endocrine glands: name, location, hormones and functions.

1. ENDOCRINE GLAND
BY
SONI KUMARI SHAH

2. Glands
Glands are group of epithelial cells which produce specialized secretion.
All glands have rich blood supply. Glands secrete the necessary materials
from blood stream. These materials are utilized for making the secretion.
Types Of Glands:
Exocrine gland
Endocrine gland

3. Endocrine Gland
Endocrine glands are groups of secretory cells surrounded by an
extensive network of capillaries that facilitates diffusion of
hormones (chemical messengers) from the secretory cells into
the bloodstream.
They are also referred to as ductless glands because hormones
diffuse directly into the bloodstream.
Hormones are then carried in the bloodstream to target tissues
and organs that may be quite distant, where they influence cell
growth and metabolism.

4. Differences Between Endocrine And Exocrine Gland
S. No. Exocrine gland Endocrine gland
1. Glands with duct Ductless gland
2. Discharge their secretion into the
ducts
Discharge their secretion directly
into the blood
3. Glands are present near the site of
action
Glands may be present at a far away
site than action
4. Secretions are called enzymes Secretions are called hormones
5. Eg. Salivary gland, gastric gland,
etc.
Eg. Pituitary gland, thyroid gland,
parathyroid gland, etc.

5. Hormone
Hormones are the chemical messengers produced by the endocrine
glands, organs or parts of the body, which is carried through the blood
to another part of the body, stimulating by chemical action to increase
its activity or to increase secretion of another hormone.
The hormones are derived from Greek word it means “to set in motion”.
The first hormone discovered was secretin by British physiologist
William Bylish and Ernest Starling in1902.

6. How Hormones Work
A hormone is formed in one organ or gland and carried in the blood
to another organ(target organ or tissue), probably quite distant,
where it influences cellular activity, especially growth and
metabolism.
When all cells are exposed to hormones circulating in the
bloodstream, not all cells react. Only a hormones “target” cells,
which have receptors for that hormone, will respond to its signal.
When the hormone binds to its receptor, it causes a biological
response within the cell.

7. Functions Of Hormone
1. It stimulates growth in all organs or tissues. Eg. Growth hormone
2. It helps in metabolism. Eg. Insulin
3. It helps in reproduction. Eg. Sex hormone
4. Maintenance of homeostasis. Eg. Hormones of hypothalamus
5. Regulation of watr and electrolyte balance within the body. Eg. ADH,
aldosterone
6. It helps in anti-stress action. Eg. adrenalin

8. Differences Between Hormone And Enzyme
S. No. Hormones Enzymes
1. They are produced at one site and are
passed by blood to another site for
action.
They may act at site where they are produced
or carried to another site for action.
2. They may act slowly or quickly They act slowly.
3. They are used up in their action. They are not used up in their action.
4. They have lower molecular weight. They have very high molecular weight
5. It may be steroids, peptides, proteins or
amino acid derivatives.
They are simple proteins.
6. The chemical controlled reactions are
not reversible.
The chemical controlled action are reversible.
7. Excess or deficiency of hormones may
cause disorders.
Excess or deficiency of enzymes which
catalyzed the chemical reactions.

9. Endocrine Glands Present In Human Body
1. Hypothalamus
2. Pituitary gland
3. Thyroid gland
4. Parathyroid gland
5. Adrenal gland
6. Thymus gland
7. Ovary in female
8. Testes in male
9. Pineal gland
10. Pancreas

10. Position Of Endocrine Glands

11. Hypothalamus
The hypothalamus is a structure of the diencephalon of the
brain located anterior and inferior to the thalamus.
It has both neural and endocrine functions, producing and
secreting many hormones.
In addition, the hypothalamus is anatomically and functionally
related to the pituitary gland (or hypophysis),

12. Hormones Secreted By Hypothalamus
Adrenocorticotrophic Releasing Hormone(ARH): it stimulates the anterior
pituitary gland to secrete its Adrenocorticotropic hormone(ACTH).
Somatotrophin Releasing Hormone(SRH): it stimulates the anterior pituitary
gland to release growth hormone(GH) or somatotrophin.
Thyrotrophin Releasing Hormone(TRH): it stimulates the anterior pituitary
gland to its thyroid stimulating hormone(TSH).
Growth Inhibiting Hormone(GIH): this hormone is also called
somatostatin.it inhibits the secretion of growth hormone from anterior lobe
of pituitary gland.
Prolactin Releasing Hormone(PRH): it stimulates the anterior pituitary gland
to secrete prolactin.

13. Hormones Secreted By Hypothalamus
Prolactin inhibiting hormone(PIH):it inhibits the secretion of prolactin
from the anterior lobe pituitary gland.
Gonadotrophin releasing hormone(GRH): it stimulates the anterior
pituitary to secrete follicle stimulating hormone (FSH) and luteinizing
hormone(LH) in ovaries and to secrete interstitial cells stimulating
hormone (ICSH) in testes.
Melanocytes inhibiting hormone(MIH): it inhibits the secretion of
melanocytes stimulating hormone from the intermediate lobe of pituitary
gland.
Melanocytes releasing hormone(MRH): it stimulates the intermediate
lobe of pituitary gland to secrete its melanocyte stimulating
hormone(MSH).

14. Pituitary Gland
Pituitary gland (or hypophysis), a bean-
sized organ suspended from it by a stem
called the infundibulum (or pituitary
stalk).
The pituitary gland is cradled within the
sella turcica of the sphenoid bone of the
skull.
It consists of two lobes that arise from
distinct parts of embryonic tissue: the
posterior pituitary (neurohypophysis) is
neural tissue, whereas the anterior
pituitary (also known as the
adenohypophysis) is glandular tissue that
develops from the primitive digestive tract.

15. Structure Of Pituitary Gland
Posterior Pituitary
The posterior pituitary is actually an
extension of the neurons of the
paraventricular and supraoptic nuclei of
the hypothalamus.
The posterior pituitary gland does not
produce hormones, but rather stores
and secretes hormones produced by
the Hypothalamus.
.

16. Anterior Pituitary
The anterior pituitary does
manufacture hormones. However,
the secretion of hormones from the
anterior pituitary is regulated by
two classes of hormones.
These hormones secreted by the
hypothalamus are the releasing
hormones that stimulate the
secretion of hormones from the
anterior pituitary and the inhibiting
hormones that inhibit secretion

17. Hormones Of Pituitary Gland
Anterior Pituitary
Growth Hormone(GH): it is necessary for the normal growth and
development of the body.
Thyroid Stimulating Hormone(TSH): it regulates the synthesis of thyroid
hormone in the thyroid gland.
Adrenocorticotrophic Hormone(ACTH):it stimulates the adrenal cortex to
synthesize glucocorticoid hormones.
Prolactin : it stimulates milk production in breast.

18. Hormones Of Pituitary Gland
Anterior Pituitary
Follicle Stimulating Hormone(FSH): it stimulates ovarian follicles of ovary
in female to synthesize estrogen and stimulates seminiferous tubules in
testes to secrete spermatozoa.
Luteinizing Hormone(LH): it stimulates corpus luteum of ovary in female
to produce progesterone and interstitial cells of testes in males to
produce testosterone.

19. Posterior Pituitary
Oxytocin
Functions: contraction of uterus during delivery and to bring about
parturition.
ejection of milk from breast.
Vasopressin
Function: decreasing urine output by increasing tubular reabsorption
in the kidney.
Increasing blood pressure by contracting capillaries and
arterioles.

23. Negative Feedback Regulation Of Secretion Of Hormones By The
Anterior Lobe Of The Pituitary Gland.

24. Hormonal Regulation Of Growth

25. Regulation Of Secretion Of Oxytocin Through A Positive Feedback
Mechanism

26. Negative Feedback Regulation Of Secretion Of Antidiuretic
Hormone (ADH).

27. Thyroid Gland
The thyroid gland is situated in the neck in front
of the larynx and trachea at the level of the 5th,
6th and 7th cervical and 1st thoracic vertebrae.
It is a highly vascular gland that weighs about 25
g and is surrounded by a fibrous capsule.
It resembles a butterfly in shape, consisting of
two lobes, one on either side of the thyroid
cartilage and upper cartilaginous rings of the
trachea.
The lobes are joined by a narrow isthmus, lying
in front of the trachea.
The lobes are roughly cone shaped, about 5 cm

28. Thyroid Gland
The arterial blood supply to
the gland is through the
superior and inferior
thyroid arteries. The
superior thyroid artery is a
branch of the external carotid
artery and the inferior thyroid
artery is a branch of the
subclavian artery.
The venous return is by the
thyroid veins, which drain into
the internal jugular veins.

29. Thyroid Gland
The gland is composed of largely
spherical follicles formed from
cuboidal epithelium. These secrete
and store colloid, a thick sticky
protein material.
Between the follicles are other cells
found singly or in small groups:
parafollicular cells, also called C-
cells, which secrete the hormone
calcitonin.

31. Functions Of Thyroid Hormone
T3 and T4
1. Increase in basal metabolic rate
2. Increase in oxygen consumption and heat production.
3. Increases the absorption and utilization of glucose.
4. Myelination of CNS
5. Increase in rate of cholesterol synthesis in liver.
6. Storage of iodine.
7. Synthesis of protein in cells.
Calcitonin
1. Deposition of calcium in bone.
2. Increase the excretion of calcium through urine.
3. It prevents the absorption of calcium from intestine into the blood.

32. Negative Feedback Regulation Of The Secretion Of Thyroxine
(T4) And Tri-iodothyronine (T3).

33. A Classic Negative Feedback Loop Controls The Regulation Of Thyroid
Hormone Levels.

34. Calcitonin
The thyroid gland also secretes a hormone called calcitonin that is
produced by the parafollicular cells (also called C cells) that stud the
tissue between distinct follicles.
Calcitonin is released in response to a rise in blood calcium levels.
It appears to have a function in decreasing blood calcium
concentrations by:
Inhibiting the activity of osteoclasts, bone cells that release calcium
into the circulation by degrading bone matrix
Increasing osteoblastic activity
Decreasing calcium absorption in the intestines
Increasing calcium loss in the urine

36. Parathyroid Gland
There are four small parathyroid
glands, each weighing around 50
mg, two embedded in the posterior
surface of each lobe of the thyroid
gland.
They are surrounded by fine
connective tissue capsules that
contain spherical cells arranged in
columns with sinusoids containing
blood in between them.

37. Parathyroid Gland
The main function of PTH is to increase blood calcium levels.
This is achieved by increasing the calcium absorption from
the small intestine and reabsorption from the renal tubules.
If these sources provide inadequate supplies then PTH
stimulates osteoclasts (bone-destroying cells) and calcium is
released from bones into the blood.

38. Parathyroid Gland
Parathormone and calcitonin from the thyroid gland act in a
complementary manner to maintain blood calcium levels within
the normal range. This is needed for:
• muscle contraction
• transmission of nerve impulses
• blood clotting
• normal action of many enzymes.

39. Functions Of Parathormone
Increased absorption of calcium from gastrointestinal tract
Increases the absorption of calcium from bones into blood.
Decreases the calcium absorption from kidney.
Increases reabsorption of calcium from renal tubule.

40. Parathyroid Hormone In Maintaining Blood Calcium Homeostasis

41. Parathyroid Hormone In Maintaining Blood Calcium
Homeostasis

42. Adrenal Gland
The two adrenal (suprarenal) glands are
situated on the upper pole of each kidney
enclosed within the renal fascia.
They are about 4 cm long and 3 cm thick.
The arterial blood supply is by branches from
the abdominal aorta and renal arteries.
The venous return is by suprarenal veins. The
right gland drains into the inferior vena cava and
the left into the left renal vein.

43. Adrenal Gland
The glands are composed of two parts
which have different structures and
functions. The outer part is the cortex
and the inner part the medulla. The
adrenal cortex is essential to life but
the medulla is not.

44. Adrenal Cortex
The adrenal cortex produces three groups of steroid hormones
from cholesterol. They are collectively called adrenocorticoids
(corticosteroids). The groups are:
glucocorticoids
mineralocorticoids
sex hormones (androgens).
The hormones in each group have different characteristic actions
but as they are structurally similar their actions may overlap.

45. Glucocorticoids
Cortisol (hydrocortisone) is the main glucocorticoid but
small amounts of corticosterone and cortisone are also
produced.
Commonly these are collectively known as ‘steroids’; they
are essential for life, regulating metabolism and
responses to stress.

46. Glucocorticoids
Glucocorticoids have widespread metabolic effects generally
concerned with catabolism (breakdown) of protein and fat that makes
glucose and other substances available for use. These include:
hyperglycemia (raised blood glucose levels) caused by breakdown
of glycogen and gluconeogenesis (formation of new sugar from, for
example, protein)
lipolysis (breakdown of triglycerides into fatty acids and glycerol for
energy production) raising circulating levels of free fatty acids
stimulating breakdown of protein, releasing amino acids, and
increasing blood levels. Amino acids are then used for synthesis of
other proteins, e.g. enzymes, or for energy production.
promoting absorption of sodium and water from renal tubules (a weak
mineralocorticoid effect).

47. Functions Of Glucocorticoids
1. It increases blood glucose level.
2. It increases breakdown of protein.
3. It helps in breakdown of fat into fatty acid and glycerol
4. It blocks the inflammatory response to allergic reaction.
5. It decreases body immunity.

48. Negative Feedback Regulation Of Glucocorticoid Secretion.

49. Mineralocorticoids (Aldosterone)
Aldosterone is the main mineralocorticoid. It is involved in
maintaining water and electrolyte balance.
Through a negative feedback system it stimulates the
reabsorption of sodium (Na+) by the renal tubules and excretion of
potassium (K+) in the urine.
Sodium reabsorption is also accompanied by retention of water
and therefore aldosterone is involved in the regulation of blood
volume and blood pressure too.

50. Functions Of Mineralocorticoids
Increase the reabsorption of sodium ions from distal convoluted
tubules and collecting duct.
Aldosterone increases the potassium excretion through the renal
tubule.

51. Renin–Angiotensin–Aldosterone System
When renal blood flow is reduced or blood sodium levels fall, the
enzyme renin is secreted by kidney cells.
Renin converts the plasma protein angiotensinogen, produced by
the liver, to angiotensin 1. Angiotensin converting enzyme (ACE),
formed in small quantities in the lungs, proximal kidney tubules
and other tissues, converts angiotensin 1 to angiotensin 2, which
stimulates secretion of aldosterone.
Angiotensin 2 causes vasoconstriction and increases blood
pressure closing the negative feedback loop.

52. Negative Feedback Regulation Of Aldosterone Secretion.

53. Sex Hormones
Sex hormones secreted by the adrenal cortex are
mainly androgens (male sex hormones) although
the amounts produced are insignificant compared
with those secreted by the testes and ovaries in
late puberty and adulthood.

54. Functions Of Androgens
1. It helps in maintenance of growth and development of reproductive
organs.
2. It helps to develop secondary sexual characteristics.
3. It helps in process of spermatogenesis.
4. It helps in male pattern of aggressive behavior.
5. It promotes RNA synthesis and protein synthesis.
6. It increases glycolysis and also increase fatty acid synthesis and citric
cycle.
7. They are responsible for bone maturation.

55. Adrenal Medulla
The medulla is completely surrounded by the adrenal
cortex.
When stimulated by extensive sympathetic nerve supply,
the glands release the hormones adrenaline
(epinephrine, 80%) and noradrenaline (norepinephrine,
20%).

56. Adrenaline (Epinephrine) And Noradrenaline
(Norepinephrine)
Noradrenaline is the postganglionic neurotransmitter of
the sympathetic division of the autonomic nervous system.
 Adrenaline and some noradrenaline are released into the
blood from the adrenal medulla during stimulation of the
sympathetic nervous system.

57. Adrenaline (Epinephrine) And Noradrenaline (Norepinephrine)
They potentiate the fight or flight response by:
increasing heart rate
increasing blood pressure
diverting blood to essential organs, including the heart, brain
and skeletal muscles, by dilating their blood vessels and
constricting those of less essential organs, such as the skin
increasing metabolic rate
dilating the pupils.
Adrenaline has a greater effect on the heart and metabolic
processes whereas noradrenaline has more influence on blood
vessel diameter.

58. Functions Of Adrenaline And Noradrenaline
Vasoconstriction and increase in blood pressure.
Dilatation of pupil.
Relaxation of intestine.

60. Response To Stress
When the body is under stress homeostasis is disturbed.
To restore it and, in some cases, to maintain life there are immediate
and, if necessary, longer-term responses.
Stressors include exercise, fasting, fright, temperature changes,
infection, disease and emotional situations.
The immediate response is sometimes described as preparing for
‘fight or flight’. This is mediated by the sympathetic nervous system.
In the longer term, ACTH from the anterior pituitary stimulates the
release of glucocorticoids and mineralocorticoids from the adrenal
cortex providing a more prolonged response to stress.

61. Responses To Stressors That Threaten Homeostasis

62. Differences Between Physical And Psychological Stress

63. Differences Between Physical And Psychological Stress

64. Pineal Gland
The pineal gland is a small body
attached to the roof of the third
ventricle and is connected to it by a
short stalk containing nerves, many
of which terminate in the
hypothalamus.
The pineal gland is about 10 mm
long, reddish brown in colour and
surrounded by a capsule.
The gland tends to atrophy after
puberty and may become calcified in

65. Pineal Gland
The pinealocyte cells that make up the pineal gland are known
to produce and secrete the amine hormone melatonin, which is
derived from serotonin.
The secretion of melatonin varies according to the level of light
received from the environment.

66. Melatonin
This is the main hormone secreted by the pineal gland.
Secretion is controlled by daylight and darkness; levels fluctuate
during each 24-hour period, the being highest at night and the
lowest around midday.
Secretion is also influenced by the number of daylight hours, i.e.
there may be seasonal variations.

67. Melatonin
The secretion of melatonin may influence the body’s circadian
rhythms, the dark-light fluctuations that affect not only sleepiness
and wakefulness, but also appetite and body temperature.
Interestingly, children have higher melatonin levels than adults,
which may prevent the release of gonadotropins from the anterior
pituitary, thereby inhibiting the onset of puberty.
Finally, an antioxidant role of melatonin is the subject of current
research.

68. Functions Of Melatonin
Coordination of circadian rhythms
Inhibition of growth and development of the sex organs
before puberty, possibly by preventing synthesis of
gonadotropins.

69. Gonads
Testes
The testes (or testicles) are a pair of sperm-producing organs that
maintain the health of the male reproductive system.
The testes are twin oval-shaped organs about the size of a large grape.
They are located within the scrotum. Within the testes are coiled masses
of tubes called seminiferous tubules. These tubules are responsible for
producing the sperm cells through a process called spermatogenesis.
In addition to their role in the male reproductive system, the testes also
have the distinction of being an endocrine gland because they secrete
testosterone—a hormone that is vital to the normal development of male
physical characteristics.

70. Ovary
The ovaries are a pair of ova-producing organs (that is, they produce egg
cells) that maintain the health of the female reproductive system.
The ovaries are oval shaped and about the size of a large grape. They are
located on opposite ends of the pelvic wall, on either side of the uterus. The
ovaries are each attached to the fimbria (tissue that connects the ovaries to
the fallopian tube).
In addition to their role in producing ova, the ovaries also have the
distinction of being an endocrine gland because they secrete hormones—
primarily estrogen and progesterone—that are vital to normal reproductive
development and fertility.

71. Gonadal Hormones
The male and female reproductive system is regulated by follicle-
stimulating hormone (FSH) and luteinizing hormone (LH) produced
by the anterior lobe of the pituitary gland in response to
gonadotropin-releasing hormone (GnRH) from the hypothalamus.

72. Hormones Of Male Gonad (Testes)
The primary hormone produced by the male testes is testosterone,
a steroid hormone important in the development of the male
reproductive system, the maturation of sperm cells, and the
development of male secondary sex characteristics such as a
deepened voice, body hair, and increased muscle mass.
Interestingly, testosterone is also produced in the female ovaries,
but at a much reduced level.
In addition, the testes produce the peptide hormone inhibin, which
inhibits the secretion of FSH from the anterior pituitary gland. FSH
stimulates spermatogenesis.

73. Functions Of Testosterone
1. Increase in size of penis, scrotum and testes.
2. Development of muscular growth.
3. Increase in bone growth.
4. Increase in thickness and color of skin.
5. Hair distribution growth increase.
6. Change in voice.

74. Hormones Of Female Gonad (Ovary)
The primary hormones produced by the ovaries are estrogens,
which include estradiol, estriol, and estrone. Estrogens play an
important role in a larger number of physiological processes,
including the development of the female reproductive system,
regulation of the menstrual cycle, the development of female
secondary sex characteristics such as increased adipose tissue
and the development of breast tissue, and the maintenance of
pregnancy.
Another significant ovarian hormone is progesterone, which
contributes to regulation of the menstrual cycle and is important in
preparing the body for pregnancy as well as maintaining
pregnancy

75. Functions Of Estrogen
1. Enlargement of uterus about double of its childhood size.
2. Increase in blood supply to endometrium.
3. It increases size of uterine tube.
4. It reduces the pH of vagina.
5. It increases the shape and size of vagina.
6. It develops the mammary gland(breast).
7. It develops hair in the pubic region and axilla.
8. It brings softness and smoothness to skin.
9. It increases bone growth(osteoblast activity.
10. Voice: the larynx remains in pre pubertal stage which produces high
pitch voice.

76. Functions Of Progesterone
1. It increases the thickness of endometrium.
2. It increases the size of uterine gland.
3. It increases the secretory activities of glandular cells.
4. It increases the deposition of lipid and glycogen in the stromal wall.
5. It promotes secretory changes in the mucosal lining of the fallopian
tube.

78. Thymus Gland
The thymus gland is a small
organ behind the breastbone that
plays an important function both
in the immune system and
endocrine system.
Though the thymus begins to
atrophy (decay) during puberty, its
effect in "training" T lymphocytes
to fight infections and even cancer
lasts for a lifetime.

79. Hormones of Thymus Gland
It secretes Thymosin hormone which promotes immune competence
in young T-lymphocytes.
It secretes Thymine hormone which inhibits acetylcholine release at
motor nerve endings.

80. Pancreas
The pancreas is a long, slender organ, most of which is located
posterior to the bottom half of the stomach.
It is made up of soft lobulated glandular tissue.
It has four parts:
head
neck
Body
Tail
Although it is primarily an exocrine gland, secreting a variety of
digestive enzymes, the pancreas has an endocrine function.

81. Pancreas
The endocrine pancreas consists of clusters of cells, known as the
pancreatic islets (islets of Langerhans), scattered throughout the
gland.
Pancreatic hormones are secreted directly into the bloodstream
and circulate throughout the body. This is in contrast to the
exocrine pancreas and its associated ducts.
There are three main types of cells in the pancreatic islets:
• α (alpha) cells, which secrete glucagon
• β (beta) cells, which are the most numerous, secrete insulin
• δ (delta) cells, which secrete somatostatin (GHRIH,.

82. Pancreas
The normal blood glucose level is between 3.5 and 8 mmol/litre
(63 to 144 mg/100 mL).
Blood glucose levels are controlled mainly by the opposing
actions of insulin and glucagon:
• glucagon increases blood glucose levels
• insulin reduces blood glucose levels.

83. Cells and Secretions of the Pancreatic Islets
The pancreatic islets each contain four varieties of cells:
The alpha cell produces the hormone glucagon and makes up
approximately 20 percent of each islet. Glucagon plays an
important role in blood glucose regulation; low blood glucose
levels stimulate its release.
The beta cell produces the hormone insulin and makes up
approximately 75 percent of each islet. Elevated blood glucose
levels stimulate the release of insulin. Insulin converts excess
of glucose into glycogen in the liver and muscles. Deficiency of
insulin causes diabetes mellitus.

84. Cells and Secretions of the Pancreatic Islets
The delta cell accounts for four percent of the islet cells and
secretes the peptide hormone somatostatin. The somatostatin
hormone decreases the rate of nutrient absorption into the blood
from GI tract. It also inhibits the secretion of growth from anterior
lobe of pituitary gland.
The PP cell accounts for about one percent of islet cells and
secretes the pancreatic polypeptide hormone. It inhibits the release
of pancreatic juice. It is thought to play a role in appetite, as well as
in the regulation of pancreatic exocrine and endocrine secretions.
Pancreatic polypeptide released following a meal may reduce
further food consumption; however, it is also released in response
to fasting.

85. Functions Of Insulin
It converts excess glucose into glycogen in the liver and
muscles.
It decreases the breakdown of glycogen (glycogenolysis).
It prevents formation of new glucose from protein and fat
(gluconeogenesis).

86. Functions Of Glucagon
It increases glycogenolysis(breakdown of glycogen into
glucose) in the liver.
It increases gluconeogenesis(formation of glucose from
protein) in the liver.
It increases the secretion of bile.
It inhibits the secretion of gastric juice.

87. Regulation of Blood Glucose Levels by Insulin and Glucagon
Glucose is required for cellular respiration and is the preferred fuel
for all body cells. The body derives glucose from the breakdown of
the carbohydrate-containing foods and drinks we consume.
Glucose not immediately taken up by cells for fuel can be stored by
the liver and muscles as glycogen, or converted to triglycerides and
stored in the adipose tissue.
Hormones regulate both the storage and the utilization of glucose
as required.
Receptors located in the pancreas sense blood glucose levels, and
subsequently the pancreatic cells secrete glucagon or insulin to
maintain normal levels.

88. Homeostatic Regulation of Blood Glucose Levels