Answer to Question 1
Answer: The key to the body's successful immune system is the ability to distinguish self (or proteins that belong to its body) from non-self (proteins that belong to any other living thing).
Answer to Question 2
Answer: Cytotoxic T cells directly kill virus-infected cells and tumor cells. Helper T cells secrete proteins that promote inflammation by calling for the microphages to the site, stimulating B cells, and activating the cytotoxic T cells. Regulatory T cells help lower the immune response once the infection is under control. Memory T cells remember an antigen and therefore can produce new fighting cells rapidly.
Calipers being used to measure body fat on the triceps of a patient.
The respiratory system.
Typical wiring diagram of a V-6 distributorless (direct fire) ignition system.
An Enzyme in Action Enzymes speed up reactions in your body
The Nervous System and Homeostasis
Overview of the Digestive System