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ENDOCRINE SYSTEM

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... Thymosin Located in the roof of the 3rd ventricle of the brain Melatonin Pancreas Located posterior and inferior to the stomach ... Stomach Duodenum ... – PowerPoint PPT presentation

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Title: ENDOCRINE SYSTEM


1
ENDOCRINE SYSTEM
2
TYPES OF GLANDS
  • Endocrine
  • Exocrine

3
Endocrine glands Endocrine tissue
  • Pineal gland
  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Thymus
  • Adrenal gland
  • Pancreas
  • Ovaries / Testes
  • Stomach
  • Duodenum
  • Kidney

4
Chemistry of Hormones
  • 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)

5
Mechanisms of Hormone Action
  • Alters plasma membran permeability
  • Stimulates synthesis of protein
  • Activates or deactivates enzymes
  • Induces secretory activity
  • Stimulates mitosis

6
Lipid Soluble Hormones
  • 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

7
Water Soluble Hormones
  • 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

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Hormone Release
  • Humoral - hormones released in response to
    changing blood levels
  • Neural - nerve fibers stimulate release
  • Hormonal - one hormone stimulates the release of
    another

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11
Endocrine Glands
12
Pituitary Gland
  • 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

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Posterior lobe - Neurohypophysis
  • Connected with the hypothalamus via the
    supraopticohypophyseal tract
  • Oxtocin (OT)
  • Antidiuretic hormone (ADH)
  • diabetes insipidus

15
Anterior lobe (Adenohypophysis)
  • Controlled by releasing and inhibiting hormones
    produced by the hypothalamus
  • Growth hormone (GH)
  • somatotropin
  • dwarfism, giantism, acromegaly
  • Thyroid - stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)

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Acromegaly
18
Anterior lobe of the Pituitary
  • Follicle - stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Prolactin (PRL)
  • Melanocyte - stimulating hormone (MSH)

19
Thyroid Gland
  • 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)
  • Goiter, Graves Disease, Cretinism, Myxedema
  • Calcitonin (CT) - lowers calcium levels

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Parathyroid gland
  • Four tiny glands located on posterior thyroid
  • Parathyroid hormone (PTH)
  • Raises blood calcium

22
Adrenal Glands
  • Located retroperitoneally and superior to the
    kidney
  • Can be subdivided into outer cortex and inner
    medulla

23
Adrenal Medulla
  • Consists of hormone-producing cells called
    chromaffin cells
  • Epinephrine / Norepinephrine (NE)
  • Sympathomimetic hormones
  • Released under stress by direct innervation from
    the autonomic nervous system

24
Adrenal Cortex
  • 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

25
Adrenal Cortex
  • Zona fasciculata (middle) - produces
    glucocorticoids such as cortisol and cortisone
    controlled by ACTH
  • Addisons Disease, Cushings Disease
  • Zona reticularis (inner) - produces adrenal sex
    hormones such as estrogens and androgens
  • virilism, gynecomastia

26
Cushings Disease
27
Thymus Pineal Gland
  • Located posterior to the sternum and between the
    lungs
  • Thymosin
  • Located in the roof of the 3rd ventricle of the
    brain
  • Melatonin

28
Pancreas
  • 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

29
Ovaries
  • Located in the pelvic cavity
  • Estrogens
  • Estradiol, estriol, estrone
  • Progesterone
  • Inhibin
  • Relaxin

30
Testes
  • Located in the scrotum
  • Testosterone
  • Inhibin

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