role of endocrinic glands in regulation of body functions
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Role of endocrinic Role of endocrinic glands in regulation of glands in regulation of
body functionsbody functions
Pineal GlandPineal Gland produces produces
DimethyltryptamineDimethyltryptamine MelatoninMelatonin
FunctionFunction The pineal gland was originally believed to be a "The pineal gland was originally believed to be a "
vestigialvestigial remnant" of a larger organ (much as the remnant" of a larger organ (much as the appendixappendix was thought to be a vestigial digestive organ). was thought to be a vestigial digestive organ). It was only after the 1960s that scientists discovered It was only after the 1960s that scientists discovered that the pineal gland is responsible for the production of that the pineal gland is responsible for the production of melatoninmelatonin, which is regulated in a , which is regulated in a circadian rhythmcircadian rhythm. . Melatonin is a derivative of the Melatonin is a derivative of the amino acidamino acid tryptophantryptophan, , which also has other functions in the which also has other functions in the Central Nervous SystemCentral Nervous System. The production of melatonin . The production of melatonin by the pineal gland is stimulated by darkness and by the pineal gland is stimulated by darkness and inhibited by light. inhibited by light. [7][7] The retina detects the light, and The retina detects the light, and directly signals and entrains the directly signals and entrains the suprachiasmatic nucleussuprachiasmatic nucleus (SCN). Fibers project from the (SCN). Fibers project from the SCN to the paraventricular nuclei (PVN), which relay SCN to the paraventricular nuclei (PVN), which relay the circadian signals to the the circadian signals to the spinal cordspinal cord and out via the and out via the sympathetic system to sympathetic system to superior cervical gangliasuperior cervical ganglia (SCG), (SCG), and from there into the pineal gland.and from there into the pineal gland.
Thyroid glandThyroid gland produces produces Triiodothyronine (T3), the potent form of Triiodothyronine (T3), the potent form of
thyroid hormonethyroid hormone Thyroxine (T4), a less active form of Thyroxine (T4), a less active form of
thyroid hormonethyroid hormone CalcitoninCalcitonin
Tetraiodothyronine (T4) orTetraiodothyronine (T4) or ThyroxineThyroxine-Triiodothyronine (T3)-Triiodothyronine (T3) a)a) helps regulate the metabolic rate of all helps regulate the metabolic rate of all
cells and cell growth and tissue cells and cell growth and tissue differentiation.differentiation.
CalcitoninCalcitonin
a)a) influence the processing of calcium by bone influence the processing of calcium by bone cells by decreasing blood calcium levels and cells by decreasing blood calcium levels and promoting conservation of hard bone matrix.promoting conservation of hard bone matrix.
Parathyroid glandParathyroid gland produces produces
Parathyroid hormoneParathyroid hormone (PTH) (PTH)
Parathyroid Hormone (PTH)Parathyroid Hormone (PTH)
a)a) an antagonist to calcitonin and acts to maintain an antagonist to calcitonin and acts to maintain calcium homeostasis.calcium homeostasis.
b)b) acts on bone: causes more bone to be dissolved, acts on bone: causes more bone to be dissolved, yielding calcium and phosphate, which enters the yielding calcium and phosphate, which enters the bloodstream.bloodstream.
c)c) acts on kidney: causes phosphate to be secreted by acts on kidney: causes phosphate to be secreted by the kidney cells into the urine to be excreted.the kidney cells into the urine to be excreted.
d)d) acts on intestinal cells: causes increased intestinal acts on intestinal cells: causes increased intestinal absorption of calcium by activating vitamin D.absorption of calcium by activating vitamin D.
ThymusThymus The thymus plays an important role in the The thymus plays an important role in the
development of the development of the immune systemimmune system, being the , being the primary site of T cell maturation. The organ is primary site of T cell maturation. The organ is most active between the late stages of gestation most active between the late stages of gestation and and early pubertyearly puberty, when most of the T cells an , when most of the T cells an individual will carry for their lifetime are formed. individual will carry for their lifetime are formed. With the onset of puberty the organ atrophies, With the onset of puberty the organ atrophies, gradually shrinking in size and function. The gradually shrinking in size and function. The atrophy is due to the increased circulating level of atrophy is due to the increased circulating level of sex hormonessex hormones, and chemical or physical castration , and chemical or physical castration of an adult results in the thymus increasing in size of an adult results in the thymus increasing in size and activity. and activity.
In the two thymic lobes, In the two thymic lobes, lymphocytelymphocyte precursors from the bone-marrow become precursors from the bone-marrow become thymocytesthymocytes, and subsequently mature into , and subsequently mature into T cellsT cells. Once mature, T cells emigrate from . Once mature, T cells emigrate from the thymus and constitute the peripheral T cell the thymus and constitute the peripheral T cell repertoire responsible for directing many repertoire responsible for directing many facets of the facets of the adaptive immune systemadaptive immune system. Loss of . Loss of the thymus at an early age through genetic the thymus at an early age through genetic mutation or surgical removal results in severe mutation or surgical removal results in severe immunodeficiency and a high susceptibility to immunodeficiency and a high susceptibility to infection. infection.
The ability of T cells to recognize foreign The ability of T cells to recognize foreign antigens is mediated by the antigens is mediated by the T cell receptorT cell receptor. The . The T cell receptorT cell receptor undergoes genetic undergoes genetic rearrangement during rearrangement during thymocytethymocyte maturation, maturation, resulting in each T cell bearing a unique T cell resulting in each T cell bearing a unique T cell receptor, specific to a limited set of receptor, specific to a limited set of peptidepeptide::MHCMHC combinations. The random nature of the combinations. The random nature of the genetic rearrangement results in a requirement genetic rearrangement results in a requirement of of central tolerancecentral tolerance mechanisms to remove or mechanisms to remove or inactive those T cells which bear a inactive those T cells which bear a T cell receptorT cell receptor with the ability to recognise self- with the ability to recognise self-peptides.peptides.
HeartHeart produces produces
Atrial-natriuretic peptideAtrial-natriuretic peptide (ANP) (ANP) ANH’s primary effects is to oppose increases ANH’s primary effects is to oppose increases
in blood volume or blood pressure; in blood volume or blood pressure; Also antagonist to ADH and aldosteroneAlso antagonist to ADH and aldosterone
StomachStomach and and intestinesintestines produce produce
CholecystokininCholecystokinin (CCK) (CCK) GastrinGastrin Neuropeptide YNeuropeptide Y (NPY) (NPY) SecretinSecretin SomatostatinSomatostatin
LiverLiver produces produces Insulin-like growth factorInsulin-like growth factor (IGF) (IGF)
AngiotensinogenAngiotensinogen ThrombopoietinThrombopoietin
Islets of LangerhansIslets of Langerhans in the in the pancreaspancreas produce produce
InsulinInsulin GlucagonGlucagon SomatostatinSomatostatin
1) 1) AlphaAlpha cells secrete glucagons. cells secrete glucagons.
2)2) BetaBeta cells secrete insulin and amylin cells secrete insulin and amylin
3)3) DeltaDelta cells secrete somatostatin. cells secrete somatostatin.
4)4) F1 or PP1F1 or PP1 cells secrete pancreatic cells secrete pancreatic polypeptides.polypeptides.
Name of Name of cellscells ProductProduct % of islet % of islet
cellscells FunctionFunction
betabeta cellscells InsulinInsulin and and AmylinAmylin 50-80%50-80% lower blood sugarlower blood sugar
alphaalpha cellscells GlucagonGlucagon 15-20%15-20% raise blood sugarraise blood sugar
deltadelta cellscells SomatostatinSomatostatin 3-10%3-10% inhibit endocrine inhibit endocrine pancreaspancreas
PP PP cellscells PancreaticPancreatic polypeptidepolypeptide 1%1% inhibit exocrine inhibit exocrine
pancreaspancreas
InsulinInsulin
Action on carbohydrate metabolism:Action on carbohydrate metabolism: 1.1. Increase permeability of cell Increase permeability of cell membrane to glucose.membrane to glucose.2.2. Stimulate synthesis of glycogen. Stimulate synthesis of glycogen.3.3. Activate transformation of Activate transformation of carbohydrates into fatscarbohydrates into fats4.4. Decrease development of glucose from Decrease development of glucose from amino acids.amino acids.
Action on fat metabolism.Action on fat metabolism.
1.1. Decrease destruction of fat Decrease destruction of fat 2.2. Activates synthesis of fatty acids Activates synthesis of fatty acids3.3. Inhibit development of ketonic bodies. Inhibit development of ketonic bodies.
Action on protein metabolism.Action on protein metabolism.
1.1. Increase transmission of amino acids in Increase transmission of amino acids in cells.cells.2.2. Increase synthesis of proteins. Increase synthesis of proteins.3.3. Decrease destruction of amino acids. Decrease destruction of amino acids.
The actions of insulin on the global The actions of insulin on the global human metabolism level include:human metabolism level include:
Control of cellular intake of certain substances, Control of cellular intake of certain substances, most prominently most prominently glucoseglucose in muscle and in muscle and adipose tissue (about ⅔ of body cells). adipose tissue (about ⅔ of body cells).
Increase of Increase of DNA replicationDNA replication and and protein synthesisprotein synthesis via control of amino acid via control of amino acid uptake. uptake.
Modification of the activity of numerous Modification of the activity of numerous enzymesenzymes ( (allosteric effectallosteric effect). ).
Mechanism of glucose dependent Mechanism of glucose dependent insulin releaseinsulin release
-Glucagon-Glucagon
1.1. tends to increase blood glucose levels tends to increase blood glucose levels 2.2. stimulates gluconeogenesis in liver cells stimulates gluconeogenesis in liver cells
(transformation of fatty acids and amino acid (transformation of fatty acids and amino acid into glucose).into glucose).
3.3. increase glycogen conversion to glucose in increase glycogen conversion to glucose in liver cells.liver cells.
4.4. stimulate lipolysis in liver. stimulate lipolysis in liver.
Increased secretion of glucagon is Increased secretion of glucagon is caused by:caused by:
Decreased Decreased plasma glucoseplasma glucose Increased Increased catecholaminescatecholamines - norepinphrine and - norepinphrine and
epinephrine epinephrine Increased plasma Increased plasma amino acidsamino acids (to protect from (to protect from
hypoglycemiahypoglycemia if an all protein meal consumed) if an all protein meal consumed) Sympathetic nervous systemSympathetic nervous system AcetylcholineAcetylcholine CholecystokininCholecystokinin
Decreased secretion of glucagon Decreased secretion of glucagon (inhibition) is caused by:(inhibition) is caused by:
SomatostatinSomatostatin InsulinInsulin
FunctionFunction Glucagon helps maintain the level of Glucagon helps maintain the level of glucoseglucose in the in the
bloodblood by binding to by binding to glucagon receptorsglucagon receptors on on hepatocyteshepatocytes, causing the , causing the liverliver to release glucose - to release glucose - stored in the form of stored in the form of glycogenglycogen - through a process - through a process known as known as glycogenolysisglycogenolysis. As these stores become . As these stores become depleted, glucagon then encourages the liver to depleted, glucagon then encourages the liver to synthesize additional glucose by synthesize additional glucose by gluconeogenesisgluconeogenesis. . This glucose is released into the bloodstream. Both of This glucose is released into the bloodstream. Both of these mechanisms lead to glucose release by the liver, these mechanisms lead to glucose release by the liver, preventing the development of hypoglycemia.preventing the development of hypoglycemia.
Increased free Increased free fatty acidsfatty acids and and ketoacidsketoacids into the blood into the blood Increased Increased ureaurea production production
-Somatostatin-Somatostatin
1. 1. Regulate the other endocrine cells of the Regulate the other endocrine cells of the pancreatic islets.pancreatic islets.
Somatostatin is classified as an Somatostatin is classified as an inhibitoryinhibitory hormone, whose main hormone, whose main
actions are to:actions are to: Inhibit the release of Inhibit the release of growth hormonegrowth hormone (GH) (GH) Inhibit the release of Inhibit the release of thyroid-stimulating hormonethyroid-stimulating hormone (TSH) (TSH) Suppress the release of Suppress the release of gastrointestinal hormonesgastrointestinal hormones
GastrinGastrin CholecystokininCholecystokinin (CCK) (CCK) SecretinSecretin MotilinMotilin Vasoactive intestinal peptideVasoactive intestinal peptide (VIP) (VIP) Gastric inhibitory polypeptideGastric inhibitory polypeptide (GIP) (GIP) EnteroglucagonEnteroglucagon (GIP) (GIP)
Lowers the rate of gastric emptying, and reduces smooth muscle contractions and Lowers the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within the intestine. blood flow within the intestine.
Suppress the release of pancreatic hormones Suppress the release of pancreatic hormones Inhibit the release of Inhibit the release of insulininsulin Inhibit the release of Inhibit the release of glucagonglucagon
Suppress the exocrine secretory action of Suppress the exocrine secretory action of pancreaspancreas. . Somatostatin opposes the effects of Somatostatin opposes the effects of Growth Hormone-Releasing HormoneGrowth Hormone-Releasing Hormone (GHRH) (GHRH)
KidneyKidney produces produces
ReninRenin ErythropoietinErythropoietin (EPO) (EPO) CalcitriolCalcitriol (the active form of vitamin D3) (the active form of vitamin D3)
SkinSkin produces produces
Vitamin D3Vitamin D3 (calciferol) (calciferol)
Adipose tissueAdipose tissue
LeptinLeptin EstrogensEstrogens (mainly (mainly estroneestrone))
TestesTestes
AndrogensAndrogens (chiefly (chiefly testosteronetestosterone) )
TestosteroneTestosterone TestosteroneTestosterone is a is a steroid hormonesteroid hormone from the from the androgenandrogen
group. Testosterone is primarily secreted in the group. Testosterone is primarily secreted in the testestestes of males and the of males and the ovariesovaries of females although small of females although small amounts are secreted by the amounts are secreted by the adrenal glandsadrenal glands. It is the . It is the principal principal malemale sex hormone and an sex hormone and an anabolic steroidanabolic steroid. . In both males and females, it plays key roles in health In both males and females, it plays key roles in health and well-being. Examples include enhanced and well-being. Examples include enhanced libidolibido, , energy, immune function, and protection against energy, immune function, and protection against osteoporosisosteoporosis. On average, the adult male body . On average, the adult male body produces about twenty to thirty times the amount of produces about twenty to thirty times the amount of testosterone that an adult female's body does.testosterone that an adult female's body does.
EffectsEffects In general, androgens promote protein synthesis and growth of In general, androgens promote protein synthesis and growth of
those tissues with androgen receptors. Testosterone effects can those tissues with androgen receptors. Testosterone effects can be classified as virilizing and anabolic effects, although the be classified as virilizing and anabolic effects, although the distinction is somewhat artificial, as many of the effects can be distinction is somewhat artificial, as many of the effects can be considered both. Anabolic effects include growth of muscle considered both. Anabolic effects include growth of muscle mass and strength, increased bone density and strength, and mass and strength, increased bone density and strength, and stimulation of linear growth and stimulation of linear growth and bone maturationbone maturation. Virilizing . Virilizing effects include maturation of the sex organs, particularly the effects include maturation of the sex organs, particularly the penispenis and the formation of the and the formation of the scrotumscrotum in fetuses, and after in fetuses, and after birth (usually at puberty) a deepening of the voice, growth of birth (usually at puberty) a deepening of the voice, growth of the the beardbeard and axillary hair. Many of these fall into the and axillary hair. Many of these fall into the category of male category of male secondary sex characteristicssecondary sex characteristics..
Testosterone effects can also be classified by the age Testosterone effects can also be classified by the age of usual occurrence. For postnatal effects in both of usual occurrence. For postnatal effects in both males and females, these are mostly dependent on the males and females, these are mostly dependent on the levels and duration of circulating free testosterone.levels and duration of circulating free testosterone.
Most of the Most of the prenatal androgen effectsprenatal androgen effects occur between occur between 7 and 12 weeks of gestation.7 and 12 weeks of gestation.
Genital virilization (midline fusion, Genital virilization (midline fusion, phallicphallic urethra, urethra, scrotal thinning and rugation, phallic enlargement) scrotal thinning and rugation, phallic enlargement)
Development of prostate and seminal vesicles Development of prostate and seminal vesicles
Early infancy androgen effectsEarly infancy androgen effects are the least are the least understood. In the first weeks of life for male infants, understood. In the first weeks of life for male infants, testosterone levels rise. The levels remain in a testosterone levels rise. The levels remain in a pubertal range for a few months, but usually reach the pubertal range for a few months, but usually reach the barely detectable levels of childhood by 4-6 months barely detectable levels of childhood by 4-6 months of age. The function of this rise in humans is of age. The function of this rise in humans is unknown. It has been speculated that "brain unknown. It has been speculated that "brain masculinization" is occurring since no significant masculinization" is occurring since no significant changes have been identified in other parts of the changes have been identified in other parts of the body.body.
Early postnatal effectsEarly postnatal effects are the first visible effects of are the first visible effects of rising androgen levels in childhood, and occur in both rising androgen levels in childhood, and occur in both boys and girls in puberty.boys and girls in puberty.
Adult-type body odour Adult-type body odour Increased oiliness of skin and hair, acne Increased oiliness of skin and hair, acne Pubarche (appearance of pubic hair) Pubarche (appearance of pubic hair) Axillary hair Axillary hair Growth spurt, accelerated bone maturation Growth spurt, accelerated bone maturation Fine upper lip and sideburn hair Fine upper lip and sideburn hair
Advanced postnatal effectsAdvanced postnatal effects begin to occur when androgen has been higher begin to occur when androgen has been higher than normal adult female levels for months or years. In males these are than normal adult female levels for months or years. In males these are normal late pubertal effects, and only occur in women after prolonged normal late pubertal effects, and only occur in women after prolonged periods of excessive levels of free testosterone in the blood.periods of excessive levels of free testosterone in the blood.
Phallic enlargement (including clitoromegaly) Phallic enlargement (including clitoromegaly) Increased libido and erection frequency Increased libido and erection frequency Pubic hair extends to thighs and up toward umbilicus Pubic hair extends to thighs and up toward umbilicus Facial hair (sideburns, beard, moustache) Facial hair (sideburns, beard, moustache) Chest hair, periareolar hair, perianal hair Chest hair, periareolar hair, perianal hair Subcutaneous fat in face decreases Subcutaneous fat in face decreases Increased muscle strength and mass Increased muscle strength and mass Deepening of voice Deepening of voice Growth of the adam's apple Growth of the adam's apple Growth of spermatogenic tissue in testes, male fertility Growth of spermatogenic tissue in testes, male fertility Growth of jaw, brow, chin, nose, and remodeling of facial bone contours Growth of jaw, brow, chin, nose, and remodeling of facial bone contours Shoulders widen and rib cage expands Shoulders widen and rib cage expands Completion of bone maturation and termination of growth. This occurs Completion of bone maturation and termination of growth. This occurs
indirectly via estradiol metabolites and hence more gradually in men than indirectly via estradiol metabolites and hence more gradually in men than women. women.
Adult testosterone effectsAdult testosterone effects are more clearly are more clearly demonstrable in males than in females, but are demonstrable in males than in females, but are likely important to both sexes. Some of these likely important to both sexes. Some of these effects may decline as testosterone levels effects may decline as testosterone levels decline in the later decades of adult life.decline in the later decades of adult life.
Maintenance of muscle mass and strength Maintenance of muscle mass and strength Maintenance of bone density and strength Maintenance of bone density and strength Libido and erection frequency Libido and erection frequency Mental and physical energy Mental and physical energy
Ovarian follicleOvarian follicle
EstrogensEstrogens (mainly (mainly estradiolestradiol) )
Corpus luteumCorpus luteum
ProgesteroneProgesterone EstrogensEstrogens (mainly (mainly estradiolestradiol) )
PlacentaPlacenta (when (when pregnantpregnant) )
ProgesteroneProgesterone EstrogensEstrogens (mainly (mainly estriolestriol) ) Human chorionic gonadotropinHuman chorionic gonadotropin (HCG) (HCG) Human placental lactogenHuman placental lactogen (HPL) (HPL)
Somatostatin is secreted not only by Somatostatin is secreted not only by cellscells of of the the hypothalamushypothalamus but also by but also by delta cellsdelta cells of of stomachstomach, , intestineintestine, and , and pancreaspancreas. It binds to . It binds to somatostatin receptorssomatostatin receptors..
SomatostatinSomatostatin Somatostatin is classified as an Somatostatin is classified as an inhibitoryinhibitory hormone, hormone,
whose main actions are to:whose main actions are to: Inhibit the release of Inhibit the release of growth hormonegrowth hormone (GH) (GH) Inhibit the release of Inhibit the release of thyroid-stimulating hormonethyroid-stimulating hormone
(TSH) (TSH) Suppress the release of Suppress the release of gastrointestinal hormonesgastrointestinal hormones
GastrinGastrin CholecystokininCholecystokinin (CCK) (CCK) SecretinSecretin MotilinMotilin Vasoactive intestinal peptideVasoactive intestinal peptide (VIP) (VIP) Gastric inhibitory polypeptideGastric inhibitory polypeptide (GIP) (GIP) EnteroglucagonEnteroglucagon (GIP) (GIP)
Lowers the rate of gastric emptying, and reduces Lowers the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within smooth muscle contractions and blood flow within the intestine. the intestine.
Suppress the release of pancreatic hormones Suppress the release of pancreatic hormones Inhibit the release of Inhibit the release of insulininsulin Inhibit the release of Inhibit the release of glucagonglucagon
Suppress the exocrine secretory action of Suppress the exocrine secretory action of pancreaspancreas. . Somatostatin opposes the effects of Somatostatin opposes the effects of
Growth Hormone-Releasing HormoneGrowth Hormone-Releasing Hormone (GHRH) (GHRH)
Gonadal production of steroids. Only the ovaries have highGonadal production of steroids. Only the ovaries have highconcentrations of the enzymes (aromatase) required toconcentrations of the enzymes (aromatase) required to
produce the estrogens estrone and estradiol.produce the estrogens estrone and estradiol.