Rotate your specimen to a lateral perspective to visualize the location of the hypothalamus within the cranium. The hypothalamus is the part of the brain that regulates the pituitary gland. It forms the lower side walls (interolateral) of the brain's third ventricle (I bet you hoped you could safely purge the nervous system from your cerebral cortex...WRONG!). The hypothalamus controls the endocrine system in two distinct ways. First, it produces "releasing hormones" that control the secretion of hormones by the anterior pituitary. Second, it produces hormones called ADH and oxytocin.
Dissect away the hypothalamus and the hypothalamus tuber. The pituitary gland (hypophysis) secretes several critical hormones that regulate other endocrine glands. For this reason, it was once known as the "master gland". We now know, however, that the pituitary takes its orders from the hypothalamus which, in turn, takes its orders from the nervous system. Locate the following:
Located within the brain's third ventricle, the pineal gland secretes melatonin, the sleep hormone. Much remains to be learned about the physiological effects of melatonin. You will learn a bit more about it later in this lesson.
Some respiratory anatomy has been included so you can gain some perspective on the relative location of the thyroid.
Locate the following:
Locate the thymus in its rather unlikely location overlying the heart. Most students are completely unaware of this organ in such close association to the heart. You will learn about a few hormones secreted by the thymus and will learn even more about its immunity functions later in the course.
Rotate your specimen to a posterior perspective. A left superior and a right inferior parathyroid have already been highlighted to help you locate them, they are small! The parathyroids are partially embedded in the posterior surface of the thyroid gland. Classically, there is one superior and one inferior parathyroid on each lobe for a total of four, however, there is some variability in this pattern between individuals.
The parathyroids produce PTH, parathyroid hormone (pretty clever naming, eh?). You will learn more about PTH's function later in the lesson.
First, realize the kidneys and adrenal glands are NOT located in the right arm! :-) From this lateral perspective you can see the paired kidney's more posterior location. Rotate your specimen back to the anterior perspective. Identify the left and right adrenal glands (suprarenal glands) in their position atop the kidneys. As you will soon learn, adrenal anatomy is divided between the more superficial adrenal cortex and the centrally located adrenal medulla. Each of these areas are hormone secreting. You will learn about these hormones and their functions later in this lesson.
Embedded within the digestive system is the pancreas, a glandular "all star". The pancreas has both exocrine functions with the digestive system (discussed in another lesson) and endocrine functions that we'll take a look at here.
Locate the pancreas. You will find it neatly tucked between the stomach and the transverse colon. Once you have found it, zoom in for a better look and then dissect away digestive structures to give you a better view. The pancreatic islet cells produce four hormones that we'll examine later in the lesson.
These paired organs are located within the male scrotal sac external to the body cavity to maintain a slightly lower temperature more conducive to sperm formation. The testes are endocrine glands, too, secreting primarily testosterone. Again, you will learn more about male androgens later in the lesson. Due to surgery, your specimen has only a left testis.
The paired ovaries obviously have a reproductive function but they also serve as critical endocrine glands secreting several hormones. Again, each of these will be studied in the remainder of this lesson.