CHEMICAL COORDINATION AND INTEGRATION
CHEMICAL COORDINATION AND INTEGRATION •
The different body activities are controlled and coordinated by the action of neural system and endocrine system .Endocrine system perform its action with the help of hormones
Hormones
Hormones are non nutrient chemicals which acts as intercellular messengers and are produced in trace amounts . –
Endocrine glands of human body –
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Hypothalamus Pituitary Pineal gland Thyroid Parathyroid Thymus Pancreas Adrenal Gland Gonads (Testes in males and Ovary in females}
HYPOTHALAMUS •
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Neurosecretery Cells The hormone producing producing cells of hypothalamus are called neurosecretery cells
Releasing hormones •
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The hormones secreted secreted by hypothalamus hypothalamus which stimulate secretion of pituitary hormones are called releasing hormones Eg. Gonadotropin Releasing Hormone (GnRH) stimulate the pituitary gland to release gonadotrophins . Growth hormone releasing hormone (GHRH)stimulate growth hormone release
Inhibiting hormones •
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The hormone secreted secreted by the hypothalamus hypothalamus which inhibit secretions secretions pituitary hormones hormones are called inhibiting hormones Eg. Somatostatin (Growth Hormone Inhibiting Hormone (GHIH) from the hypothalamus inhibits the release of growth hormone from the pituitary .
Oxytocin and vasopressin 1. These are hormones secreted by hypothalamus and stored in the pituitary.
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PIUITARY GLAND Sella tursica
It is the bony cavity in which pituitary gland is located . Parts of pituitary gland •
Adenohypophysis
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Neurohypophysis
Adenohypophysis Adenohypop hysis has two portions portions –
Pars distalis (anterior pituitary)
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Pars intermedia
Hormones of anterior pituitary (pars distalis) •
Growth hormone (GH)
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Prolctin (PRL)
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Thyroid stimulating hormone hormone (TSH)
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Adrenocorticotrophic hormone (ACTH)
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Luteinizing hormone (LH)
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Follicle stimulating hormone (FSH)
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Hormone of pars intermedia Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH) MSH make skin colour daeker in amphibians , reptiles and human beings .Lack of skin pigmentation is due to its absence. Hormones of neurohypophysis (posterior pituitary) Neurohypophysis stores and release the hypothalamic hypothalamic hormone oxytocin and vasopressin.
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Gigantism Over secretion of growth hormone stimulates abnormal growth of the body leading to gigantism. Dwarfism Low secretion of growth hormone results in stunted growth known as pituitary dwarfism . Function of prolactin Prolactin regulates the growth of mammary gland and stimulate milk production Function of thyroid stimulating hormone (TSH) TSH stimulates the synthesis and secretion of thyroid hormones from the thyroid gland. Function of adrenocoticotrophic hormone(ACTH) ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex .
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Function of adrenocoticotrophic hormone(ACTH) ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex . Function of luteinizing hormone (LH) in males LHstimulates the synthesis and secretion of male hormones called androgens from testis . Function of luteinizing hormone (LH) in females LH induces ovulation and maintains the corpus luteum , formed from the remnants of the graffian follicles . Function of follicle stimulating hormone (FSH) in males In males FSH stimulates spermatogenesis .
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Function of follicle stimulating hormone (FSH) in females In females FSH stimulates growth and development of ovarian follicles. Function of oxytosin Oxytocin stimulates contraction of uterine muscles during child birth and initiates ejection of milk from mammary gland . Function of vasopressin (ADH)-antidiuretic hormone. It stimulates reabsorption of water and electrolytes from the kidney tubules and thereby reduces loss of water through urine .(diuresis)
THE PINEAL GLAND GLAND •
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The hormone of pineal pineal gland is melatonin . Melatonin plays an important role in the regulation of a 24 hr rhythm of our body .So it is known as biological clock of the human body . Melatonin also influences metabolism , pigmentation , menstrual cycle as well as our defense capability. –
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THYROID GLAND •
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Has two lobes and situated on either side of the trachea . Isthmus The two lobes of thyroid thyroid gland are interconnected by thin flap of connective tissue called isthumus. Hormones of thyroid Teraiodothyronine Or Thyroxine (T4) Triiodothyronine (T3)
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Functions of thyroid gland
It regulates basal metabolic rate. It maintains normal body temperature . It controls the metabolism of carbohydrates , proteins and fats. It controls blood- bone calcium level. Goiter Iodine is essential for the normal rate of hormone synthesis in thyroid . Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland commonly called goiter .So we should eat iodised salts. Cretinism Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth , mental retardation , low intelligence , abnormal skin , deaffnes etc.known as cretinism
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Myxoedema Hypothyroidism in adults leads to protruded eyes , oedema in the face known as myxoedema. Hypothyroidism in adult women cause irregular menstrual cycle . Hyperthyroidism Hyperthyroidism is the increase of thyroid hormones than normal level . This occurs due to cancer of thyroid glands or development of nodules of the thyroid gland . Thyrocalcitonin The protein hormone secreted by the parafollicular cells of thyroid gland is known as thyrocalcitonin. Calcitonin regulates blood calcium level.
PARATHYROID GLAND •
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Four parathyroid glands are present on the back side of thyroid gland The hormone of parathyroid gland is parathyroid hormone (PTH) Functions of parathyroid hormone PTH increases blood calcium level by the release of calcium ions into the blood from bones .PTH also stimulates reabsorption of calcium by the renal tubules and increases calcium absorption from the digested food .
THYMUS • • •
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It is situated on the dorsal side of the heart and aorta. The hormones of thymus is thymosins . Thymus is degenerated in old individuals resulting in a decreased production of thymosins .As a result , the immune response of old persons become weak. Functions of thymosin Thymosins play a major role in the differentiation of T- lymphocytes , which provide cell mediated immunity . It also promote production of antibodies to provide humoral immunity .Hence thymus is known as throne of immunity.
ADRENAL GLAND •
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One pair of adrenal glands are present on the anterior part of each kidney. It has two parts outside adrenal cortex and central adrenal medulla .
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Layers of adrenal cortex
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zona glomerulosa (outer layer)
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zona fasciculate (middle layer)
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zona reticularis (inner layer )
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Hormones of adrenal cortex
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The hormones of adrenal cortex are called cortico steroids .There are three types of cortico steroids.
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mineralo corticoids
eg . aldosterone
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glucocorticoids
eg. Cortisone , cortisol
gonadocorticoids estrogen
eg. Testosterone ,
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Functions of mineralocorticoids (aldosterone) It regulates water and electrolyte balance in the body . It increases blood Na+ level . It decreases blood K+ level Functions of glucocorticoids (cotisol) It raises blood glucose level . It stimulates gluconeogenesis , lipolysis and proteolysis . It inhibit cellular uptake and utilization of aminoacids . It produces antiinflamatory reactions and suppresses the immune response . It stimulate RBC production . Function of gonadocorticoids Gonadocorticoids involve in the development of secondary sexual characteristics .
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Hormones of adrenal medulla – –
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adrenalin (epinephrine ) noradrenalin (norepinephrine)
These hormones are commonly called as catecholamines Adrenaline is commonly called as emergency hormones or hormones of fight or flight . Functions of adrenaline . Increase blood glucose level . Rise blood pressure Increase heart beat Constricts skin and visceral muscles . Raising of hairs . Dilation of pupil . Increase respiration , sweating etc.
PANCREAS •
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Pancreas has both exocrine and endocrine parts. Endocrine part of pancreas is Islets of Langerhans. Islets of Langerhans has two types of cells alpha cells and beta cells. Alpha cells secretes glucagons Beta cells secretes insulin –
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Functions of insulin Insulin decreases blood glucose level by various methods . Hence insulin is a hypoglycemic hormone . Insulin stimulates conversion of glucose to glycogen known as glycogenisis Insulin promotes synthesis of fat from glucose . Enhance cellular glucose uptake and utilization . Diabetes mellitus Hyposecretion of insulin leads to the rise of blood glucose level known as diabetes mellitus . Symptoms include excessive thirst , frequent and excessive urination , sugar appears in the urine (glycosuria ) Insulin therapy is the treatment for this .
TESTIS • •
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Testis functions as sex organ and endocrine gland . The leydig cells or interstitial cells of testis produce group of hormones called androgens mainly tesosterones. Functions of androgens Stimulates male sexual characteristics and expression of secondary sexual characteristics . Regulate the development and maturation of accessory sex organs like epididymis ,vas deferens , seminal vesicles , prostate gland etc. Stimulate muscular growth , growth of facial and axillary hair , aggressiveness , low pitch voice . It stimulate spermatogenesis
OVARY •
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Females have a pair of ovaries located in the abdomen. The hormones of ovary are estrogens and progesterone. Corpus luteum After ovulation , the ruptured follicle follicle is converted converted to a structure known as corpus luteum , which secretes progesterone . Functions of estrogens Estrogens stimulates growth and development of female secondary sex organs and characters like high pitch voice , puberty etc. Regulates female sexual behaviour . Regulate mammary gland development . Functions of progesterone It helps to maintain pregnancy . Stimulate mammary gland for the formation of alveoli , for storing milk and milk secretion.
Hormones Of Heart , Kidney And Gastrointestinal Tract
Atrial Natriuretic factor factor (ANF) •
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It is the hormone secreted by atrial wall of heart . When blood pressure increases ANF is secreted and which causes the dilation of blood vessels .This reduces the blood pressure .
Erythropoietin •
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It is the hormone secreted by the juxtaglomerular cells of kidney. It stimulates erythropoiesis (formation of RBC)
Hormones of gastrointestinal tract hormones
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function functi on
Gastrin
stomach
Secretion of gastric juice
Gastric inhibitory duodenum peptide(GIP)
Inhibition of gastric juice
Or enterogastrone Secretin
duodenum
Secretion of pancreatic juice
cholecystokinin
duodenum
Rele elease ase of bil bilee
Classification of hormones on the basis of chemical nature Name of hormone
Example Exam pless
Peptide ,polypeptide ,
Insulin , glucagon ,pituitary hormones
Protein hormones
Hypothalamic Hypothal amic hormones hor mones Steroids
Cortisol , testosterone , estradiol , progestrone
Iodothyronines
Thyroid hormones hor mones
Aminoacid derivatrives derivatrives
Epinephrine
MECHANISM OF HORMONE ACTION •
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Hormones produce their effects on target tissues by binding bi nding to specific proteins called hormone receptors located in the target tissues. Hormone receptors present on the cell membrane of target cells are called membrane bound receptors . The receptors present inside the cell are called intracellular receptors . At the target tissues tissues hormone binds binds with the receptor receptor leading to the formation of hormone receptor complex . Hormones which interact with membrane bound receptors generate second messengers like cyclic AMP, IP3, Ca++ etc. These second messengers messengers regulate cellular cellular metabolism. metabolism. Hormones like steroid hormones which interact with intracellular receptors regulate gene expression by the interaction of hormone receptor complex with the genome
Mechanism of action of a protein hormone
Mechanism of action of a steroid hormone
