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The Endocrine Glands

The Endocrine Glands. SBI 4U January 10 th , 2013. Answer the Following Questions!. Protein hormones are hydrophilic. True False What are prohormones ? How are hormones different from local regulators?. What is the Endocrine System?.

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The Endocrine Glands

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  1. The Endocrine Glands SBI 4U January 10th, 2013

  2. Answer the Following Questions! • Protein hormones are hydrophilic. True False • What are prohormones? • How are hormones different from local regulators?

  3. What is the Endocrine System? • The endocrine system is made up of glands that produce and secrete hormones • Hormones regulate body’s growth, metabolism and sexual development and function • In charge of body processes that happen slowly

  4. Water vs. Lipid-soluble Mechanisms • Single target cell may have receptors for several hormones. Ex: liver cells (insulin & glucagon) • Hormones can interact with different types of receptors in a host of cells

  5. Mechanisms by which hormones work • Only cells with receptors respond to hormones • Once bound to receptors, hormones produce response by inactivating or activating cellular processes • Hormones effective in very small concentrations • Response to a hormone differs among target organs and among species

  6. Hormones as Feedback Mechanisms • Secretion of most hormones as a result of negative feedback mechanisms • Ex: hypothalamus  thyroid releasing hormone  triggers pituitary gland to release TSH  triggering thyroid to release thyroid hormones. Where is the negative feedback?

  7. The Endocrine Glands • Hypothalamus • Anterior Pituitary and Posterior Pituitary • Adrenal glands • Ovaries • Testes • Pineal gland • Thyroid gland • Parathyroid glands

  8. Hypothalamus • Hypothalamus is a region of the brain  also a part of the nervous system • Neurohormones: control production of other hormones in pituitary gland • 2 types of neurohormones: releasing hormones & inhibiting hormones • Controlled by input from nervous system

  9. Pituitary Gland • Pituitary gland: 2-lobed gland within the cranial cavity that produces hormones that control the other endocrine glands • “Master gland”  production of hormones controlling most endocrine glands • Located below brain, within the cranium • Anterior lobe & posterior lobe • Neurohormones travel through portal vein  connecting hypothalamus to pituitary gland

  10. Anterior Pituitary Gland • Endocrine system largely controlled by the anterior pituitary hormones, which are controlled by the hypothalamus inhibiting or releasing hormones • Regulator hormones like ‘thyroid stimulating hormone’ • Ex: Growth hormone (GH) • GH  cell division, protein synthesis, and bone growth • GH binds to muscle, causing the release of insulin-like growth factor (IGF) • GH also maintains availability of glucose and fatty acids

  11. Deficiencies in GH Overproduction of GH • GH binds to muscle, causing the release of insulin-like growth factor (IGF) • GH also maintains availability of glucose and fatty acids • Overproduction of GH: pituitary giant • Deficiency of GH: pituitary dwarf

  12. Posterior Pituitary Gland • Stores and released 2 hormones: antidiuretic hormone and oxytocin (both produced in hypothalamus) • ADH: stimulates kidney cells to absorb more water from urine, increases blood volume • Ethanol and caffeine inhibit ADH • Nicotine and stress stimulate ADH • ADH helps maintain blood pressure by reducing water loss

  13. Posterior Pituitary Gland • Oxytocin stimulates release of milk from mammary glands • Also helps in the stimulation of contractions during childbirth

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