The endocrine system is comprised of glands that produce hormones which regulate the activity of cells and organs. The major glands include the hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body, and reproductive organs. Hormones are released into the bloodstream and affect target organs. The hormones regulate growth, metabolism, and sexual development. Imbalances in hormone levels can cause health issues, which doctors sometimes treat by controlling hormone production or replacement.

1. Endocrine System Introduction
 The endocrine system is made up of glands that produce and
secrete hormones, chemical substances produced in the body that
regulate the activity of cells or organs.
 These hormones regulate the body's growth, metabolism (the
physical and chemical processes of the body), and sexual
development and function.
 The hormones are released into the bloodstream and may affect
one or several organs throughout the body.
 The major glands of the endocrine system are the
hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal
body, and the reproductive organs (ovaries and testes).
 The pancreas is also a part of this system; it has a role in
hormone production as well as in digestion.

2. Endocrine Glands Defined
18-2
• Exocrine glands
– secrete products into ducts which empty into body
cavities or body surface
– sweat, oil, mucous, & digestive glands
• Endocrine glands
– secrete products (hormones) into bloodstream
– pituitary, thyroid, parathyroid, adrenal, pineal
– other organs secrete hormones as a 2nd function
• hypothalamus, thymus, pancreas,ovaries,testes, kidneys,
stomach, liver, small intestine, skin, heart & placenta

3. 18-6
Hormones
• The endocrine system is a collection of glands
that secrete chemical messages we call
hormones.
• These signals are passed through the blood to
arrive at a target organ, which has cells
possessing the appropriate receptor.

4. 18-7
WhatDoesthe Endocrine
 Once a hormon
S
e i
y
s s
sec
t
re
ete
m
d, it D
trav
o
els
?from the endocrine
gland that produced it through the bloodstream to the cells

designed to receive its message. These cells are called target
cells.
Along the way to the target cells, special proteins bind to
some of the hormones. These proteins act as carriers that
control the amount of hormone that is available for the cells to
use.
 The target cells have receptors that latch onto only specific
hormones, and each hormone has its own receptor, so that
each hormone will communicate only with specific target cells
that have receptors for that hormone.
 When the hormone reaches its target cell, it locks onto the
cell's specific receptors and these hormone-receptor
combinations transmit chemical instructions to the inner
workings of the cell.

5.  When hormone levels reach a certain normal amount,
the endocrine system helps the body to keep that level
of hormone in the blood.
 Another example of this process is :
parathyroid hormone. Parathyroid hormone
increases the level of calcium in the blood. When the
blood calcium level rises, the parathyroid glands sense
the change and reduce their secretion of parathyroid
hormone. This turnoff process is called a negative
feedback system.

6. Circulating & Local Hormones
18-6
• Circulating hormones
– act on distant targets
– travel in blood
• Local hormones
– paracrines act on
neighboring cells
– autocrines act on same
cell that secreted them

7. General Mechanisms of HormoneAction
18-7
• Hormone binds to cell surface or receptor inside
target cell
• Cell may then
– synthesize new molecules
– change permeability of membrane
– alter rates of reactions
• Each target cell responds to hormone differently
– liver cells---insulin stimulates glycogen synthesis
– adipose---insulin stimulates triglyceride synthesis

8. Mechanism of Hormone Action
18-8

9. Control of Hormone Secretion
18-9
• Regulated by signals from nervous system,
chemical changes in the blood or by other
hormones
• Negative feedback control (most common)
– decrease/increase in blood level is reversed
• Positive feedback control
– the change produced by the hormone causes
more hormone to be released
• Disorders involve either hyposecretion or
hypersecretion of a hormone

10. Endocrine-related Problems
18-10
 Overproduction of a hormone
 Underproduction of a hormone
 Nonfunctional receptors that cause target
cells to become insensitive to hormones

11. 18-14
• The hypothalamus contains neurons that control releases
from the anterior pituitary.
• Seven hypothalamic hormones are released into a portal
system connecting the hypothalamus and pituitary, and
cause targets in the pituitary to release eight hormones.
HYPOTHALAMUS

12. The location and roles of the hypothalamus
and pituitary glands.
18-12

13. Hypothalamus and Pituitary Gland
18-13
• Both are master endocrine glands since their hormones
control other endocrine glands
• Hypothalamus is a section of brain above where pituitary
gland is suspended from stalk (surrounds 3rd ventricle)
• Hypothalamus receives input from cortex, thalamus,
limbic system & internal organs
• Hypothalamus controls pituitary gland with different
releasing & inhibiting hormones (gonadotropin-releasing
hormone, growth hormone-releasing hormone, growth
hormone-inhibiting hormone)
• Major integrating link between nervous and endocrine
systems

14. STIMULUS
18-14
Hypothalamus
Releasing Hormone
(Release-Inhibiting Hormone)
m
Pituitary
Stimulating
Hor one
Gland
Hormone
Target

15. Pituitary gland
18-15
•
MASTER GLAND
Anterior and posterior
portions
1. Posterior connected to
hypothalamus by
infundibulum
2. Anterior connected via
blood stream

16. 2004-2005
1
18
8-
-1
19
9
Hypothalamus
Gonadotropic
hormones:
Follicle-
stimulating
hormone (FSH)
& luteinizing
hormone (LH)
Mammary
glands
in mammals
Muscles
of uterus
Kidney
tubules
Posterior
pituitary
Anterior
pituitary
Thyroid-stimulating
Hormone
(TSH)
Thyroid gland
Antidiuretic
hormone
(ADH)
Adrenal
cortex
Bone
and muscle Testis
Ovary
Melanocyte
in amphibian

17. Anterior Pituitary & Flow of Blood
18-17
• Controlling hormones enter blood
• Travel through portal veins
• Enter anterior pituitary at capillaries

18. 1.Human Growth Hormone (HGH)
18-18
• Produced by somatotrophs (somatostatin) of
anterior pituitary
• Within target cells increases synthesis of insulin
like growth factors that act locally or enter
bloodstream
– common target cells are liver, skeletal muscle,
cartilage and bone
– increases cell growth & cell division

19. What
can go
wrong
• Too much or too
little of any
hormone can be
harmful to your
body.
For example, if the
pituitary gland produces
too much growth
hormone, a teen may
grow excessively tall. If it
produces too little, a teen
may be unusually short.
Doctors can often treat
the problems by
controlling the
production of hormones
or replacing certain
hormones with
medication.

20. 2.Thyroid Stimulating Hormone (TSH)
18-20
• Hypothalamus regulates thyrotroph cells
• Thyrotroph cells produce TSH
• TSH stimulates the synthesis & secretion of T3
and T4
• Metabolic rate stimulated

21. 3.Follicle Stimulating Hormone (FSH)
18-21
• GnRH from
hypothalamus controls
gonadotrophs
• Gonadotrophs release
FSH
• FSH functions
– initiates the formation of follicles within the ovary
– stimulates follicle cells to secrete estrogen
– stimulates sperm production in testes

22. 4.Luteinizing Hormone (LH)
18-22
• GnRH from hypothalamus stimulate gonadotrophs
• Gonadotrophs produce LH
• In females, LH stimulates
– secretion of estrogen
– ovulation of oocyte from ovary
– secretion of progesterone
• In males, stimulates interstitial cells
to secrete testosterone

23. 5.Prolactin (PRL)
18-23
• Hypothalamus regulates
lactotroph cells (PRH)
• Lactotrophs produce prolactin
• Under right conditions, prolactin
causes milk production
• Suckling reduces levels of hypothalamic
inhibition and prolactin levels rise along
with milk production

24. 6.Adrenocorticotrophic Hormone (ACTH)
18-24
• Corticotrophin-RH
stimulate corticotrophs
• Corticotrophs secrete
ACTH & MSH
• ACTH stimulates cells
of the adrenal cortex that
produce glucocorticoids

25. 7.Melanocyte-Stimulating Hormone (MSH)
18-25
• Secreted by corticotroph cells
• Releasing hormone from hypothalamus
increases its release from the anterior pituitary
• Function not certain in humans (increase skin
pigmentation in frogs )

26. Posterior Pituitary Gland
18-26
• Does not synthesize
hormones
• Consists of axon
terminals of hypothalamic
neurons and pituicytes
(neuroglia)
• Neurons release two
neurotransmitters that
enter capillaries
– antidiuretic hormone
– oxytocin

27. 1
1
18
8
8-
-
-3
3
30
0
0
Posterior Pituitary Hormones
• Manufactured in Hypothalamus, released from
Post. Pit.
• Oxytocin
– Target = smooth ms. Uterus and Breast (&brain)
– Function = labor and delivery, milk ejection,(pair
bonding)
• ADH (Vasopressin AVP)
– Target = kidneys
– Function = water reabsorption

28. 1.Oxytocin
• Two target tissues both involved in
neuroendocrine reflexes
• During delivery
– baby’s head stretches cervix
– hormone release enhances
uterine muscle contraction
– baby & placenta are delivered
• After delivery
– Baby’s cry stimulates milk ejection
– hormone causes muscle contraction & milk ejection
18-31

29. 2.Antidiuretic Hormone (ADH)
18-29
• Known as vasopressin
• Functions
– decrease urine production
– decrease sweating
– increase BP by retaining
water

30. • Thepinealgland,or
thepinealbodyisin
themiddleof the
brain.Itsecretes
melatonin,a
hormonethat
regulateswhenyou
sleepatnightand
wakeupinthe
morning.
18-30

31. 18-31
• Pineal gland is a small, cone shaped gland found
in the roof of the third ventricle of the brain.
• Melatonin hormone appears to be secreted in
substantial amounts.
• It is believed to coordinate the hormones of
fertility and to inhibit the reproductive system
(especially the ovaries of females)
• so that sexual maturation is prevented from
occurring before adult body size has been reached.

32. THYMUS GLAND
18-32
• Located in the upper thorax region.
. • Large in infants and children, it decreases in size
throughout adult hood.
• By old age, it is composed mostly of fibrous
connective tissue and fat.
• Thymus produces a hormone called thymosin.
• During childhood, it acts as an incubator for the
maturation of a special group of whiteblood
cells(T lymphocytes or T cells).
• T cells are play a great role in immune respose.

33. Adult
THYMUS
18-33

34. 1
1
18
8
8-
-
-3
3
38
8
8
Adult
THYMUS

35. The Thyroid
Thyroid Gland
is UNIQUE among other endocrine glands
in 3 ways
1. PHYSICAL
Only gland which can
be seen & palpated.
2. BIOCHEMICAL
Only hormone that
needs a trace element
Iodine for its
production
3. PHYSIOLOGY
Hormone is stored in
an extracellular site in
the Thyroid Colloid.

36. THE THYROID
GLAND
- The thyroid gland is the
largest, butterfly-shaped
endocrine glands & is located
at the base of the neck
immediately below the
Larynx, on each side of &
anterior to the trachea.
- The thyroid gland
consists of two lobes of
endocrine tissue (lying on
either side of trachea) joined
in the middle by a narrow
portion of the gland called as
the Isthmus.
- The thyroid has one of
the highest rates of blood
flow per gram of tissue.
- In a normal adult male, it
weighs 15-20 g but is capable
of enormous growth,
sometimes achieving a weight
of several hundred grams.

37. LOCATION OF THE THYROID GLAND

38. Thyroid Gland
18-38
• On each side of trachea is lobe of thyroid
• Weighs 1 oz & has rich blood supply

39. THYROID GLAND
The thyroid gland
consists of 2 types of
cells:
1. Follicular cells: These
are more abundant,
and the major
secretory cells. They
secrete Thyroid
hormone.
2. Parafollicular cells or
C-cells: These are
fewer in number &
interspersed. They
secrete Calcitonin.

40. THYROID HORMONES
• The Thyroid gland secretes 3 major
hormones:
1. Thyroxine or T4 : having 4 atoms of
Iodine. (secreted in largest amount)
2. Triiodothyronine or T3 : having 3 atoms of
Iodine (secreted in lesser amount)
3. Reverse T3 also called RT3. (secreted in the
least amount) inctive.
4. Calcitonin: which is an important hormone
of calcium metabolism.

42. THYROID HORMONES
• About 93% of secreted hormone is T4, while 7% is T3.
However, almost all T4 is ultimately converted into T3.
• The functions of the 2 hormones are the SAME but
they differ in rapidity & intensity of action.
• T3 is about 4 times as potent as T4, and has a much
greater biological activity but is present in blood in
much smaller quantities & for a much shorter time.

43. Actions of Thyroid
Hormones
18-43
• T3 & T4 = thyroid
hormones responsible for
our metabolic rate,
synthesis of protein,
breakdown of fats, use of
glucose for ATPproduction
• Calcitonin = responsible for
building of bone & stops
reabsorption of bone (lower
blood levels of Calcium)

44. 1
18
8-
-4
42
2
2004-2005
Goiter
Iodine deficiency causes
thyroid to enlarge as it
tries to produce thyroxine

45. Mechanism
• Goiters A thyroid goiter is a dramatic
enlargement of the thyroid gland.

46. PARATHYROID GLAND
• The parathyroid glands are four tiny glands,
located in the neck, that control the body's
calcium levels. Each gland is about the size of a
grain of rice (weighs approximately 30
milligrams and is 3-4 millimeters in diameter).
• The parathyroid gland produce a hormone
called parathyroid hormone (PTH).

47. PARATHYROID GLAND
Location:
•Usually paired.
•Very small
•Called parathyroid glands because of their position on
posterior margins outer surface of thyroid gland.
•More superior of each pair usually near middle of margin of
lobe.
•More inferior of each pair usually at inferior apex of lobe.
Development: Like thyroid gland, develop from endodermal
thickening in floor of early pharynx and epithelium of 3rd and
4th gill slit pouches.

48. Parathyroid Glands
• 04 Pea-sized glands found on back of thyroid gland

49. • PTH raises the blood calcium level by:
 Breaking down the bone and causing calcium release
increasing the body's ability to absorb calcium from food
increasing the kidney's ability to hold on to calcium that
would otherwise be lost in the urine.
 Normal parathyroid glands work like the thermostat in
your home to keep blood calcium levels in a very tightly
controlled range.
 When the blood calcium level is too low, PTH is released
to bring the calcium level back up to normal.
 When the calcium level is normal or gets a little too high,
normal parathyroids will stop releasing PTH.
 Proper calcium balance is crucial to the normal
functioning of the heart, nervous system, kidneys, and
bones.
FUNCTION OF PTH

50. Parathyroid Hormone
18-50
• Raise blood calcium levels
– increase activity of osteoclasts (large
multinucleate bone cell which absorbs bone
tissue during growth and healing)
– increases reabsorption of Ca+2 by kidney
– promote formation of calcitriol (vitamin D3) by
kidney which increases absorption of Ca+2 and
Mg+2 by intestinal tract

51. 18-47
Regulation of Calcium Blood Levels
• High or low blood levels of Ca+2 stimulate the release of
different hormones --- PTH or CT

52. 18-52
• Hyperthyroidism Hyperthyroidism means too
much thyroid hormone.
• Hypothyroidism Hypothyroidism means too little
thyroid hormone and is a common problem.
• Thyroid Cancer Thyroid cancer is a fairly
common malignancy, however, the vast majority
have excellent long term survival.
• Thyroiditis Thyroiditis is an inflammatory
process ongoing within the thyroid gland.

53. Adrenal gland
18-53

54. Adrenal Gland
18-54
• Adrenal gland located atop kidney
• Outer part = cortex
– Secretes Cortisol (stress), Androgens,
Aldosterone (electrolytes)
• Inner part = medulla
– SNS control
– Secretes EPI & NEPI (fight or flight)

55. 18-55
• Each kidney has an adrenal gland located above it.
• The adrenal gland is divided into an inner medulla and
an outer cortex.
• The medulla synthesizes amine hormones, the cortex
secretes steroid hormones.
• The adrenal medulla consists of modified neurons that
secrete two hormones: epinephrine and
norepinephrine.
• Stimulation of the cortex by the sympathetic nervous
system causes release of hormones into the blood to
initiate the "fight or flight" response.
• The adrenal cortex produces several steroid hormones
in three classes: mineralocorticoids, glucocorticoids,
and sex hormones.

56. Mineralocorticoids maintain electrolyte balance.
Glucocorticoids produce a long-term, slow
response to stress by raising blood glucose levels
through the breakdown of fats and proteins; they
also suppress the immune response and inhibit the
inflammatory response.
18-56

57. Thestructure of the kidney asrelates tohormones
18-57

58. Two diseases associated with
the adrenal cortex:
1. Cushing’s Disease :
Cushing's disease refers to a pituitary-dependent cause of Cushing's
syndrome: a tumor (adenoma) in the pituitary gland produces large
amounts of ACTH, causing the adrenal glands to produce elevated
levels of cortisol
SYMPTOMS:
WEIGT GAIN HAIR LOSS
HYPERFPIGMENTA
TION
HYPRECALICMEIA
18-54

59. 2. Addison’s disease
Addison’s disease (also chronic adrenal
insufficiency, hypocortisolism, and hypoadrenalism) is a
rare, chronic endocrine disorder in which the adrenal glands do
not produce sufficient steroid hormones (glucocorticoids and
often mineralocorticoids). It is characterised by a number of
relativelynonspecific symptoms, such as abdominal pain and
weakness….
SYMPTOMS:
NAUSEA
FEVER
VOMITING
FATIGUE

60. • A triangular gland, which has both exocrine and endocrine
cells.
• Strategic location
• The pancreas is an elongated organ located toward the back
of the abdomen behind the stomach.
• Acinar cells produce an enzyme-rich juice used for digestion
(exocrine product)
• Pancreatic islets (islets of Langerhans) produce hormones
involved in regulating fuel storage and use.
Pancreatic gland

61. PANCREAS
18-61
The pancreas has digestive and hormonal functions.
One part of the pancreas, the exocrine pancreas, secretes
digestive enzymes.
The other part of the pancreas, the endocrine pancreas,
secretes hormones called insulin and glucagon.
These hormones regulate the level of glucose (sugar) in
the blood.
Secretes other hormones, such as amylin, somatostatin,
and pancreatic polypeptide

62. • Physiologic Anatomy of the Pancreas
• Two major types of tissues
1) The acini,which secrete digestive juices into duodenum
2) The islets of Langerhans, which secrete insulin and glucagon into blood.
• 1 to 2 million islets of Langerhans, organized around small
capillaries into which its cells secrete their hormones.
• The islets contain three major types of cells alpha, beta, delta cell
middle of each islet and secrete insulin and amylin,
• The alpha cells, 25 % of the total, secrete glucagon
• The delta cells, about 10 %, secrete somatostatin.
• One other type of cell, the PP cell, is present in small numbers in
the islets and secretes pancreatic polypeptide.

64. 18-64

65.  Both insulin and glucagon are synthesized as large
preprohormones.
 In Endoplasmic reticulum, the prohormones are formed.
 Most of this is further cleaved in the Golgi apparatus to
form hormone and peptide fragments before being
packaged in the secretory granules.
 In the case of the beta cells, insulin and connecting (C)
peptide are released into the circulating blood in
equimolar amounts.

66.  Insulin is a polypeptide containing two amino acid chains
(21 and 30 amino acids, respectively) connected by
disulfide bridges.
 Glucagon is a straight-chain polypeptide of 29 amino acid
residues.
 Both insulin and glucagon circulate unbound to carrier
proteins and have short half-lives of 6 minutes.
 Approximately 50% of the insulin and glucagon in blood
is metabolized in the liver; most of the remaining
hormone is metabolized by the kidneys.

67. Insulin and its Metabolic Effects
Insulin was first isolated from the pancreas in 1922 by
Banting and Best.
Hormone of nutrient abundance.
A protein hormone consisting of two amino acid chains
linked by disulfide bonds.
Synthesized as part of proinsulin (86 AA) and then excised
by enzymes, releasing functional insulin(51 AA) and C
peptide (29 AA).

68.  Associated with blood sugar,
 Insulin has effects on carbohydrate metabolism.
 Insulin affects fat and protein metabolism
 Insulin is a Hormone Associated with Energy
Abundance.
 When there is great abundance of energy-giving foods
in the diet, especially excess amounts of carbohydrates,
insulin is secreted in great quantity.

69. Insulin Structure
1- Large polypeptide 51 AA (MW 6000)
2- Tow chains linked by disulfide bonds.
A chain (21 AA)
B chain (30 AA)
3 disulfide bonds.

70. Insulin plays an important role in storing the excess
energy.
In the case of excess carbohydrates, it causes them to be
stored as glycogen mainly in the liver and muscles.
Excess carbohydrates is also converted under the stimulus
of insulin into fats and stored in the adipose tissue.
 Insulin has a direct effect in promoting amino acid uptake
by cells and conversion of these amino acids into protein.
 In addition, it inhibits the breakdown of the proteins that
are already in the cells.

71. Insulin Action on Cells:
• Insulin is the hormone of abundance.
• The major targets for insulin are:
Liver
Skeletal muscle
Adipose tissue
The net result is fuel storage.
Liver:
• Stimulates glucose oxidation
• Promotes glucose storage as glycogen
• Inhibits glycogenolysis
• Inhibits gluconeogenesis

72. Muscle:
• Stimulates glucose uptake (GLUT4)
• Promotes glucose storage as glycogen
Adipose Tissue:
• Stimulates glucose transport into adipocytes
• Promotes the conversion of glucose into triglycerides and fatty acids.
Glucose Transport
GLUT2 (liver, pancreas)
GLUT4, insulin sensitive transporter (muscle, adipose tissue)
GLUT3 (brain)
Glycogen Synthesis
Short term storage of glucose
Activates glycogen synthase
Inhibit glycogen phosphorylase
Glycolysis is also stimulated by insulin

73. Lipogenic and antilipolytic
Insulin promotes lipogenesis and inhibits lipolysis
– Promotes formation of α-glycerol phosphate and fatty acid
synthesis
– Stimulates fatty acid synthase (FAS)
– Inhibits hormone sensitive lipase (HSL)
– Activates lipoprotein lipase (LPL)
Insulin promotes protein accumulation:
1. Stimulates amino acid uptake
2. Increases the activity of protein synthesis
3. Inhibits protein degradation
Protein Synthesis and Degradation

74. Action of insulin on Liver:

75. Action of insulin on Muscle:

77. Lecture 30/03/2021
Glucagon Hormone

78. Glucagon
Glucagon is hormone produced by α-cells of islet of Langerhans
of pancreas and important hormone involved in:
Rapid mobilization of hepatic glycogen to give glucose by
glycogenolysis.
To lesser extent F.A from adipose tissue.
Thus, it act as a hormone required to mobilize metabolic substrate
from storage depots.
Chemistry:
Glucagon has been purified and crystallized from pancreatic extracts
and also the hormone has been synthesized.
It is polypeptide containing amino acid sequence has been determine,
histidine is the N-terminal Amino acid and threonine is the C-terminal.
Molecular weight is approximately.3485

79. Synthesis:
It is synthesized first as a pro-hormone, proglucagon
in α-cells. Lysosomal enzymes peptidases like carboxy-peptidase B
and trypsin-like peptidases in α-cells hydrolyze pro-glucagon from
both N-terminal end and C-terminal end to yield glucagon and
inactive peptides.
Mechanism of action: Glucagon binds to specific receptors on the
Plasma membrane of hepatocytes and adipocytes and activates adenyl
cyclase to produced c-AMP in the cells, which is the principle
Second messenger and duplicates the functions of hormone.
c-AMP inturn activates c-AMP dependent protein kinases which is
further phosphorylates specific enzymes to increase/decrease their
activities

80. Hormone that is a potent hyperglycemic agent. Assist insulin in
regulating blood glucose(sugar) in the normal range (actions are
opposite of insulin).
Its major target is the liver, where it promotes:
Glycogenolysis – the breakdown of glycogen to glucose
Gluconeogenesis – synthesis of glucose from lactic acid and non
carbohydrates. Release of glucose to the blood from liver cells.
On Lipid Metabolism (↑Lipolysis, Anti- lipogenic action).
On Protein Metabolism (Reduce protein synthesis, ↑ protein
catabolism).
Action on Heart (+ inotropic effect on heart)
Glucagon actions;

82. Glucagon
Control
Liver
 Glycogen breakdown
 Glucose synthesis
 Glucose release
Brain
No effect
Pancreas
Alpha cells
Exercise
Feedback
Adipose
 Triglyceride breakdown
 Triglyceride storage
 Blood glucose
 Fatty acids
Epinephrine
(stress)
Amino acids

83. Some times nothing,
• Disease due to deficient action:
sometimes hypoglycemia
• Disease due to excess action: Hyperglycemia
Diabetes (inhibits insulin production), gallstones, and
dietary fat intolerance.

84. Factors Affecting Glucagon Secretion:

86. 18-86
• Diabetes results from inadequate levels of insulin.
• Type I diabetes is characterized by inadequate levels of
insulin secretion, often due to a genetic cause.
• Type II usually develops in adults from both genetic
and environmental causes.
• Loss of response of targets to insulin rather than lack of
insulin causes this type of diabetes.
• Diabetes causes impairment in the functioning of the
eyes, circulatory system, nervous system, and failure of
the kidneys.
• Diabetes is the second leading cause of blindness in the
US.
• Treatments involve daily injections of insulin,
monitoring of blood glucose levels and a controlled diet.

87. Regulation of Glucagon & Insulin Secretion
18-87
• Low blood glucose
stimulates release of
glucagon
• High blood glucose
stimulates secretion of
insulin

88. Hormone secreted by the delta cells of the Islets of Langerhans
14 & 28 amino acid forms.
Found in hypothalamus, throughout CNS and Gut (including
pancreas)
Major inhibitory peptide of Gut.
Inhibits secretion of
– insulin
– glucagon
– CCK (Cholecystokinin)
– secretin
– gastrin
– VIP (Vasoactive Intestinal Peptide)
– Somatostatin (autocrine)
Somatostatin

89. • Secreted in response to
– Hyperglycemia
• Action
– Interferes with glucagon
– Interferes with growth hormone
Somatostatin
Somatostatin inhibits insulin and glucagon secretion.
Has a hypoglycemic effect.

90. Steroid hormone is a steroid that acts as a hormone.
Steroid hormones can be grouped into two
classes: corticosteroids and sex steroids.
Five types according to the receptors to which they
bind: glucocorticoids, mineralocorticoids, androgens,
estrogens, and progestogens (sex steroids).
Vitamin D derivatives are a sixth closely related
hormone system.
Steroid Hormones

91. Steroid Hormones
18-91
• Small
• Hydrophobic/Lipophilic
• Travel in blood w/carrier
• Cytoplasmic or nuclear receptors
• change protein synthesis
• Example: estradiol

92. 18-65
Reproductive Glands
The reproductive glands are the main source of sex hormones.
In males, the testes, located in the scrotum, secrete hormones called
androgens; the most important of which is testosterone.
These hormones affect many male characteristics as well as sperm
production.
In females, the ovaries, located on both sides of the uterus,
produce estrogen and progesterone as well as eggs.
These hormones control the development of female
characteristics and they are also involved in reproductive
functions

93. Gland Hormone
18-93
Chemical
Class
Representative
Actions
Regulated
By
Hypothalamus
Pituitary gland
Posterior pituitary
(releases
hormones
made by hypo-
thalamus)
Anterior pituitary
Oxytocin
Antidiuretic hormone
(ADH)
Growth hormone (GM)
Prolactin (Pith)
Follicle—stimulating
hormone )FSII)
Luteinizing hormone
(LB)
Thyroid-stimulating
hormone (TSH)
Adrenocorticotropic
hormone (ACTH)
Peptide
Peptide
Protein
Protein
Glycoprotein
Glycoprotein
Glycoprotein
Peptide
Stimulates contraction of uterus
and mammary gland cells
Promotes retention of water
by kidneys
Stimulates growth (especially
bones) and metabolic functions
Stimulates milk production
and secretion
Stimulates production of
ova and sperm
Stimulates ovaries and testes
Stimulates thyroid gland
Stimulates adrenal cortex
to secrete glucocorticoids
Nervous system
Water/salt
balance
Hypothalamic
hormones
Hypothalamic
hormones
Hypothalamic
hormones
Hypothalamic
hormones
Thyroxine in
blood;
hypothalamic
hormones
Glucocorticoids;
hypothalamic
hormones

94. Chemical
Class
18-94
Gland Hormone Representativ
e
Actions
Regulated
By
Thyroid
gland
Triiodothyronine
(T3)
and thyroxine
(T4)
Calcitonin
Amine
Peptide
Lowers blood
calcium level
Stimulate and TSH
maintain
metabolic
processes
Calcium in
blood
Parathyroid
glands
Parathyroid
hormone
(PTH)
Peptide Raises blood
calcium level
Calcium in
blood

95. 18-95
Gland Hormone Regulated By
Pancreas Insulin
Glucagon
Chemical
Class
Protein
Protein
Representative
Actions
Lowers blood glucose
level
Raises blood glucose
level
Glucose in blood
Glucose in blood
Adrenal glands
Adrenal medulla
Adrenal cortex
Epinephrine and
Norepinephrine
Glucocorticoids
Amine
Steroid
Raise blood glucose level;
increase metabolic activities;
constrict certain blood
vessels
Raise blood glucose level
Nervous system
ACTH
Gonads
Testes
Ovaries
Andrugens
Estrogens
Progesterone
Steroid
Steroid
Steroid
Support sperm
formation; promote
development and
maintenance of
male secondary
sex characteristics
Stimulate uterine
lining growth;
promote development and
maintenance of female
secondary sex
characteristics
Promotes uterine
lining growth
FSH arid LH
ESH and LH
ESH and LH

96. Chemical
Class
18-96
Gland Hormone Regulated By
Pineal
gland
Melatonin Amine
Represent
ative
Actions
Involved in
biological
rhythms
Light/dark cycles
Thymus Thymosin Peptide Stimulates
T
lymphocytes
Not known

97. 18-76
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