Gland Endocrine glands secrete substances that circulate through the blood stream. The glands secrete their products through basal lamina into the blood stream. Basil lamina typically can be seen a layer around the glands to which a million maybe more tiny blood vessels are attached. These glands often secrete hormones which play an important role in maintaining homeostasis. The pineal gland, thymus gland, pituitary gland, thyroid gland, and the two adrenal glands are all endocrine glands. Exocrine glands secrete their products through a duct onto an outer surface of the body, such as the skin or the gastrointestinal tract. Secretion is
Evolution of the brain Evolution of the brain The principles that govern the evolution of brain structure are not well understood. Brain to body size does not scale isometrically (in a linear fashion) but rather allometrically. The brains and bodies of mammals do not scale linearly. Small bodied mammals have relatively large brains compared to their bodies and large mammals (such as whales) have small brains; similar to grow If brain weight is plotted against body weight for primates, the regression line of the sample points can indicate the brain power of a primate species. Lemurs for example fall below this line which means