Endocrine and Exocrine Glands

The pituitary gland is located at the base of the brain, inside the skull (specifically in the sella turcica of the sphenoid bone).

The pancreas is a heterocrine (mixed) gland because it functions both as an endocrine gland (releasing insulin and glucagon) and an exocrine gland (releasing digestive enzymes into the digestive tract).

Sebaceous glands are exocrine glands that secrete sebum (an oily substance) onto the skin surface through ducts, whereas the others secrete hormones directly into the bloodstream.

The hypothalamus serves as the primary link between the nervous system and the endocrine system, controlling the pituitary gland and thereby regulating other endocrine glands.

Mammary glands are exocrine glands because they secrete milk through ducts to the external environment. In contrast, the adrenal, thyroid, and pituitary glands are endocrine glands that secrete hormones directly into the bloodstream.

Endocrine glands are ductless glands that secrete chemical messengers called hormones directly into the bloodstream to act on distant target organs. Exocrine glands, by contrast, secrete substances into ducts or body cavities.

The parathyroid glands produce parathyroid hormone, which is the primary regulator of calcium levels in the blood and bones.

Acne is primarily caused by the overactivity of sebaceous glands, which produce oil (sebum). The option provided contains a typo ('celebrations' instead of 'sebaceous').

The pituitary gland is known as the master gland because it secretes hormones that regulate the activity of other endocrine glands.

• Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood(ductless) rather than through a duct.
•  The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. Hence, Ductless gland is a feature of endocrine glands.

The adrenal glands, specifically through the secretion of hormones like aldosterone and adrenaline, play a critical role in regulating blood pressure. Aldosterone helps regulate blood volume by managing sodium and water retention.

While the pituitary gland is known as the 'master' endocrine gland, both of its lobes are under the control of the hypothalamus; the anterior pituitary receives its signals from the parvocellular neurons and the posterior pituitary receives its signals from magnocellular neurons.

In humans, pheromones are secreted onto our skin through the apocrine glands (sometimes called as human scent glands). These are similar to eccrine glands but the apocrine glands secrete a more oily substance. The apocrine glands are normally associated with hairy areas, such as armpits and the crotch area, and are also usually accompanied by eccrine glands, which help to disperse the pheromone secretions. Apocrine glands are activated at puberty, along with hair growth in the axillary (armpit) regions and crotch, which increase the surface area for pheromone dispersal. 

a) Hypothalamus maintains the constant human body temperature by regulation of the diameter of blood vessels (constriction to conserve heat during body temperature lower than normal or dilation to lose heat by increasing blood flow during body temperature higher than the normal range), shivering and sweating mechanisms.