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CONTROL AND COORDINATION (HORMONES) The nervous system and endocrine system control the activities of our body. These systems maintain homeostasis in the body. The endocrine system consists of different glands situated in various parts of body. The glands which do not posses special ducts to carry their secretion to the site of action are called as endocrine glands. These are also called as ductless glands. The secretions of endocrine glands are called hormones. The hormone acts on some specific organs. These organs are called as target organs. The hormones are carried to the target organs through blood. The hormones are called as chemical regulators or informational molecules. The hormones are produced in minute quantities .They are destroyed in liver or in the target organs. Q. Mention common properties of hormones. Ans: 1. Hormones are carried through blood all over the body. 2. They are produced in organ called Endocrine gland. They alter or stimulate the activity of Target organs. 3. Hormones are generally bound to any specific carrier protein. Only in such form they are transported . 4. Hormones are produced in response to specific stimulus. 5. They have a considerable high degree of target specificity. 6. The rate of secretion varies from low to high. It depends upon the nature and intensity of stimulus. 7. The hormones generally affect the cellular metabolism. 8. Excessive secretion of hormones or deficiency leads to any disorder. Pituitary gland or Hypophysis: It is small bean shaped endocrine gland. It is about 1cm in sagittal diameter (length) and 1.2 to1.5cm in breath. It weighs about larger and enlarged during pregnancy. The pituitary is situated on the ventral side of the brain just below the hypothalamus (or the floor of Diencephalon. It is lodged in a small cavity called Hypophyseal fossa or sella turcica present in the Sphenoid bone of the cranium. The Pituitary is connected to the Hypothalamus by a stalk of nervous tissue. The region where stalk is attached to Hypothalamus is a swollen median part called Median eminence. The stalk is often called as infundibulum. Hypophysis can be differentiated into two parts viz. Adenohypophysis (Anterior lobe of pitutory gland) and Neurohypophysis (posterior lobe of pitutory gland) The pituitary is a compound body with double origin. The anterior pituitary is formed by an out pushing (Rathke’s pouch) from the dorsal part the buccal cavity. The posterior part is formed from the funnel like downgrowth of the Hypothalamus called infundibulum. Thus the anterior and posterior parts correspond to the epithelial and neural regions respectively. They fuse with each other. The connection / contact of Rathke’s pouch for the buccal cavity vanishes. Thus the pitutory gland is established. The pitutory gland is thus derived entirely from the ectoderm. hormones secreted by the neurosecretary cells of the hypothalamic nuclei. (Rathke’s pouch – Buccal ectoderm) Down growth of neural tube – Neural plate ectoderm. The adenohypophysis as well as the neuro hypophysis is ectodermal in origin in nature. Hormones secreted by Pars distilis (i.e. anterior pitutory) of the Adenohypophysis. Adenohypophysis can be differentiated in three parts viz. Pars tuberalis, pars distilis and pars intermedia. The anterior part is called as Adenohypophysis and posterior part is called as Neurohypophysis. 2 Thyrotropin or thyrotrophic hormone or TSH i.e. thyroid stimulating hormone Adenohypophysis – It consists of reticular connective tissue along with epithelial cells (also called parenchyma). It is differentiated into 3 regions viz.Pars distalis,Pars tuberalis and Pars intermedia. Of these, the Pars distalis is the most prominent. In this part blood sinusoids are present forming a rich network. Also epithelial cells are found around the sinusoids. These cells are secretary in nature. They secrete hormones The pars distalis is made up of loose chords of epitheloid secretary cells.The masses of epitheloid tissues are surrounded by reticular connective tissue containing blood capillaries. The Neurohypophysis is also called as the posterior lobe of the pituitary gland. It is about 25% of the total pituitary gland. It is made up of large spindle-shaped cells called Pituicytes.There are blood capillaries and nerve fibres around the pituicytes. But the pituicytes are non-secretory in nature.In Hypothalamus,there are two groups of neurosecretory cells called as supraoptic and para-ventricular nuclei. They are secretory in nature. The nerve fibers arising from these nuclei enter the neurohypophysis. The hormones secreted by these hypothalamic nuclei are stored in the axon terminals of the nerve fibers. ( in the enlarged bodies called as Herring bodies.)Thus the neurohypophysis does not have a secretary role of its own. But it only stores the 1 Growth hormone (GH) or somatotropin or STH i.e. somatotrophic hormone 3 Adrenocorticotrophic Adrenocorticotropin. hormones (ACTH) or 4 Prolactin 5 Gonadotropins or Gonadotrophic hormones a) FSH or follicle stimulating hormone b) LH or Luteinizing hormone. Pars intermedia – MSH i.e. Melanocyte stimulating hormone Pars nervosa Pitressin or Vasopressin or Antidiuretic hormone ADH Pitocin or Oxytocin Coherin Hormones secreted by Pars distalis i.e. anterior pituitary. 1. Growth hormone(GH) somatotrophic hormone or somatotropin or STH This hormone is necessary for the normal growth of the body. The growth of the body is under the control of the hereditary factors (genes) and the diet. But this hormone is also essential for growth. This hormone stimulates the body growth by retention of the proteins and calcium .It also enhances (increases) the synthesis and deposition of the proteins in the tissues.Hence there is low excretion of nitrogen. This leads to growth and elongation of the bones by absorption of calcium from blood.It brings about proportionate growth of the muscles and visceral organs. GH is regulated by the hypothalamic hormones i.e. the hormones secreted by the hypothalamus. These are as follows- It promotes protein synthesis, lipolysis in adipose tissue to release more fatty acids Throughout the life the GH is essential for replenishment of the tissues and therefore for the recovery of ‘wear and tear’. b) Growth hormone inhibitory hormone – (GHIH). ( a ) Deficiency of GH in early age i.e. in infants and children stops the growth of long bones. The child attains the height only about 2.5 to 3 ft. Such a condition is called pituitory dwarfism. The intelligence of such persons is normal only the physical and sexual growth is retarded.The pituitary dwarfs are of 2 types viz. Lorain dwarfs and Frolich dwarfs. The midgets in circus are Lorain dwarfs. They are just physically retarded but mentally normal. a) Growth hormone releasing hormone (GHRH). This hormone stimulates the pitutory to secrete GH This Growth hormone inhibiting hormone is also called as somatostasin. The Growth hormone inhibiting hormone inhibits the pituitary secretion of GH. 2. Thyrotrophic hormone ( TTH ): (Thyroid stimulating hormone TSH or Thyrotropin) This hormone stimulates the growth and activity of thyroid gland. Thus it stimulates the follicles of the thyroid gland to take up the Iodine from blood and to utilize it for the production of the T3 and T4 hormones i.e. the thyroid hormones. The Frolich dwarfs are mentally as well as physically retarded. The secretion of TSH by the anterior pituitary is under the control of the Thyrotropin releasing hormone (TRH) of the hypothalamus. (b) Hyposecretion of GH in adults leads to Simmond’s disease.it is characterized by early senescence or ageing. 3. Adrenocorticotrophic Adrenocorticotropin ( b ) Over secretion of GH from childhood to maturity leads to a condition called pitutory gigantism or gigantism. In such cases the bones and the muscles undergo elongation and growth tremendously due to which the person attains the height more than 7ft. it looks as a giant hence the name gigantism or gigantism. ( c ) Over secretion of GH after adolescence (adulthood) leads to abnormal enlargement of the jaws and the bones of the hands and feet. The eyebrow ridges become more prominent giving a gorilla like appearance.Such person has no giant structure. These persons may be mentally retarded. This condition is called Acromegaly. The secretion of hormone (ACTH) or This hormone stimulates the cortical region of the adrenal gland, to produce and secrete the cortical hormone. The adrenal cortical hormones are often called as corticoids. The mineralocorticoids are concerned with mineral metabolism i.e. Na-K metabolism. Therefore it is related with the fluid and electrolyte balance. The glucocorticoids are related with the metabolism of carbohydrates and fats. The sex corticoids stimulate the development of external sex characters of male type. The secretion of ACTH by the anterior pitutory is under the control of a hormone called Corticotrophin releasing hormone (CRH) by the hypothalamus. 4. Prolactin – It is not secreted in males.It is secreted in females in the three months of pregnancy ( 3 rd trimester ) and after the after the birth of the child for about a year. This is also called as lactogenic hormone. It initiates and maintains the secretion of milk by the mammary glands in mothers. Thus it is necessary for initiation and maintaining lactation. The presence of this hormone in blood reduces the changes of pregnancy so long as mother is feeding her baby. 5. Gonadrotropins /Gonadotrophic hormones As the names indicate, these hormones primarily act upon the gonads. There are two types of gonadotrophic hormones FSH – Follicle stimulating hormone LH – Luteinizing hormone FSH--- In male, the FSH also brings about descent of testes into scrotum just before the birth or after the birth. It stimulates the testis in males to develop the seminiferous tubules. It also stimulates the germinal epithelium of the seminiferous tubules to produce a large number of the spermatogonia. FSH also helps in the production of the sperms. Thus the FSH basically induces the cell divisions and differentiation. In female, FSH stimulates the germinal epithelium of the ovary to produce the follicles.Therefore stages upto the double-layered follicles are formed in the ovary before the birth. It stimulates the developing follicles to undergo development of the Primary oocyte and further the secondary oocyte. Further the FSH stimulates follicular cells to secrete the female sex hormone called estrogen. The FSH also stimulates the follicular cells to divide more . FSH is also responsible for arrest of menstruation at the end of menstrual phase. It also brings about regeneration of uterine endometrium after this phase. The development of Mature follicle also takes place in the ovary. Luteinizing hormone (LH) – This hormone stimulates the ovaries for the maturation of ovarian follicle ( Graafian follicle). The ovulation i.e. discharge of ovum from the ovary is also brought about by this hormone. After the ovulation this hormone stimulates the follicular cells to undergo luteinization which finally forms corpus luteum. This is a temporary endocrine gland which secretes another sex hormone called progesterone. The secretion of progesterone takes place under the control of LH. In males LH is called as interstitial cells stimulating hormone (ICSH). This hormone stimulates the interstitial cells of Leydig which are found in the connective tissue of the testis. These cells secrete the male sex hormone called testosterone. Thus if the pitutory gland is removed (hypophysectomised) then the gonads of the person fail to develop. The secretion of this hormone is under the control of Gonadotropin Releasing hormone (GnRH) of the hypothalamus. The posterior pituitory is also secretary in nature but the hormones are not actually synthesized by the pituicytes. The pituicytes present in the Pars nervosa are non secretary but the hypothalamic nucleus consists of neuro-secretory cells. These cells synthesize the hormones. The axons of these neurosecretory cells pass through the hypophysial stalk. These axons terminate in pars nervosa. The hormone Produced by the hypothalamic nuclei are stored in the axon terminals (Herring bodies) of these neurosecretary cells. The axon terminals lie in the pars nervosa hence it appears that the pars nervosa secretes the hormones. There are two hormones secreted by pars nervosaAntidiuretic hormone (ADH) or Vasopressin or pitressin Oxytocin or pitocin Coherin Pitressin or Vasopressin-This hormone is useful to the person in maintaining or conserving water in the body. Whenever there is adequate quantity of water in blood, the osmotic pressure of the blood increases. This may be also due to loss of water from the body through perspiration, etc. the increased osmotic pressure stimulates the hypothalamic nuclei to secrete Vasopressin. This hormone acts upon the distal convoluted tubules and collecting tubules of the kidney due to which reabsorption of water increases. Thus the volume of urine decreases. It is because of this activity vasopressin is also called as Antidiuretic hormone ( ADH ) Failure of this hormone leads to reduced renal reabsorption of water. Hence large volume of hypotonic i.e. dilute urine is formed. This condition is called as Diabetes insipidus. But in this disorder no glucose is eliminated in urine. Pitressin or vasopressin also increases the arterial blood pressure because it makes the arteries to constrict. Failure of this hormone leads to reduced renal reabsorption of water. Hence large volume of hypotonic i.e. dilute urine is formed. This condition is called as Diabetes insipidus. But in this disorder no glucose is eliminated in urine. Oxytocin This is another hormone actually secreted by the hypothalamic nuclei. This hormone is useful in the ejection of the milk from the mammary glands. Hence oxytocin is also called as milk ejection hormone. Oxytocin is secreted due to the sucking of the breast by an infant (new born child). It is also secreted due to the distension of the uterus by fully formed foetus. The oxytocin contracts the smooth muscles of the uterus (also mammary glands). It thus helps in child birth. Hence oxytocin is also called as birth hormone. In males, it is essential to bring about the ejaculation of semen at the end of coitus. It is supposed to induce prolonged rhythmic integrated contractions of the jejunum. Feed back mechanism/ feed back control/feedback regulation Hypothalamus TRH (Thyrotropin Releasing hormone) Anterior pituitary TSH (thyroid stimulating hormone) Thyroid gland Thyroxine Feed back mechanism is a self regulatory mechanism. It is due to this mechanism he regulation of the hormones by different endocrine glands takes place. e.g. the Hypothalamus secretes TRH whenever the concentration of Thyroxine in blood is poor. TRH then stimulates the Anterior pituitary to release TSH. The TSH acts upon thyroid gland to release thyroxine in the blood. The increased level of thyroxine in the blood inhibits the TRH secretion by the hypothalamus. Hence the TSH secretion by the anterior pituitary is stopped. Further in absence of TSH the secretion of the thyroxine is stopped Again if the concentration of thyroxine becomes lower the hypothalamus is stimulated to release TRH. It ultimately leads to thyroxine secretion as mentioned earlier. Coherin Intermediate lobe (Pars intermedia) This lobe is vestigial in human beings. Hence the name of hormone Melanocyte stimulating hormone (MSH). Its presence in human being is doubtful. This hormone affects the pigment cells i.e. the Melanocytes present in the skin. The MSH stimulates the Melanocyte for the synthesis of the black pigment called melanin. This hormone darkens the skin of the lower vertebrates. Thyroid gland: Thyroid gland is a soft labile gland. It is usually 30 gms in weight. It enlarges to certain extent during pregnancy. It is more or less H- shaped / Butterfly shaped gland. It is situated in neck region. It is found to be attached to the anterior surface of larynx. It covers the lower end of larynx and upper end of trachea. The thyroid gland is differentiated into two lobes. The lobes are connected with each other by a band of connective tissue called isthmus. Histological structure of thyroid gland: The thyroid gland is differentiated into two conical lobes. Each lobe is covered by a thick connective tissue sheath called as capsule. From the capsule a number of septa/ trabeculae arise. The septa thus divide thyroid lobe into a number of polyhedral lobules. In each lobule, the connective tissue is present which is called as the intralobular connective tissue. In this tissue blood vessels, lymph vessels, nerve fibers, thyroid follicles and Para-follicular cells are situated. This tissue is often called as the interfollicular connective tissue. The thyroid gland is generally spherical or ovoid. Therefore in this section they appear circular or oval. Each follicle is lined by follicular cells. These cells are generally cuboidal in shape. They may become columnar during their hyperactivity or thin squamous like indicating their less activity (hypo activity). The follicular cells have prominent nuclei and granular cytoplasm. There are secretary granules in cytoplasm. Therefore it appears granular. They also have well developed endoplasmic reticulum (ER) and Golgi complex(GC). The follicular cells secrete the hormones called T3 and T4. There are Para follicular cells or C cells around the follicles, in inter follicular connective tissue. These cells secrete a hormone called Calcitonin / Thyrocalcitonin / TCT. In each follicle there is a cavity or lumen. It is filled with a gelatinous amber colored substance called colloid. It is amber colored due to the presence of iodine in colloid. The thyroid hormone (T3 and T4) can not be stored in pure form. They are combined with a protein globulin thus forming thyroglobulin molecules. The thyroglobulin is stored as colloid in the lumen. As per the necessity, thyroglobulin molecules are pinocytosed by follicular cells. Thyroglobulin is split to release thyroid hormone. The thyroid hormone is thus released into the interfollicular connective tissue and further in blood vessels. Role of Calcitonin / TCT Calcitonin / thyrocalcitonin is secreted by the Para follicular cells or C- cells especially when they are stimulated due to hypercalcemia. Hypercalcemia means high plasma Ca++. The Para follicular cells are stimulated when they receive blood having more Ca++. As a response they secrete the calcitonin. The calcitonin helps to reduce the plasma Ca++ and PO4-- by the following activities. 1. Absorption of Ca++ and PO4--by the intestinal epithelial lining is temporarily arrested. 2. Reabsorption of Ca++ and PO4--from the PCT of nephron is temporarily arrested. Thus they are released into urine and further excreted. Thyroxin is essential metamorphosis. 3. The liberation of Ca++ and PO4-- from bones and cartilage is temporally arrested. These attempts helps to maintain low Ca++ in plasma. (If more thyroxin is injected or administered to the tadpoles, they undergo metamorphosis rapidly due to which they are converted into tiny frogs.) Thyroid follicular hormones On the contrary, if no thyroxine is produced then they fail to undergo metamorphosis and remain in the same larval stage. Such a phenomenon is called as Neotany e.g. Axolotl larva of salamander. As mentioned earlier, the follicular cells of thyroid secrete T3 and T4. T3 means triiodo thyronine and T4 means the Tetra- iodo thyronine or thyroxin. These are the iodinated derivatives of the amino acid called Tyrosine. The absorption of iodine from blood into follicular cells takes place under the effect of TSH of hypophysis. Also the iodination of tyrosine takes place under the effect of TSH. The T3 is produced in fewer amounts than T4 but T3 is found to be at least 5 times more active or potent than T4 . Roles of T3 and T4 1. The T3 and T4 increase the basal metabolic rate(BMR) therefore the rate of utilization of oxygen by the cells increases. 2. T3 and T4 increase the rate of protein synthesis as well as synthesis of amino acids. 3. T3 and T4 also play very significant role in carbohydrate metabolism. They stimulate the cells of Islet of Langerhans. Therefore more insulin is secreted. Hence the glucose is absorbed by the liver cells. Also the glucose metabolism is increased. The absorption of glucose by the intestinal epithelial lining increases. In liver it is converted to glycogen. 4. T3 and T4 increases fat degradation. Therefore cholesterol level of blood increases. 5. T3 and T4 stimulate the sympathetic nerve. Thus the heart rate, breathing rate etc increases. 6. in Amphibians for Initially the tadpoles are herbivorous. They consume the leaves of the aquatic plants. Therefore they get iodine in the diet. The iodine is utilized to produce thyroxin. The thyroxin is further utilized for metamorphosis. Later on after production of sufficient thyroxin, the tadpole becomes carnivorous.) Hypothyroidism - Insufficient production of T3 and T4 leads to a disorder called hypothyroidism. The T3 and T4 are not produced in such a person to the required level.Hypothyroidism in children leads to Cretinism. Hypothyroidism in adult leads to Myxedema. Cretinism Hypothyroidism in children leads to disorder called Cretinism. Such child is called as Cretin. The peculiar features of a cretin are as follows1.It is due to improper metabolism, the growth of the body (physical growth) is retarded. (Stunted) so the cretin is physically dwarf. The height of such a child reaches maximum up to 3 to 3.5 ft. Also the cretins are mentally retarded. 2. More fat is deposited over the chest leading to Pigeon chest and over the abdomen resulting into pot belly. 3. As less fat is metabolized, energy production is also reduced. Hence the cretin is less energetic. 4. The cretin exhibit lack of initiation and lack of alertness. Also the cretin is less active and sluggish. 5. It is due to the same reason the body temp. In found to be very low. 6. In such a child, due to less stimulation of the sympathetic nerves and less demand for oxygen, the heart rate, respiratory rate and breathing rate are found to be low. 7. The cretin has expressionless face. 8. The tongue enlarges and protrudes out of the mouth cavity. 9. The blood pressure of such a child is low. 10. Comparatively body weight is more. Myxedema Hypothyroidism is deficiency of T3 and T4. In adults it leads to Myxedema The characteristic features of Myxedema are as follows. More fat is deposited allover the body leading to puffness. Such person exhibit low metabolic rate therefore the energy production is less. They suffer from weakness. As less energy is produced there body temperature is found to be low. required quantity of thyroid hormone. So the blood contains less T3 andT4. When the hypothalamus receives such blood, it gets stimulated. It then releases TRH (Thyrotropin releasing hormone) the TRH then stimulates the hypophysis (Adenohypophysis) to secrete more TSH. The TSH further acts upon thyroid follicles and stimulates them. As a response follicular cells enlarge and become columnar. Also overall the thyroid gland enlarges (Goiter). The thyroid follicular cells fail to produce required amount ofT3 and T4 as there is shortage of the raw material (i.e. iodine.)Therefore the disorder is called as iodine deficiency Goiter. It may result into cretinism or Myxedema as per the age of person. Hyperthyroidism- Grave’s disease or Ex-ophthalmic goiter Over secretion or excessive secretion of thyroid hormone (T3 &T4) results into Graves’s disease or Exophthalmic Goiter. The ill effects are as follows The basal metabolic rate (BMR) increases tremendously. Therefore body proteins are utilized. It results in weight loss. It is due to more metabolism of fat and protein extreme thinning of the body results (emaciation) Their heart rate is less. Breathing rate is also less. More fat is metabolized so more energy is produced therefore the person becomes overactive. It results into restlessness, sleeplessness (insomnia) as well as nervousness. Reproductive failure is also seen. Their BP is also less. The BP increases due to rise in cholesterol level. Iodine deficiency Goiter / simple Goiter: Since more energy is produced body temperature increases sweating is observed ever during winter at the surface of palms and soles of feet They are sluggish and exhibit lack of alertness. Goiter means enlargement / enlarged thyroid gland. It results due to dietary deficiency of iodine. Generally in mountain regions, the superficial iodine rich soil is eroded during raining. Therefore it is not incorporated into the vegetables. Consumption of such vegetables for a prolonged period leads to deficiency of iodine in blood. Therefore thyroid gland fails to produce the Due to excessive stimulation of sympathetic nerves, the heart rate increases. The breathing rate also increases the oxygen consumption by the body also increases Muscle tremor develops The feed back mechanism fails. Therefore the follicles are more stimulated by TSH they enlarge resulting into enlarged thyroid gland. It is called goiter. The follicular cells become columnar and hyperactive. 2. Also the Thymosins promote production of Antibodies thereby providing Humoral immunity. Therefore the Thymosins are important in development of immune system. In aged people, the thymus gland undergoes degeneration. Hence they suffer from weakening of immunity. A fibrous tissue develops behind the eyeballs. It leads to protrusion of eyeball (exophthalmos) i.e. Exophthalmic Goiter. Adrenal gland (Supra-renal gland) Parathyroid gland Location- Attached to the kidneys on the dorsal side. Location- On the backside of the thyroid gland. Appearance- They appear pyramid shaped. Appearance- in the form of 2 pairs of spherical lobes. Adrenal gland can be differentiated into 2 parts viz. Adrenal cortex and Adrenal medulla. Role- secretes the hormone Parathormone ( PTH) Role of PTH Increases the level of Ca++ in plasma by the following ways--1. Reabsorption of the Ca++ by the PCT of the renal tubule. Therefore less excretion of Ca++ alongwith urine. 2. Decalcification of bones and cartilages. 3. More absorption of Ca++ by the lining of intestine. Therefore PTH is Hypercalcemic hormone. It is antagonistic to TCT Adrenal cortex can be further differentiated into 3 regions such as Zona Glomerulosa ( outer), Zona Fasciculata( middle) and Zona Reticularis ( inner). Adrenal cortex secretes 3 types of corticoids such as Mineralo corticoids, Glucocorticoids and sex corticoids of male type. Mineralocorticoids --- These are the hormones which control electrolyte metabolism.( Na+- K+ ) metabolism and water balance. One of the mineralocorticoids is Aldosterone. ( Thyrocalcitonin) of the thyroid gland. Role of Aldosterone --Thymus gland 1. Increases renal reabsorption of Na+. Location- On the dorsal side of the heart and the aorta. 2. Increases renal reabsorption of water. Appearance as lobules. Role- secretes Thymosins. the peptide hormones called 3. Increases renal excretion of K+ and PO4-- . 4. Maintains body fluid volume. 5. Maintains osmotic pressure and blood pressure. Role of Thymosins--1. Essential in differentiation of T lymphocytes. These cells produce cell mediated immunity. Role of Glucocorticoids—One of them is Cortisol which is predominant. 1. Controls carbohydrate metabolism. 2. Increase in total quantity of electrolytes (Na+ and Cl-) in ECF i.e. extra cellular fluid. Therefore there is increase in quantity of ECF. 3. More retention of water in ECF. Maintains cardio-vascular system and kidney functions. 4. Alkalosis and Polydypsia ( more thirst). 5. Increased BP. 6. Involved in anti-inflammatory reactions and suppresses immune response. 6. Muscle paralysis. 7. Stimulates RBCs production. Hormones of Adrenal medulla--- It secretes 2 hormones viz. Adrenaline 2. Increases Gluconeogenesis. 3. Increases Proteolysis and Lipolysis. 4. Inhibits cellular uptake and utilization of amino acids. 5. Role of Male sex-corticoids (Androgenic corticoids) 1. Growth of hair in the armpits. 2. Growth of pubic hair and facial hair during puberty. ( secondary sex characters). ( Epinephrine) and Nor-adrenaline ( Nor-epinephrine). These are also called as emergency hormones or hormones of fight-flight-fright.They are secreted in stress condition. They are also called as Catacholamines. Roles of the adrenal medullary hormones----1. Increase alertness. Addison's disease--- 2. Increase papillary dilation. 1. Hyposecretion or deficiency of Cortisteroids results into Addison's disease. 3. Piloerection i.e. hair erection. 2. Generalized weakness. 4. Increase sweating. 3. Weight loss. 5. Increase heart rate ( Tachycardia). 4. Low body temperature. 6. Increase the rate of breathing and respiration. 5. Low BP and low pulse rate. 7. Increase the strength of heart. 6. Acidosis. 8. Breakdown of Glycogen , Lipids and Proteins. 7. Feeble heart action. 9. Increase in blood glucose level. 8. More loss of Na+ and Cl- in urine. 9. Impaired kidney function and kidney failure. Pancreas – Dual gland (Mixed gland) or Exo-endocrine gland: Cushing’s syndrome Exocrine portion – Acini of Pancreas 1. Endocrine portion – Islets of Langerhans Hypersecretion of corticosteroids results into Cushing’s syndrome. Islets of Langerhans – Made up of 3 types of cells viz , and cells. - cells – (A cells) secrete Glucagon. It reduces the absorption of Glucose by liver cells. There is breakdown of Glycogen into glucone. Therefore Blood Glucose level increases (Hyperglycemia). Hence it is described as Hyperglycemic hormone. It stimulates Gluconeogenesis (glycogenolysis). It reduces uptake of glucose by cells and its utilization. -cells - (B cells) secrete Insulin. It is antagonistic to Prolonged and extreme condition of Diabetes Mellitus results into formation of Ketone bodies and their excretion in urine (Ketosis leading to Ketonuria). Hormones of GIT (Gastro Intestinal Trait) – The endocrine cells present in the wall of stomach secrete the hormones such as Gastrin, Secretin, Cholecystokinin, Pancreaozymin, Gastric Inhibitory Peptide (GIP). Gastrin stimulates the gastric gland cells to secrete Gastric enzymes. Glucagon. It stimulates liver cells (hepatocytes) and adipocytes for cellular uptake of Glucone and its Secretin stimulates the intestinal glands to secrete intestinal juice. utilization. Therefore Glucose from blood decreases (Hypoglycemia). Cholecystokinin stimulates for the contraction of Gall bladder to push the bile into intestine. It also stimulates for glycogenosis (conversion of Glucose into Glycogen). Pancreaozymin stimulates the pancreate acids to secrete Pancreatic juice. The GIP – inhibits gastric secretion and motility. There is always a balanced secretion of Insulin and Glucagon. Therefore blood glucose level is maintained constant. Hormones of the Heart – ANF – Atrial Natriuretic Factor -Cells - (Delta cells) – Secrete Somatostatin. decreases Glucagon and Insulin secretion. Diabetes Mellitus – Takes place due to deficiency of Insulin Blood Glucose level increases (Hyperglycemia) Appearance of glucose in urine (Glucasuria) It The wall of atrium of heat secretes ANF (Atrial Natriuretic Factor). This hormone is secreted when there is increase in Blood Pressure. Effect – It causes dilation of blood vessels. Therefore, the BP reduces. It causes increased Na+ excretion. Also it causes increased excretion of water in urine. Therefore, the blood volume reduces. Also the BP decreases. secretes usually the progesterone, but it also secretes Relaxin at the time of parturation. Hormones of Kidney – Erythropoietin. The Estrogen – The JG complex of kidney secretes the hormone called (1) Erythropoietin. It is a peptide hormone. It stimulates the bone marrow for production of RBCs. It is necessary for the growth of reproductive organs like ovaries, oviducts, uterus and vagina. (2) It is necessary for the development of secondary sexual characters like high pitch voice, development of mammary glands, broadening of pelvis, pubic hairs and depositing of subcutaneous fat to give rise to feminine appearance. (3) It is also necessary to regulate female sexual behaviour. Hormones of the Gonads – Testes and Ovaries are the male and female gonads respectively. Testes – The Interstitial cells of Leydig secrete the androgens. One of them is predominant. It is testosterone. They are all steroids. Role of Androgens – (1) Regulates and stimulates the development, maturation and functions of male reproductive system. It acts upon the seminiferous tubules, epididymis, vasa-deferentia, seminal vesicles, prostate gland, urethra etc. (2) Also the endrogens are essential for the formation of secondary sex characters in male. They include development of pubic hair, facial hair, hair in the armpits, masculine development, low pitch voice, aggressiveness, etc. Corpus Luteum – secretes Progesterone. It maintains the pregnancy. It also acts on the mammary glands and stimulate them for milk secretion. Hormones of Hypothalamus – There are several groups of neurosecretory cells in the hypothalamus. They secrete neurohormones like CRH (Corticotropin Releasing Hormone) for controlling the ACTH secretion. TSH RF – Thyroid Stimulating Hormone Releasing Factor. (3) They are also necessary for spermatogenesis. FSH RF (FSHRH) – Follicular Stimulating Hormone Releasing Factors Ovary – The ovaries are the female gonads. The follicular cells secrete estrogen. The corpusluteum GHRF – Growth Hormone Releasing Factor. GHIF – Growth Hormone Inhibiting Factor PRIF – Prolactin Release Inhibiting Factor (i) The hormone normally does not enter the target cell. It generates the second messengers like cyclic AMP, Ca++ or IP3 (Inositol triphosphate), etc. (ii) The second messenger further regulates the cellular metabolism. MSHRF – Melanocyte Stimulating Hormone Releasing Factor. MSH RF – Melanocyte Stimulating Hormone Release Inhibiting Factor.Etc. Also it secretes the hormones like Vasopressin (ADH), Oxytocin (Pitocin) and Coherin Explain the Mechanism of action of hormone. Ans: (1) Hormones act on specific tissues and/or organs. Such tissues and/or organs are regarded as Target tissues or target organs. (2) The cells of Target tissues have specific binding sites which are regarded as receptor sites. (3) The hormone receptors are generally present at the surface of cell membrane also called as the Membrane Bound Receptors. They may be present inside the cell (4) When the hormone molecule binds with the receptor molecule, it forms a hormone-receptor complex. (5) The receptor is specific for a particular hormone. (6) The formation of such a complex leads to certain biochemical changes in the target tissue. (7) Thus the hormone regulates the metabolism and physiological functions. tissue (iii) The steroid hormones and Thyroxine interact with intracellular receptors. So they regulate the gene expression or chromosome function. (iv) When the receptor is intracellular and within the nucleus, the hormone receptor complex is formed inside the nucleus. It then interacts with the genome thereby resulting into changes in physiological and developmental functions.