Chegg Guided Solutions for Human Anatomy 7th Edition: Chapter 23

0 Stars(0 users)
  • Step 1 of 1

    7126-23-1RC AID: 2498 | 09/05/2013

    Thymus is an important and specialized organ in the immune system. It is pyramid shaped lymphoid organ, present beneath the breast bone at the level of the heart. It has cortex and medullary regions.

    The thymus contains developing T cells. The main role of thymus is to prepare T cell for the adaptive immunity. The T cells will be educated to identify a foreign substance and are provided with receptors within the thymus.

    Thymosin is the hormone produced by thymus. That stimulates development of T cells. If the thymus failed to produce this hormone, a decrease in the number of cytotoxic T cells can be observed.

    The B cells are kind of white blood cells (lymphocytes). They make a vital part of the immune system. They are responsible for the humoral immunity of the adaptive immune system. The B cells have a protein receptor on their surface. That receptor is known as B cell receptor (BCR). It differentiates the B cells from T cells and NK (Natural killer) cells. B lymphocytes mature in bone marrow. Hence, option (a) is incorrect.

    NK cells stands for Natural Killer cells. They are a type of cytotoxic lymphocytes and play a critical role in innate immune system. They need not to be activated by some other cells, hence so named as “Natural Killer cells.” They provide rapid responses to viral infected cells. They also respond to tumor cells. NK cells differentiate and mature in lymph node, spleen, thymus, and bone marrow where they enter into the circulation. Hence, option (b) is incorrect.

    Neutrophils are one of the common types of WBC (white blood cells). These cells can ingest pathogens, and other cells, hence called phagocytic. Neutrophils start work at the site of infection for the first through a process called chemotaxis. They release number of primary, secondary, and tertiary granules that kill the bacteria. The hormone Thymosin does not have any impact on the decreasing the levels of neutrophils. Hence, option (d) is incorrect.

    Hence, the correct option is (c) cytotoxic T cells.

Step-by-step solutions for this book and 2,500 others
Already used by over 1 million students to study better