Answer the following.
Explain chemical co-ordination in humans and give the names and functions of some hormones.
Coordination in humans occurs in two levels i.e. nervous coordination and chemical coordination. The coordination which occurs with the help of hormones is called chemical coordination. Hormones are the organic chemicals produced by the body, which are released into the blood. The key feature of the hormones is that they are secreted by the ductless glands. The glands that secrete hormones do not have ducts. Hormones are released directly into the bloodstream and reach the target organ. The endocrine system works in association with nervous system to control and coordinate our bodies.
Characteristics of Hormones
- Hormones are the organic chemicals that are secreted in response to environmental changes in or outside the body.
- Hormones are secreted by ductless glands and transported along with the blood stream to the site of their action. The site of their production and the organ of their influence are different.
- They can be amino-acid derivatives, proteins, or steroids.
- Being low molecular weight substances, they can easily diffuse through the cell membrane.
- They are produced in small quantities and are effective in extremely lower concentrations.
- Abnormal production of hormones (be it less or more) affects the body in a negative manner.
- Prolactin- Growth of mammary glands and formation of milk in them.
- TSH- Synthesis and release of thyroid hormones.
- Adrenocorticotrophic hormone (ACTH)- Stimulates synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex.
- Vasopressin- Stimulates reabsorption of water from the distal tubules, and hence, prevents loss of water through urine (diuresis); therefore, also called anti-diuretic hormone (ADH).
ii. Thyroxine hormone is produced by thyroid gland and its functions are:
- Control of BMR (Basal metabolism rate)
- Control of working of kidney and urine formation
- Regulation of physical, mental, and sexual growth
- Regulation of growth of CNS and bones
- Regulation of carbohydrate and fat metabolism