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  1. Endocrine glands Presented by Qasim Ali Reg no; ZO120142031 BS 5th Zoology
  2. Out line • Definition • Overview of the Endocrine System • Endocrine Organs • Pituitary Gland • Pineal Gland • Thyroid gland • Parathyroid glands • Pancreas • Thymus • Gonads • Hypothalamus • References
  3. Endocrine glands • Definition: Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. • The foundations of the endocrine system are the hormones and glands.
  4. Overview of the Endocrine System • System of ductless glands that secrete hormones –Hormones are “messenger molecules” –Circulate in the blood –Act on distant target cells –Target cells respond to the hormones for which they have receptors –The effects are dependent on the programmed response of the target cells –Hormones are just molecular triggers
  5. Endocrine Organs • Purely endocrine organs – Pituitary gland – Pineal gland – Thyroid gland – Parathyroid glands – Adrenal: 2 glands • Cortex • Medulla • Endocrine cells in other organs – Pancreas – Thymus – Gonads – Hypothalamus
  6. • Pituitary Gland – A marble-sized gland at the base of the brain – Controlled by the hypothalamus or other neural mechanisms and therefore the middle man. – Exercise appears to be a strong stimulant to the hypothalamus for the release of all anterior pituitary hormones • Posterior Lobe: Antidiuretic hormone(ADH): Stimulates reabsorption of water from kidney tubules Oxytocin: Stimulates utrine contraction and Brest contraction for milk release.
  7. • Anterior  Prolactin(PRL) Production of breast milk .  Human Growth hormone (HGH) Growth Hypo- Dwarfism Hyper- Gigantism  Thyroid stimulating hormones (TSH) Stimulates the thyroid to release thyroxin.  Adrenocorticotrophic Hormones(ACTH) Stimulates the adrenal cortex to produce: Corticosteroids: mineral corticoids,cortisol ,glucocorticoids,androgens.
  8. Luteinizing hormone (LH) Brings about ovulation and maintains the corpus luteum. Follicle-stimulating hormone (FSH) Stimulates follicle growth and ovarian estrogen production; stimulates sperm production and androgen-binding protein. Gonadotrophin Secondary sexual characteristics Interstitial Cell Stimulating hormones(ICSH) Works on the somniferous tubules in the testes – to produce sperm – which take 21 days to mature.
  9. Hypothalamus___________ Pituitary__________ (hypophysis) Anterior pituitary__ (adenohypophysis) _____________Posterior pituitary (neurohypophysis
  10. • Pineal Gland A pea-sized mass of nerve tissue attached by a stalk to the posterior wall of the third ventricle of the brain, deep between the cerebral hemispheres at the back of the skull.  Melatonin A hormone produced by the pineal gland in darkness but not in bright light. o Informing the brain about night and day, o Also regulate the sleep cycle.
  11. • Thyroid Gland The thyroid gland is a very vascular organ that is located in the neck. It consists of two lobes, one on each side of the trachea, just below the larynx or voice box. – Secretes two hormones Triiodothyronine (T3) Thyroxin (T4) • Regulates metabolism • increases protein synthesis • promotes glycolysis, gluconeogenesis, glucose uptake
  12. Calcitonin Involved in the calcium and phosphorus metabolism Uptake of calcium to bone. regulates calcium and phosphate in blood.
  13. • Parathyroid Gland Four small masses of epithelial tissue are embedded in the connective tissue capsule on the posterior surface of the thyroid glands.  Secrete Parathyroid hormone Associated with the growth of muscle and bone. Distribution of calcium and phosphate in the body.
  14. • Parathyroid Gland
  15. • Adrenal Gland The adrenal gland is paired that located near the upper portion of each kidney. Each gland is divided into an outer cortex and an inner medulla. Adrenal Medulla Situated directly at the top of each kidney and stimulated by the sympathetic nervous system, that Secretes Epinephrine (fight or flight response) Increase H.R. and B.P. Increase respiration Increase metabolic rate
  16. Increase glycogenolysis Vasodilation Norepinephrine House keeping system Adrenal Cortex Secretes over 30 different steroid hormones Mineralocorticoids  Aldosterone maintains electrolyte balance Glucocorticoids  Cortisol Stimulates gluconeogenesis Mobilization of free fatty acids Anti-inflammatory agent
  17. Gonadocorticoids testosterone, estrogen, progesterone
  18. • Pancreas Located slightly behind the stomach Insulin: reduces blood glucose – Facilitates glucose transport into the cells – Inhibits gluconeogenesis Glucagon: increases blood glucose
  19. • Thymus The thymus gland is located across the trachea & bronchi in the upper thorax in the root of the neck, above and in front of the heart. The thymus is enclosed in a capsule and divided internally by cross- walls into many lobules.  Thymosin Activates the immune system by activating the T-Cell.
  20. • The Gonads • Testes – Interstitial cells secrete androgens – Primary androgen is testosterone • Maintains secondary sex characteristics • Helps promote sperm formation • Ovaries – Androgens secreted by thecal follicle • Directly converted to estrogens by follicular granulose cells – Granulose cells also produce progesterone – Corpus luteum also secretes estrogen and progesterone
  21. • Hypothalamus The hypothalamus is a collection of specialized cells that is located in the lower central part of the brain, is the main link between the endocrine and nervous systems. Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary.
  22. • References pituitary-gland/endocrine-glands/ ne_Glands.php