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The Endocrine System

The Endocrine System

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The Endocrine System

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  1. The Endocrine System

  2. Lesson 1 • Intro Major Glands & Functions • Hypothalamus • Pituitary (not enough time for all videos)

  3. Location of Major Endocrine Organs Word Bank • Adrenal glands • Hypothalamus • Ovaries & Testes • Pancreas • Parathyroid glands • Pineal gland • Pituitary gland • Thymus gland • Thyroid gland Figure 9.3

  4. The Endocrine System • Uses chemical messengers called hormones that are released into the blood to target sites • Hormones control several major processes • Reproduction • Growth and development • Maintenance of homeostasis • Regulation of metabolism

  5. Video - The Endocrine System (intro) Mechanisms of Hormone Action • Hormones affect only certain tissues or organs called target cells or organs • Target cells must have specific shaped protein receptors • Which is a target cell for both hormones? Why?

  6. Control of Hormone Release • Hormone levels in the blood are mostly maintained by negative feedback • A stimulus or low hormone level in the blood triggers the release of more hormone • Hormone release stops once an appropriate level in the blood is reached • Endocrine glands are activated by other hormones • Example: Anterior pituitary hormones

  7. Video - Hypothalamus & Pituitary Hypothalamus • Part of both the nervous and endocrine systems • Communicates with the pituitary gland with both releasing and inhibiting hormones

  8. Pituitary Gland • Located in the brain, size of a pea • Has two functional lobes • Anterior & Posterior pituitary • Often called the “master endocrine gland” because it can affect other glands

  9. Hormones of the Anterior Pituitary Figure 9.4

  10. Anterior Pituitary Hormones • Six anterior pituitary hormones • Growth hormone • 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 • Causes fats to be broken down for a source of energy

  11. Hormones of the Anterior Pituitary • Growth hormone (GH) disorders • Dwarfism: hyposecretion of GH during childhood Video - Dwarfism Figure 9.5b

  12. Hormones of the Anterior Pituitary • Gigantism: hypersecretion of GH during childhood Video - Gigantism (stop at 4:00)

  13. Hormones of the Anterior Pituitary • Acromegaly: hypersecretion of GH during adulthood • Enlargement of facial bones, hands and feet Video - Acromegaly

  14. Hormones of the Anterior Pituitary • Prolactin (PRL) • Stimulates and maintains milk production following childbirth • Adrenocorticotropic hormone (ACTH) • Regulates endocrine activity of the adrenal cortex • Thyroid-stimulating hormone (TSH) • Influences growth and activity of the thyroid gland

  15. Hormones of the Anterior Pituitary • Gonadotropic hormones • Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries • Stimulates sperm development in testes • Luteinizing hormone (LH) • Triggers ovulation of an egg in females • Stimulates testosterone production in males

  16. Hormones of the Posterior Pituitary • Oxytocin • Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding • Causes milk ejection (“let down”) in a nursing woman Video - Labor & Birth (animation)

  17. Hormones of the Posterior Pituitary • Antidiuretic hormone (ADH) aka Vasopressin • Inhibits urine production by promoting water reabsorption by the kidneys • Causes vasoconstriction of vessels leading to increased blood pressure

  18. Lesson 2 • Thyroid • Parathyroid • Adrenal

  19. Endocrine System Diagram Worksheet Pituitary Parathyroid Thymus Thyroid Pancreas Adrenals Ovaries Testes

  20. Hypothalamus & Pituitary Worksheet (pg 159) hypothalamus Hypophyseal fossa Turk’s saddle of sphenoid Anterior pituitary Posterior pituitary ACTH Growth hormone (GH) Prolactin (PRL) TSH FSH LH

  21. Thyroid Gland • Found at the base of the throat • Consists of two lobes • Produces two hormones • Thyroid hormone (2 iodine based hormones: thyroxine & triiodothyronine, a.k.a. T4 & T3) • Major metabolic hormone, controls rate at which glucose is converted into energy • Calcitonin • Decreases blood calcium levels by causing its deposition on bone

  22. Thyroid Gland Figure 9.7a

  23. Thyroid Hormone Disorders • Goiters • Enlarged thyroid due to lack of iodine • Salt is iodized to prevent goiters Figure 9.8

  24. Thyroid Hormone Disorders • Cretinism • Caused by hyposecretion of thyroxine • Results in dwarfism during childhood but body proportions remain childlike • If untreated can cause mental retardation

  25. Thyroid Hormone Disorders • Myxedema • Caused by hypothyroidism in adults • Results in physical and mental sluggishness • Puffiness of face, poor muscle tone, dry skin

  26. Thyroid Hormone Disorders • Graves’ disease • Caused by hyperthyroidism • Results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos (bulging protruding eyes) Figure 9.9

  27. Video - Parathyroid glands & hyperparathyroidism Parathyroid Glands • Tiny masses on the posterior of the thyroid • Secrete parathyroid hormone (PTH) • Stimulates osteoclasts to remove calcium from bone to raise calcium levels in the blood

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

  29. Hormonal Regulation of Calcium in Blood • When blood calcium levels fall, the ___________ glands release _________________________, stimulating ____________ to degrade bone and release _________into the blood. • When blood calcium levels rise, the __________ gland releases ___________, stimulating calcium to be __________ in bone. parathyroid Parathyroid hormone (PTH) osteoclasts calcium thyroid calcitonin deposited

  30. Hormonal Regulation of Calcium in Blood • Explain why this is an example of negative feedback. • Since both hormones involved in the feedback mechanism can be stimulated AND inhibited

  31. Adrenal Glands • Located on top of the kidneys • Two regions • Adrenal cortex — outer glandular region • Adrenal medulla — inner neural tissue region

  32. Hormones of the Adrenal Medulla • Produces two similar hormones • Epinephrine (adrenaline) • Norepinephrine (noradrenaline) • These hormones prepare the body to deal with short-term stress (“fight or flight”) by • Increasing heart rate, blood pressure, blood glucose levels • Dilating small passageways of lungs Video - Fight or Flight Response

  33. Adrenal Gland Disorders • Addison’s disease • Hyposecretion of adrenal hormones • Bronze skin tone, muscles are weak, burnout, susceptibility to infection

  34. Adrenal Gland Disorders • Hyperaldosteronism • May result from an ACTH-releasing tumor in anterior pituitary • Excess water and sodium are retained leading to high blood pressure and edema • May disrupt activity of heart & nervous system

  35. Adrenal Gland Disorders • Cushing’s syndrome • Results from a tumor in the middle cortical area of the adrenal cortex • Swollen “moon face,” “buffalo hump” of fat on the upper back, high blood pressure, hyperglycemia, weakening of bones, depression

  36. Masculinization • Results from hypersecretion of adrenal sex hormones (androgens) • Beard and male distribution of hair growth • Effects are masked in males, dramatic in females

  37. Lesson 3 • Pancreas • Pineal • Thymus • Gonads • Placenta

  38. Endocrine System & Hormone Function - An Overview Worksheet (pg 157) F slower & prolonged E nervous system B hormones D nerve impulses A cardiovascular system

  39. Endocrine System & Hormone Function - An Overview Worksheet (pg 158) I receptors N target cells A altering activity L stimulating new K steroid or amino acid based G neural C hormonal D humoral F negative feedback B anterior pituitary J releasing hormones E hypothalamus H neuroendocrine

  40. Pancreatic Islets • The pancreatic islets produce hormones • Insulin - produced by beta cells of pancreas • Allows glucose to cross plasma membranes into cells reducing blood sugar levels • Glucagon - produced by alpha cells of pancreas • allows stored glucose to enter the blood, raising blood sugar levels • These hormones are antagonists that maintain blood sugar homeostasis

  41. Pancreatic Islets Figure 9.14a–b

  42. Video - Blood sugar regulation Beta cells of the pancreasactivated; releaseinsulin into theblood Uptake of glucosefrom blood is enhanced in most body cells Blood glucoselevels declineto set point;stimulus forinsulin releasediminishes Elevatedblood sugarlevels Liver takes upglucose and storesit as glycogen Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts) Imbalance Stimulus: declining blood glucose levels(e.g., after skipping a meal) Homeostasis: Normal blood glucoselevels (90 mg/100ml) Imbalance Low bloodsugar levels Rising bloodglucose levelsreturn blood sugarto homeostatic setpoint; stimulus forglucagon releasediminishes Alpha cells of pancreasactivated; release glucagon into blood; target is the liver Liver breaks down glycogen stores and releases glucose to the blood Figure 9.15

  43. Feedback Mechanism of the Liver & Pancreas • When blood glucose levels rise, _______ cells of the _____________ release the hormone _________ into the blood, causing body cells and the ______ to take up glucose and store it as glycogen. This brings blood glucose levels down to set point. • When blood glucose levels decline, __________ cells of the _____________ release the hormone ____________ into the blood, causing the liver to break down ___________ releasing glucose into the blood. This returns blood glucose levels to set point. beta pancreas insulin liver alpha glucagon pancreas glycogen

  44. Feedback Mechanism of the Liver & Pancreas • Is this an example of positive feedback or negative feedback? How do you know? • Negative feedback because the responses can be both stimulated (increased) AND inhibited (decreased) to maintain homeostasis

  45. Pancreas Disorders • Diabetes mellitus • Inability to regulate blood glucose levels • 3 signs of diabetes • Polyuria – excessive urination to flush out glucose & keytones (acidic product of fat metabolism) • Polydipsia – excessive thirst resulting from water loss • Polyphagia – hunger due to inability to use sugars

  46. Pancreas Disorders • Diabetes mellitus (con’t) • Type 1 – Juvenile diabetes • More severe, inability to produce insulin • Insulin pump worn externally or administered by planned injections

  47. Pancreas Disorders • Diabetes mellitus (con’t) • Type 2 – Adult onset diabetes • Insulin resistance (receptors don’t respond to insulin well) • Controlled with diet or oral medications

  48. Pineal Gland / Body • Secretes melatonin • Helps establish the body’s day-night cycles • Believed to coordinate the hormones of fertility in humans, inhibiting the reproductive system to prevent sexual maturation before adult body size is reached

  49. Thymus Gland • Located posterior to the sternum • Largest in infants and children (shrinks with age) • Releases thymosin • Matures T-cells (a type of white blood cell) • Important in developing the immune system

  50. Gonads • Ovaries (female gonad) • Produce eggs / ova • Produce two groups of steroid hormones • Estrogens • Progesterone • Testes (male gonad) • Produce sperm • Produce androgens, such as testosterone