The Endocrine System: The Pituitary Gland and How it Regulates Other Glands (Essay Sample)

THE ENDOCRINE SYSTEM
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3.1 The pituitary gland and how it regulates other glands
The pituitary gland plays a vital in role in controlling other important glands in the body. First, the posterior pituitary gland secretes oxytocin hormone that controls mammary gland. The hormone induces milk-injection reflex that bring about smooth muscle contraction around the ducts and mammary gland. The contraction causes injection of milk to the nipple during breastfeeding. Second, the anterior pituitary gland produces adrenocorticotropic hormone (ACTH) (Pituitary, Hypothalamus, Central Nervous System 2007). ACTH arouses the cortex of the adrenal gland to release corticosteroids hormones such as cortisol, aldosterone, and sex hormones. The secretion of cortisol regulates glucose equilibrium in the blood. Third, it regulates mammary gland through the production of prolactin (PRL) by the anterior pituitary gland. Prolactin induces milk production (Lancraft 2003).
Fourth, production of thyroid-stimulating hormone (TSH) controls the thyroid gland. FSH stimulates the thyroid gland to secrete thyroxine hormone which helps in iodine production. Thyroxine also is used to initiate oxidative respiration. Lastly, luteinizing hormone (LH) and follicle stimulating hormone (FSH) produced by anterior pituitary gland are used to control gonads; testes and ovaries. FSH stimulates the testes to produce sperms in male and stimulate ovarian follicle development in female. LH stimulates secretion of testosterone in male while in female it induces corpus and ovule formation (Grossman 2013).
3.2 Description on how the pituitary is linked with the nervous system
The pituitary gland and the nervous system are linked through the function of hypothalamus. The hypothalamus is largely involved in the manufacture of several hormones that play part in either inhibiting or stimulating the pituitary gland in producing its various hormones (Watson & Miller 2004). Therefore, the functions of the pituitary gland are regulated by the hypothalamus. The hypothalamus receives a signal from the nervous system which stimulates production of signals recognized as neurohormones that are used to stop or start hormonal production in the pituitary gland. For example, corticotropin-releasing hormone (CRH) signals the anterior part of the pituitary gland to stimulate the adrenal gland which in turn releases corticosteroids. Gonadotropin-releasing hormone (GnRH) is used to signal the anterior pituitary gland to discharge luteinizing hormone and follicle stimulating hormone used to ensure that ovaries and test work properly. The hypothalamus also induces the anterior pituitary gland to secrete growth hormone or inhibit growth hormone release through growth hormone-releasing (GHRH) and growth hormone inhibiting hormone (GHIH) respectively (Grossman 2013).
4.1 Condition under which adrenaline production is initiated
The adrenal medulla and sympathetic system of the nervous work together in the manufacture of adrenaline (epinephrine). The circumstance leading to the production of adrenaline varies from one individual to another. They include;
* Exercise. The concentration of adrenaline increases steadily during exercises. This is due to increased production from the medulla part of the cortex and also due to decreased blood flow in the hepatic artery (Watson & Miller 2004).
* Emotional response. Adrenaline production can also be initiated by emotional response due to stress. The most disturbing emotion that can lead to epinephrine release is fear. Elevated concentration of epinephrine is correlated to the level of aroused state of harmful feelings (Grossman 2013).
* Chemicals. Imbalance in the body of acid-base as well as decreased levels of oxygen supply to the system result to the production of epinephrine. High levels of cortisol can also increase concentration of epinephrine since the conversion of norepinephrine to epinephrine is regulated by phenyl ethanolamine-N-methyltransferase which in turn is induced by cortisol (Rogers 2012).
4.2 Describe some of the hormones of adrenal gland and their effects
Through its secretion of hormones, the adrenal gland plays a vital role in regulating body function such as response to stress and biological substances balance. Both the medulla and cortex secrete different types of hormones (Endocrine System 2014). The cortex releases the following hormones;
* Mineralocorticoids they are released from the outermost part of the cortex. These hormones help in maintaining proper concentration of minerals such as sodium, potassium, and chlorines ions and also play a role in regulation of blood volume (Endocrine System 2014). Aldosterone helps in regulating sodium and potassium ions in blood. The secretion of aldosterone is initiated when the level of sodium falls below the required concentration. The response starts with renin from the kidney to produce angiotensin II which is used to signal the adrenal gland to secrete aldosterone (Lancraft 2003). Aldosterone also regulates water in the blood. Aldosterone is also stimulated by increased levels of potassium ions in blood.
* Glucocorticoids hormones are manufactured in the inner and middle parts of the cortex. A major glucocorticoid hormone is cortisol which is involved in regulating glucose synthesis during the conversion of proteins or fats into amino acids which also undergo conversion to form glucose. The formation of glucose is called gluconeogenesis and because of this function, these hormones are also known as hyperglycemic. This class of hormones also ensures proper functioning of cells (Pathophysiology, Homeostasis and Nursing 2003).
* Androgens and estrogens are manufactured by the innermost and middle parts of the adrenal cortex. They are referred as sex hormones. For the female, estrogen is the sex hormone while male contain androgen hormone. Estrogen and androgen causes feminizing and masculinizing effects respectively. Estrogen causes development of breasts and female genital organs and uterus growth in females. Androgen helps in the development of genital tract in male and also protein generation that leads to muscle mass increase (Jänig 2007).
The adrenal medulla on the other hand produces epinephrine and norepinephrine in different proportions. The two hormones are produced due to stress. Norepinephrine narrows the blood vessels while epinephrine arouses the heart. The two action increases blood pressure and heart rate. They play part in fight and flight mechanism that is initiated by the nervous system (Hoffman 2013).
4.3 How the adrenal gland plays to maintain homeostasis
The cortex part of the adrenal gland produces essential hormones that are used to control human body homeostasis. The mineralocorticoids are example of corticosteroids hormones secreted by the adrenal cortex to regulate water and electrolyte balance in the blood. The major mineralocorticoid is aldosterone hormone. This hormone is used to regulate sodium ion and potassium ion in the blood. Aldosterone is used to signal the nephrons to reabsorb sodium ions and eliminate potassium ions (Rogers 2012). The hormone is secreted due to low levels of sodium. In the occurrence of low sodium ion, renin is produced from the kidney to initiate the formation of angiotensin II. Angiotensin II in turn arouses the cortex of the adrenal gland to secrete more aldosterone. Increased level...