Tag: parts of the brain

Antidiuretic hormone, also known commonly as vasopressin, is a nine amino acid peptide secreted from the posterior pituitary. It has two principal sites of action: the kidney and blood vessels. Its two primary functions are to retain water in the body and to constrict blood vessels. 

Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. Bleeding occurs after oestrogen and progesterone levels decrease at the end of the previous cycle. This decrease causes the top layers of thickened lining of the uterus (endometrium) to break down and be shed. 

The adrenal cortex produces a hormone, called as aldosterone, that is involved in regulating the amount of salt and water in the body. Aldosterone is a mineralocorticoid, which acts on the principal cells of the collecting ducts, ducts of sweat and salivary glands.

In the male, luteinizing hormone promotes the development of the interstitial tissue (Leydig cells) of the testes and hence promotes the secretion of the male sex hormone, testosterone. 

Insulin helps control blood glucose levels by signaling the liver and muscle and fat cells to take in glucose from the blood. Insulin therefore helps cells to take in glucose to be used for energy.

Adrenaline is a natural stimulant hormone made in the adrenal gland of the kidney. Adrenaline is carried in the bloodstream and affects the autonomous nervous system, which controls functions such as the heart rate, dilation of the pupils, and secretion of sweat and saliva.

Progesterone is a hormone secreted by ovaries. It maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy. If a pregnancy occurs, progesterone is produced in the placenta, and levels remain elevated throughout the pregnancy. One of the progesterone's most important functions is to cause the endometrium to secrete special proteins during the second half of the menstrual cycle, preparing it to receive and nourish an implanted fertilized egg. If implantation does not occur, estrogen and progesterone levels drop, the endometrium breaks down and menstruation occurs.

In females, ovulation of mature follicles on the ovary is induced by LH secretion known as the preovulatory LH surge. Residual cells within ovulated follicles proliferate to form corpus luteum, which secretes the steroid hormones progesterone and estradiol. Progesterone is necessary for the maintenance of pregnancy, and, in most mammals, LH is required for continued development and function of corpora lutea. The name luteinizing hormone derives from this effect of inducing luteinization of ovarian follicles.

Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle. They produce testosterone in the presence of luteinizing hormone (LH). 

In men, testosterone plays a key role in the development of male reproductive tissues, such as the testis and prostate as well as promoting secondary sexual characteristics, such as increased muscle, bone mass, and the growth of body hair.