Chemical control and coordination Mind map NEET Class 11 Best for revision short notes FREE mind map
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There are special chemicals which act as hormones and provide chemical coordination, integration and regulation in the human body. These hormones regulate metabolism, growth and development of our organs, the endocrine glands or certain cells. The pituitary gland is divided into three major parts, which are called as pars distalis, pars intermedia and pars nervosa.
Pars distalis produces six trophic hormones. Pars intermedia secretes only one hormone, while pars nervosa (neurohypophysis) secretes two hormones.
The endocrine system is composed of hypothalamus, pituitary and pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads (testis and ovary). In addition to these, some other organs, e.g., gastrointestinal tract, kidney, heart etc., also produce hormones.
The pituitary hormones regulate the growth and development of somatic tissues and activities of peripheral endocrine glands. Pineal gland secretes melatonin, which plays a very important role in the regulation of 24-hour (diurnal) rhythms of our body (e.g., rhythms of sleep and state of being awake, body temperature, etc.).
The thyroid gland hormones play an important role in the regulation of the basal metabolic rate, development and maturation of the central neural system, erythropoiesis, metabolism of carbohydrates, proteins and fats, menstrual cycle. Another thyroid hormone, i.e., thyrocalcitonin regulates calcium levels in our blood by decreasing it. The parathyroid glands secrete parathyroid hormone (PTH) which increases the blood Ca2+ levels and plays a major role in calcium homeostasis.
These hormones increase alertness, pupilary dilation, piloerection, sweating, heart beat, strength of heart contraction, rate of respiration, glycogenolysis, lipolysis, proteolysis. The adrenal cortex secretes glucocorticoids and mineralocorticoids. Glucocorticoids stimulate gluconeogenesis, lipolysis, proteolysis, erythropoiesis, cardio-vascular system, blood pressure, and glomerular filtration rate and inhibit inflammatory reactions by suppressing the immune response.
The thymus gland secretes thymosins which play a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. In addition, thymosins also increase the production of antibodies to provide humoral immunity. The adrenal gland is composed of the centrally located adrenal medulla and the outer adrenal cortex. The adrenal medulla secretes epinephrine and norepinephrine.
Mineralocorticoids regulate water and electrolyte contents of the body. The endocrine pancreas secretes glucagon and insulin. Glucagon stimulates glycogenolysis and gluconeogenesis resulting in hyperglycemia. Insulin stimulates cellular glucose uptake and utilisation, and glycogenesis resulting in hypoglycemia. The ovary secretes estrogen and progesterone. Estrogen stimulates growth and development of female accessory sex organs and secondary sex characters. Progesterone plays a major role in the maintenance of pregnancy as well as in mammary gland development and lactation.
Insulin deficiency and/or insulin resistance result in a disease called diabetes mellitus. The testis secretes androgens, which stimulate the development, maturation and functions of the male accessory sex organs, appearance of the male secondary sex characters, spermatogenesis, male sexual behaviour, anabolic pathways and erythropoiesis.
The atrial wall of the heart produces atrial natriuretic factor which decreases the blood pressure. Kidney produces erythropoietin which stimulates erythropoiesis. The gastrointestinal tract secretes gastrin, secretin, cholecystokinin and gastric inhibitory peptide. These hormones also regulate the secretion of digestive juices and help in digestion.
Hormones are chemical messengers produced by the endocrine glands. They are responsible for controlling many of the body's functions, such as growth, metabolism, reproduction and sexual development. Hormones play an important role in maintaining homeostasis—the body's balance—and they can have a significant impact on our physical and mental well-being.
There are many different types of hormones found in the human body, each with its own unique function. The following is a brief overview of some of the most common hormones and their roles:
1) Adrenaline: Also known as epinephrine, adrenaline is released by the adrenal glands during times of stress or excitement. It increases heart rate and blood pressure, boosts energy levels and prepares the body for “fight or flight” situations.
2) Cortisol: Produced by the adrenal glands, cortisol helps regulate blood sugar levels and metabolism. It also plays a role in immune system function and stress response.
3) Estrogen: Produced primarily in women’s ovaries, estrogen is responsible for regulating menstrual cycles and female reproductive development. It also helps to maintain bone density and skin elasticity during menopause.
4) Progesterone: This hormone is released by the ovaries during pregnancy to help prepare the uterus for implantation of an embryo and sustain a healthy pregnancy until delivery. In non-pregnant women it helps regulate menstrual cycles as well as certain aspects of fertility such as egg maturation and release from the ovary .
5) Testosterone: This hormone is primarily produced in men’s testes but it is also present in women’s bodies in smaller amounts. Testosterone plays an important role in male sexual development but it can also affect muscle mass, bone density, red blood cell production and overall energy levels .
6) Human Growth Hormone (HGH): Produced mainly by the pituitary gland , this hormone stimulates growth throughout childhood but its effects diminish after puberty . HGH affects many other bodily processes including muscle growth , fat burning , metabolism , calcium retention , immune system function , glucose regulation , fluid balance , kidney function etc..
7) Thyroid Hormone : This hormone regulates metabolic rate which affects how quickly we burn calories . Thyroid hormones are essential for normal brain development during fetal life . Hypothyroidism (low thyroid hormone levels )
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