Major<unk> s The human<unk>  consists of several<unk> s that operate via feedback loops. Several important feedback<unk> s are mediated via the hypothalamus and pituitary. * TRH – TSH – T3/T4 * GnRH – LH/FSH – sex hormones * CRH – ACTH – cortisol * Renin – angiotensin – aldosterone * leptin vs. Ghrelin Glands<unk>  glands are glands of the<unk>  that secrete their products, hormones, directly into interstitial spaces where they are absorbed into blood rather than through a duct. The major glands of the<unk>  include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs. The hypothalamus and the anterior pituitary are two out of the three<unk>  glands that are important in cell signaling. They are both part of the HPA axis which is known to play a role in cell signaling in the nervous<unk> . Hypothalamus: The hypothalamus is a key regulator of the autonomic nervous<unk> . The<unk>  has three sets of<unk>  outputs which include the magnocellular<unk> , the parvocellular<unk> , and autonomic intervention. The magnocellular is involved in the expression of oxytocin or vasopressin. The parvocellular is involved in controlling the secretion of hormones from the anterior pituitary. Anterior Pituitary: The main role of the anterior pituitary gland is to produce and secrete tropic hormones. Some examples of tropic hormones secreted by the anterior pituitary gland include TSH, ACTH, GH, LH, and FSH. Cells There are many types of cells that make up the<unk>  and these cells typically make up larger tissues and organs that function within and outside of the<unk> . * Hypothalamus * Anterior pituitary gland * Pineal gland * Posterior pituitary gland * The posterior pituitary gland is a section of the pituitary gland. This organ does not produce any hormone but stores and secretes hormones such as antidiuretic hormone (ADH) which is synthesized by supraoptic nucleus of hypothalamus and oxytocin which is synthesized by paraventricular nucleus of hypothalamus. ADH functions to help the body to retain water; this is important in maintaining a homeostatic balance between blood solutions and water. Oxytocin functions to induce uterine contractions, stimulate lactation, and allows for ejaculation. * Thyroid gland * follicular cells of the thyroid gland produce and secrete T3 and T4 in response to elevated levels of TRH, produced by the hypothalamus, and subsequent elevated levels of TSH, produced by the anterior pituitary gland, which further regulates the metabolic activity and rate of all cells, including cell growth and tissue differentiation. * Parathyroid gland * Epithelial cells of the parathyroid glands are richly supplied with blood from the inferior and superior thyroid arteries and secrete parathyroid hormone (PTH). PTH acts on bone, the kidneys, and the GI tract to increase calcium reabsorption and phosphate excretion. In addition, PTH stimulates the conversion of Vitamin D to its most active variant, 1,25-dihydroxyvitamin D3, which further stimulates calcium absorption in the GI tract. * Adrenal glands * Adrenal cortex * Adrenal medulla * Pancreas * Pancreas contain nearly 1 to 2 million islets of Langerhans (a tissue which consists cells that secrete hormones) and acini. Acini secretes digestive enzymes. * Alpha cells * The alpha cells of the pancreas secrete hormones to maintain homeostatic blood sugar. Insulin is produced and excreted to lower blood sugar to normal levels. Glucagon, another hormone produced by alpha cells, is secreted in response to low blood sugar levels; glucagon stimulates glycogen stores in the liver to release sugar into the bloodstream to raise blood sugar to normal levels. * Beta cells * 60% of the cells present in islet of Langerhans are beta cells. Beta cells secrete insulin. Along with glucagon, insulin helps in maintaining glucose levels in our body. Insulin decreases blood glucose level ( a hypoglycemic hormone) whereas glucagon increases blood glucose level. * Delta cells * F Cells * Ovaries * Granulosa cells * Testis * Leydig cells
Endocrine system
Reproductive system
Autonomic nervous system
Somatosensory system
Integumentary system
Immune system
Immune cycle
Female reproductive system