Identify the hormones that are released from the adrenal cortex and are involved in stress response. (Select all that apply)

A. Osteocyte; maintaining bone tissue:Osteocytes are mature bone cells embedded within the bone matrix. Their primary role is to maintain the mineral concentration of the matrix and communicate mechanical stress to other cells, but they do not primarily break down or build bone mass.

B. Osteoclast; breaking down bone tissue:Osteoclasts are large, multinucleated cells responsible for resorption-the process of breaking down bone tissue to release minerals (like calcium) into the blood. In osteoporosis, osteoclast activity often outpaces osteoblast activity, leading to net bone loss.

C. Chondrocyte; forming cartilage:Chondrocytes are the cells found in cartilage, not bone. They are responsible for producing the cartilaginous matrix (collagen and proteoglycans).

D. Osteoblast; forming new bone tissue:Osteoblasts are the "builders." They synthesize the bone matrix (collagen) and coordinate the mineralization process. While essential for health, the question specifically asked for the cell responsible for resorption.

A. Parathyroid hormone (PTH):PTH is the principal hormone that raises blood calcium. It increases bone resorption (releasing Ca²⁺), enhances renal calcium reabsorption, and stimulates activation of vitamin D (calcitriol) in the kidney, which increases intestinal calcium absorption.

B. Thyroxine:Thyroxine (T4) regulates metabolic rate and growth. It does not play a primary role in acute regulation of serum calcium, although chronic thyroid disease can influence bone turnover indirectly.

C. Cortisol:Cortisol (a glucocorticoid) can affect bone metabolism and calcium balance with long-term excess (promotes bone resorption and can reduce calcium absorption), but it is nota primary hormone for short-term physiologic regulation of serum calcium.

D. Insulin:Insulin primarily regulates glucose uptake and metabolism; it does not directly regulate serum calcium levels.

E. Calcitonin:Secreted by the thyroid C cells, calcitonin lowers blood calcium by inhibiting osteoclast activity and decreasing bone resorption. Its role in humans is less critical than PTH for everyday calcium homeostasis, but it is a classical calcium-lowering hormone.

F. Glucagon:Glucagon primarily raises blood glucose by stimulating glycogenolysis and gluconeogenesis. It does not have a primary role in calcium regulation.