It is called autocrine action. A hormone is a chemical substance produced in the body that controls and regulates the activity of certain cells or organs. Many hormones are secreted by special glands, such as thyroid hormone produced by the thyroid gland. They are essential for every activities of life, including the processes of digestion, metabolism among other activities. There are five types of signalling which include; intracrine, autocrine, juxtacrine, paracrine and endocrine cells.
Answer:
The correct answer would be - attention towards astronomy, mathematics, and science.
Explanation:
The Hellenistic period or age that covers the time period between 323 BC to the 31 BC also known as Mediterranean history. The major events that cover the Hellenistic period are the death of Alexander to the battle of the Actium which is significant as the emergence of the roman empire.
The Hellenistic Age has major achievements in the different fields of science, astronomy, and mathematics that include medicine, geography, and physics.
Thus, the correct answer is - attention to astronomy, mathematics, and science.
Hair follicles is the hair coming out of the subcutaneous layer
I believe it's B. Apologies if I'm wrong.
Answer:
A. Cholecalciferol, or vitamin D3, is necessary for the normal absorption of calcium and phosphate ions. Vitamin D3 is made by cells in the epidermis due to exposure to sunlight. Without enough exposure to sunlight, the body won't produce enough vitamin D3
Explanation:
Hydroxyapetite is the organic mineral in the bone that maintain the mechanical strengthening of the bone, by interacting with collagen fibres. Calcium and Phosphate ions are the two major components of this bone materials. Generally 90%of bone is calcium , while 80% is phosphate. Phosphate stimulate growth of Oesteocytes. And the latter is important for bone mineralization. Together they maintain bone mineralization and maintenance,thereby preventing bone resorption.
Absorption of Ca and P. into the blood stream to reach the bones cells is conducted by Vit D. Dietary supply is not the only route through which Vit D get to the blood stream. Exposure of the skin to UVB rays of the early morning sunlight is another route.
Vitamin D plays major role in absorption of Ca and P in the body.
Vit. D is naturally synthesized in humans when the skin is exposed to early morning sunlight (UVB). It is usually produce in inactive forms,and undergoes hydroxylation( i.e addition of hydroxyl group -OH) in the liver to be biologically active .
Its active forms acts on the epithelial cells of the intestinal wall to facilitate calcium absorption into the blood stream to reach the bone cells .it also stimulate absorption of Phosphate.
Since these two minerals ensures, mechanical strength, prevention of bone resorption, there availability in the bone must be maintained by Vit, D supply from exposure to sunlight.
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