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What is the primary function of lymphocytes in the tonsils?
What is the primary function of lymphocytes in the tonsils?
The thymus increases in size after puberty.
The thymus increases in size after puberty.
False
What are the three groups of tonsils?
What are the three groups of tonsils?
Pharyngeal, Palatine, Lingual
The lymph nodes are usually less than ___ cm in length.
The lymph nodes are usually less than ___ cm in length.
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Match the following types of lymph nodes with their locations:
Match the following types of lymph nodes with their locations:
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Which of the following structures is responsible for processing and maturation of T-lymphocytes?
Which of the following structures is responsible for processing and maturation of T-lymphocytes?
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Afferent lymphatic vessels carry lymph away from the lymph nodes.
Afferent lymphatic vessels carry lymph away from the lymph nodes.
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Where is the spleen located in the body?
Where is the spleen located in the body?
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What is the function of the overlapping ends of simple squamous cells in the lymphatic capillaries?
What is the function of the overlapping ends of simple squamous cells in the lymphatic capillaries?
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Lymphatic vessels have walls that are thicker than blood vessels.
Lymphatic vessels have walls that are thicker than blood vessels.
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Name two locations where superficial lymphatics are found.
Name two locations where superficial lymphatics are found.
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The Thoracic Duct drains lymph inferior to the ______ and from the left side of the body superior to the diaphragm.
The Thoracic Duct drains lymph inferior to the ______ and from the left side of the body superior to the diaphragm.
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Match the following lymphatic trunks with their corresponding areas they drain:
Match the following lymphatic trunks with their corresponding areas they drain:
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What are lymphoid nodules primarily composed of?
What are lymphoid nodules primarily composed of?
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What are the primary cells responsible for the functions of the lymphatic system?
What are the primary cells responsible for the functions of the lymphatic system?
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The Right Lymphatic Duct drains lymph from the entire body.
The Right Lymphatic Duct drains lymph from the entire body.
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The lymphatic system is responsible for returning excess interstitial fluid to the heart.
The lymphatic system is responsible for returning excess interstitial fluid to the heart.
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List one example of Mucosa-Associated Lymphoid Tissue (MALT).
List one example of Mucosa-Associated Lymphoid Tissue (MALT).
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Name one organ that plays a role in filtering lymph.
Name one organ that plays a role in filtering lymph.
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Lymphatic trunks join to form larger structures called ______.
Lymphatic trunks join to form larger structures called ______.
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Which of the following statements regarding lymphatic vessels is correct?
Which of the following statements regarding lymphatic vessels is correct?
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Lymphatic vessels carry lymph from peripheral tissues to the ________ system.
Lymphatic vessels carry lymph from peripheral tissues to the ________ system.
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What is the primary role of lacteals in the lymphatic system?
What is the primary role of lacteals in the lymphatic system?
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Match the components of the lymphatic system with their functions:
Match the components of the lymphatic system with their functions:
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Lymphatic capillaries are found in the epidermis.
Lymphatic capillaries are found in the epidermis.
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What causes the formation of lymph in the lymphatic system?
What causes the formation of lymph in the lymphatic system?
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Study Notes
The Lymphatic System
- The lymphatic system is a network of cells, tissues, and organs that defend the body against environmental hazards (pathogens) and internal threats (cancer cells).
- Lymphocytes are the primary cells of this system.
- The lymphatic system consists of lymph, lymphatic vessels, lymphoid tissues and organs, and lymphocytes and other cells.
Formation of Lymph
- Plasma seeps from capillaries, surrounds cells, and forms tissue fluid.
- Most tissue fluid returns to general circulation via venules.
- Excess tissue fluid enters lymphatic vessels and forms lymph.
- Hydrostatic pressure pushes fluid out of blood capillaries into the interstitial space.
- Osmotic pressure pulls some of the fluid back into the capillaries, but not all.
- Excess fluid enters lymphatic capillaries through one-way valves.
Functions of the Lymphatic System
- Function 1: Produces, maintains, and distributes lymphocytes for defense against infection and environmental hazards.
- Lymph nodes and other lymphatic organs filter lymph to remove microbes and foreign particles and lymphocytes destroy them.
- Function 2: Returns excess interstitial fluid to the bloodstream.
- Lymph capillaries pick up excess interstitial fluid and proteins and return them to the venous blood.
- Lymph rejoins the bloodstream at the right and left subclavian veins.
- Function 3: Absorbs fats and fat-soluble vitamins from the digestive tract and transports them to the circulatory system.
- Lacteals absorb fats and fat-soluble vitamins from the intestinal tract.
Lymphatic Vessels
- Lymphatic capillaries merge to form lymphatic vessels.
- Lymphatic vessels lead towards the body's trunk.
- The walls of these vessels are similar to those of veins.
- Lymphatic vessels are lined with valves, which are visible as bulges on the vessel's surface.
- Valves prevent backflow.
Lymphatic Capillaries
- Begin in tissue spaces as pockets.
- Found throughout the body except bone marrow, central nervous system, and epidermis.
- Composed of endothelium with limited or absent basal lamina.
- Simple squamous cells of the endothelium have overlapping ends that form one-way valves.
Other Features of Lymphatic Capillaries
- Larger diameters compared to blood capillaries.
- Thinner walls compared to blood capillaries.
- Typically flattened or irregular in outline.
Two Sets of Lymphatic Vessels
- Superficial lymphatics: Located in the subcutaneous layer deep to the skin, areolar tissue, mucous membranes of the digestive, respiratory, urinary, and reproductive tracts, and serous membranes of the pleural, pericardial, and peritoneal cavities.
- Deep lymphatics: Located in skeletal muscles, other organs of the neck, limbs, and trunk, and walls of visceral organs.
Lymphatic Trunks
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Lymphatic vessels join to form larger tributaries called lymphatic trunks.
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Types of lymphatic trunks: right and left lumbar, intestinal, right and left bronchomediastinal, right and left subclavian, and right and left jugular.
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Trunks drain into lymphatic ducts.
Lymphatic Ducts
- Lymphatic trunks merge until lymph enters two lymphatic ducts.
- Right lymphatic duct: Drains lymph from the upper right quadrant of the body.
- Thoracic duct: Drains areas inferior to the diaphragm and from the left side of the body superior to the diaphragm.
Areas drained by Lymphatic Ducts
- Right lymphatic duct: Drains the upper right quadrant of the body.
- Thoracic duct: Drains the remaining areas of the body.
Lymph Nodes
- Small, bean-shaped structures (usually less than 2.5 cm long).
- Distributed throughout the body along lymphatic pathways.
- Three superficial regions on each side of the body where lymph nodes cluster: inguinal, axillary, and cervical.
- Surrounded by a connective tissue sheath.
- Divided into compartments called lymph nodules.
- Lymph nodules are dense masses of lymphocytes and macrophages separated by lymph sinuses.
Lymphatic Organs
- Clusters of lymphocytes and other cells (e.g., macrophages) embedded in a connective tissue framework of short, branching fibers.
- Lymphocytes proliferate in lymph organs when the body is exposed to microbes or other foreign agents.
- They are sent to the site of invasion via the blood.
The Thymus
- Soft, bi-lobed organ located anterior to the ascending aorta and posterior to the sternum.
- Decreases in size after puberty.
- Functions:
- Processing and maturation of T-lymphocytes.
- T-cells do not respond to pathogens and foreign agents within the thymus.
- Mature T-cells enter the blood to other lymphatic organs to help with defense.
- Production of thymosins, which stimulate the maturation of lymphocytes in other lymphatic organs.
- Processing and maturation of T-lymphocytes.
The Spleen
- Located in the upper left abdominal cavity, just beneath the diaphragm and posterior to the stomach.
- Similar in structure to lymph nodes but much larger; the largest lymphatic organ.
- Surrounded by a connective tissue capsule that divides the organ into lobules.
- Consists of two types of tissue:
- White pulp: Lymphatic tissue consisting mainly of lymphocytes around arteries.
- Red pulp: Venous sinuses filled with blood and cords of lymphatic cells.
- Functions:
- Filters blood, removing pathogens, debris, damaged cells, and large particles.
- Removes old and damaged red blood cells (RBCs).
- Produces lymphocytes, especially in response to invading pathogens.
- Functions as a reservoir for blood, releasing blood into the bloodstream in emergencies.
Lymphoid Tissues
- Connective tissues dominated by lymphocytes.
- Lymphoid nodules have densely packed lymphocytes in an area of areolar tissue.
- Lymphoid nodules may occur in clusters in many areas of the body.
Lymphoid Tissue (MALT)
- Mucosa-Associated lymphoid tissue (MALT) is a collection of lymphoid tissues in the mucous membranes of the digestive, respiratory, urinary, and reproductive tracts.
- Examples of MALT include aggregated lymphoid nodules (Peyer's patches), appendix, and tonsils.
Tonsils
- Clusters of lymphatic tissue under the mucous membranes lining the nose, mouth, and pharynx.
- Three groups of tonsils:
- Pharyngeal (adenoid) tonsils
- Palatine tonsils
- Lingual tonsils
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Lymphocytes and macrophages in the tonsils provide protection against harmful substances and pathogens entering the body through the nose or mouth.
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Description
Test your knowledge on the lymphatic system's components and functions, including lymphocytes, tonsils, lymph nodes, and the spleen. This quiz covers essential terms and concepts vital for understanding human anatomy and the immune system's role in defense mechanisms.
