Download Endocrine Introduction

Dr. Mohammed Kalimi
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The peptide hormones are synthesized by rough
endoplasmic reticulum as a pre-pro-hormone
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The steroid and amine hormones are synthesized
from cholesterol and tyrosine respectively through a
series of enzymatic reactions by smooth
endoplasmic reticulum, and mitochondria
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Excitation secretion coupling and release
↑ Intracellular calcium
↑ cAMP
↑ Activation of microtubular or microfilament
system
↑ Fusion of membrane of the secretory granule
with that of the cell
↑ Ejection of the hormone by exocytosis
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Secretion rate or production rate of a
hormone:
n moles / minute or ng / minute
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Plasma concentration of a hormone:
n moles / mL or ng / mL
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Bound to carrier proteins: Steroid and thyroid
hormones circulate bound to specific
globulins
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Unbound or free: With few exceptions (IGFI), peptides and protein hormones circulate
unbound
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By specific target tissues (internalization and
lysosomal degradation)
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By liver and kidneys
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By both of the above
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Radioimmunoassay
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Localization of hormones in tissues of origin
and action: Immunocytochemistry
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Positive or Negative Feedback
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Neuro-Endocrine Integration
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Neuronal Control (dopaminergic,
adrenergic,cholinergic)
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Sleep-wake cycle, menstrual cycle, diurnal
rhythm
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Initiates, mediates and regulates the processes of growth,
differentiation, development, maturation and aging
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Maintenance of homeostasis, fluid and electrolyte balance
(Na+, K+, Ca++, glucose, water )
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Regulation of cellular metabolism (fats, carbohydrates,
proteins)
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Sexual development and function, lactation and behavior
Primarily caused by:
 Overproduction of a hormone
(hyperfunction)
 Underproduction of a hormone
(hypofunction)
 Unresponsiveness of target organ (lack of
receptor, etc.)
 Production of abnormal hormone
Similarities between the two:
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Each synthesizes and releases specific
chemical agents which are capable of
influencing another cell by interacting with
specific receptors
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Both neurons and endocrine cells generate
electrical potentials and can be depolarized
Differences between the two:
Nervous system:
 Specific chemical agents released are disseminated
only a very short distance
 System is fast acting
 Actions are relatively short-lived
 Operates with point to point precision
 Affects only glandular secretions and muscular
contractions
Endocrine system:
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Specific chemical agents are released and
carried via the blood stream throughout the
whole body
System is slow acting
Actions are relatively long-lived
Affects a whole variety of cell types
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Thyroid-stimulating-hormone-releasinghormone (TRH)
Corticotrophin-releasing-hormone (CRH)
Luteinizing-hormone-releasing-hormone
(LHRH)
Growth-hormone-releasing-hormone (GHRH)
Somatostatin
Dopamine
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Growth Hormone (GH)
Prolactin
Thyroid Stimulating Hormone (TSH)
Adrenocorticotrophic Hormone (ACTH)
Luteinizing Hormone (LH)
Follicle Stimulating Hormone (FSH)
Melanocyte stimulating Hormone (MSH)
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Oxytocin
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Vasopressin or Anti Diuretic Hormone (ADH)
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Thyroid Hormones (T3 and T4): Follicular cells
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Calcitonin : Parafollicular cells
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Glucocorticoids : Cortisol and Corticosterone
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Aldosterone
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PTH
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Epinephrine and Norepinephrine
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Insulin
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Glucagon
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Somatostatin
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Vitamin D
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Testis: Testosterone
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Ovaries: Estrogen, Progesterone
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Human Chrionic Gonadotropin (hCG)
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Human Placental Lactogen (hPL)
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Estrogens
Androgens
Progesterone
Aldosterone
Glucocorticoids
Thyroid Hormones
Vitamin D
Vitamin A
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LH
FSH
TSH
ACTH
ADH (via V2 Receptor)
hCG
MSH
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CRH
Catecholamines
Calcitonin
Glucagon
PTH
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Somatostatin
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Dopamine
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GnRH (LHRH)
TRH
Angiotensin II
ADH via the V1 receptor
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Prolactin
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GH
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Insulin
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IGF-I
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Calcium-Phospholipid Mechanism
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TRH, LHRH
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↑Adenylyl Cyclase, ↑cAMP Mechanism
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CRH,GHRH
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Adenylyl Cyclase,cAMP Mechanism
Somatostatin
Dopamine
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Janus Kinase (associated tyrosine kinase)
Mechanism
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GH, Prolactin
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↑ cAMP Mechanism
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TSH, LH, FSH, ACTH, MSH
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Calcium-Phospholipid Mechanism
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Oxytocin, ADH (via V1 receptor)
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↑cAMP Mechanism
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ADH (via V2 receptor)
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Adrenal Medulla
Epinephrine and Norepinephrine
Parathyroid Gland
PTH
TH Gland (Parafollicular Cells)
Calcitonin
Pancreas (α Cells)
Glucagon
Placenta
hCG