The document summarizes key aspects of the endocrine system. It describes how the endocrine system is composed of glands that secrete hormones directly into the bloodstream to regulate distant target tissues. It provides details about major endocrine glands like the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, and how they regulate important body functions through negative feedback loops and secretion of hormones like thyroid hormones, growth hormone, cortisol, and others. It also explains the different types of stimuli that regulate hormone release and the chemical nature of hormones.

1. GOOD MORNING!

2. PAINT ME A
PICTURE!
(Pre-activity)

3. Athletes
preparing for
Olympic

4. Uterine
contraction of
a woman in
labor

5. Control of food
intake and
digestion

6. BY: PAULA MARIE M. LLIDO
RACHEL M. TACUBAO
GROUP 6

8. Composed of ENDOCRINE GLANDS and ENDOCRINE
CELLS located throughout the body
ENDOCRINE SYSTEM
ENDOCRINE – (Greek) “endo” within and “krino” to secrete
Traveling to TARGET TISSUES (specific sites)
Secretes some HORMONES (chemical messengers)
COORDINATED RESPONSE!
Bloodstream

9. ENDOCRINE VS. EXOCRINE GLANDS
EXOCRINE SYSTEM
GLANDS HAVE DUCTS OR HOLLOW ORGANS
FOR SECRETION OUTSIDE THE BODY

10. ENDOCRINE SYSTEM FUNCTIONS
1 Metabolism
2 Control of food intake and digestion
3 Tissue development
4 Ion regulation
5 Water balance

11. 6 Heart rate and blood pressure regulation
7 Control of blood glucose and other nutrients
8 Control of reproductive functions
9 Uterine contractions and milk release
10 Immune system regulation

12. What are the
3 TYPES OF STIMULI
that regulate hormone release?
HUMORAL
NEURAL
HORMONAL

13. HORMONAL STIMULI
Hormones are released in
response to other hormones
from another endocrine gland
Tropic hormones
Example: Thyroid releasing
hormone triggers the release of
thyroid stimulating hormone
which triggers the release of
thyroid hormone

14. NEURAL STIMULI
Hormones are released in
response to a nerve
stimulation
Example: Epinephrine and
oxytocin

15. HUMORAL STIMULI
Hormones Are Released in
response to ions and
nutrients
Example: Calcitonin,
parathyroid hormone,
insulin, glucagon,
aldosterone

16. Hormone levels are
primarily
controlled through
negative feedback,
in which rising
levels of a
hormone inhibit
its further
release
HORMONAL
INHIBITING HORMONES – from the hypothalamus
that prevent the secretion of tropic hormones
from the pituitary gland
NEURAL
Neurons inhibit targets just as often as they
stimulate targets.
If the neurotransmitter is inhibitory, the target
endocrine gland does not secrete its hormone
HUMORAL
a rise in blood glucose levels triggers the
pancreatic release of insulin. Insulin causes blood
glucose levels to drop, which signals the pancreas
to stop producing insulin in a negative feedback
loop.

17. REGULATION OF HORMONE LEVELS IN THE BLOOD
NEGATIVE FEEDBACK
POSITIVE FEEDBACK
• Hormone’s secretion is inhibited by the hormone
itself once blood levels have reached a certain point
• Self-limiting system
• Promote the synthesis and secretion of the tropic
hormone in addition to stimulating their target cell
• Self-propagating system

18. CHEMICAL NATURE OF HORMONES
Lipid-soluble Water-soluble
Steroid
hormones
(cholesterol)
Thyroid
hormones
(tyrosine)
Amino
acids

19. LIPID-SOLUBLE HORMONE
• Steroid Hormones:
• Lipid soluble
• Diffuse through cell membranes
• Endocrine organs
• Adrenal cortex
• Ovaries
• Testes
• Thyroid

20. WATER-SOLUBLE HORMONE
 Hormones and Plasma Membrane Receptors
 Bind to receptors in plasma membrane
 Cannot have direct effect on activities inside target cell
 Use intracellular intermediary to exert effects
 First messenger:
 leads to second messenger
 may act as enzyme activator, inhibitor, or cofactor
 results in change in rates of metabolic reactions

21. CLASSES OF RECEPTORS
NUCLEAR RECEPTOR
(binded by Lipid-soluble hormones)
MEMBRANE-BOUND RECEPTOR
(binded by water-soluble hormones)

22. ACTION OF NUCLEAR RECEPTORS

23. MEMBRANE-BOUND RECEPTORS
THAT ACTIVATE G PROTEINS

25. CASCADE EFFECT
TO SIGNAL AMPLIFICATION
• The combination of a hormone with a
membrane-bound receptor activates
several G proteins.
• The G proteins, in turn, activate many
inactive adenylate cyclase enzymes,
which cause the synthesis of a large
number of cAMP molecules
• The large number of cAMP molecules, in
turn, activate many inactive protein
kinase enzymes
• Produces a rapid and amplified
response.

26. ENDOCRINE
GLANDS AND
HORMONES

27. PITUITARY AND HYPOTHALAMUS
PITUITARY GLAND
• Hypophysis
• Small gland, about size of a pea
• Master gland
• 2 parts:
ANTERIOR PITUITARY
POSTERIOR PITUITARY
HYPOTHALAMUS
• Important autonomic nervous system
and endocrine control center
• Located inferior to the thalamus
• Controls the pituitary gland : hormonal
control and direct innervations

29. • Produce and release hormones
• The hypothalamus synthesizes hormones called
releasing factors, which are released into the portal
vein that extends to the anterior lobe
• The releasing factors cause endocrine cells in the
anterior pituitary to release specific hormones into
the bloodstream to act on distant cells
• Release hormones
• The posterior lobe (neurohypophysis) releases
hormones produced by neurosecretory cells of the
hypothalamus
• These cells extend from the hypothalamus into the
posterior lobe and release hormones into the
bloodstream in response to nerve signals
POSTERIOR PITUITARY
ANTERIOR PITUITARY

30. Anterior Pituitary Hormones
•Adrenocorticotropic (ACTH)
•Growth hormone (GH)
•Thyroid-stimulating hormone (TSH)
•Follicle-stimulating hormone (FSH)
•Luteinizing hormone (LH)
•Prolactin (PRL)
•Melanocyte-stimulating hormone (MSH)

31. “Dwarfism & Gigantism”
• Growth Hormone (GH)
–Stimulates body cells to grow and
reproduce and speeds the rate at
which cells use carbohydrates and
fats
• Prolactin (PRL)
–Promotes milk production following
the birth of an infant.
• Thyroid-Stimulating Hormone (TSH)
–Controls the secretion of hormones
from the thyroid gland.

32. Posterior Pituitary Hormones
• Plays a role in childbirth by contracting muscles in the
uterine wall and in milk-letdown by forcing milk into
ducts from the milk glands.
OXYTOCIN
ANTI-DIURETIC HORMONE (ADH)
• Causes the kidneys to conserve water
(prevents dehydration)
• Vasopressin

33. Thyroid Gland

35. One of the largest
endocrine glands
Highly vascular

36. Thyroid hormones, bind to
nuclear receptors in cells
and regulate the rate of
metabolism in the body

38. Thyroid hormone secretion is regulated by
hormones from the hypothalamus and
pituitary.
Hypothalamus > TSH-releasing
hormone (TRH)
Anterior pituitary gland > Thyroid-
stimulating hormone (TSH)
Thyroid gland > Thyroid
hormone

39. Small fluctuations in blood TSH levels
occur on a daily basis, with a small
increase at night
blood levels of TSH = synthesis and
release
of thyroid
hormones
blood levels of TSH = synthesis and
release
of thyroid
hormones

40. Negative –feedback
effect
hypothalamus Pituitary
gland

41. Thyroid hormone level - inhibits the secretion
of TRH and TSH
Thyroid hormone level - allows additional
secretion of
TRH and TSH
Because of the negative-feedback effect,
the thyroid hormones fluctuate within a
narrow concentration range in the blood.
A loss of negative feedback will result in
excess TSH

42. Goiter
As less thyroid hormone is
synthesized and secreted, TSH-
releasing hormone and TSH
secretion increase above normal
levels and cause dramatic
enlargement of the thyroid gland.

43. Hypothyroidism, lack of thyroid
hormones
(Infants)
Cretinism; mental
retardation, short
stature, and
abnormally formed
skeletal structures.
(Adults)
decreased
metabolic rate,
sluggishness, a
reduced ability to
perform routine
tasksMyxedema

44. the accumulation of fluid and other
molecules in the subcutaneous tissue.

45. Hyperthyroidism, elevated
rate of
thyroid hormone secretion
increased metabolic rate, extreme
nervousness, and chronic fatigue
Graves disease is a type of hyperthyroidism
that results when the immune system
produces abnormal proteins that are similar
in structure and function to TSH. Graves
disease is often accompanied by bulging of
the eyes, a condition called exophthalmia

47. The thyroid gland requires iodine to
synthesize thyroid hormones. Iodine
is taken up by the thyroid follicles.

48. Thyroxine, or
tetraiodothyronine
(T ₄)
Triiodothyronine (T ₃)

49. Thyroxine, or
tetraiodothyronine
(T ₄)
Triiodothyronine (T ₃)
Insufficient iodine,
production and secretion
of the thyroid hormones
decrease

50. Parafollicular cells secretes calcitonin
Blood concentration of Ca 2+
Secretes calcitonin > Ca 2+ level to normal range
Calcitonin binds to membrane-bound
receptors of osteoclasts and reduces the rate
of Ca2+ resaborption (breakdown) from bone
by inhibiting the osteoclasts. Calcitonin may
prevent blood Ca2+ levels from becoming
overly elevated following a meal that contains
a high concentration of Ca2+

51. Parathyro
id Glands

53. secrete parathyroid hormone (PTH),
which is essential for the regulation
of blood calcium levels.
PTH has many effects:
1. PTH binds to membrane-bound receptors of
renal tubule cells, which increases active
vitamin D formation.
2. PTH binds to receptors on osteoblasts.
3. PTH binds to receptors on cells of the renal
tubules and decreases the rate at which Ca2+ is
lost in the urine.
4. PTH acts on its target tissues to raise blood
Ca2+ levels to normal.

56. Hyperparathyroidism,
abnormally high rate of PTH secretion
Bones can become soft, deformed, and easily
fractured.
The elevated blood Ca2+ levels make nerve and
muscle cells less excitable, resulting in fatigue
and muscle weakness.
The excess Ca2+ can be deposited in soft
tissues of the body, causing inflammation.
In addition, kidney stones can result

57. Hypoparathyroidism,
abnormally rate of PTH secretion
The low blood levels of PTH lead to reductions in
the rate of bone reabsorption and the formation
of vitamin D. As a result, blood Ca2+ levels
decrease. In response to low blood Ca2+ levels,
nerves and muscles become excitable and
produce spontaneous action potentials that
cause frequent muscle cramps or tetanus.
Severe tetanus can affect the respiratory
muscles; breathing stops, resulting in death.

58. Adrenal Glands

60. Adrenal medulla
Epinephrine, or
adrenaline
Norepinephrine
Fight-or-flight hormones

61. The major effects
of the hormones
released from the
adrenal medulla
are :

62. Adrenal Cortex
Steroid hormones:
mineralocorticoids glucocorticoids
androgens

63. Mineralocorticoids, secreted
by the outer layer of the adrenal cortex
helps regulate blood volume and
blood levels of K+ and Na+
Aldosterone, causes Na+ and water to be
retained in the body and increases the rate
at which K+ is eliminated

64. Changes in blood pressure indirectly affect the
rate of aldosterone secretion.
Low BP > Renin (protein
molecule from kidney) acts as
an enzyme
Angiotensinogen (blood
protein)
convert to Angiotensin IAngiotensin-converting
enzyme
Angiotensin II

65. Angiotensin II causes smooth
muscle in blood vessels to constrict,
and acts on the adrenal cortex to
increase aldosterone secretion.
Aldosterone causes retention of Na+
and water, which leads to an
increase in blood volume. Both blood
vessel constriction and increased
blood volume help raise blood
pressure.

66. Glucocorticoids, secreted by
the middle layer of the adrenal cortex
helps regulate blood nutrient levels
The major glucocorticoid hormone is
cortisol, which increases the
breakdown of proteins and lipids and
increases their conversion to forms of
energy the body can use.

67. Adrenocorticotropic hormone (ACTH)
molecules from the anterior pituitary bind to
membrane-bound receptors and regulate the
secretion of cortisol from the adrenal cortex.
blood glucose levels - cortisol secretion

68. ACTH then stimulates cortisol
secretion.
The low blood glucose acts on the
hypothalamus to increase the secretion of
the ACTH-releasing hormone
Stimulates ACTH secretion from the
anterior pituitary.

69. Androgen, secreted by the
inner layer of the adrenal cortex
which stimulate the development of
male sexual characteristics

70. Pancreas

72. A below-normal blood glucose level
causes the nervous system to
malfunction because glucose is the
nervous system’s main source of energy.
If blood glucose levels are too high, the
kidneys produce large volumes of urine
containing substantial amounts of
glucose. Because of the rapid loss of
water in the form of urine, dehydration
can result.

73. Insulin is released from the beta cells primarily in
response to the elevated blood glucose levels and
increased parasympathetic stimulation
associated with digestion of a meal.
The major target tissues for insulin are the
liver, adipose tissue, muscles, and the
area of the hypothalamus that controls
appetite, called the satiety center.

74. Insulin binds to membrane-bound
receptors and, either directly or
indirectly, increases the rate of
glucose and amino acid uptake in
these tissues.
Glucose is converted to glycogen or
lipids, and the amino acids are used
to synthesize protein

76. Diabetes mellitus
Type 1 diabetes
mellitus , too little
insulin is secreted
from the pancreas
Type 2 diabetes
mellitus , insufficient
numbers of insulin
receptors on target
cells or by defective
receptors that do not
respond normally to
insulin.

77. Type 1 diabetes mellitus,
tissues cannot take up glucose
effectively, causing blood
glucose levels to become very
high, a condition called
hyperglycemia

78. Glucagon, released from the
alpha cells when blood glucose
levels are low.
Glucagon binds to
membranebound receptors
primarily in the liver, causing the
glycogen stored in the liver to be
converted to glucose. The glucose
is then released into the blood to
increase blood glucose levels

79. Somatostatin is released by
the delta cells in response to
food intake. Somatostatin
inhibits the secretion of insulin
and glucagon and inhibits
gastric tract activity.

80. Testes and Ovaries

81. Testosterone
Estrogen and progesterone
LH and FSH stimulate the
secretion of hormones from the
ovaries and testes.

82. Thymus

84. It is important in the function of the
immune system
Thymosi

85. White blood cells called T
cells, help protect the body
against infection by foreign
organisms

86. Pineal Gland

87. Melatonin, which is thought to
decrease the secretion of LH and FSH
by decreasing the release of
hypothalamic-releasing hormones
Thus, melatonin inhibits the functions
of the reproductive system

88. Other hormones
Cells in the lining of the stomach
and small intestine secrete
hormones that stimulate the
production of digestive juices
from the stomach, pancreas,
and liver

89. Prostaglandins
widely distributed in tissues of the body,
where they function as intercellular
signals
cause relaxation of smooth muscle,
such as dilation of blood vessels
also play a role in inflammation
cause contraction of smooth
muscle, such as contraction of the
uterus during the delivery of a baby

90. Erythropoietin
hormone secreted by the kidney in
response to reduced oxygen levels in
the kidney
acts on bone marrow to increase the
production of red blood cells

91. the placenta is an important source of
hormones that maintain pregnancy and
stimulate breast development
estrogen, progesterone, and
human chorionic
gonadotropin, which is similar
in structure and function to LH

92. Effects Of
Aging On
The
Endocrine