X Her brotherâs illness forced her to explore feelings that had lied dormant for some time. â â¦. that had lain dormantâ¦ [past perfect of lie (1)]. X I laid down on my bed and went to sleep. â I lay down on my bedâ¦ [simple past of lie (1)]. X Sheâs laying flat on her back, out for the count. â Sheâs lying flat on her backâ¦ [present continuous of lie (1)]. X When she died, she was lain in an ornate wooden coffin. â â¦she was laid in an ornate wooden coffin.
The receptors match only one specific antigen. White blood cells called lymphocytes originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus. There are two main types of lymphatic cells, T cells and B cells.he receptors match only one specific antigen. White blood cells called lymphocytes originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus. There are two main types of lymphatic cells, T cells and B cells.
Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells.The killer T cell has receptors that are used to search each cell that it meets. cells can also produce memory cells with an even longer life span than B memory cells. The second time an intruder tries to invade the body, B and T memory cells help the immune system to activate much faster. The invaders are wiped out before the infected human feels any symptoms.