Glands - MCAT Biological and Biochemical Foundations of Living Systems

Of all the hormones listed, antidiuretic hormone (ADH) is the only one that neither acts on, nor is released by, the adrenal cortex. ADH is released from the posterior pituitary and causes the kidneys to retain more water.

Aldosterone (a mineralcorticoid) and cortisol (a glucocorticoid) are both incorrect choices because they are released by the adrenal cortex and would be greatly affected by trauma to that area. ACTH is released by the anterior pituitary and acts to stimulate the adrenal cortex; these hormones act as part of a negative feedback chain, so damage to the target area would temporarily cause more ACTH to be produced. The same goes for CRH, which is released by the hypothalamus and stimulates secretion of ACTH.

Endocrine glands secrete hormones into the blood stream, lined with endothelium, allowing them to travel through the blood and to act at a distant site. Exocrine organs, in contrast, secrete products into lumens that are lined with epithelium.

Mammary glands are used in lactation. Because the milk is not secreted into the blood, the mammary glands are not endocrine glands.

The hypothalamus releases hormones into the blood, such as corticotropin-releasing hormone (CRH). The pituitary releases hormones such as prolactin. The adrenal gland secretes hormones such as cortisol.

The adrenal medulla, derived from neural crest cells, is responsible for making and releasing epinephrine and norepinephrine. Epinephrine and norepinephrine are responsible for increasing heart rate and activating the sympathetic nervous system when released.

In contrast, the adrenal cortex is derived from mesoderm and releases steroid hormones like aldosterone and cortisol. Corticotropin-releasing hormone is made by the parvocellular neurons of the hypothalamus.

Epinephrine and norepinephrine are released by the neuroendocrine cells of the adrenal medulla. In times of stress and sympathetic nervous system activation, the adrenal medulla will release epinephrine to cause blood vessel constriction. These hormones allow for the "fight-or-flight" response.

In contrast, the adrenal cortex will secrete cortisol and other mineralcorticoids in response to long-term stress. These hormones are not involved in the fight-or-flight response, and rather serve to prepare the body to endure prolonged harsh conditions, such as dehydration, starvation, and extreme temperatures. Adrenocorticotropic hormone is released from the anterior pituitary to stimulate the adrenal cortex.

Growth hormone and thyroid-stimulating hormone do not interact with the adrenal gland.

Hormones cortisol and aldosterone are synthesized in the adrenal glands. Adrenal glands are made up of the adrenal cortex and the adrenal medulla. Adrenal medulla is involved in the synthesize of catecholamines (epinephrine and norepinephrine) whereas adrenal cortex synthesizes mineralocorticoids (aldosterone), glucocorticoids (cortisol), and androgens (testosterone, DHT, and DHEA).

Aldosterone is released upon stimulation from the renin-angiotensin system and serves to increase reabsorption of sodium in the collecting ducts of the kidney. Cortisol is released due to stress and serves to increase the metabolic rate.

Luteinizing hormone is produced and secreted by the anterior pituitary gland.

Antidiuretic hormone is produced by the hypothalamus, but secreted by the posterior pituitary gland. Epinephrine is produced by the adrenal medulla; aldosterone is produced by the adrenal cortex. Thyroxine (T4) is produced by the thyroid.

The correct answer is glucagon. Glucagon is secreted by the pancreas, not the pituitary gland. All the other answer choices are major hormones secreted by the pituitary that are essential to bodily functions.

Oxytocin is produced by the hypothalamus, but stored and released by the posterior pituitary, making it the correct answer. Antidiuretic hormone (ADH) is also released by the posterior pituitary, so its pairing with the hypothalamus was incorrect. Calcitonin is released by the thyroid, and aldosterone (like other corticosteroids) is released by the adrenal cortex. Thyroid-stimulating hormone (TSH) is released from the anterior pituitary.

The posterior pituitary secretes oxytocin, which is important for milk ejection from breasts and uterine contractions during labor.

Calcitonin, which serves to decrease serum calcium, is secreted by the thyroid gland. The adrenal cortex secretes aldosterone, which increases blood pressure by increasing sodium reabsorption and potassium secretion. The adrenal cortex also secretes cortisol, a steroid hormone that acts to increase serum glucose, aid in fat, protein, and carbohydrate metabolism, and suppress the body's immune system.

The posterior pituitary gland does in fact secrete oxytocin; however, all of the hormones secreted by the posterior pituitary gland are created in the hypothalamus. The hormones are then sent to the posterior pituitary gland in order to be secreted.

The anterior pituitary creates and secretes follicle-stimulating hormone. The pancreas creates and secretes glucagon and insulin. The adrenal cortex creates and secretes aldosterone.

The pituitary gland is comprised for the anterior and posterior pituitary. The anterior pituitary arises from the oral ectoderm, while the posterior pituitary arises from the neuroectoderm. Hormones are secreted from the anterior pituitary in response to stress or to promote milk production, growth, or reproduction. Follicle-stimulating hormone (FSH) is required for growth of the reproductive system.

The posterior pituitary is responsible for production and secretion of neurohypophysical hormones, including oxytocin and vasopressin. Somatostatin is produced from within the digestive system, and signals to the anterior pituitary to inhibit growth hormone secretion.

The hormones of the anterior pituitary can be remembered by using the pneumonic "FLAT PEG." The anterior pituitary secretes follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, prolactin, endorphins, and growth hormone.

The parvocellular neurons of the hypothalamus are responsible for secreting numerous hormones into the portal system, which are then delivered to the anterior pituitary. Thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH) are released from the parvocellular neurons. TRH stimulates the release of thyroid-stimulating hormone from the anterior pituitary, while CRH stimulates the release of adrenocorticotropic hormone from the anterior pituitary.

Vasopressin and oxytocin are secreted from the magnocellular neurons of the hypothalamus, and are released from the posterior pituitary.

The anterior pituitary releases a number of key hormones. These hormones can be memorized using the anagram "FLAT PEG."

Follicle-stimulating hormone (FSH)

Luteinizing hormone (LH)

Adrenocorticotropic hormone (ACTH)

Thyroid-stimulating hormone (TSH)

Prolactin (PRL)

Endorphins

Growth hormone (GH)

Thyrotropin-releasing hormone is actually released from the hypothalamus to trigger the anterior pituitary to secrete TSH.

The posterior pituitary releases antidiuretic hormone (vasopressin), which causes water retention in the kidneys, making this the correct answer.

Follicle-stimulating hormone causes follicle development, and is released from the anterior (not the posterior) pituitary.

Oxytocin causes uterine contractions, and is released from the posterior (not the anterior) pituitary.

Calcitonin helps to reduce blood calcium, and is released from the thyroid. Parathyroid hormone acts counter to calcitonin, and increases blood calcium.

Glucagon helps to increase blood glucose levels by stimulating glycogen break-down, and is released from the pancreas (not the adrenal gland).

The anterior pituitary is responsible for secreting hormones into the blood stream, once their respective releasing factors from the hypothalamus arrive through the hypothalamus-pituitary portal system. The anterior pituitary releases growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing-hormone, and prolactin.

The posterior pituitary is under neuronal control and releases vasopressin (antidiuretic hormone) and oxytocin.

The posterior pituitary is under neuronal control and is responsible for releasing vasopressin (antidiuretic hormone) and oxytocin.

In contrast, the anterior pituitary is under hormonal control from the hypothalamus, and is responsible for releasing growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin.

Oxytocin is produced by the hypothalamus and stored in the posterior pituitary gland. Upon stimulation, oxytocin is released from the posterior pituitary to cause lactation and uterine contractions during pregnancy, though it has also been linked to some social phenomena.

Growth hormone, follicle-stimulating hormone, and prolactin are produced and secreted from the anterior pituitary gland. Growth hormone promotes bone elongation and cell division. Follicle-stimulating hormone works to regulate the menstrual cycle. Prolactin stimulates milk production, while oxytocin stimulates the actual act of lactation.

Posterior pituitary gland has a direct connection to the hypothalamus whereas the anterior pituitary gland does not. The hormones secreted from posterior pituitary gland (oxytocin and ADH) are synthesized in the hypothalamus. Since there is a direct connection between the hypothalamus and the posterior pituitary, the synthesized hormones are transported directly into the posterior pituitary where they are stored and secreted.

Both glands are involved in releasing several important hormones; however, all the hormones released by both pituitary glands are peptide hormones. Steroid hormones are typically synthesized in the gonads and in the adrenal medulla.

Posterior pituitary does not synthesize its own hormones. As mentioned earlier, it receives hormones synthesized in the hypothalamus. Posterior pituitary serves to store and secrete the hormones. Anterior pituitary, on the other hand, can synthesize hormones. It often receives a signaling hormone from hypothalamus that initiates synthesis and release of hormones. For example, growth hormone releasing hormone (GHRH) released from the hypothalamus signals the anterior pituitary to synthesize growth hormone.

A major player in a growing person is the human growth hormone (hGH). hGH is a peptide hormone released from the anterior pituitary gland. Recall that the hormones secreted from the anterior pituitary gland are synthesized in the gland itself. It receives signaling hormones from the hypothalamus which tells the anterior pituitary gland to start synthesizing a particular hormone. In the case of hGH, hypothalamus releases GHRH (growth hormone releasing hormone) which signals the anterior pituitary to signal and release hGH. Since this person has a short stature, the person likely has a problem with synthesis or release of hGH from anterior pituitary gland.

The posterior pituitary is under neuronal control and is responsible for releasing vasopressin (antidiuretic hormone) and oxytocin.

In contrast, the anterior pituitary is under hormonal control from the hypothalamus, and is responsible for releasing growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin.