Download ENDOCRINE SYSTEM

ENDOCRINE SYSTEM
TYPES OF GLANDS
Endocrine
Exocrine
Endocrine glands; Endocrine
tissue
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Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal gland
Pancreas
Ovaries / Testes
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Stomach
Duodenum
Kidney
Chemistry of Hormones
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Amines - simple hormones synthesized from
tyrosine
Proteins and Peptides - chains of amino
acids hooked together
Steroids - lipid soluble hormones derived
from cholesterol
Eicosanoids - hormones derived from
arachidonic acid (from lipids)
Mechanisms of Hormone
Action
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Alters plasma membran permeability
Stimulates synthesis of protein
Activates or deactivates enzymes
Induces secretory activity
Stimulates mitosis
Lipid Soluble Hormones
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Thyroid and steroid hormones cross the cell
membrane and bind to INTRACELLULAR
receptors in the cytoplasm or nucleus
The hormone- receptor complex triggers
activation or inactivation of specific genes
Synthesis of new protein alters cellular
activity causing a physiological response
Water Soluble Hormones
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Protein and catecholamine hormones act by
binding to receptors located on the cell
membranes of target cells
Hormones act as the 1st messenger which in
turn activates a series of events involving
cAMP as the 2nd messenger
cAMP activates protein kinases
G-proteins link the first messenger and the
second messenger
Hormone Release
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Humoral - hormones released in response
to changing blood levels
Neural - nerve fibers stimulate release
Hormonal - one hormone stimulates the
release of another
Endocrine Glands
Pituitary Gland
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Master gland
Located within the sella turcica of the
sphenoid bone
Associated closely with the hypothalamus
Differentiated into the anterior pituitary, or
glandular portion, the posterior pituitary, or
nervous portion and the avascular pars
intermedia located in between
Posterior lobe Neurohypophysis
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Connected with the hypothalamus via the
supraopticohypophyseal tract
Oxtocin (OT)
Antidiuretic hormone (ADH)
 diabetes insipidus
Anterior lobe
(Adenohypophysis)
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Controlled by releasing and inhibiting
hormones produced by the hypothalamus
Growth hormone (GH)
 somatotropin
 dwarfism, giantism, acromegaly
Thyroid - stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Acromegaly
Anterior lobe of the Pituitary
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Follicle - stimulating hormone (FSH)
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Luteinizing hormone (LH)
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Prolactin (PRL)
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Melanocyte - stimulating hormone (MSH)
Thyroid Gland
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Located below the larynx, two lobes connected
by an isthmus
Hormones synthesized from iodine and tyrosine
Follicle cells manufacture thyroglobin and store
it as colloid
Triiodothyronine (T3) / Thyroxine (T4)
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Goiter, Graves Disease, Cretinism, Myxedema
Calcitonin (CT) - lowers calcium levels
Parathyroid gland
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Four tiny glands located on posterior
thyroid
Parathyroid hormone (PTH)
Raises blood calcium
Adrenal Glands
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Located retroperitoneally and superior to
the kidney
Can be subdivided into outer cortex and
inner medulla
Adrenal Medulla
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Consists of hormone-producing cells called
chromaffin cells
Epinephrine / Norepinephrine (NE)
Sympathomimetic hormones
Released under stress by direct innervation
from the autonomic nervous system
Adrenal Cortex
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Manufactures steroid hormones called
corticosteroids
Divided into three regions: zona glomerulosa,
zona fasciculata, zona reticularis
Zona glomerulosa (outer) - releases
mineralocorticoids, principally aldosterone
which controls electrolyte balance in the
kidneys
Adrenal Cortex
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Zona fasciculata (middle) - produces
glucocorticoids such as cortisol and
cortisone; controlled by ACTH
 Addison’s Disease, Cushing’s Disease
Zona reticularis (inner) - produces adrenal
sex hormones such as estrogens and
androgens
 virilism, gynecomastia
Cushings Disease
Thymus
Gland
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Located posterior
to the sternum
and between the
lungs
Thymosin
Pineal
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Located in the
roof of the 3rd
ventricle of the
brain
Melatonin
Pancreas
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Located posterior and inferior to the stomach
Both exocrine and endocrine
Islets of Langerhans
 Alpha cells - glucagon
 Beta cells - insulin
 Delta cells - somatostatin
Diabetes mellitus - Type I, TypeII
Ovaries
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Located in the pelvic cavity
Estrogens
 Estradiol, estriol, estrone
Progesterone
Inhibin
Relaxin
Testes
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Located in the scrotum
Testosterone
Inhibin