1. Endocrine Pathophysiology I
Kyong Soo Park
Dept of MMBS & Dept of Internal Medicine,
Seoul National University College of Medicine

2. Introduction
The endocrine system assists the nervous system with communication and control of the body
Endocrine glands
They are ductless
They secrete hormones into bloodstream
There are also similar glands called paracrine and autocrine glands that are quasi-endocrine
Exocrine glands
They have ducts
They deliver their products directly to a specific site

3. Hormone: is a chemical messenger secreted by one endocrine gland or cell into the bloodstream and targeted toward cells in another organ

4. Hormones that bind to cells near the cell that released them mediate paracrine effects

5. General Characteristics of the Endocrine System
The endocrine and nervous systems communicate using chemical signals

6. Endocrine Gland The endocrine system.
Endocrine organs are located throughout the body

8. Chemistry of Hormones Chemically, hormones are either:
Steroid or steroid-like hormones such as:
Sex hormones
Adrenal cortex hormones
Non-steroid hormones such as:
Amines
Proteins
Peptides
Glycoproteins

9. Action of Steroid Hormones
Steroid hormone cross the plasma membrane and bind to intracellular receptors. Hormone receptor complex bind to DNA then regulate target gene transcription.

10. Action of Non-Steroid Hormones
While nonsteroid hormones bind to cell surface receptor.. Exception is thyroid hormone which cross plasma membrane and binds to nuclear receptor. Binding to cell surface receptor lead to intracellular signalling cascade such as G-protein coupled receptor -cAMP signalling

11. Control of Hormonal Secretions
Hormones can be short-lived or may last for days Amines (2-3 minutes) polypeptides (4-40 minutes) steroid and proteins (4-170 minutes), thyroid hormones ( days)
Primarily controlled by negative feedback mechanism
Hormone secretions are precisely regulated –
Hypothalamus –
Nervous system –
Changing level
of substance
in plasma –
Anterior pituitary gland
Peripheral
endocrine
gland
Endocrine
gland
Endocrine
gland
Target cells
Target cells
Target cells
Action
Action
Action
(a)
(b)
(c)

12. Pituitary Gland Lies at the base of the brain in the sella turcica
Optic nerve
Sphenoid bone
Hypothalamus
Optic chiasma
Sella turcica
Third ventricle T
rochlear nerve
Basilar artery
Anterior cerebral
artery
Pituitary stalk
(Infundibulum)
Anterior lobe
of pituitary
gland
Sphenoidal
sinus
Posterior lobe
Oculomotor
nerve
Lies at the base of the brain in the sella turcica
Consists of two distinct portions:
Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)

13. Anterior Pituitary Hormones
Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones –
Hypothalamus –
Third ventricle
Releasing
hormone
(Hormone 1)
Optic chiasma
Neurosecretory
cells that secrete
releasing hormones + –
Anterior pituitary
Hypophyseal
portal veins
Anterior pituitary
hormone
(Hormone 2)
Secretory cells
of anterior
pituitary gland
Superior hypophyseal
artery
Capillary bed +
Peripheral endocrine gland
Capillary bed
Hypophyseal veins
Anterior lobe of pituitary gland
(Hormone 3)
Stimulation +
Inhibition T
arget cells
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14. Hormones from Hypothalamus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hormones from Hypothalamus
GHRH
Growth
hormone-
releasing
hormone SS
Somatostatin
PRF
Prolactin-
releasing
factor
PIH
Prolactin-
release
inhibiting
hormone
TRH
Thyrotropin-
releasing
hormone
CRH
Corticotropin-
releasing
hormone
GnRH
Gonadotropin-
releasing
hormone
Hormones from
Anterior Pituitary GH
Growth
hormone
PRL
Prolactin
TSH
Thyroid-
stimulating
hormone
ACTH
Adrenocorticotropic
hormone LH
Luteinizing
hormone
FSH
Follicle-
stimulating
hormone
Bone
Muscle
Adipose
tissue
Mammary gland
Thyroid
Adrenal
cortex
Ovary T
estis

15. Posterior Pituitary Hormones
Structurally consists of nerve fibers and neuroglia v. glandular epithelial cells of the anterior pituitary gland
The nerve fibers originate in the hypothalamus
Two hormones are produced:
Antidiuretic hormone (vasopressin)
Oxytocin
Third ventricle
Optic chiasma
Neurosecretory cells
that secrete posterior
pituitary hormones
Neurosecretory
cells that secrete
releasing hormones
Hypothalamus
Superior hypophyseal
artery
Capillary bed
Inferior hypophyseal
artery
Hypophyseal veins
Sella turcica of
sphenoid bone
Posterior lobe of pituitary gland

17. Thyroid Gland
The thyroid gland has two lateral lobes and lies just below the larynx
It produces three hormones:
T4 (thyroxine), T3 (triiodothyronine), Calcitonin
Follicular cells
Colloid
Extrafollicular
cells
Larynx
Isthmus
(a)
(b)
Thyroid
gland
Follicular
cell
Extrafollicular cell

18. Thyroid Hormones OH OH I I I O O I I I I CH2 CH2 NH2CHCOOH NH2CHCOOH
Thyroxine (T4)
Triiodothyronine (T3)

20. Parathyroid Glands
The parathyroid glands are on the posterior surface of the thyroid gland
There are typically four parathyroid glands
It secretes one hormone: PTH (parathyroid hormone or parathormone)
Posterior view
Esophagus
Pharynx
Thyroid
gland
Parathyroid
glands
Trachea
Secretory cells
Capillaries

21. – Changing level of substance in plasma Endocrine gland Target cells
Action

22. Adrenal Glands
The adrenal glands are closely associated with the kidneys
The gland sits like a cap on each kidney
Hormones are secreted from two different areas of the gland, the adrenal cortex and the adrenal medulla
Numerous hormones are secreted by the adrenal glands
Adrenal gland
Kidney
Adrenal cortex
(a)
Zona glomerulosa
Connective
tissue capsule
(b)
Zona fasciculata
Zona reticularis
Adrenal medulla
Adrenal
medulla
Surface of
adrenal gland

23. Hormones of the Adrenal Gland

24. Cushing’s syndrome
Addison’s disease

25. Pancreas The pancreas has two major types of secretory tissue
This is why it is a dual functioning organ as both an exocrine gland and endocrine gland
Pancreatic islet (Islet of Langerhans)
Gallbladder
Common bile duct
Pancreatic duct
Pancreas
Duct
Capillary
Small
intestine
Digestive enzyme-
secreting cells
Pancreatic islet
(Islet of Langerhans)
Hormone-secreting
islet cells

26. Hormones of the Pancreatic Islets

27. Other Endocrine Glands
Pineal Gland
Secretes melatonin
Regulates circadian rhythms
Thymus Gland
Secretes thymosins –
Promotes development of certain lymphocytes
Important in role of immunity
after puberty, it starts to shrink and become replaced by fat
Reproductive Organs
Ovaries produce estrogens and progesterone
Testes produce testosterone
Placenta produces estrogens, progesterone, and gonadotropin
Other organs: digestive glands, heart, and kidney