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The Endocrine System Part 1

The Endocrine System Part 1. Figure 9.3. The Pituitary Gland - approximately the size of a pea and hangs by a stalk from the hypothalamus in the brain. - often called the “Master Endocrine Gland”.

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The Endocrine System Part 1

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  1. The Endocrine System Part 1

  2. Figure 9.3

  3. The Pituitary Gland -approximately the size of a pea and hangs by a stalk from the hypothalamus in the brain. - often called the “Master Endocrine Gland” The pituitary is located directly behind the bridge of the nose. It forms a link between the nervous and endocrine systems. It weighs .5 gram and secretes approximately .00001 grams of hormone a day.

  4. There are six anterior pituitary hormones • Two affect non-endocrine targets • Growth hormone • Prolactin • Four stimulate other endocrine glands (tropic {turn on} hormones) • Thyroid-stimulating hormone (thyrotropic hormone) • Adrenocorticotropic hormone • Two gonadotropic hormones

  5. Growth Hormone is a general metabolic hormone • Major effects are directed to growth of skeletal muscles and long bones • Plays a role in determining final body size • Causes amino acids to be built into proteins (anabolic) • Causes fats to be broken down for a source of energy sparing glucose for blood sugar homeostasis.

  6. Abuse of Human Growth Hormone (HGH)

  7. Growth hormone (GH) disorders include: • Pituitary dwarfism results from hyposecretion of GH during childhood • Gigantism results from hypersecretion of GH during childhood • Acromegaly results from hypersecretion of GH during adulthood

  8. Gonadotropic hormones • Regulate hormonal activity of the gonads (ovaries and testes) • Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries. As follicles mature they produce estrogen. Eggs are readied for ovulation. • Stimulates sperm development in testes

  9. Luteinizing hormone (LH) • Triggers ovulation of an egg in females • Stimulates testosterone production in males in the interstitial cells of the testes.

  10. Gonadotropic hormones • Regulate hormonal activity of the gonads (ovaries and testes) • Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries. As follicles mature they produce estrogen. Eggs are readied for ovulation. • Stimulates sperm development in testes • Luteinizing hormone (LH) • Triggers ovulation of an egg in females • Stimulates testosterone production in males in the interstitial cells of the testes.

  11. Pituitary–Hypothalamus Relationship Hormonal release by the pituitary is regulated by releasing and inhibiting hormones produced by the hypothalamus

  12. Antidiuretic Hormone (diuresis=urine production) inhibits or prevents urine production. ADH causes the kidneys to reabsorb more water from the forming urine thereby increasing blood volume and decreasing urine output.

  13. Pineal Gland • Produces melatonin • a hormone that affects the modulation of wake/sleep patterns and photoperiodic (seasonal) functions. (circadian rhythms)

  14. The Thyroid Gland is a fairly large gland found at the base of the throat, slightly inferior to the Adam’s apple.

  15. The Thyroid Gland Consists of two lobes and a connecting isthmus (central mass).

  16. The Thyroid Gland produces two hormones… • Thyroid hormone consists of two iodine-containing hormones Thyroxine (T4) and Triiodothyronine (T3). • T4 is secreted by the thyroid follicles and is converted to T3 at the target tissue. • Thyroid hormone is the major metabolic hormone as it controls the rate at which glucose is burned. It is also important for normal tissue growth and development.

  17. The Thyroid Gland produces two hormones… • Calcitonin decreases blood calcium levels by causing calcium to be deposited in bones. • Calcitoninacts antagonistically with parathyroid hormone, which stimulates the release of calcium from bonetissuebetween follicles.

  18. Goiters-thyroid gland enlarges due to lack of iodine

  19. Cretinism Caused by hyposecretion of thyroxine. Results in dwarfism during childhood

  20. Thyroid Cancer Figure 9.8

  21. The Parathyroid Glands are tiny masses located on the posterior of the thyroid. Typically there are two parathyroid glands on each lobe of the thyroid.

  22. The Parathyroid Glands are tiny masses located on the posterior of the thyroid. Typically there are two parathyroid glands on each lobe of the thyroid. • Secrete parathyroid hormone (PTH) • Stimulate osteoclasts to remove calcium from bone • Stimulate the kidneys and intestine to absorb more calcium • Raise calcium levels in the blood

  23. The Parathyroid Glands secrete parathyroid hormone (PTH) which • Stimulates osteoclasts to remove calcium from bone • Stimulates the kidneys and intestine to absorb more calcium • Raises calcium levels in the blood

  24. Tetany-if blood calcium levels fall too low overstimulation of neurons occurs leading to uncontrollable muscle spasms

  25. Calcitoninstimulatescalcium saltdepositin bone Calcitonin Thyroid glandreleasescalcitonin Thyroidgland RisingbloodCa2+ levels FallingbloodCa2+levels Imbalance Calcium homeostasis of blood9–11 mg/100 ml Imbalance Thyroidgland Parathyroidglands Osteoclastsdegrade bonematrix and releaseCa2+ into blood Parathyroidglands releaseparathyroidhormone (PTH) PTH Hormonal Regulation of Calcium in Blood Figure 9.10

  26. 5 Pink = gland names • 8 Yellow = hormone names • 8 blue = role of hormone

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