A. Doctors and nurse are constantly exposed to many infectious patients. Why are doctors and nurses not continuously ill?

B. Why is the lymphatic system a “highway” for the spread of certain metastatic cancers?

C. Erythrocyte-structure and function

Erythrocytes (mature red blood cells) lose their mitochondria, nucleus, ribosomes and many cytoplasmic enzymes during development. How does this affect the shape of the cell? How does its structure relate to its function?

D.Humoral versus cell mediated immunity

Describe humoral immunity and cell-mediated immunity. Include in your answer the types of immune cells involved in each, the location of antibodies and receptors that bind foreign antigens, and the ways in which invading cells are destroyed.

Please provide references