ANATOMY

AND
PHYSIOLOGY
THIS SECTION INCLUDES BRIEF DESCRIPTION
OF ANATOMY AND PHYSIOLOGY OF DIFFERENT
ENDROCRINE GLANDS WITH HIGH YIELDINIG
POINTS PREPARED ESPECIALLY TARGETING
ENDOCRINE
STUDENTS PREPARING PUBLIC SERVICE
COMMISSION AND BACHLOER LEVEL SYSTEM
ENTRANCE.

RAMESH KARKI
BPH (CDPH, IOM
MAHARAJGUNJ)
Endocrinology
 There are two integrating system in body; nervous and endocrine. Both
are interdependent
 The endocrine system achieves coordination and integration by
transmitting information through chemical messenger called hormone.
 Huxley called hormones as chemical messenger
 Hormones are also called autacoids.
 Hormones are first messenger.
 Second messenger includes CAMP, CGMP, etc.
 Third messenger is calcium.
 Sodium is not chemical messenger.
 The word hormone was introduced by starling.
 First hormone developed was secretin by bayliss and starling.
 Insulin was first protein to be synthesized in laboratory by scientist.
 Hormone are secreted by ductless gland called endocrine gland; released
directly to blood.
 Hormone regulates metabolism, growth, secretion, digestion, excretion,
reproduction etc.
 The study of endocrine gland is called endocrinology.
 Study of hormone is called hormonology.
 Formation of hormone is called hormonogenesis.
 The father of endocrinology is Thomas Addison.
 The first endocrine disease reported was Addison disease caused by
destruction of adrenal cortex.
 The gland with duct is called exocrine gland.
 The gland without duct is called endocrine gland.
 Pancreases is called mixed gland or heterocrine gland as it contain both
exocrine and endocrine gland.
 The basic difference between endocrine and exocrine gland are;

ENDOCRINE GLANDS EXOCRINE GLANDS

 Ductless glands  Ducted glands
 Present far away from site of action  Present near the site of action
 Secrete hormone  Secrete enzymes
 Secretion is directly released  Secretion released through ducts
into blood
 Epinephrine, nor epinephrine and dopamine are collectively called
catecholamine.
  When hormone work together to control a process is called
synergism eg; FSH and LH.
 When hormone work against each other; a process is called
antagonism.eg; insulin and glucagon, calcitonin and parathormone.
 Parahormone are hormone like substance , but not product of endocrine
gland.eg; prostaglandin and pheromones

Regulation of hormone secretion

Negative feedback mechanism

 A hormone has biologic actions that directly or indirectly inhibit further

secretion of hormone.
 Most common , self limiting
 E.g.; insulin secretion

Positive feedback mechanism

 A hormone has biologic action that directly or indirectly causes more

secretion of hormone.
 Rare , explosive and self –reinforcing
 Eg; LH surge before ovulation, parturition, Prolactin release.

Origin of endocrine glands

Ectodermal mesodermal endodermal

 pituitary  adrenal  thyroid
cortex
 pineal  gonads  parathyroid P
 adrenal
medulla i
 pancreas t
,thymus
u
itary gland
o Smallest endocrine gland, weight 500 mg.
o Pituitary regulates so many body activities so it has been nicknamed as master
gland or the conductor of endocrine symphony.
o Pituitary lies in hypophyseal fossa or sella turcica of the sphenoid bone and is
attached to hypothalamus by a short infundibular stalk.
o Divided into three parts; anterior , intermediate and posterior
o Anterior lobe is also called adenohypophysis
o Intermediate lobe is also called pars intermedia but it is rudimentary in human
o Posterior pituitary lobe is also called neurohypohysis.
o Adenohypophysis is connected to hypothalamus by blood vessel and posterior
pituitary is connected to hypothalamus by nerves
o Adenohypophysis consists of 75% of total pituitary

Hormones secreted by anterior pituitary are ;

Growth hormone;
o also called somato-tropic hormone
o Secreted by somatotrope cell
o GH is more effective in presence of thyroid hormone
o Hyposecretion in children- dwarfism
o Hyposecretion in adult –simmonds disease
o Hypersecretion in children –gigantism
o Hypersecretion in adulthood - acromegaly
o Acromegaly patient has gorilla like appearance with huge hands and legs

o Thyroid stimulating hormone – thyrotropin

 Secreted by thyrotrope cell
 TSH stimulate the synthesis and secretion of hormones produced by thyroid
gland
 T4 control secretion of TSH

o Adrenocorticotrophic hormone ;ACTH

 Secreted by corticotrope cell
 Control production and secretion of certain adrenal cortex hormones
 It stimulate the flow of blood to the adrenal cortex , increase level of cholesterol
and steroid within the gland and increase output of steroid hormone

o Follicle stimulating hormone

 Secreted by gonadotrope cell
 In female FSH helps in maturation of primodial follicle into graffian follicle
 In male, FSH stimulates the testis to initiate sperm production that is help
in spermatogenesis.

o Luteinizing hormone
 Secreted by gonadotrope cell
 LH is called luteotropin in female and interstitial cell stimulating hormone
ICSH in the male
 LH surge in female cause ovulation
 LH also stimulate the formation of corpus luteum
 In male ICSH stimulates the interstitial cell of Leyding in testis to develop
and secrete large amount of testosterone.
o Prolactin
Secreted by lactrotrope cell
Also known as milk producing hormone or hormone of maternity
Prolactin is regulated by dopamine
Hypersecretion of Prolactin cause amenorrhea and galactorrhea
Hypersecretion in male cause infertility

Hormone of intermediate lobe

 MSH is also called intermedin, is vestigial hormone, its secretion is
doubtfull.
 MSH stimulates cutaneous pigmentation of skin by the dispersion of
melanin granules in melanocyte of the skin.

Hormone of neurohypophysis
 Neurohypophysis is not endocrine gland because it does not secrets
its own hormone .it stores and release hormone of hypothalamus.
Antidiuretic hormone or ADH or vasopressin or pitressin
 ADH is produced mainly by the supraoptic nucleus which lies
above the optic chiasma.
 ADH is related with concerntration of urine.
 ADH promotes reabsorption of water from glomerular filtrate.
 Stimulate contraction of blood vessels, cause vasoconstriction
resulting in increase blood pressure.
 Decrease ADH in blood result in increase micturaton.
 Alcohol inhibits secretion of ADH so increase the urine output.
 Hyposecretion result in diabetes insipidus.

OXYTOCIN
 Also called birth hormone, abortion hormone, emotional
hormone, cuddle hormone, love hormone.
 Oxytocin stimulates the contraction of smooth muscle of uterus
inducing labour pain for child birth.
 Have role in milk ejection.

 The accumulation of ADH and Oxytocin in the stalk and lobe of

pituitary are called Herring bodies.
 All hormone secreted from anterior pituitary have negative
feedback mechanism except Prolactin.
  THYROID GLAND
 BUTTERFLY SHAPED
 On the anterior part of neck
 Weight 25gm
 H shaped
 Blobbed, right and left lobes are connected by isthmus.
 Largest endocrine gland
 Composed by spherical sacs called thyroid follicles lined by simple
cuboidal epithelium
 The principle cells or follicle cells secretes hormone namely
tetraiodothyronine or thyroxin or t4 and triodothyronin or t3
 90% of total secretion is thyroxin
 Thyroxin synthesize from iodine and amino acid called tyrosine.
 The greatest concerntration of iodine is found in thyroid
 Only endocrine gland that store its secretion in large quantity.
 Man function of thyroxin is to control metabolism.
 Hyposecretion result in
 Children- cretinism
 Adult –myxoedema or gulls disease
 Enlargement of thyroid is called goiter.
 Simple goiter is caused by lower intake of iodine.
 Exophthalmic goiter is also called grave disease is
hyperthyroidism is autoimmune disorder.
 Hashimoto disease is autoimmune hypothyroidism also called
suicide of thyroid.
 The thyroid disorder is more frequent in females than in males.
 Parafollicle cells of the thyroid secrete thyro- calci- tonin also
called calcitonin which lower the amount of calcium and
phosphate in blood.
 Calcitonin is antagonist to parathormone.
 Parathyroid glands
 Two pairs
 Partially or completely embedded in the posterior surface of
thyroid gland
 Contains two kinds of cell; chief cell and oxyphil cell
 Chief cells are major synthesizer of parathormone
 Parathormone decrease blood phosphate level and increase blood
calcium
 Increase PTH;
 rickets in children
 Osteomalacia or ostesporesis in adult
  Decrease PTH- tetany [prolonged spasm of skeletal muscle.]

 ADRENAL GLAND
 Are paired and pyramid shaped
 Located superior to kidneys, hence called supra renal gland.
 Has two part ;
 Adrenal cortex-outer part
 Adrenal medulla-inner part.
 Adrenal gland is also called as 4S gland.
 Sugar metabolism
 Salt retention
 Sex hormone
 Source of energy

Adrenal cortex
 Derived from mesoderm
 Bright yellow in color due to stored cholesterol and fatty acids ,
constituting 80-90 % of gland
 Essential for life
 Subdivided into 3 zones namely outer; zona glomerulosa,middle;zona
fasciculata,inner;zona reticularis
 ZG;mineralocorticoids
 ZF;glucocorticoids
 ZR;gonadocorticoids/ sex steroids
 All are steroids and precursor is cholesterol.
 Removal; death
 The principle mineralocorticoid is aldosterone commonly called salt
retaining hormone
 Functions; conservation of salt and water and elimation of
potassium
 About 95% of mineralocorticoid activity is due to aldosterone
 Most important glucocorticoids are;
 cortisol[90%],
 Hydrocortisone
 corticosteroid
 Functions; influence vital functions, inflammatory reactions ,cope with stress
 Increase blood glucose
 Zona reticularis secretes sex steroid which is testosterone in male and
progesterone and estrogen in female.
 Increase mineralocorticod-conh's syndrome;
hypertension,hypernatremia,hypokalemia
  Increase glucocorticoids –Cushing syndrome; red moon face and
buffalo hump
 Decrease both mineralocorticoid and glucocorticoid;addisons
disease and vitiligo
 Virilism-development of male characters in female like growth of beard,
deep voice and baldness due excessive secretion of sex steroid

Adrenal medulla
 Derived from ectoderm
 Reddish brown color
 Constitute 10-20% of adrenal gland
 Contain chromaffin cells
 Chromaffin cells secretes two hormone ;epinephrine[adrenalin] and
nor epinephrine[noradrenalin]
 Adrenalin is life saving hormone so adrenal gland is life saving
gland[adrenal medulla]
 Secretion; 80%;epinephrine and 20% nor epinephrine
 Secretion of epinephrine is directly controlled by autonomic nervous
system
 Also called 3F gland- fright ,fight or flight which occurs in emergency
so also called emergency gland
 Emergency hormone is epinephrine
 Epinephrine increase in emotional disturbance
 When a person’s suffers from marked fall in blood pressure , it is
helpful to give epinephrine
 Pheochromocytomas; due to tumor of chromaffin cells of adrenal
medulla
 Hypersecretion-high blood pressure, high level of sugar in blood and
urine, high metabolic rate, nervous ness and sweating

 PINEAL GLAND
 Located in the posterior portion of the roof of third ventricle
 Also called as epiphysis cerebri/seat of soul/ remnant of third eye
 Resembles to pine cone so called pineal gland
 Calcium and magnesium salt are deposited in pineal gland so also called
as BRAIN SAND
 Starts to degenerate at the age of 7 years and in adult it is largely
fibrous tissue.
 Secretes hormone in direct response to nervous activity
  Secretes three hormone;melatonin,serotonin and
adrenoglomerulotropin
 Serotonin[5ht] acts as vasoconstriction
 Histamine vasodilator
 Adrenoglomerulotropin stimulates ZG to secrete aldosterone

 THYMUS GLAND
 Bilobed lymphoid organ
 Situated infront of heart in the upper part of the sternum.
 Also called the throne of immunity or training school of t-
lymphocyte or master gland of immunity.
 Thymus is active in young one but gradually becomes inconspicuous
after sexual maturity.
 Consists of central medulla and peripherally cortex.
 The medulla contains characteristics thymic [Hassall’s ]corpuscles
 The reticuloendothelial cell secretes a hormone, thymosin, which
promotes immunocompetence in young t – lymphocytes.
 Thymosin released in blood stream stimulates entire immune systems.
 The thymus also secretes a hormone thymin which inhibit acetylcholine
release at motor nerve ending.
 Produce t- lymphocytes and antibodies which keep the young ones
immune to some diseases.
 Like other lymphoid tissues, thymus undergoes atrophy in response to
adrenal glucocorticoids.

 PANCREEASE
 Leaf like structure
 Endodermal in origin
 Located within curve of duodenum
 Mixed / heterocrine gland with both exocrine and endocrine gland
 The exocrine portion of pancrease consists of pancreatic acini ; 98-
99% which secretes about 1 liter of pancreatic juice
 The endocrine portion of pancrease consists of cluster of cells known as
pancreatic Islets or Islet of langerhan’s.
 Four kinds of cells found in langerhan’s namely ; alpha cell[15-25]%,
beta cells [70-80]%,delta cells and F- cells
 Glucagon
 Product of alpha cells
 Chemically straight chain polypeptide containing 29 amino acids
 Functions-increase blood sugar level
 Hypersecretion- hyperglycemia,glucosuria
Insulin
 Product of beta cells
 Chemically protein[ large polypeptide], containing 51 amino acids
 Insulin is first protein to be synthesized by scientist in laboratory
 Most important regulator of carbohydrate metabolism
 Stimulate glycogenesis and maintain normal glucose level in blood
 Normal blood glucose level; 70-100 mg/dl
 Renal threshold for blood glucose is 180 mg /dl
 Decrease blood glucose level by promoting liver glycogen formation.
 Hyposecretion- diabetes mellitus

Somatostatin
 Delta cells secretes small amounts of peptides hormone somatostatin
[ growth hormone inhibiting hormone] which inhibit the secretions of
glucagon and insulin
Pancreatic polypeptide [Pp]
 F- CELLS PRODUCE THE HORMONE PANCREATIC POLYPEPTIDE WHICH INHIBITS GALL BLADDER
CONTRATION.

 STOMACH
 GASTRIN ; secreted by G – cells of pyloric gland , stimulate gastric juice
secretion
 DUODENUM
 Secretin; stimulate pancrease possibly liver to secrete fluid base of
pancreatic juice
 Pancreo-zymin[PZ];stimulates pancrease to secrete enzymes
 Chole-cysto- kinin[cck]; STMULATES GALL BLADDER TO RHYTHMIC
CONTRACTION and these result in increase in the rate of bile into
duodenum
 Duocrinin;stimulates secretion of mucus from brunner's gland
Note; secretin stimulate pancreatic gland to release pancreatic juice
whereas CCK/PZ stimulates pancrease to secrete pancreatic juice.

 SMALL NTESTINE
 ENTEROCRININ ; STIMULATES THE INTESTINAL MUCOSA TO SECRETE THE INTESTINAL
JUICE
  ENTEROGASTRONE ; Retards the secretion of gastric juice
 Villikinin; stimulates movement of villi for increased absorption.

 KIDNEY
 THREE hormone ; renin,erythropoietin,calcitriol

Note; rennin is enzyme secreted by stomach

Renin;hormone, controls aldosterone secretion through Renin

angiotensin pathway
 Erythropoietin; released by kidney in response to low oxygen level n
kidney
 Stimulates red blood cell production by bone marrow
 Calcitriol; steroid secreted by kidney in response to the presence of
parathyroid hormone
 Calcitriol stimulate the absorption of calcium and phosphate ions in
digestive tract
 LIIVER
 HORMONE SECRETED BY Liver
 SOMATOMEDINS; somatomedins or insulin like hormone that mediate
action of growth hormone.
 Erythropoietin; 15 % of erythropoietin is produced by liver
 Angotensinogen; in blood angotensinogen is converted to angiotensin
I by Renin and then to angiotensin ii by angiotensin converting
enzyme[ ACE] secreted by lung
 Angiotensin second stimulates vasoconstriction and aldosterone secretion.
 HEART
 Specialized muscles cells in the heart produce, atrial natriuretic
hormone also known as atrial natriutic peptide when blood volume
becomes excessive.
 It increases the sodium excretion and lowers blood pressure
 GONADS
 MAIN FUNCTION; PRODUCE GONADS
 ALSO SECRETES SEX HORMONE
 SEX HORMONE ARE MOSTLY STEROID
 ADRENAL CORTEX ALSO PRODUCE SEX HORMONE
Male HORMONE
 Are called androgens
 Produced by interstitial cells of leyding by stimulation of ICSH from
anterior pituitary
 Principle male hormone is testosterone
  Testosterone is responsible for puberty in men.
 Under FSH stimulation, Sertoli secrete inhibin hormone
 Inhibin inhibits the secretion of FSH from anterior pituitary
 Surgical removal of testis is known as Orchidectomy or castration
FEMALE HORMONE
 Are estrogen and progesterone
 Theca interna of graffian follicle produce estrogen
 Regulates growth and development of female accessory reproductive
organs , secondary sexual character and sexual behavior
 Suppress secretion of pituitary FSH
 Corpus luteum secrete progesterone
 Responsible for growth and maintenance of fetus
 Corpus luteum is temporary endocrine gland
 Cause development of endometrium, implantation, formation of placenta.
 Zona pellucida of graffian follicle also produce progesterone
 Suppress ovulation and production of pituitary LH
 Corpus luteum remain for about three month if pregnancy occurs
 LH is present in greatest concerntration during ovulation
 Ovulation occurs usually 14th day of menstruation
 Menarche ; first menstruation ,13 years
 Menopause ; permanent stoppage of menstruation of menstruation at the
end of reproductive age
 Hormone taken in the form of drug for contraception are estrogen and
progesterone

 PLAACENTAL HORMONE
 Chorionic gonadotropin; detected as early as 14 days after conception
 Relaxin; secreted by ovary and placenta
 Relaxin increase flexibity of symphasis pub is during pregnancy and help
to dilate uterine cervix for easy child birth

READ AND DIGEST

 the regulation of metabolic processes by hormone is irreversible and by

enzyme is reversible
 The opposing the effect of insulin are counter – regulating hormones
;e.g.; glucagon, cortisol
 Largest endocrine gland is thyroid gland gland but largest endocrine
organ is gastro-intestinal tract
 milk producing hormone is Prolactin but milk let down hormone is
Oxytocin
 Thyroid gland is larger in female than in male
 Thyroid gland is highly vascular.
 First discovered hormone is secretin by starlin

Thank you‼‼‼

By Ramesh karki