User:Phys98/Endocrine system

CELLS

Hypothalamus- the hypothalamus has major releasing and inhibiting hormones that play an important role in the regulation of many bodily functions such as eating and drinking, blood pressure and heart rate, body temperature maintenance,sexual functions and behaviors,  the sleep-wake cycle, and emotional states. (1)

Anterior pituitary gland- the anterior pituitary gland produces several hormones that stimulate the adrenal glands, gonads or thyroid gland to produce target gland hormones or affect target organs. (1)

Pineal gland- The pineal gland is a small endocrine gland. Its main function is to produce and secrete the hormone melatonin at night. (2)

Adrenal glands-consist of an outer layer (cortex) and an inner layer (medulla)


 * Adrenal cortex- Produces various hormones primarily corticosteroids as well as sex hormones (1)
 * Adrenal medulla- produces the hormones adrenaline and noradrenaline that are involved in the fight-flight response to stress factors. (1)

Pancreas- the pancreas acts an exocrine organ, it plays a role in digestion by producing enzymes that break down food. It also acts as an endocrine organ because it secreted blood sugar regulating hormones: insulin and glucagon. (1)


 * Beta cells- is a cell able to secrete insulin in response to elevated glucose levels(3)
 * Delta cells- are somatostatin producing cells, a negative regulator of insulin, glucagon and pancreatic polypeptide secretion. (3)
 * F Cells-  pancreatic polypeptide also called PP cells, an inhibitor of glucagon release at low glucose levels. (3)
 * Ovaries-  are able to secret two major hormones oestrogen and progesterone  These hormones are involved in the menstrual cycle process.
 * Granulosa cells are important in the female reproductive system and development. These cells produce steroids then after ovulation is complete the cells start to secret progesterones.
 * Testis-  also known as testicle is male reproductive gland responsible for production of sperm and testosterone. Testosterone is a hormone which has many roles in a male’s development such as facial and body hair growth.

Leydig cells- also able to produce testosterone and androgen, they are connective tissues surrounding testes.
 * CELL SIGNALLING  The typical mode of cell signalling in the endocrine system is endocrine signaling, that is, using the circulatory system to reach distant target organs. The hormones released by endocrine signalling travel via the bloodstream, moving slower throughout the body. (4) However, there are also other modes, i.e., paracrine, autocrine, and neuroendocrine signaling. Purely neurocrine signaling between neurons, on the other hand, belongs completely to the nervous system.
 * Autocrine signaling is a form of signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on the same cell, leading to changes in the cells. Autocrine signalling also regulates pain sensation and inflammatory responses. The cells can signal themselves to undergo programmed cell death if they are infected with a virus. (4)
 * (Addition to Paracrine) - mostly cells with paracrine signaling only communicate short distance through secretion of chemical messengers.They can actively interact and work together with neighboring cells.
 * Juxtacrine is a type of signaling that occurs within close contact of cells. This contact dependent signalling is an example of notch signaling.
 * REFERENCES ADDED
 * Hiller-Sturmhöfel, S., & Bartke, A. (1998). The endocrine system: an overview. Alcohol health and research world, 22(3), 153–164.
 * Aulinas A. Physiology of the Pineal Gland and Melatonin. [ Updated 2019 Dec 10]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK550972/
 * Da Silva Xavier G. (2018). The Cells of the Islets of Langerhans. Journal of clinical medicine, 7(3), 54. https://doi.org/10.3390/jcm7030054
 * Hinić-Frlog, S. (2020, August 13). Signaling Pathways, Hormones and Endocrine System. Retrieved March 10, 2021, from https://chem.libretexts.org/@go/page/9591