Podcast
Questions and Answers
What are the three types of tonsils?
What are the three types of tonsils?
Where is the spleen located?
Where is the spleen located?
What is the primary function of the thymus gland?
What is the primary function of the thymus gland?
Which part of the spleen consists mainly of lymphatic tissue?
Which part of the spleen consists mainly of lymphatic tissue?
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What happens to T-cell production after thymectomy?
What happens to T-cell production after thymectomy?
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Which of the following is NOT a function of the spleen?
Which of the following is NOT a function of the spleen?
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What is the common name for nasopharyngeal tonsils?
What is the common name for nasopharyngeal tonsils?
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What primarily denotes the red pulp of the spleen?
What primarily denotes the red pulp of the spleen?
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What is the primary function of the lymphatic system?
What is the primary function of the lymphatic system?
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Which of the following components is NOT part of the lymphatic system?
Which of the following components is NOT part of the lymphatic system?
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How does lymph flow through the lymph nodes?
How does lymph flow through the lymph nodes?
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What mechanism drives the movement of lymph in the lymphatic vessels?
What mechanism drives the movement of lymph in the lymphatic vessels?
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What does the thoracic duct primarily collect lymph from?
What does the thoracic duct primarily collect lymph from?
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Which lymph nodes filter lymph from the abdominal cavity?
Which lymph nodes filter lymph from the abdominal cavity?
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What is the role of lymph nodes in the lymphatic system?
What is the role of lymph nodes in the lymphatic system?
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Where does the right lymphatic duct empty the lymph?
Where does the right lymphatic duct empty the lymph?
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Which of the following best describes lymph?
Which of the following best describes lymph?
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What is metastasis in the context of the lymphatic system?
What is metastasis in the context of the lymphatic system?
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Study Notes
Lymphatic System Overview
- The lymphatic system protects the body against foreign materials.
- It assists in circulating body fluids between cells and the bloodstream.
- It transports dietary fats.
- It consists of lymphatic vessels, lymph, lymph nodes, tonsils, spleen, and the thymus gland.
Lymph
- Lymph is derived from tissue fluid.
- It contains more white blood cells than plasma.
- Lymph enters lymph nodes through afferent lymphatic vessels.
- Lymph flows through the node in one direction.
- Lymph flows through sinuses in the cortex and medulla of a lymph node.
- Lymph exits the lymph node through efferent lymphatic vessels.
- Lymph must be returned to the bloodstream to maintain blood volume and pressure.
Lymphatic Vessels
- Lymphatic vessels resemble veins but have thinner walls and more valves.
- Lymph movement is facilitated by vessel constriction, skeletal muscle pumps, and respiratory pumps.
- Lymph flows, at intervals, into lymph nodes along the vessels.
- Lymphatic vessels unite to form lymph trunks.
Lymph Trunks
- Lymph trunks are formed by uniting lymphatic vessels.
- They are large tubes that empty lymph into lymphatic ducts.
Lymphatic Ducts
- Lymph empties into two ducts: the thoracic duct (left lymphatic duct), and the right lymphatic duct.
- Lymph from these ducts enters the bloodstream via the left subclavian vein and the right subclavian vein.
Thoracic Duct
- The thoracic duct (left lymphatic duct) is about 38-45 cm long.
- It begins as a dilation called the cisterna chyli.
- It is the main collecting duct of the lymphatic system.
- It receives lymph from the lower body and upper left quadrant.
- It empties into the left subclavian vein.
Right Lymphatic Duct
- The right lymphatic duct is about 1.5 cm long.
- It receives lymph from the upper right quadrant.
- It empties into the right subclavian vein.
Lymph Nodes
- Lymph nodes are oval or bean-shaped masses of lymphatic tissue.
- They aid in defense and white blood cell formation.
- They are located along the length of lymphatic vessels.
- They are scattered throughout the body, usually in clusters.
Major Lymph Nodes
- Cervical nodes are located in the neck, filtering lymph from the head and neck.
- Axillary nodes are located in the armpits, filtering lymph from the hand, arm, and breast.
- Inguinal nodes are located in the groin, filtering lymph from the lower extremities and external genital organs.
- Mesenteric nodes are located in the abdominal peritoneum, aiding in infection control after abdominal surgery and filtering lymph from the abdominal cavity.
Metastasis
- Metastasis is the process by which bacteria or body cells spread from one body part to another, through lymphatic or circulatory systems.
- Cancer cells often migrate to nearby nodes (e.g., breast cancer to axillary nodes).
Tonsils
- Tonsils are aggregations of large lymphatic nodules embedded in mucous membranes.
- They are located beneath the epithelium of the pharynx and oral cavities.
- They protect nasal and oral cavities.
- Three types of tonsils include nasopharyngeal, palatine, and lingual tonsils.
Nasopharyngeal Tonsils
- Also called adenoids, these tonsils are located behind the nose, on the roof of the posterior wall of the pharynx, and the posterior opening of the nasal cavity.
Palatine Tonsils
- Commonly referred to as just "tonsils."
- Located in the back of the mouth and lateral walls of the pharynx.
- Frequently removed through tonsillectomy.
Lingual Tonsils
- Found at the base of the tongue.
- Act as a first line of defense against external threats.
Spleen
- The spleen is the largest lymphatic organ, located in the upper left abdominal quadrant, between the stomach fundus and the diaphragm.
- It resembles a large lymph node and filters blood.
Spleen Structure
- The spleen is covered by a capsule.
- The hilum is a depression on the medial surface of the spleen, where nerves, arteries, veins, and lymphatic vessels enter and exit.
- Trabeculae are extensions of the spleen capsule that form partitions within the spleen.
- The spleen's tissue/substance (pulp) is divided into the white and red pulp.
White Pulp
- White pulp consists of lymphatic tissue and mostly lymphocytes, arranged around central arteries.
Red Pulp
- Red pulp consists of venous sinuses filled with blood, and cords of splenic tissue; it contains red blood cells, macrophages, lymphocytes, plasma cells, and granulocytes.
Spleen Functions
- Phagocytosis of bacteria, worn-out or damaged red blood cells, and platelets.
- Blood storage and release (e.g., during hemorrhage).
- Immune function as a site for B cell proliferation into plasma cells.
- Does not filter lymph (no afferent lymphatic vessels or lymph sinuses).
Thymus Gland
- The thymus gland is a bilobed organ in the upper part of the chest, along the trachea, inferior to the thyroid gland and posterior to the sternum.
- It's the largest and most active during the prenatal period and infancy.
- It decreases in size after puberty.
Thymus Gland (cont.)
- It's composed of lymphatic tissue.
- It's subdivided into lobules.
- Immature T cells originate in bone marrow and migrate to the thymus via blood.
- Within the thymus, cells mature into T cells and then are released into circulation.
- Thymic hormones aid in T cell maturation.
Thymus Removal
- Removing the thymus (thymectomy) can decrease T-cell production, potentially increasing susceptibility to acute infections.
Spleen Removal
- Removing the spleen (splenectomy) can be compensated by function in other organs (e.g. liver and bone marrow).
- Removal can also increase susceptibility to diseases.
MALT (Mucosa-Associated Lymphoid Tissue)
- MALT is mucosa-associated lymphatic tissue.
- It's the infiltration of mucosa by a large number of lymphocytes.
- Peyer's patches of the small intestine are an example of MALT.
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Description
Explore the crucial functions and components of the lymphatic system, which plays a vital role in protecting the body and maintaining fluid balance. This quiz covers the structure and flow of lymph, as well as the organization of lymphatic vessels and nodes.
