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The Sella Turcica Home of the Pituitary Gland

The Sella Turcica Home of the Pituitary Gland. Pituitary Gland Secretes/releases hormones that affect endocrine glands in the body Regulate other hormones as a “hormone control center”

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The Sella Turcica Home of the Pituitary Gland

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  1. The Sella Turcica Home of the Pituitary Gland

  2. Pituitary Gland Secretes/releases hormones that affect endocrine glands in the body Regulate other hormones as a “hormone control center” Has effects on blood pressure, growth, metabolism, water retention, body temperature, sexual development, and pregnancy. What Do the Pituitary and Hypothalamus Do? • Hypothalamus • Receives stimulation/information from various parts of the brain • Secretes hormones that regulate the pituitary gland (anterior) • Secretes hormones that are released directly by the pituitary (posterior)

  3. The Pituitary and The Hypothalamus

  4. The Two Lobes of the Pituitary and Relationship to other Structures

  5. Pituitary Anatomy and Two Modes of Secretion 2 lobes of the pituitary 2 Types of hypothalamic neurons 2 blood vessel system

  6. Neuron Review 1) Receive Signal at dendrites 2) Generate “action potential” 3) Propagate action potential along axon 4) Signal next cell with Neurotransmitters at a synapse

  7. Various Brain Cells Regulation of Hypothalamic Secretion by Neurons using “Classical” Neurotransmitters(e.g.serotonin, dopamine) Hypothalamus Cell

  8. Pituitary Anatomy and Two Modes of Secretion Posterior pituitary hypothalamic neurons create hormones and release them directly into the bloodstream

  9. The Posterior Pituitary Gland Isn’t a Gland • Posterior pituitary hormones actually come from the hypothalamus • Hormones: • Oxytocin -> Childbirth, breastfeeding, love. • Vasopressin ->water retention

  10. Pituitary Anatomy and Two Modes of Secretion Hypothalamic neurons associated with the Anterior Pituitary release “tropic” hormones into the “portal vessels.” These travel to the Anterior pituitary.

  11. Hypothalamus Releasing Factor (topic hormone) on the Anterior Pituitary • Example • Growth Hormone Releasing Hormone (GHRH) -> Portal System • Portal System -> Anterior Pituitary • Anterior Pituitary -> Growth Hormone Melmed, S et al (2011) Williams Textbook of Endocrinology, Figure 3-7

  12. Hypothalamic Hormones That Regulate 5 Anterior Pituitary Secretions • Pituitary hormones with positive and negative hypothalamic regulators • Growth hormone controlled by • GHRH (+) • Somatostatin (-) • Prolactin controlled by • Prolactin inhibitory factor (PIF; dopamine) (-) • Prolactin releasing factor (PRF) (+) • Pituitary hormones with positive hypothalamic regulators • Thyrotropin releasing hormone (TRH)-> Thyrotropin • Corticotropin releasing hormone (CRH) -> Corticotropin • Gonadotropin releasing hormone (GnRH) -> Gonadotropin

  13. Hormones & Cell Types of Anterior Pituitary Growth hormone (GH): Somatotrope Prolactin (PRL): Lactotrope Thyroid stimulating hormone (TSH): Thyrotrope Adrenocorticotropic hormone (ACTH) : Corticotrope Follicle stimulating hormone (FSH) and Luteinizing hormone (LH): Gonadtrope Heaney AP & Melmed S (2004) Nat Rev Cancer, 4, 285-295

  14. Homeostasis: Negative Feedback Systems Keep body functions in balance How does this apply to Pituitary hormones?

  15. Hypothalamus Water Loss Retain Water Stimulate Thirst Control of Water Metabolism by Vassopressin (AVP) Increase in Blood viscosity AVP Drink Decreased Blood Viscosity

  16. Hypothalamus Water Loss Retain Water Stimulate Thirst Control of Water Metabolism by Vassopressin (AVP) Increase in Blood viscosity AVP Drink Decreased Blood Viscosity

  17. Thyroid Hormone Feedback System

  18. Anterior Pituitary AxesHypothalamic Control, Hormones and their Targets and Feedback Control Growth Hormone Axis Prolactin Axis Adrenal Axis Thyroid Axis Gonadal Axis Melmed, S et al (2011) Williams Textbook of Endocrinology, Figure 8-6

  19. MRI of Normal Pituitary

  20. MRI of Large Pituitary Tumor

  21. Microadenoma Macroadenoma Schlechte, JA (2003) NEJM, 349, 2035-2041

  22. Effects of Pituitary Adenoma • Visual field defects due to growth pushing on the optic chiasm • Increasing Inter Cranial Pressure • Headaches • Hyperpituitarism • Too much production of one or several hormones

  23. Hyperpituitarism Acromegaly Pituitary Giantism

  24. Key Points • The Hypothalamus produces hormones that: • Are released by the posterior pituitary • Raise or lower production of anterior pituitary hormones • The pituitary gland: • Produces hormones that regulate other endocrine glands in the body • Each of these hormones has a feedback loop that maintains homeostasis • Disease of the pituitary or hypothalamus can have serious effects

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