Unit 12 - Lymphatic

1. Describe the general functions of the lymphatic system

• Maintaining fluid balance, transporting dietary fats, and protecting the body through the immune response. It collects excess interstitial fluid and returns it to the bloodstream, helps in the absorption of fats in the digestive system, and contains immune cells that respond to pathogens.

2. Describe how tissue fluid and lymph form

• Plasma leaks out of the capillaries into the spaces between cells. This extracellular fluid, primarily composed of water, electrolytes, and small molecules, becomes lymph when it enters the lymphatic capillaries.

3. Explain the function of lymph

• Transport excess interstitial fluid back to the bloodstream, transport dietary fats from the intestines, and play a critical role in immune function by carrying lymphocytes and presenting antigens to immune cells.

4. Explain the path of lymph within the lymph vessels, from tissue fluid back to bloodstream

• Lymph flows from tissue fluid into lymphatic capillaries, then into larger lymphatic vessels, and eventually into lymph nodes where it is filtered. From there, lymph continues to larger lymphatic trunks and finally enters the bloodstream via the thoracic duct or right lymphatic duct.

5. Differentiate the parts of a lymph node visually and based on their functions

• A lymph node consists of the outer cortex (which contains follicles and is involved in the activation of B cells), the paracortex (rich in T cells), and the inner medulla (which contains macrophages). Each region plays a different role in filtering lymph and mounting an immune response.

6. Discuss the roles of the thymus & spleen

• The thymus is responsible for the maturation and differentiation of T lymphocytes, while the spleen filters blood, recycles iron, and provides a site for immune responses against blood-borne pathogens.

7. Distinguish between innate (non-specific) and adaptive (specific) immunity and give examples of each

• Innate immunity is a non-specific defense mechanism that includes physical barriers (like skin), phagocytic cells, and inflammatory responses. Adaptive immunity is specific and involves lymphocytes such as B cells and T cells, which generate a targeted response against specific pathogens.

8. Explain the mechanisms behind the innate defense system

• The innate defense system utilizes physical barriers (such as skin), chemical barriers (like enzymes in saliva), and cellular defenses such as macrophages and neutrophils that engulf and destroy pathogens.

9. Explain how lymphocytes are formed and activated

• Lymphocytes are formed in the bone marrow and undergo maturation processes. T cells migrate to the thymus for maturation, while B cells mature in the bone marrow. Both are activated upon encountering specific antigens.

10. Explain the steps in antibody formation via both B & T cells

• Antibody formation involves B cells that, upon activation by antigens, proliferate and differentiate into plasma cells that produce antibodies. T cells also provide help through cytokine signaling.

11. Explain how lymphocytes play a role in adaptive immunity

• Lymphocytes, particularly B and T cells, play essential roles in adaptive immunity by targeting specific pathogens, presenting antigens, and producing antibodies as part of the immune response.

12. Name the major immunoglobulins and discuss their origins and actions

• Major immunoglobulins include IgG, IgA, IgM, IgE, and IgD, with their origins stemming from B cells. Each type has distinct actions, such as neutralizing toxins or pathogens and activating complement.

13. Distinguish between the primary and secondary immune responses

• The primary immune response occurs upon first exposure to an antigen, typically resulting in a slower response. The secondary immune response is faster and more robust due to memory cells generated from the initial exposure.

14. Distinguish between active and passive immunity

• Active immunity results from the body’s own immune response to an antigen, while passive immunity involves the transfer of antibodies from another source, like maternal antibodies to an infant.

15. Distinguish between artificially and naturally acquired immunity and give an example

• Naturally acquired immunity results from exposure to pathogens, while artificially acquired immunity occurs through vaccination. For example, acquiring measles through infection versus receiving a measles vaccine.

17. Explain how vaccinations function to prevent us from illness

• Vaccinations function by introducing a harmless part or a weakened/inactivated form of a pathogen, prompting the body to produce an immune response, including memory cells that protect against future infections.

18. Explain how tissue rejection arises

• Tissue rejection arises when the immune system recognizes transplanted tissue as foreign due to differences in antigens and mounts an immune response against it, which can lead to the failure of the transplant.