Hypothalamic, Pituitary, Adrenal And Parathyroid Histology

Somatotrophs are the cell type that produces growth hormone. Growth hormone is a hormone that stimulates growth, cell reproduction, and regeneration in humans and other animals. Somatotrophs are found in the anterior pituitary gland and are responsible for the secretion of growth hormone.

Aldosterone is the correct answer because it is the hormone produced by the zona glomerulosa. The zona glomerulosa is one of the three layers of the adrenal cortex, and it specifically produces aldosterone, which is responsible for regulating blood pressure and electrolyte balance in the body. LH, FSH, melatonin, and cortisol are not produced by the zona glomerulosa.

The correct answer is E) Neuroectoderm gives rise to the neurohypophysis. The neurohypophysis, also known as the posterior pituitary, is derived from neuroectoderm during embryonic development. This is in contrast to the anterior pituitary, which is derived from the oral ectoderm. The neurohypophysis is responsible for storing and releasing hormones produced by the hypothalamus, while the anterior pituitary produces and releases its own hormones.

Aldosterone is produced as a result of angiotensin II stimulation. Angiotensin II is a hormone that is released by the kidneys in response to low blood pressure or low blood volume. It acts on the adrenal glands to stimulate the production and release of aldosterone. Aldosterone is responsible for regulating the balance of water and electrolytes in the body, particularly sodium and potassium. It helps to increase blood volume and blood pressure by promoting the reabsorption of sodium and the excretion of potassium in the kidneys.

Somatotrophs are a type of acidophilic cells found in the anterior pituitary gland. They are responsible for producing and secreting growth hormone (GH), also known as somatotropin. GH plays a crucial role in regulating growth, metabolism, and body composition. Acidophils are characterized by their affinity for acidic dyes and make up a significant portion of the anterior pituitary gland.

The correct answer is E) Thyroid follicular cells secrete T4 hormone. The thyroid gland is derived from the endoderm of the pharyngeal floor, not the 3rd pharyngeal pouch (option A is incorrect). The parathyroid gland, not the thyroid gland, secretes parathyroid hormone (option B is incorrect). Chief cells in the parathyroid gland, not the thyroid gland, are involved in the production of calcitonin (option C is incorrect). The colloid in the thyroid gland is primarily composed of thyroglobulin, not calcitonin and T3 (option D is incorrect). Thyroid follicular cells secrete thyroxine (T4) hormone, not calcitonin (option E is correct).

Androstenedione is produced by the zona reticularis, which is the innermost layer of the adrenal cortex. It is an androgen hormone that is converted into testosterone and estrogen in the body. Androstenedione plays a role in the development of secondary sexual characteristics and is involved in the regulation of reproductive functions.

The correct answer is D) Oral ectoderm gives rise to the anterior pituitary. During embryonic development, the anterior pituitary gland is formed from a structure called Rathke's pouch, which is derived from the oral ectoderm. The oral ectoderm invaginates to form Rathke's pouch, which eventually differentiates into the anterior pituitary gland. The posterior pituitary gland, on the other hand, is derived from neuroectoderm. Therefore, option D is the correct statement regarding the embryology of the pituitary gland.

Herring bodies are specialized structures found in the posterior pituitary gland that store and release hormones such as oxytocin and vasopressin. These hormones are produced in the hypothalamus and are transported to the posterior pituitary for storage and subsequent release into the bloodstream when needed. Therefore, option B is correct as it accurately states that Herring bodies store oxytocin and vasopressin.

The correct answer is B) the patient's short stature is due to hypothalamic dysfunction. This is indicated by the substantial increase in plasma GH after the injection of GHRH. GHRH stimulates the release of GH from the pituitary gland, and if there is a significant increase in GH levels, it suggests that the patient's pituitary gland is capable of producing GH. Therefore, the short stature is likely due to a dysfunction in the hypothalamus, which regulates the release of GHRH.

When hormones are bound to proteins in the plasma, it usually prolongs the hormone's half-life. This is because the protein-bound form of the hormone is protected from rapid metabolism and excretion. Therefore, the hormone remains in circulation for a longer period of time, allowing it to exert its effects on target tissues.

Hypothalamic releasing hormones are proteins or polypeptides that are released in a pulsatile manner. This means that they are released in short bursts or pulses rather than continuously. This pulsatile release allows for precise control and regulation of hormone levels in the body. By releasing these hormones in a pulsatile manner, the hypothalamus can effectively communicate with the pituitary gland and other target cells to regulate various physiological processes.