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Chemical control

QuestionAnswer
What does nervous system do It receives and sends the information in the form of electrical impulses. It is in direct connection with every part under its control. It shows Rapid transmission and quick response but its response is limited to only those cells innervated by neurones
What does endocrine system do It receives and send the information in the form of chemicals called hormones. It is not directly connected with parts under its control and shows slow transmission and slow response. Response is produced by all the cells of target tissue
Define exocrine gland It doesn't pour its secretion into lymph or blood. A duct is often present. Its secretion is poured directly over the target tissue. The secretion is enzymatic, lubricant or excretory. Eg. Sweat glands, sebaceous glands etc
Define endocrine gland It pour its secretion into lymph or blood. Duct is absent. Secretion is transported to the target tissue through blood. Secretions contains hormones. Example pituitary, thyroid, adrenal etc
Define properties of hormones It do not provide energy or building materials but they do have effects on growth and differentiation of the body. It is highly specific in nature and do not initiate a reaction but can influence its rate
Definition of hormone Hormones are non nutrient chemicals which acts as intracellular messengers and are produced in trace amounts
What constitute the endocrine system Endocrine glands and hormones producing diffused tissues or cells located in different parts of our body constitued the endocrine system
Which are the organised endocrine bodies in our body Pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads
Which organs also produce hormones Gastrointestinal tract, liver, kidney, heart
What is the master of Master endocrine gland The hypothalamus
Write about hypothalamus It is the Basal part of diencephalon, forebrain and it regulates a wide spectrum of body functions. It contains several groups of neurosecretory cells called nuclei which produce hormones which regulate the synthesis and secretion of pituitary hormones
Two types of hormones produced by hypothalamus First, the releasing hormones which stimulate secretion of pituitary hormones and second is the inhibiting hormones which inhibit secretions of pituitary hormones
Role of gonadotropin releasing hormone It stimulates the pituitary synthesis and release of gonadotropins
Role of somatostatin It inhibits the release of growth hormone from the pituitary
How does hormones of hypothalamus reach pituitary gland These hormones reach the pituitary gland through a portal circulatory system and regulate the functions of the anterior pituitary. The posterior pituitary is under the direct neural regulation of the hypothalamus
Location of pituitary gland It is located in a Bony cavity called Sella turcica and is attached to hypothalamus by a stalk. It is divided anatomically into an adenohypophysis and a neurohypophysis
What is adenohypophysis It consists of 2 portions, pars distalis and pars intermedia. The pars distalis region of pituitary,aka anterior pituitary, produces growth hormone, prolactin, thyroid stimulating,adrenocorticotropic,luteinizing and follicle stimulating hormones.
Which hormone is secreted by pars intermedia Its secrets only one hormone called melanocyte stimulating hormone. Inhumans, the pars intermedia is almost merged with pars distalis
What is neurohypophysis (pars nervosa) Also known as posterior pituitary, stores and releases two hormones called Oxytocin and vasopressin which are actually synthesized by the hypothalamus and are transported axonally to neurohypophysis.
What is the effect of secretion of growth hormone Over secretion of GH stimulates abnormal growth of the body leading to gigantism and low secretion of GH results in stunted growth resulting in pituitary dwarfism.
Role of prolactin It regulates the growth of the mammary glands and formation of milk in them
Role of thyroid stimulating hormone It stimulates the synthesis and secretion of thyroid hormones from the thyroid gland
Role of adrenocorticotropic hormone It stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex
Role of LH and FSH in males LH and FSH stimulate gonadal activity and hence are called gonadotropins. In males, LH stimulates the synthesis and secretion of hormones called androgens from testis. In males, FSH and androgens regulate spermatogenesis.
Role of LH and FSH in females LH induces ovulation of 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.
Role of melanocyte stimulating hormone It acts on the melanocytes and regulates pigmentation of the skin
Role of Oxytocin It acts on the smooth muscle of our body and stimulates their contraction. In females it stimulates a vigorous contraction of uterus at the time of childbirth, and milk ejection from the mammary gland
Role of vasopressin IT Act smelly at the kidney and stimulates reservation of water and electrolyte by the distal tubes and thereby reduce loss of water through urine. Hence it is also called as antidiuretic hormone
How does hormones released from the hypothalamus reach adenohypophysis It reaches through the hypophyseal portal veins
The another name of growth hormone It is also known as somatotropin. Soma means body and Trophe means Nourishment
Difference between pituitary dwarfism and acromicria Pituitary dwarfism occurs before puberty and is called atleiosis and the dwarfs are called midgets. If deficiency of GH occurs after puberty then it causes acromicria. The sufferer have normal body and intelligence but small hands, feet and face
What is acromegaly If the oversecretion of GH occurs after puberty, then the individual suffers from acromegaly
What is kyphosis Sometimes a person develops Humpty to bending of vertebral column. This is called kyphosis
Which one is the milk ejection hormone and birth hormone Oxytocin
Location of pineal gland It is located on the dorsal side of forebrain
Secretion of pineal gland It's secretes a hormone called melatonin which plays a very important role in the regulation of a 24 hour rhythm of our body. For example it helps in maintaining the normal Rhythm hours of sleep wake cycle, body temperature.
Other effects of melatonin It also influences metabolism, pigmentation, the menstrual cycle and as well as our defence capability. It delayed puberty in humans by opposing the action of LH and FSH and hence affects the menstrual cycle and working of gonads
Location of thyroid gland
Location of thyroid gland, the largest endocrine gland. It is composed of two lobes which are located on either side of the trachea. Both the lobes are interconnected with a thin flap of connective tissue called isthmus. The thyroid gland is composed of follicles and stromal tissues.
Role of follicular cells in thyroid gland These synthesise 2 hormones, Tetraiodothyronine or thyroxine (T4) and triiodothyronine (T3).
Importance of Iodine Iodine is essential for the normal rate of hormone synthesis in the thyroid. Its deficiency results in Hypothyroidism and enlargement of the thyroid gland commonly called goitre.
Hypothyroidism During pregnancy it causes defective development and maturation of the baby leading to stunted growth, mental retardation, low intelligence quotient, abnormal skin, deaf mutism etc. In adult women hypothyroidism may cause irregularity in menstrual cycle
What is hyperthyroidism Due to cancer of the thyroid gland or due to development of nodules of the thyroid glands the rate of synthesis and secretion of the thyroid hormones is increased to abnormal high levels leading to a condition called hyperthyroidism.
Important roles of thyroid hormones It helps and regulation of the basal metabolic rate. Also support the process of red blood cell formation. It control the metabolism of Carbohydrates, proteins and fats. Maintenance of water and electrolyte balance is also influenced by thyroid hormones
Which protein hormone is secreted by thyroid gland Thyrocalcitonin which regulates the blood calcium levels
Role of thyroxine Which stimulate tissue differentiation because of this action they promote metamorphosis of tadpoles in adults frog. It also enhance the action of neurotransmitter: adrenaline and noradrenaline.
Location of parathyroid gland Four parathyroid glands are present on the back side of the thyroid gland, one pair is in the two lobes of the thyroid gland.
Hormone secreted by parathyroid glands it secretes a peptide hormone called parathyroid hormone. The secretion of PTH is regulated by the circulating levels of calcium ions.
Role of PTH It increases the calcium levels in the blood. It acts on bones and stimulates the process of bone resorption (dissolution/demineralization). It also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption from the digested food.
role of Parathyroid hormone with thyrocalcitonin Parathyroid hormone is a hypercalcemic hormone that is it increases the blood calcium levels. Along with thyrocalcitonin, it plays a significant role in calcium balance in the body.
Location of thymus The thymus gland is a lobular structure located between lungs behind sternum on the ventral side of aorta. It plays a major role in the development of the immune system.
Hormone secreted by thymus Thymosin. It plays a major role in the differentiation of t Lymphocytes, which provide cell mediated immunity. In addition, thymosin also promote production of antibodies to provide humoral immunity.
What happens to thymus of old person Thymus is degenerated in old individuals resulting in a decreased production of thymosin. As a result the immune responses of old persons become weak
What is parathyroid tetany It is a disease caused due to deficiency of calcium which causes sustained contraction of the muscles of larynx, face hands and feet.
What is hyperparathyroidism Parathyroid tumors secretesa excessive amount of parathormone which causes increased mobilisation of bone minerals into the blood, softening of bones, rise in the concentration of the calcium ion in the plasma.
What is hypercalcemia It may cause osteitis fibrosa cystis. Some of the bone substances is replaced by cavities that are filled with fibrous tissue. Due to high blood calcium level, its deposition in gallbladder and kidney leads to stone formation.
What is the origin of thymus and another name for it It is endodermal and it is known as the Throne of immunity or the training school of t lymphocytes.
Location of adrenal gland Our body has one pair of adrenal glands, one at the interior part of each kidney. The centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.
Hormones secreted by adrenal medulla
It secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. These are commonly called as catecholamines.
Adrenaline and noradrenaline These are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones are hormones of flight or fight. These increase alertness, papillary dilation, piloerection, sweating etc.
Role of catecholamines They stimulate The breakdown of glycogen resulting in an increased concentration of glucose in blood. They also stimulate The breakdown of lipids and proteins. They increase the Heartbeat, the strength of heart contraction and the rate of respiration.
Division of adrenal cortex It can be divided into three layers, called zona reticularis(inner layer), zona fasciculata(middle layer) and zona glomerulosa(outer layer).
Hormones of adrenal cortex Its secrets many hormones commonly called as corticoids. The corticoids, which are involved in carbohydrate metabolism are called glucocorticoids. These are produced by zona fasciculata. In our body, cortisol is the main glucocorticoid.
Mineralocorticoid Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids. Aldosterone is the main mineral corticoid in our body.
Role of glucocorticoids It's stimulate gluconeogenesis, life policies and proteolysis; and inhibit cellular uptake and utilisation of amino acids. Cortisol is also involved in maintaining the cardiovascular system as well as the kidney functions.
Roles of cortisol Glucocorticoids, particularly cortisol, produces anti inflammatory reactions and surprises the immune response. It also stimulates the RBC production.
Role of aldosterone IT Act smiley at the renal tubules and stimulates the reabsorption of sodium and water and excretion of potassium and phosphate ions. It helps in the maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure.
Androgenic steroids and its role Small amounts of androgenic Steroids are also secreted by the adrenal cortex which play a role in the growth of axial hair, pubic hair and facial hair during puberty.
Origin of adrenal glands These have dual origin that is from mesoderm and ectoderm of embryo. Adrenal cortex is derived from Mesoderm of embryo whereas adrenal medulla develops from neuroectoderm of the embryo.
Different layers of adrenal gland and hormones produced by them Mineralocorticoids are released from zona glomerulosa. Glucocorticoids are produced by zona fasciculata. Sex corticoids or Gonadocorticoids are produced by zona reticularis.
What does deficiency of aldosterone causes It causes addison's disease and its excess causes aldosteronism. Addison's disease is destruction of adrenal cortex by disease like tuberculosis due to deficiency of both glucocorticoids and mineral corticoids.
Cushing's syndrome It is a disorder caused due to tumor of the adrenal cortex which secretes too much cortisol.
Adrenal virilism Excessive secretion of sex corticoids produces the male type external sex character such as beards and moustaches and male voice in women.
Pancreas (endodermal origin) It is a composite gland which acts as both exocrine and endocrine gland. The endocrine pancreas consists of islets of langerhans. There are about 2 million islets of langerhans in a normal human pancreas representing only 1 to 2% of the pancreatic tissue.
Two main types of cells in islets of langerhans These are called Alpha cells and Beta cells. The Alpha cells secrete a hormone called glucagon, while the Beta cells secrete insulin.
Glucagon and its role It is a peptide hormone which maintains the normal blood glucose levels. It acts mainly on the liver cells and stimulates glycogenolysis resulting in an increased blood sugar. It stimulates the process of gluconeogenesis which also causes hyperglycemia.
Why glucagon is called hyperglycemic hormone It reduces the cellular glucose uptake and utilisation and causes hyperglycemia.
Insulin and its role It is peptide hormone which regulate glucose homeostasis. It acts on hepatocytes and adipocytes and enhances cellular glucose uptake and utilisation which causes rapid movement of glucose from blood to hepatocytes and adipocytes resulting in hypoglycemia.
Glycogenesis by insulin Insulin also stimulates conversion of glucose to glycogen in the target cells. The glucose homeostasis in blood is thus maintained jointly by the two- insulin and glucagons.
Diabetes mellitus Prolonged hyperglycemia leads to a complex disorder called Diabetes mellitus which is associated with loss of glucose through urine and formation of harmful compounds known as Ketone bodies.
Role of pancreas in maintaining Glucose level When Glucose level in the blood increases, then pancreas secretes insulin which causes glycogenesis and when the Glucose level decreases in the blood then pancreas secretes glucagon which causes glycogenolysis and gluconeogenesis.
Location and functions of testis It is present in the scrotal sac of male individuals. It performs dual functions as a primary sex organ as well as an endocrine gland.
Parts of testis It is composed of seminiferous tubules and stromal or interstitial tissue.
Hormone produced by testis The leydig's cells are interstitial cells, which are present in the intertubular spaces produce a group of hormones called androgen mainly testosterone.
Role of androgens Androgens regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferans, seminal vesicles, prostate gland, urethra etc. Androgens play a major role in the process of spermatogenesis.
Secondary roles of androgens They stimulate muscular growth comma growth of facial and axillary hair, aggressiveness, low pitch of voice etc. It acts on the CNS and influence the male sexual behaviour (libido). It also produce anabolic effects on protein and carbohydrate metabolism.
Location of ovary It is located in the abdomen. It is the primary female sex organ which produces 1 ovum during each menstrual cycle. It also produces two groups of steroid hormones called androgen and progesterone. It is composed of ovarian follicles and stromal tissues.
Role of follicles Oestrogen is synthesized 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.
Role of oestrogen It stimulates growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters, mammary gland development and also regulate female sexual behaviour.
Role of progesterone It supports pregnancy. It also acts on the memory glands and stimulates the formation of alveoli and milk secretion.
Origin of testis and ovary These are of Mesodermal origin
What is relaxin It is a hormone secreted by Corpus luteum at the end of pregnancy causing relaxation of pelvic ligaments and cervix during childbirth.
Control of oestrogen and progesterone Oestrogen is controlled by FSH and progesterone is controlled by LH. Oestrogen controls the appearance and maintenance of secondary sex characteristics and controls the growth and maintenance of endometrium during pregnancy.
Atrial natriuretic factor ANF The atrial wall of our heart secrets a very important peptide hormone called ANF which decreases blood pressure. When the blood pressure is increased, ANF is secreted which causes dilation of the blood vessels. This reduces the blood pressure.
Hormones of kidney The juxtaglomerular cells of kidney produce a peptide hormone called erythropoietin which stimulates erythropoiesis (formation of RBC).
Hormones of endocrine cells of gastrointestinal tract Its secrets four Major peptide hormones namely gastrin, securiton, cholecystokinin and gastric inhibitory peptide.
Role of gastrin and secretin Gastrin apps on the gastric glands and stimulates the secretion of hydrochloric acid and pepsinogen. Secretin acts on the exocrine pancreas and stimulates secretion of water and bicarbonate ions.
Role of cholecystokinin and gastric inhibitory peptide Cholecystokinin acts on both pancreas and gallbladder and stimulates the secretion of pancreatic enzymes and bile juice, respectively. GIP inhibits gastric secretion and motility.
Growth factors Several other non endocrine tissues secrete hormones called growth factors. These factors are essential for the normal growth of tissues and their repairing or regeneration.
Hormone receptors Hormones produced their effects on target tissues by binding to hormone receptors located in the target tissues only. Hormone receptors present on the cell membrane of the target cells are called membrane bound receptors.
Nuclear receptors Hormone receptors present inside the target cell are called intracellular receptors, mostly nuclear receptors (present in the nucleus).
Hormone receptor complex Binding of hormone to its receptor leads to the formation of a hormone receptor complex. Each receptor is specific to 1 hormone only and hence receptors are specific.
Groups of hormones 1) peptide, polypeptide, protein hormones 2) steroids 3) iodothyronines 4) amino acid derivatives
Example of peptide, polypeptide and protein hormones Insulin, glucagon, pituitary hormones, hypothalamic hormones, etc
Example of Steroids Cortisol, testosterone, estradiol and progesterone.
Example of iodothyronine Thyroid hormones
Example of amino acid derivatives Epinephrine
Hormones of membrane bound receptors Hormones which interact with membrane bound receptors normally do not enter the target cell, but generate second messengers (example cyclic AMP, IP3, Ca2+) which in turn regulate cellular metabolism.
Hormones of intracellular receptors Hormones which interact with intracellular receptors (example steroid hormones, iodothyronine, etc) mostly regulate gene expression or chromosome function by the interaction of hormone receptor complex with the genome.
Created by: sherickp