequently in smaller lymphatics?
Semilunar valves
What are the functions of the lymphatic vessels?
-Remove high molecular weight substances and even particulate matter from interstitial spaces
-Lacteals absorb fats and other nutrients from the small intestine
What can happen if anything blocks lymphatic return?
-Blood protein concentration, and blood osmotic pressure drops
-Fluid imbalance
-Death
From lymphatic capillaries, lymph flows through progressively larger lymphatic vessels to eventually reenter blood at the junction of what?
-Internal jugular
-Subclavian veins
Lymph moves through the system in the right direction as a result of what?
The large number of valves
What establishes a fluid pressure gradient in the lymphatic system?
-Breathing movements
-Skeletal muscle contractions
What is the the movement (flow) of lymph called?
Lymphokinesis
What extend from the covering capsule toward the center of the lymph node?
Trabeculae
What are oval structures enclosed by a fibrous capsule and are a type of biological filter?
Lymph nodes
What are lined with specialized reticuloendothelial cells capable of phagocytosis?
Cortical and medullary sinuses of a lymph node
What are the location of groups with greatest clinical importance?
-Submental and submaxillary group
-Superficial cervical
-Superficial cubital
-Axillary
-Iliac
-Inguinal lymph nodes
What nodes are located in front of the ear and drain superficial tissues and skin on the lateral side of the head and face?
Preauricular lymph nodes
Lymph nodes perform what two distinct functions?
-Defense
-Hematopoiesis
What are the two defense functions of the lymph nodes?
-Filtration
-Phagocytosis
What type of filtration physically stops particles from progressing further in the body?
Mechanical filtration
What type of filtration does the biological activity of cells destroy and removes particles?
Biological filtration
What can occur if lymph nodes become overwhelmed?
Lymph nodes can become infected or damaged
Distribution of lymphatics in the breast
are drained by what two sets of lymphatic vessels?
-Lymphatics that drain skin over the breast with the exception of areola and nipple
-Lymphatics that drain substance of breast itself, as well as skin of areola and nipple
What are located under areola surrounding nipple; where communication between cutaneous plexus and large lymphatics that drain the secretory tissue and ducts of the breast occurs?
Subareolar plexus
What amount of lymph from the breast enters lymph nodes of axillary region?
More than 85%
What tonsil is located on each side of throat?
Palatine tonsils
What tonsil is located near posterior opening of nasal cavity and is known as "adenoids" when swollen?
Pharyngeal tonsils
What tonsil is located near base of the tongue?
Lingual tonsils
What protect against bacteria that may invade tissues around the openings between the nasal and oral cavities?
Tonsils
What is the primary central organ of lymphatic system?
Thymus
What is the single, unpaired organ located in the mediastinum, extending upward to lower edge of thyroid and inferiorly as far as fourth costal cartilage?
Thymus
What is the structure of the thymus?
-Pyramid-shaped lobes are subdivided into small lobules
-Each lobule is composed of a dense cellular cortex and an inner, less dense, medulla
-Medullary tissue can be identified by presence of thymic corpuscles
What plays vital role in immunity mechanism
and is the source of lymphocytes before birth?
Thymus
Shortly after birth, what does the Thymus secrete?
Thymosin and other regulators, which enables lymphocytes to develop into T cells
What is the location of the spleen?
-In left Hypochondrium,
-directly below diaphragm, above left kidney and descending colon, and behind fundus of stomach
What are the two types of pulp that the spleen is made of?
-White pulp
-Red pulp
What are dense masses of developing lymphocytes found in the spleen?
White Pulp
What is found near outer regions of the spleen, which are made up of a network of fine reticular fibers submerged in blood that comes from nearby arterioles?
Red Pulp
What are the functions of the spleen?
-Defense
-Hematopoiesis
-Red blood cell and platelet destruction
-Blood reservoir
Where do monocytes and lymphocytes complete their development?
In the spleen (Hematopoiesis)
Organs with lymphocytes appear when?
Before birth and grow until puberty
Lymphatic system benefits the whole body by acomplising what?
-Maintaining fluid balance
-Promoting freedom from disease
What is the elevated protein concentration in the thoracic duct due to?
Protein-rich lymph coming from the liver and the small intestine
What is higher in protein content the I.F. or the lymph from the thoracic duct?
Thoracic duct lymph
What are the lymphatic capillaries originating in the villi of the small intestine called?
Lacteals
What function do Lacteals serve?
Absorption of fats and other nutrients
The milky lymph found in lacteals after digestion contains 1-2% fat and is called what?
Chyle
How much total blood proteins leak out of the capillaries and into the tissue fluid and is returned to the blood via the lymphatic vessels?
50%
What serve as the first line of defense from the exterior and as such are subject to chronic infection?
Tonsils
Whats relative size to the rest of the body is largest in a child about 2 years old?
Thymus
When is the thymus at it's largest absolute size?
Puberty
How can medullary tissue of the Thymus be identified?
By the presence of Thymic corpuscles (hassall's corpuscles)