Chemical Coordination and Integration Test 17

Pituitary gland also known as the master gland. It is responsible for the production of various hormones e.g. Thyroid stimulating hormone, prolactin, oxytocin, Growth hormone etc.

The pineal gland or epiphysis synthesizes and secretes melatonin, a structurally simple hormone that communicates information about environmental lighting to various parts of the body. The precursor to melatonin is serotonin, a neurotransmitter that itself is derived from the amino acid tryptophan. Within the pineal gland, serotonin is acetylated and then methylated to yield melatonin.

Calcitonin or thyrocalcitonin is a polypeptide hormone produced by the parafollicular cells or the c-cells present in thyroid. This hormone is responsible for regulation of blood calcium and phosphorus. It results in generation of opposite effects of parathyroid hormone. Main effect of calcitonin is to reduce the blood calcium level in blood by inhibiting the bones’ osteoclastic activity, stimulation of osteoblastic activity in bones and promotes excretion of calcium in the urine.

The endocrine parts of the pancreas are islets of Langerhans that produce and secrete insulin and glucagon hormones. 

A group of cells performing a same function is known as tissue. Many tissues together form the organ of the organ system in an organism. Thus the group of cells making insulin in the organ pancreas is the tissue.

Thyroid, adrenal, testis all are endocrine glands because they are ductless glands and they pour secretion directly into the blood and secretes hormones.

Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle. They produce testosterone. A Sertoli cell is a part of a seminiferous tubule and helps in the process of spermatogenesis; that is, the production of sperm.

• Glucagon is secreted by the alpha cells of the Islets of Langerhans in response to a fall in the blood glucose level. 
• It stimulates the change of glycogen stored in the liver to blood glucose. It also triggers the formation of glucose from amino acids and fats. 
• Both the processes increase the blood-glucose level to provide energy between meals. 
• Estrogen and progesterone are female sex hormones.
• Oxytocin is a hormone and a neurotransmitter that is involved in childbirth and breastfeeding.
  
• Vasopressin or antidiuretic hormone (ADH) causes the kidneys to reabsorb solute-free water from urine.