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The Hypothalamus

The Hypothalamus. Found in diencephalon – below the thalamus. Plays a key role in maintaining homeostasis Regulates and integrates the autonomic nervous system [ANS] Primary neuroendocrine link –makes/secretes regulating hormones – affect pituitary gland directly. Autonomic Nervous System.

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The Hypothalamus

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  1. The Hypothalamus • Found in diencephalon – below the thalamus. • Plays a key role in maintaining homeostasis Regulates and integrates the autonomic nervous system [ANS] Primary neuroendocrine link –makes/secretes regulating hormones – affect pituitary gland directly

  2. Autonomic Nervous System Sympathetic Nervous System Concerned primarily with preparing the body for stressful or emergency situations. ‘fight or flight’ Increases breathing, heart rate, & blood flow to skeletal muscles, pupils dilate, stimulates adrenal gland function Parasympathetic Nervous System Active under normal, relaxed conditions. ‘Rest and digest’ Increases digestive system activity, slows breathing & heart rate, pupils constrict

  3. Endocrine System

  4. Hormone from the Greek horman ‘to set in motion’ Defined as: a chemical messenger from one cell [or group of cells] to another. All multicellular organisms [including plants] produce hormones

  5. Types of Hormones • Water Soluble – protein based hormones- use secondary messenger  • Fat Soluble – steroid hormones - able to enter cell

  6. Control of Hormone levels Feedback regulation Positive feedback Negative Feedback 

  7. Functional regulation Central Nervous System control Hypothalamus -- secretes regulator hormones – releasing hormone [RH] and inhibitory hormone [ IH] -- contains autonomic centers and interacts when sympathetic nervous system is activated

  8. Primary Endocrine Glands – adrenals, gonads, pancreas, parathyroid, pineal, pituitary & thyroid Secondary Endocrine Glands – heart, kidney, liver, placentas, thymus

  9. Pituitary Gland‘master gland’ hypophysis Anterior lobe – adenohypophysis Posterior lobe – neurohypophysis Anterior Lobe Produces 7 Hormones: ACTH – adrenocorticotrophic hormone GH – growth hormone – also known as somatotrophin PRL - prolactin FSH – follicle stimulating hormone LH – luteninzing hormone - female / ICSH – interstitial cell stimulating hormone – male  TSH – thyroid stimulating hormone MSH – melanocyte stimulating hormone

  10. ACTH – adrenocorticotrophic hormone Works with sympathetic nervous system to stimulate adrenal cortex to produce glucocorticoids needed for stress response As adrenaline/epinephrine are released into the blood stream, glucocorticoids are also released, they stimulate the liver to release stored glycogen for use as energy, also breaks down proteins and fats for energy use. MSH – melanocyte stimulating hormone Stimulates melanocytes to produce melanin, and increase skin pigmentation

  11. GH – growth hormone – also known as somatotrophin Produced primarily while sleeping. Effects all tissues of body – see results primarily on musculoskeletal system In adult – responsible for repair of tissue

  12. PRL – prolactin Causes milk production in lactating women FSH – follicle stimulating hormone – in women starts maturation of ovum/ in men causes sperm production LH – luteninzing hormone : causes ovulation and progesterone production ICSH – interstitial cell stimulating hormone : stimulates testosterone production

  13. TSH – thyroid stimulating hormone Causes production of thyroid hormones [thyroxine T4 and triiodothyronine T3] that maintain metabolism

  14. Pancreatic Hormones Both an endocrine and exocrine gland Exocrine secretions are digestive enzymes Endocrine hormones monitor and maintain blood glucose levels: glucagon [alpha cells] and insulin [beta cells] and somatostatin [delta cells] Blood glucose levels at fasting should be between 80-100 mg/dl

  15. Parathyroid Hormones Work in conjunction with Calcitonin [ produced in thyroid gland – parafollicular cells] to maintain blood calcium levels

  16. Parathyroid Hormone [PTH] is released when blood calcium levels are low Causes: activation of Vitamin D: enhanced absorption of calcium from digestive tract, decreased excretion of calcium via kidneys. Osteoclasts increase activity Calcitonin is released when blood calcium levels are too high Causes: enhanced excretion of calcium via kidneys, decreased absorption of calcium in digestive tract. Slows osteoclastic activity – enhances osteoblastic activity

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