Question

1.How does the lymphatic system react to a foreign antigen (i.e. bacteria). Include the cells and chemicals involved in the immune reaction. How will the reaction be different the second time this antigen is introduced to the body?

2.Describe the path of urinary filtrate from where it leaves the glomerulus to the ureter. Specifically, what happens to water, sodium and urea during this trip? How is the reabsorption of water and sodium regulated by hormones?

3.Discuss the difference between the sympathetic and parasympathetic nervous systems. Be sure to include a discussion of the different ganglia found in each system and their roles.

4.Describe the major events of the menstrual cycle and what triggers those events (Be specific).

5.Give a complete description of the cardiac cycle. Include the electrical stimulation, specifics of blood flow and volume changes during the cycle.

6. Discuss in detail how the pH of the blood is regulated. Describe 2 situations in which pH levels might be abnormal and what would occur in the body to compensate for these alterations.

7. Discuss how the body reacts to a large amount of blood loss. Be sure to include how this loss in volume is sensed and what chemicals are released to signal the compensatory mechanisms.

8.Describe in detail the digestion and absorption of lipids. How are lipids transported and utilized throughout the body.

Answer 1

1. In the lymphatic system,When naive B cells encounter the foreign antigens (like bacteria), expresses the membrane bound antibodies on their surface ,it helps in differentiation of the naive cells into memory and effector plasma cells. The memory cells contains the membrane bound antibodies exactly like the naive B cells which helps in identifying the antigen ,if it attacks second time. The plasma cells produces the antibodies which helps in killing the foreign antigens. On the other hand, T cells present in thymus contains the receptors such as T-cell receptor , CD4 and CD8receptors. They expresses either CD4 or CD8 in one cells , one cell can't express both receptors together. Now T cell receptor recognize the antigen which are expressing membrane bound receptors (MHC I and II) .MHCI and II are present on the surface of the dendritic cells and macrophages.Mature T cells recoginze the foreign antigen with self MHC molecule to elicit the immune response. The mature T cells after clonal selection in the thymus , produces the Helper T cells, cytotoxic cells and regulatory T cells. Helper T cells expresses the CD4 and activate other T cells ,B cells and other immune cells to fight off the antigen.Cytotoxic cells expresses CD8 and helps in killing the foreign antigen by secreting cytotoxic proteins. T regulatory cells helps in recognizing self and foreign antigen and expresses CD24 on their surface.

The memory T and B cells helps in remembering the antigen attack called as immunological memory.The second time infection will be recognized by the memory cells and in response it will activate other immune cells to fight back with higher immune reponse.