1. Essentials of
Anatomy & Physiology
Fifth edition
Seeley • Stephens • Tate
Chapter 10
The Endocrine System
PAUL E. MANAIG,MD
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 1. Water balance
2. Uterine contraction
3. Growth, metabolism, and milk secretion
4. Ion regulation
5. Heart rate and blood pressure regulation
6. Blood glucose control
7. Immune system regulation
8. Reproductive function control

3. Chemical signals
Chemical signals
Chemical signals or Ligands
- Molecules released from one location that move to
another location to produce a response.
Intracellular response – produces from one part of a cell
and travel to another part of the SAME cell
Autocrine Paracrine
Neuromodulators Pheromones

6. Receptors
Receptors
Chemical signals bind to proteins and glycoproteins
(RECEPTORS)
Specificity – Tendency for each receptor site to bind to a
specific chemical signal and not the others.

7. Membrane-bound receptors
Extend across the cell membrane, with
their receptor sites outside the
surface of the cell membrane
Responds to chemical signals that are
large, and water-soluble
Intracellular receptors
Chemical signals DIFFUSES and bind to the
intracellular receptor located at the
cytoplasm or nucleus

8. Hormones
Hormones
 Hormones are distributed in the blood to all parts of the
body, but only its corresponding target tissue respond to
each type of hormone
 Influences target cells by chemically binding to their
receptors.
 2,000-100,000 receptors for a particular hormone
 Hormones that pass in the blood and act on distant cells
are called Circulating hormones or ENDOCRINE
 PARACRINE - Hormones that act on neighboring cells
 AUTOCRINE – Acts on the same cell
 Local hormones usually are inactivated quickly

11. Pituitary and Hypothalamus
Pituitary and Hypothalamus
Pituitary gland / Hypophysis –
 Small gland about the size of pea
 Rest in the depression of sphenoid bone inferior to
the hypothalamus of the brain.
 Infundibulum – Stalk connecting the pituitary
gland to the hypothalamus
 Once known as “Master Gland”

12. Pituitary and Hypothalamus
Pituitary and Hypothalamus

15. Hormones of the Anterior Pituitary
1. Growth hormone
2. Thyroid-Stimulating Hormone (TSH)
3. Adrenocorticotropic Hormone (ACTH)
4. Gonadotropins
a. Leutinizing hormone (LH)
b. Interstitial Cell-stimulating hormone (ISCH)
5. Prolactin
6. Melanocyte-Stimulating Hormone

16. 1. Growth Hormone
Stimulates the growth of bones, muscles, and
other organs by increasing protein synthesis.
Resist protein breakdown during periods of food
deprivation
Secretion of growth hormone is controlled by 2
hormones from the hypothalamus (releasing and
inhibitory hormone)
Daily peak levels during sleep, also increases
during fasting and exercise
Dwarfism
Gigantism

18. • In gigantism - ACROMEGALY - facial
features and hands become abnormally large
• Somatomedins – Protein chemical signal
which together with Growth hormone to bind
to the receptors of bone and cartilage tissues
to stimulate growth

19. 2. Thyroid-Stimulating Hormone (TSH)
Binds on Membrane-bound receptors of the
thyroid gland, causes to secrete thyroid
hormones.
↑ TSH- Thyroid gland enlarges

20. 3. Adrenocorticotropic Hormone (ACTH)
 Binds on Membrane-bound receptors on the cells in
cortex of adrenal glands.
 Increases secretion of Cortisol ( hydrocortisone),
which keeps the adrenal cortex from degenerating
 Binds to melanocytes and increase skin
pigmentation.
 ↑ ACTH - Darkening of the skin

21. 4. Gonadotropins
Leutinizing hormone (LH)
Interstitial Cell-stimulating hormone (ISCH)
Binds on Membrane-bound receptors of the gonads.
Regulates growth, development and of functions of
gonads
Leutinizing hormone (LH) – Ovulation of oocytes and
the secretion of estrogen and progesterone from
ovaries
Interstitial Cell-stimulating hormone (ISCH) – stimulates
interstitial cells of the testes to secrete testosterone.
Follicle-Stimulating Hormone – Stimulates
the development of follicles in the
ovaries and sperm cells in the testes.

22. 5. Prolactin
Binds on Membrane-bound receptors in the cells
of the Breast, during pregnancy and stimulates
the production of milk.
6. Melanocyte-Stimulating Hormone
Binds on Membrane-bound receptors on
melanocytes and causes them to
synthesize melanin.
↑ ACTH - Darkening of the skin

23. Hormones of the Posterior Pituitary
.
A
n
t
i
d
i
u
r
e
t
i
c
2. Oxytoxin h
o
r
Binds on Membrane-bound receptors and m
o
causes Uterine contraction and milk n
e
ejection (milk let-down) (
A
D
H
)

26. Thyroid Gland
Thyroid Gland
• Made up of 2 lobes connected by the isthmus
• Located on either side of trachea, just below the
larynx
• Largest endocrine gland
• Thyroid follicles – small spheres with walls that
consist of simple cuboidal epithelium
• Each follicle is filled with protein to which
thyroid hormones attached.

28. Thyroid Hormones
Binds to intracellular receptors in cells and regulate the
rate of metabolism in the body.
Participates in normal rate of growth and development.
Hypothyroidism
Infants – Cretinism - Mentally retarded and short in
stature, with abnormally formed skeletal structures.
Adults – reduced rate of metabolism
sluggishness, reduced ability to perform
routine task.

29. Hyperthyroidism
Elevated rate of metabolism, extreme nervousness, and
chronic fatigue.
Grave’s disease – bulging of the eyes (exopthalmia).
Thyroid gland requires iodine to synthesize thyroid
hormone.
Iodine is taken up by thyroid follicles, hormone synthesis
Thyroxine / tetraiodothyronine (T4)
Triiodothyronine (T3)
Lack of iodine results in reduced T3
and T4 synthesis

32. Para-thyroid Gland
Para-thyroid Gland
• Embedded in posterior wall of the thyroid gland
• Secretes parathyroid hormone (PTH)
– Regulation of blood calcium
– Increases the absorption of Ca+ from the intestine by causing an
increase in active vitamin D formation
Hyperparathyroidism
Elevated Blood Ca+ results in nerve and muscle less excitable,
resulting in fatigue and muscle weakness
Hypoparathryroidism
Reduced Vitamin D formation. Nerves and muscles
become more excitable and produce spontaneous
action potential. Frequent muscle cramps or tetanus

34. Hyperparathyroidism
Bones become soft, deformed
and easily fractured

35. Adrenal Glands
Adrenal Glands
1. Adrenal Medulla – Inner part
1. Epinephrine (adrenaline)
2. Norephinephrine
2. Adrenal Cortex – Outer part

36. Adrenal Medulla – Inner part (narrow or middle)
Secretes Epinephrine (adrenaline) and small
amounts of Norephinephrine
Released in response to stimulation of Sympathetic
nervous system
Fight or Flight hormones

39. Fig. 10.18

40. Pancreas, Insulin, Diabetes
Pancreas, Insulin, Diabetes
• Endocrine part consist of pancreatic islets a.k.a.
“Islets of Langerhans” – has two types of cells.
• Alpha cells – secrete glucagon
• Beta cells – secrete insulin
• A decline in the blood glucose below the normal
range causes the nervous system to
malfunction (Glucose is the Nervous
system’s main source of energy)

42. Insulin – Released in response the elevated blood
glucose levels and increased sympathetic
stimulation.
• The major target of insulin are the liver, adipose
tissue, muscles, and the area of the hypothalamus
that controls the appetite, satiety center.
Diabetes Mellitus – Result from: (1) secretion of too little
insulin from pancreas, (2) Insufficient numbers of
insulin receptors on target cells, and (3) defective
receptors that do not respond normally to insulin.
Triad of Diabetes Mellitus
1. Polyuria - ↑ urination
2. Polyphagia - ↑ food intake
3. Polydypsia - ↑ water intake

43. (Diabetes Mellitus)
Hyperglycemia- Tissues cannot take up glucose effectively,
causing blood glucose to become very high.
Polyphagia – Glucose cannot enter cells of the satiety
center of the brain without insulin, the brain responds
as if there were little blood glucose, resulting in
exaggerated appetite.
Polyuria – Excess of glucose in the blood is
excreted in the urine, thus…
Polydypsia – Because of polyuria, the person
becomes dehydrated and thirsty, thus
the need to drink often.

46. Testes and Ovaries
Testes and Ovaries
Testosterone – Main sex hormone in male
Responsible for the growth and
development of male reproductive
structures, muscle enlargement, growth of
body hair, voice changes and male sexual
drives.

47. Estrogen & Progesterone
• Development of female reproductive structures
and sexual characteristics
• Enlarges the breast and distribute fat, which
influences the shape of the hips, breast, and
thighs.
• Maintains menstrual cycle

50. Thymus Gland
Thymus Gland
• Lies at the upper part of the thoracic cavity
• Plays an important role in immune system
• Thymosin – Helps in the development of T-Cells
(helps protect the body against infection by
foreign organism)
• Most important in early life.

51. Pineal Body
Pineal Body
• Small pinecone-shaped structure located superior
and posterior to the thalamus of the brain.
• Melatonin – decrease secretion of LH and FSH by
decreasing release of hypothalamic-releasing
hormones. Acts to inhibit reproductive system

52. Thank You…
Good Luck!