NCERT Solution Class 11th Biology Chapter – 22 Chemical Coordination and Integration Notes

NCERT Solution Class 11th Biology Chapter – 22 Chemical Coordination and Integration

NCERT Solution Class 11th Biology Chapter – 22 Chemical Coordination and Integration

?Chapter – 22?

✍Chemical Coordination and Integration✍

?Notes?

There are special chemicals that act as hormones and provide chemical coordination, integration, and regulation in the human body.

These hormones regulate the metabolism, growth, and development of our organs, the endocrine glands, or certain cells.

The endocrine system is composed of the 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 gland is divided into three major parts, which are called pars distalis, pars intermedia, and pars nervosa. Pars distalis produces six tropic hormones. Pars intermedia secretes only one hormone, while pars nervosa (neurohypophysis) secretes two hormones.

The pituitary hormones regulate the growth and development of somatic tissues and activities of peripheral endocrine glands.

The 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 them.

The parathyroid glands secrete parathyroid hormone (PTH) which increases the blood Ca²⁺ levels and plays a major role in calcium homeostasis.

The thymus gland recreates 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. These hormones increase lateness, pupillary dilation, piloerection, sweating, heartbeat, the 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.

Mineralocorticoids regulate the water and electrolyte content of the body.

The endocrine pancreas secretes glucagon and insulin.

Glucagon stimulates glycogenolysis and gluconeogenesis resulting in hyperglycemia. Insulin stimulates cellular glucose uptake and utilization, and glycogenesis resulting in hypoglycemia.

Insulin deficiency and/ or insulin resistance results 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 behavior, anabolic pathways, and erythropoiesis.

The ovary secretes estrogen and progesterone. Estrogen stimulates the 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.

The atrial wall of the heart produces an atrial natriuretic factor that decreases blood pressure.

The kidney produces erythropoietin which stimulates erythropoiesis.

The gastrointestinal tract secretes gastrin, secretin, cholecystokinin, and gastric inhibitory peptide. These hormones regulate the secretion of digestive juices and help indigestion.

Hormones – Hormones are non-nutrient chemicals that act as intercellular messengers and are produced in trace amounts.

Anterior pituitary – The pars distalis region of the pituitary, commonly called the anterior pituitary, produce growth hormone (GH)

Gonadotrophins – FSH stimulates gonadal activity and hence are called gonadotrophins.

Androgens – In males, LH stimulates the synthesis and secretion of hormones called androgens from the testis.

Melatonin – Pineal secretes a hormone called Melatonin.

Corticoids – The adrenal cortex secretes many hormones, commonly called corticoids.

Mineralocorticoids – Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids.

Hormone receptors – Hormones produce their effects on target tissues by binding to specific proteins called hormone receptors located in the target tissues only.