Lecture 27: What are the functions of the immune system & lymphatic organs?

Immune System Organs Common Themes Lobule/ Nodule Design Tonsils Spleen : Blood, Interstitial, Lymphatic Vessels Destination of Lymph Lymph Nodes Lymphedema Thymus

Dr. Casey Self, Biology 118, Autumn 2016 11/7/2016 1 Describe these general “themes” of an immune response.

Diffuse: small, mobile cells scattered everywhere

Duplication: Similar actions by different cells or chemicals

Positive Feedback: Speeds up, amplify defensive reactions

Swelling: Increased cell production & edema

http://www.cancer.gov/about-cancer/treatment/side-effects/lymphedema/lymphedema-pdq & 11/7/2016 https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/media/ch23/human_lymphatic.swf 2 Lymphatic tissues share a common design: many units of nodules/lobules

Tonsils Thymus

Leukocyte

Reticular fibers

11/7/2016 Spleen 3 Where are your tonsils? What are their functions?

http://www.wisegeek.org/what-are-tonsils.htm

What are the risks if the 11/7/2016 tonsils “swell up”? 4 Where is the spleen located? What are its functions? What happens if your spleen is removed?

• White pulp: lymphatic nodules Stores blood for emergencies Red pulp: blood • Filters pathogens out of blood Sickle cell disease can • Phagocytes removes old RBCs lead to spleen damage

11/7/2016 • Fetal function? 5 Where does lymph fluid come from? How does it differ from blood?

Blood plasma leaks out  interstitial fluid  excess into lymph

https://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_Syst 11/7/2016 em_-_Lymphatic_Development 6 How & why do lymph vessels ensure 1-way flow? What blood cells & substances are NOT in lymph?

11/7/2016 7 What are the roles of the lymph nodes? Afferent lymph vessels enter & efferent lymph vessels exit each node.

11/7/2016 "Diagram of a CRUK 022" by Cancer Research UK 8 What is lymphedema? How can it damage tissues? • High blood pressure  excess fluid leaks into interstitial spaces. • Blockage or loss of lymphatic vessels (increased lymphatic pressure)

11/7/2016 https://www.dermquest.com/image-library/image/5044bfd1c97267166cd6746c & http://davislymphedemafund.org/wordpress1/2012/09/17/warning-signs/ 9 What are the major functions of the thymus? Controls early development of T (cell) lymphocytes. Produces hormone thymosin Thymus

Newborn Adult

What happens if T lymphocytes are not produced? https://courses.candelalearning.com/ap2x2master/chapter/anatomy-of-the-lymphatic-and-immune-systems/ 11/7/2016 https://my.bpcc.edu/content/blgy225/Hormones/Hormones_print.html 10 ExplainHow does why the the size thymus of the reaches thymus its change largest over size our in childhood. lifetime? What happens to the immune response as the thymus shrinks?

Vallejo, 2007

http://immunesystemimmunity.blogspot.com/2011/11/thymus.html

11/7/2016 11 Lynch, Goldberg, Chidgey, et al.,2009 Things to know or review: 1. Describe 4 major “themes” that help explain how the immune system fights infections. Explain the role of positive & negative feedback in that immune response. Describe the structure of lymphatic lobules/nodules. Describe the reticular fibers that support a nodule. 2. Where are your tonsils located? Why are tonsils part of the “front-line” defenses of the digestive & respiratory system? What can happen if tonsils swell up? 3. Describe the structure & location of the spleen. What is red & white pulp? What are 4 of the major functions of the spleen? What are the risks from infection or sickle cell disease to a spleen? How does the removal of the spleen affect a person’s health? 4. What is lymph & where is it found? Describe the composition of lymph. Describe the structure of lymph . Why are their walls so “permeable”? Why do lymph vessels contain 1-way valves? 5. Explain this pathway: fluid leaks out of a blood -> extracellular fluid moves into a lymph capillary -> lymph fluid moves toward the (from any part of the body). What moves fluid once it is in a lymph vessel? Why is the volume of lymph moved so small? 6. Describe 2 major functions of the lymphatic circulation. What is the benefit of having a slow fluid flow? Define edema & 2 common causes of it. How are tissues damaged? 7. What are the advantages of having lymph nodes “filtering’ lymph? Describe the afferent & efferent vessels of a lymph node. Why do lymph nodes swell up during an infection? 8. Where is the thymus located? What are 2 of its major functions? Graph the size of the thymus from birth to old age. Explain why the thymus is large when we are young. What happens to the disease fighting potential of our T cells as we get old? 11/7/2016 12 Additional Resources

1. Brousse V, Buffet P, & Rees D. (2014) The spleen and sickle cell disease: the sick(led) spleen. British Journal of Haematology 166:165–176. 2. Choi I, Lee S, & Hong Y-K. (2012) The new era of the : no longer secondary to the blood vascular system. Cold Spring Harb Perspect Med 2:a006445. 3. Dorshkind K, & Swain S. (2010) Age-associated declines in immune system development and function: causes, consequences, and reversal. Curr Opin Immunol. 21(4):404–407. 4. Lynch HE, Goldberg GL, Chidgey A, et al. (2009) Thymic involution and immune reconstitution. Trends in Immunology 30(7): 366-373. 5. Vallejo AN. (2007) Immune remodeling: lessons from repertoire alterations during chronological aging and in immune-mediated disease. Trends in Molecular Medicine 13(3):94-102.

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