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Questions and Answers
What is the primary function of lymphatic vessels?
What is the role of macrophages in lymph nodes?
What is the characteristic of lymphatic vessels that allows them to absorb leaked fluid?
What is the function of the right lymphatic duct?
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What is the role of lymph nodes in the immune response?
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What is the characteristic of lymphatic vessels that is similar to veins of the cardiovascular system?
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What is the mechanism by which lymph is transported through lymphatic vessels?
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What is the shape of most lymph nodes?
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What is the function of the germinal centers in the lymph node?
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Where is the thymus located?
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What is the function of the spleen?
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What is the function of the tonsils?
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What is the path of lymph flow through a lymph node?
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What is the function of Peyer's patches?
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Study Notes
The Lymphatic System
- Consists of two semi-independent parts: lymphatic vessels and lymphoid tissues and organs
Lymphatic Vessels
- Transport escaped fluids from the cardiovascular system back to the blood
- Form an elaborate drainage system that picks up excess interstitial fluid (lymph) and returns it to the blood
- Form a one-way system, with lymph flowing only toward the heart
Lymph Capillaries
- Weave between tissue cells and blood capillaries, absorbing leaked fluid
- Walls overlap to form flap-like minivalves that open when fluid pressure is higher in the interstitial space, allowing fluid to enter the lymphatic capillary
Lymphatic Collecting Vessels
- Collect lymph from lymphatic capillaries
- Carry lymph to and away from lymph nodes
- Return fluid to the venous system through two large ducts in the thoracic region: right lymphatic duct and thoracic duct
Characteristics of Lymphatic Vessels
- Thin-walled
- Larger vessels have valves
- Low-pressure, pumpless system
- Lymph is transported by the same mechanisms as the milking action of skeletal muscles, pressure changes in the thorax during breathing, and smooth muscle in the walls of lymphatics
Lymph Nodes
- Cells in lymph nodes help protect the body by removing foreign material, producing lymphocytes that function in the immune response
- Filter lymph before it is returned to the blood
- Other materials that are filtered include viruses, cancer cells, and cell debris
Defense Cells within Lymph Nodes
- Macrophages engulf and destroy bacteria, viruses, and other foreign substances in the lymph
- Lymphocytes respond to foreign substances in the lymphatic stream
Structure of a Lymph Node
- Most lymph nodes are kidney-shaped, less than 1 cm long, and buried in connective tissue
- Each surrounded by a fibrous capsule called trabeculae and divided into a number of compartments
- Cortex (outer part) contains follicles and germinal centers
- Medulla (inner part) contains phagocytic macrophages
Flow of Lymph through Nodes
- Lymph enters the convex side of a lymph node through afferent lymphatic vessels
- Lymph flows through a number of sinuses (spaces) inside the node
- Lymph exits via efferent lymphatic vessels
Other Lymphoid Organs
- Spleen: filters and cleanses blood, destroys worn-out red blood cells, stores platelets, and acts as a blood reservoir
- Thymus: functions at peak level only during youth
- Tonsils: trap and remove bacteria or other foreign pathogens entering the throat
- Peyer's patches: capture and remove bacteria or other foreign pathogens from the small intestine
- Appendix: contributes to lymphatic function
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Description
This quiz covers the basics of the lymphatic system, including its components, functions, and roles in body defense and resistance.
