hormone produced by different glands and its function

Regulation of Hormone Secretion

Endocrine glands release hormones when they are required. Changes in the blood or other hormones in the blood cause the cells of the endocrine glands to react. These stimuli provide information on how to boost or lower hormone secretion. An endocrine gland will release its hormone into the blood when it is activated. The hormone's blood level falls in the absence of stimulation. The nervous system's signal, a chemical shift in the blood, and other hormones all work together to control hormone secretion.

Hormone secretion in the human body is controlled by a system of positive and negative feedback. Information concerning the hormone's side effects is fed back to the gland during negative feedback. As a result, the hormone is secreted less frequently. The mechanism is known as "negative" because of this.

The hormones' effects counteract the stimulus and reduce hormone secretion. In a positive feedback mechanism, for instance, during childbirth, the hormone oxytocin stimulates uterine contractions, which in turn stimulate the release of more oxytocin. The mechanism is known as "positive" because of this.

The Hypothalamus and the Pituitary Gland

The hypothalamus is an essential endocrine gland and regulatory center for the neurological system. The hypothalamus' cells produce a variety of hormones. The majority of the endocrine glands are controlled by the pituitary and hypothalamus working together. They are frequently referred to as "the master control" of the endocrine system or "the master of the master gland" as a result.

A stalk connects the hypothalamus, which is situated below the thalamus, to the pituitary gland. Hormones that release and inhibit are secreted by the hypothalamus.

Releasing Hormones:

• TRH (thyroid releasing hormone): Cause to release TSH
• CRH (corticotropin releasing hormone): Cause to release ACTH
• GnRH (gonadotropin releasing hormone): Cause to release FSH and LH
• PRF (Prolactin releasing hormone): Cause to be release PRL
• GHRH (Growth hormone Releasing hormone) : Cause to be release GH

Inhibiting Hormones:

• PIF (Prolactin Inhibiting Factor): Inhibits the secretion of the PRL
• GH (Growth hormone): Inhibits the secretion of GH

Pituitary Gland

The pituitary gland, also known as the hypophysis, is a pear-shaped structure that is located in the sphenoid bone's hypophyseal fossa (sella trucica). It is wedged between the hypothalamus and is stalk-attached to it (infundibulum). It weighs about 500 mg and has a diameter of about 1 cm. It has three lobes that are distinct both physically and functionally. Between the anterior pituitary, also known as the adenohypophysis, and the posterior lobe, also known as the neurohypophysis, is a thin strip of tissue known as the intermediate lobe.

Blood Supply of the Pituitary gland

The internal carotid artery's branches supply the hypothalamus with arterial blood. A network known as the hypothalamo pituitary portal system supplies the hypothalamus and anterior lobe with blood. The posterior lobe is supplied by the carotid artery branch.

Anterior lobe of Pituitary Gland

At the base of the brain, the anterior pituitary gland is located beneath the hypothalamus. This structure is crossed by the optic chiasma. About 75% of the weight of the pituitary gland is made up of the anterior pituitary gland, also known as the adenohypophysis. The hypothalamus releases hormones that control the majority of the pituitary gland's hormone secretions. The anterior pituitary gland receives the released hormones through a capillary network in the hypophyseal portal veins. There are five different cell types in the anterior pituitary: somatotrophs, thyrotrophs, gonadotrophs, lactotrophs, and corticotrophs.

Hormones of the Anterior lobe of Pituitary Gland

The hypothalamus regulates the anterior pituitary lobe's ability to secrete hormones. Six hormones are produced and secreted by the anterior lobe. Growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, follicle stimulating hormone, leutinizing hormone, and prolactin are among the hormones generated by the anterior pituitary gland. Trophic hormones that control the activity of other endocrine glands include thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), follicular stimulating hormone (FSH), and leutinizing hormone (LH).

Growth hormone (GH): Somatotrophs of the adenohypophysis release growth hormone, also known as somatotropin, predominantly under hypothalamic control. GHRH (Somatocrinin), hypoglycemia, fasting, elevated plasma levels of amino acids (such as arginine), stress (either physical or psychological), exercise, deep sleep, and blood glucagon levels are just a few of the many variables that may influence GH secretion. The release of GH may be inhibited by GHIH (somatostatin), hyperglycemia, increased plasma levels of free fatty acids, blood cortisol levels, and alpha-adrenergic blocking medications.

Functions of the Growth Hormone:

• IGF, a hormone that promotes cellular growth and metabolism, is produced by cells in response to growth hormone.
• The growth of bones, cartilage, organs, and other tissues is encouraged by GH.
• Effects of GH on protein, lipid, and carbohydrate metabolism
• In the liver and muscles, it aids in protein synthesis.

Prolactin (PRL): It is produced by lactotrophs, whose size and population significantly increase during pregnancy. They start secreting PRL as soon as the woman gives birth and keep doing so throughout the breastfeeding phase. PRL influences the mammary gland to encourage the production of milk. It has a gonadotropic impact on males and increases the sensitivity of the testes to LH.

Control of secretion

The anterior pituitary lobe's lactotrophs secrete prolactin (PRL). Sucking and tactile nipple stimulation increase PRL secretion, which rises during pregnancy and peaks close to the time of delivery. A negative feedback mechanism controls prolactin secretion by facilitating dopamine release in the hypothalamus.

Functions of PRL:

• The hormone prolactin starts and keeps the breasts' milk production going.
  Additionally, it blocks the effects of gonadotropins and may stop lactating women's ovulation.

Thyroid stimulating hormone (TSH): The thyroid gland is the target organ of the thyroid stimulating hormone (TSH), which is also known as thyrotropin. Thyroxin (T4) and triiodothyronine are secreted from the thyroid in accordance with typical development patterns when TSH is present (T3). Thyrotropin releasing hormone (TRH) from the hypothalamus stimulates the secretion of TSH, which is then released by thyrotrophs cells in the anterior pituitary lobe.

Function of TSH:

• The thyroid gland is maintained and stimulated by thyroid-stimulating hormones. It encourages the production of the thyroid hormones triiodothyronine (T3) and thyroxine (T4).

Adreno-corticotropic hormone (Corticotropin, ACTH): The corticotrophic cells secrete ACTH. It encourages the adrenal cortex to release cortisol and other chemicals. The corticotropin-releasing hormone (CRH) hypothalamus, which has a daily circadian rhythm with peak production in the morning, increases the secretion of ACTH. The hypophyseotropic hormone corticotropin-releasing hormone controls the release of ACTH (CRH). Numerous stressors seem to cause an increase in ACTH production, which is thought to be mediated by the hypothalamus and CRH. Increased plasma free glucocorticoid (cortisol) levels prevent the release of both CRH and ACTH. Any physical strain, injury, exercise, or hypoglycemia will result in the production of CRH.

Functions of ACTH:

• Effects of the adrenocorticotropic (ACTH) hormone on the adrenal glands that support corticosteroid production and structural integrity.

Luteinizing Hormone (LH): The LH is a gonadotropic hormone also known as interstitial cell stimulating hormone. It stimulates ovulation in women (the release of mature ova form an ovarian follicles). The corpus luteum, which secretes progesterone, develops from that follicle after being stimulated by LH. In male, LH stimulates the interstitial cells in the tests to secrete testosterone". GnRH causes the glycoprotein hormone LH to secrete more.

The adenohypophysis is directly affected by testosterone, which also has a negative feedback effect on LH (in the absence of progesterone), whereas high estrogen levels have an indirect effect by preventing the release of GnRH from the hypothalamus. The production of LH increases as a result of consistent, moderate estrogen levels. In the luteal phase of the ovulatory cycle, high levels of progesterone and estrogen inhibit LH secretion.

Functions of LH:

• This hormone increases testosterone production in males by the testicular interstitial cells.
• LH supports the maintenance of ovarian follicle maturation and estrogen secretion in females.
• Ovulation and the development of the corpus luteum are additional processes governed by LH.

Follicle stimulating Hormone (FSH): The gonadotrophs, a type of cell, secrete the FSH. It encourages the growth of the ovaries in females. It promotes the production of in the testicles in males.

Functions of FSH:

• Male spermatogenesis is aided by the FSH's direct stimulation of the sertoli cells in the testicular seminiferous tubules.
• FSH encourages follicular development and growth in the ovaries of females.