Chapter-14-Endocrine-System-complete-PDF-Notes-D.Pharma1st-year-Noteskarts

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com Chapter - 14 Endocrine system Endocrine system (Hormones and their functions) ● Pituitary gland ● Adrenal gland ● Thyroid and parathyroid gland ● Pancreas and gonads By Noteskarts.com

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com Endocrine system Introduction — Endocrine system is defined as the complex glandular structure (cell modification or aggregation) which secrete the hormones and neurotransmitter in the body and regulate the body physiology and major participate in the defensive mechanism of the body. Major endocrine gland

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com  Adrenocorticotropic hormone (ACTH) — ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex  Prolactin (PRL) — Prolactin regulates the growth of the mammary glands and formation of milk in them.  Follicle stimulating hormone (FSH) and luteinizing hormone (LH) — LH and FSH stimulate gonadal activity and hence are called gonadotrophins. In males, LH stimulates the synthesis and secretion of hormones called androgens from testis. In males, FSH and androgens regulate spermatogenesis. In females, LH induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum, formed from the remnants of the graafian follicles after ovulation. FSH stimulates growth and development of the ovarian follicles in females. NOTE — Pars intermedia secretes the only one hormone melanocyte stimulating hormone (MSH). MSH acts on the melanocytes (melanin containing cells) and regulates pigmentation of the skin. 2 .Posterior pituitary or neurohypophysis — Also known as pars nervosa and it release two hormone-  Oxytocin — Oxytocin acts on the smooth muscles of our body and stimulates their contraction. In females, it stimulates a vigorous contraction of uterus at the time of child birth, and milk ejection from the mammary gland.  Vasopressin — Vasopressin acts mainly at the kidney and resorption of water and electrolytes by the distal tubules and thereby reduces loss of water through urine (diuresis). Hence, it is also called as anti-diuretic hormone (ADH). NOTE — Hypothalamus release the both type (stimulating as well as inhibitory) Hormone through the portal circulatory system and regulate the functions of Pituitary gland, so it called as master of master gland.

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com Adrenal gland. Introduction — Our body has one pair of adrenal glands, one at the anterior part of each kidney. The gland is composed of two types of tissues. The centrally located tissue is called the adrenal medulla, and outside this lies the adrenal cortex. Adrenal medulla — Adrenal medullary hormones are the amines derived from catechol and so these hormones are called catecholamines. 1. Adrenaline or epinephrine. 2. Noradrenaline or norepinephrine. 3. Dopamine.  Adrenaline and noradrenaline are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones or hormones of Fight or Flight. Pituitary gland and Hypothalamus relation a. Adrenal gland above kidney b. sectional part of adrenal gland.

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com Stages of synthesis of thyroid hormones — five stages.  Thyroglobulin synthesis.  Iodide trapping.  Oxidation of iodide.  Transport of iodine into follicular cavity.  Iodination of tyrosine.  Coupling reactions. Functions of thyroid hormone .  Thyroid hormones play an important role in the regulation of the basal metabolic rate.  It also supports the process of red blood cell formation.  Thyroid hormones control the metabolism of carbohydrates, proteins and fats.  Maintenance of water and electrolyte balance is also influenced by thyroid hormones.  Thyroid gland also secretes a protein hormone called thyrocalcitonin (TCT) which regulates the blood calcium levels. Disorder related to thyroid gland.  Hyperthyroidism — Increased secretion of thyroid hormone is called hyperthyroidism. It is caused by- Graves’ disease, Thyroid adenoma.  Hypothyroidism — decreased secretion of thyroid hormone is called hypothyroidism. It leads to myxoedema in adults and cretinism in children.  Goitre — Goitre means enlargement of thyroid gland. It occurs both in hypothyroidism and hyperthyroidism.  Goitre in hyperthyroidism — Also called as toxic goitre. It is the enlargement of thyroid gland with increased secretion of thyroid hormone, caused of thyroid tumor.  Goitre in hypothyroidism — Also known as non-toxic goitre/hypothyroid goitre. It is the enlargement of thyroid gland without increase in hormone secretion

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com Parathyroid gland. Introduction — In humans, four parathyroid glands are present on the back side of the thyroid gland, one pair each in the two lobes of the thyroid gland. Each parathyroid gland is made up of chief cells, which secrete a peptide hormone called parathyroid hormone (PTH)/parathormone. The secretion of PTH is regulated by the circulating levels of calcium ions. Functions of parathyroid hormone.  Parathyroid hormone (PTH) increases the Ca2+ levels in the blood.  PTH acts on bones and stimulates the process of bone resorption (dissolution/ demineralisation).  PTH also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption from the digested food.  It is, thus, clear that PTH is a hypercalcaemic hormone, i.e., it increases the blood Ca2+ levels. NOTE — Both PTH and TCT plays a significant role in calcium balance in the body. Disorder related to parathyroid gland .  Hypoparathyroidism — less secretion of PTH is called hypoparathyroidism. It leads to hypocalcaemia (decrease in blood calcium level)  Hyperparathyroidism — Hyper secretion of PTH is called hyperparathyroidism. It leads in hypercalcemia (Increase in blood calcium level).

Noteskarts Subscribe & Visit our Website For Notes For Notes Regular Visit our Website: www.noteskarts.com 1. Testis — It performs dual functions as a primary sex organ as well as an endocrine gland. Testis is composed of seminiferous tubules and stromal or interstitial tissue. The Leydig cells or interstitial cells, which are present in the intratubular spaces produce a group of hormones called androgens mainly testosterone Function of androgens .  Androgens regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra etc.  These hormones stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice etc.  Androgens play a major stimulatory role in the process of spermatogenesis (formation of spermatozoa). Androgens act on the central neural system and influence the male sexual behaviour (libido).  These hormones produce anabolic (synthetic) effects on protein and carbohydrate metabolism. 2. Ovary — Ovary is the primary female sex organ which produces one ovum during each menstrual cycle. In addition, ovary also produces two groups of steroid hormones called estrogen and progesterone. Ovary is composed of ovarian follicles and stromal tissues. The estrogen is synthesised and secreted mainly by the growing ovarian follicles. After ovulation, the ruptured follicle is converted to a structure called corpus luteum, which secretes mainly progesterone. Functions of estrogen .  Estrogen produces wide ranging actions such as stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development.  Estrogen also regulates female sexual behaviour Function of progesterone  Progesterone supports pregnancy. Progesterone also acts on the mammary glands and stimulates the formation of alveoli (sac-like structures which store milk) and milk secretion.