Lymphatic And Immune Systems
After reviewing and studying this module’s content, answer the following questions. Be sure to complete all lab activities and attend/watch all live lectures before completing this assignment. All of your answers should be written in your own words, using full sentences, correct terminology, and proper spelling and grammar.
- Explain the anatomical concepts associated with the lymphatic and immune systems. Summarize this module’s key points in 5-6 sentences.
- Explain the physiological concepts associated with the lymphatic and immune systems. Summarize this module’s key points in 5-6 sentences.
- How will you apply the concepts you have learned about the heart in real life and in your future career?
- Which topic within this module has been the most valuable to your learning experience and why?
- Which topic(s) within this module did you struggle to understand and why?
- (Optional) Do you have any suggestions for your instructor on how they could help you connect with the difficult topics you’ve noted?Why do some people acquire an infection or autoimmune condition, yet others do not? The answer lies partially within the immune system and its responses. The immune system is comprised of organs that are shared with other body systems, as well as the lymphatic system. Its job is to fight pathogens, with pathogens being biological cells or organisms that can cause illness in the host body.
Skin, tonsils, lymph nodes, the thymus, the digestive system, the urinary system, bone marrow, and the spleen all work together to create immune responses. The thymus, bone marrow, and spleen are considered the primary lymphoid organs.
Skin contains epithelial cells and sweat, which are protective. Tonsils are located in the pharynx, and primarily serve to teach children’s bodies to recognize, destroy, and develop immunity to pathogens. The thymus is located on the superior aspect of the heart, between the aorta and sternum; interestingly, the thymus shrinks with age in the natural age-related process called thymic involution. Thymic involution may partially be responsible for age-related immune and auto-immune deficiencies that appear in adulthood. The digestive system contains flora (good bacteria) to fight infection, as well as being lined by protective mucosa surfaces. The spleen is located in the upper left abdominal quadrant, with attachments to the stomach. The spleen functions as a primary immune response center for blood-borne pathogens, and is nicknamed the “filter of the blood.”
The Lymphatic System
The lymphatic system refers to the vessels, cells, and organs that carry fluids into the bloodstream, while filtering pathogens from the blood. The lymphatic system contains lymphatic vessels, lymph fluid, and 500-600 lymph nodes. The nodes are located near the groin, armpits, neck, chest, and abdomen. The fluid within the lymphatic system, called lymph, is not specifically regulated by the heart. Instead, lymph movement is regulated by skeletal muscle contraction, breathing, semi-lunar valves within the vessels, and pressure differentials surrounding the lymphatic capillaries. Lymph fluid brings pathogens and debris to lymph nodes, where the T cells and B cells fight infection. Lymph vessels entering the lymph node are called afferent lymph vessels, while those exiting are called efferent lymph vessels.
Some of the major organs and tissues working together to create the immune response.
Blood Cells
The blood contains specific kinds of cells that serve in the immune response:
Types of blood cells (Betts et al., 2013)
Lymphocytes come in four varieties: B cells, plasma cells, T cells, and natural killer cells.
B cells mature in red bone marrow. T cells mature in the thymus. Once the cells are mature, they circulate in the bloodstream, and take up residence to act in the spleen and lymph nodes.
B cells produce antibodies. Antibodies attack specific antigens. Think of antigens as nametags on pathogens. Each type of antibody can recognize its own antigen-labeled invader and moves to action to fight it. Plasma cells are also a type of antibody-producing B cell, but they are remarkably different in structure, as they primarily contain cytoplasm.
T cells also fight specific invaders, but in a different way, without secreting antibodies.
Natural killer cells are far less specific in what kind of pathogen they will fight, as they serve as a first response to viruses and some cancers.
Table: Types of lymphocytes and their functions
The cells work together in different ways, depending on the type of pathogen, and depending on previous exposures to the pathogen; we will examine this interaction more in the following physiology section
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