Coordination of
activities in humans
Nervous
system
Endocrine
system
Nervous System vs Endocrine System
Nervous System
 Transmits electrical
impulses
 Use the neurons to
transmit the signal
 Signal transmission is
fast and long lasting
 Effect is localized
Endocrine System
 Transmits chemical
biological messengers
Impulses
 Use the circulatory
system to transmit the
signal
 Signal transmission is
slow and short
duration effect
 Effect is widespread
Endocrine glands are called
ductless glands.
They secrete hormones.
Hormones are non-nutrient
chemicals act as intercellular
messengers.
They are produced in trace
amounts.
HUMAN ENDOCRINE SYSTEM
Pituitary Gland
Pineal Gland
Thyroid Gland
Parathyroid Gland
Thymus Gland
Adrenal Gland
Pancreas
Gonads (Testis & Ovary)
 Location - Below the thalamus &
just above the brainstem
 It synthesizes and secretes certain
neurohormones.
 These hormones regulate the
synthesis and secretion of pituitary
hormones.
 Two types of hormones are
produced by hypothalamus:
Releasing Hormones
Inhibiting Hormones
Synthesizes & releases hypophysiotropic
hormones:
Thyrotropin-releasing hormone (TRH)
Corticotropin-releasing hormone (CRH)
Gonadotropin-releasing hormone (GnRH)
Growth hormone-releasing hormone
(GHRH)
Growth hormone-inhibiting hormone
(GHIH)
Prolactin-releasing factor (PRF)
Prolactin-inhibitn hormone (PIH)
 A marble-sized
gland at the
base of the brain
 Location - in the bony
cavity called sella tursica.
 Controlled by the
hypothalamus or other
neural mechanisms and
therefore the middle man.
 Divided anatomically into:
(i) Adenohypophysis
(ii) Neurohypophysis
Anterior Pituitary
Growth hormone
(GH)
Thyroid stimulating
hormone (TSH)
Adrenocorticotrophic
hormone (ACTH)
Prolactin (PRL)
Luteinizing hormone
(LH)
Follicle stimulating
hormone (FSH)
Posterior Pituitary
Oxytocin
Vasopressin or
Anti-diuretic hormone
Hormone
Target(s)
Function
GH
All cells in
the body
Stimulates growth and repair. Hyper-secretion of GH
leads to Gigantism and low secretion of GH results
stunted growth called Dwarfism.
TSH
Thyroid
Stimulates the thyroid gland to secrete the hormone
thyroxine (T4) and triiodothyronine (T3). It regulates
the body's metabolic activities.
ACTH
Adrenals
Stimulates the adrenal gland to produce
glucocorticoids.
PRL
Breasts
Stimulates the growth of the mammary glands and
formation of milk.
LH and FSH are called gonadotrophins as stimulate
gonadal activity.
LH stimulates the synthesis and secretion of
hormones called androgens from testis.
Stimulates the ovaries to produce oestrogen and
progesterone.
LH
Testes (men)
Ovaries
(women)
FSH
Ovaries
(women)
Stimulates growth and development of the
ovarian follicles in females.
MSH
Melanocytes
in skin
Stimulate the production and release of
melanin which regulates pigmentation of the
skin.
Oxytocin
Uterus
Breasts
Stimulates a vigorous contraction of uterus
at the time of child birth, and milk ejection
from the mammary gland.
Vasopressin
Kidneys
(ADH)
Stimulates reabsorption of water and
electrolytes by the distal tubules and reduces
loss of water through urine (Diuresis).
 The pineal gland is reddish-gray and about
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the size of a grain of rice in humans.
Location - on the dorsal side of forebrain.
Hormone – Melatonin
Function - It affects the modulation of
sleep patterns in the circadian rhythms
and seasonal functions.
It helps in maintaining the body
temperature.
It influences metabolism, pigmentation,
the menstrual cycle as well as our defense
capability.
Sources:
http://www.bibliotecapleyades.ne
t/ciencia/ciencia_brain01.htm
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Location - Thyroid is a
small, butterfly-shaped
gland located at the base
of the neck below the
thyroid cartilage.
Composition - It is
composed of two lobes
located on either side of
the trachea.
 The thyroid gland is
composed of follicles and
stromal tissues.
 Each thyroid follicle is
composed of follicular
cells, enclosing a cavity.
 Thyroid hormones:
Tetraiodothyronine or
thyroxine (T4)
Triiodothyronine (T3)
Function of
Thyroid hormones
Regulation of the basal metabolic rate.
Control the metabolism of carbohydrates,
proteins and fats.
Maintenance of water and
electrolyte balance.
Secrete thyrocalcitonin (TCT) which
regulates the blood calcium levels.
Support the process of red blood
cell formation.
 Hypothyroidism is a
condition characterized by
abnormally low thyroid
hormone production.
 Hyperthyroidism is a
condition in which the
thyroid gland produces and
secretes excessive amounts
of thyroid hormones,
triiodothyronine (T3)
and/or thyroxine (T4).
Goiter
Hypothyroidism
in Man
Hyperthyroidism
Hypothyroidism
In Child
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Location - Two pairs of
parathyroid glands located
behind the outer wings of the
thyroid.
It secrete a peptide hormone
called parathyroid hormone
(PTH).
The secretion of PTH is
regulated by the circulating
levels of calcium ions.
Function - PTH regulates the
amounts of calcium,
phosphorus and magnesium in
the bones and blood.
It increases the blood Ca2+
levels and maintain calcium
balance in the body.
 Location - Dorsal side of the
heart and the aorta
 Hormone – Thymosins
 Role - Plays an important role in
the development of the immune
system.
 Role of Thymosin :
 Provide cell-mediated immunity
 Promote production of antibodies
to provide humoral immunity
o Thymus is degenerated in old
individuals
Location - anterior
part of each kidney
Composed of two
types of tissues:
 Centrally located
tissue adrenal
medulla
 Outside tissue
adrenal cortex
Source : http://robbwolf.com/2012/04/09/real-deal-adrenal-fatigue/
Adrenal
Gland
Adrenal
Medulla
Adrenaline or
Epinephrine
Noradrenaline
Norepinephrine
Adrenal
Cortex
Corticoids
ADRENAL MEDULLA
Adrenal medulla releases the catecholamines:
i)Adrenaline or Epinephrine
ii)Noradrenaline or Norepinephrine
 These hormones are released in stressful
situations, hence called emergency hormones or
hormones of Fight or Flight.
 These hormones increase the heart beat,
alertness, pupilary dilation, piloerection (raising of
hairs), sweating etc.
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ADRENAL CORTEX
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Adrenal cortex divided into three layers:
Zona
reticularis
(inner layer)
zona
fasciculata
(middle layer)
Zona
glomerulosa
(outer layer)
Androgens
Glucocorticoids
Mineralocorticoids
Function of Adrenal Medulla and Cortex
Sources: http://www.austincc.edu/apreview/PhysText/Endocrine.html
The pancreas is a
flattened organ lies in
the abdomen, posterior
and slightly inferior to
the stomach.
 It is a composite gland
and acts as both exocrine
and endocrine gland.
 Histologically, it consists
of islets of Langerhans
and acini cells.

Islets of
Langerhans
α-cells
β-cells
Glucagon
Insulin
Source: https://www.atrainceu.com/course-module/1691107-090_diabetes-type-2-module-04
 Location - Present in the scrotal sac (outside abdomen) of male.
 Testis performs dual functions as a primary sex organ as well as an
endocrine gland.
Composed of seminiferous tubules and interstitial
tissue.
The Leydig cells or interstitial cells produce a
hormones called androgens mainly testosterone.
During puberty, testosterone helps to bring about the
following physical changes that turn a boy into an
adult male:
Increase in muscle mass and strength, and increase in
height.
 Growth of facial and pubic hair,
 Deepening of the voice, male hair patterns,
 Sperm production (spermatogenesis)
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 Location - A pair of ovaries located in the abdomen of female.
 It is the primary female sex organ which produces one ovum
during each menstrual cycle.
 It produces two groups of steroid hormones :
Estrogen and Progesterone.
Estrogen
 Estrogen is synthesised and secreted by ovarian follicles.
 It is responsible for development of growing ovarian follicles, the
appearance of female secondary sex characteristics at puberty such
as high pitch of voice, development of mammary gland.
Progesterone
 Progesterone is secreted by corpus luteum.
 It regulates female sexual behaviour.
 It prepares the uterus for pregnancy, and the mammary glands for
lactation.
 Progesterone supports pregnancy.
 Atrial wall of heart secretes peptide hormone atrial
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natriuretic factor (ANF), which decreases blood pressure.
Juxtaglomerular cells of kidney produce a peptide hormone
erythropoietin which stimulates erythropoiesis
(formation of RBC).
Gastro-intestinal tract secrete four major peptide hormones:
Gastrin,
Secretin,
Cholecystokinin (CCK)
Gastric inhibitory peptide (GIP).
 Gastrin acts 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.
 Cholecystokinin (CCK) acts on both pancreas and gall
bladder and stimulates the secretion of pancreatic enzymes
and bile juice, respectively.
 Gastric Inhibitory Peptide (GIP) inhibits gastric
secretion and motility.