Download Hormone

Endocrine Pathophysiology I
Kyong Soo Park
Dept of MMBS &
Dept of Internal Medicine,
Seoul National University College of
Medicine
1
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
Hormone: is a chemical
messenger secreted by one
endocrine gland or cell into
the bloodstream and
targeted toward cells in
another organ
General Characteristics
of the Endocrine System
• The endocrine and nervous systems communicate
using chemical signals
Endocrine Gland
7
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
8
Action of Steroid Hormones
Action of Non-Steroid
Hormones
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 (0.75-6.7 days)
• Primarily controlled by negative feedback mechanism
• Hormone secretions are precisely regulated
–
–
Hypothalamus
–
Nervous system
Changing level
of substance
in plasma
– Anterior pituitary gland
(a)
Peripheral
endocrine
gland
Endocrine
gland
Endocrine
gland
Target cells
Target cells
Target cells
Action
Action
Action
(b)
(c)
Pituitary Gland
• Lies at the base of the brain in the sella turcica
• Consists of two distinct portions:
• Anterior pituitary (adenohypophysis)
• Posterior pituitary (neurohypophysis)
Third ventricle
Hypothalamus
Anterior cerebral
artery
Optic chiasma
Optic nerve
Oculomotor
nerve
Pituitary stalk
(Infundibulum)
Trochlear nerve
Anterior lobe
of pituitary
gland
Sphenoidal
sinus
Sphenoid bone
Posterior lobe
of pituitary
gland
Sella turcica
Basilar artery
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)
Superior hypophyseal
artery
Secretory cells
of anterior
pituitary gland
Capillary bed
–
+
Peripheral endocrine gland
Capillary bed
Hypophyseal veins
Anterior lobe of pituitary gland
(Hormone 3)
Stimulation
+
Target cells
Inhibition
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hormones from Hypothalamus
GHRH
SS
Growth
Somatostatin
hormonereleasing
hormone
PRF
Prolactinreleasing
factor
PIH
Prolactinrelease
inhibiting
hormone
TRH
Thyrotropinreleasing
hormone
CRH
Corticotropinreleasing
hormone
GnRH
Gonadotropinreleasing
hormone
Hormones from Anterior Pituitary
GH
Growth
hormone
Bone
Muscle Adipose
tissue
PRL
Prolactin
Mammary gland
TSH
Thyroidstimulating
hormone
Thyroid
ACTH
Adrenocorticotropic
hormone
Adrenal
cortex
LH
Luteinizing
hormone
Ovary
Testis
FSH
Folliclestimulating
hormone
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
Thyroid Gland
• The thyroid gland has two lateral lobes and lies just
below the larynx
• It produces three hormones:
• T4 (thyroxine), T3 (triiodothyronine), Calcitonin
Larynx
Colloid
Thyroid
gland
Follicular
cell
Follicular cells
Colloid
Isthmus
Extrafollicular
cell
(a)
(b)
Extrafollicular
cells
Thyroid Hormones
OH
I
OH
I
I
O
I
O
I
CH2
I
I
CH2
NH2CHCOOH
NH2CHCOOH
Thyroxine (T4)
Triiodothyronine (T3)
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)
Pharynx
Thyroid
gland
Parathyroid
glands
Esophagus
Trachea
Posterior view
Secretory cells
Capillaries
–
Changing level
of substance
in plasma
Endocrine
gland
Target cells
Action
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
Surface of
adrenal gland
Connective
tissue capsule
Zona glomerulosa
Adrenal gland
Kidney
Zona fasciculata
Adrenal cortex
Adrenal cortex
Adrenal
medulla
Zona reticularis
(a)
Adrenal medulla
(b)
Hormones of the Adrenal Gland
Cushing’s syndrome
Addison’s disease
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
Duct
Small
intestine
Digestive enzymesecreting cells
Pancreatic islet
(Islet of Langerhans)
Capillary
Hormone-secreting
islet cells
Pancreas
Hormones of the Pancreatic
Islets
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