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Chapter 10

Chapter 10 . The Endocrine System. Regulation of body systems HOMEOSTASIS!. Nervous system Fast! Nerve impulses Integration of information by the brain and spinal cord Endocrine system Endocrine glands secrete hormones

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Chapter 10

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  1. Chapter 10 The Endocrine System

  2. Regulation of body systemsHOMEOSTASIS! • Nervous system • Fast! • Nerve impulses • Integration of information by the brain and spinal cord • Endocrine system • Endocrine glands secrete hormones • Regulate growth, the use of foods to produce energy, resistance to stress, pH of body fluids and fluid balance, and reproduction.

  3. Exocrine Ducts Secrete outside the body Ex. Sweat glands, stomach, salivary glands Endocrine Ductless Secrete into the blood Hormones: exert specific effects on specific organs/tissues (target) Ex. Thyroid, pancreas, adrenal, pituitary Glands

  4. Chemistry of Hormones • Amines • Variations of tyrosine (amino acid) • Thyroxin, epinephrine, norepinephrine • Proteins • Chains of amino acids • Insulin, growth hormone, calcitonin, ADH, oxytocin • Steroids • Made from cholesterol • Cortisol, aldosterone, estrogen, progesterone, testosterone

  5. Regulation of Hormone Secretion • Endocrine glands produce their secretions when needed in response to a stimulus: • Changes in blood • The effects of other hormones • Negative feedback mechanism • Example: Insulin • Antagonistic pairs of hormones • Example: Calcitonin, PTH • Assignment: control of hormone secretion

  6. Insulin/Glucagon: Feedback system

  7. Pituitary gland • Inferior to hypothalamus • Enclosed in sphenoid bone • 2 major portions • Posterior pituitary (neurohypophysis) • Anterior pituitary (adenohypophysis)

  8. Posterior pituitary • 2 hormones • Produced by hypothalamus • *Stored and secreted by the posterior pituitary • Nerve impulses stimulate secretion • *ADH: antidiuretic hormone • *Oxytocin

  9. ADH: Antidiuretic hormone • *Increases water reabsorption by kidney • *Increases BP • *Decreases urinary output • Hypothalamus senses dehydration in the blood, and signals the posterior pituitary to secrete ADH. • Alcohol inhibits the secretion of ADH

  10. Oxytocin • *Contractions of the uterus at the end of pregnancy • Cervix stretches; send impulses to the hypothalamus; hypothalamus signals the posterior pituitary to release oxytocin • Oxytocin causes strong contraction of myometrium to deliver baby and placenta • Placenta also secretes oxytocin

  11. Oxytocin continued • *Release of milk from mammary glands- “Let down” • When the baby sucks on the mother’s nipple; impulses sent to the hypothalamus; hypothalamus signals the release of oxytocin • Oxytocin causes contraction of the mammary ducts, and this releases milk “let down”

  12. Anterior pituitary • *Secretions of the anterior pituitary are controlled by releasing hormones (or releasing factors) from the hypothalamus • Hypothalamus secretes releasing hormones into capillaries that carry them to the hypophyseal portal veins to the anterior pituitary

  13. Growth hormone Aka: Somatotropin • Functions • Stimulates growth and repair • Increases transport of amino acids into cells • Increases the rate of protein synthesis • *Stimulates mitosis • Stimulates the release of fat from adipose tissue • Adults do have smaller amounts • Secretion is under the control of • GHRH: increases the release of GH • GHIH (Somatostatin): decreases the release of GH

  14. Dwarfism: deficiency of GH in childhood 3-4 feet normal body proportions Dwarfism

  15. *Giantism: hypersecretion of GH in childhood May attain 8 feet in height *Acromegaly: hypersecretion of GH in adulthood Long bones DO NOT grow Face, hands and feet Caused by pituitary tumor

  16. TSH: Thyroid Stimulating Hormone • Aka: Thyrotropin • Targets the thyroid gland • *Increases the secretions of thyroid hormones • Controlled by TRH from hypothalamus • When metabolic rate (energy production) slows

  17. ACTH: Adrenocorticotropic Hormone • *Stimulates the secretion of cortisol and other hormones by the adrenal cortex • Controlled by CRH from the hypothalamus • Released in times of stress • Injury, disease, exercise, hypoglycemia

  18. Prolactin • *Initiates and maintains the production of breast milk • Controlled by PRH and PIH from the hypothalamus • Mammary glands are first stimulated by large amounts of estrogen and progesterone from the placenta during pregnancy • After delivery, prolactin increases and milk is produced • If mother continues to breastfeed; production remains high

  19. FSH: Follicle stimulating hormone • Gonadotropic hormone • *Stimulates the testes to produce sperm • *Stimulates the ovaries to produce a mature egg • FSH also stimulates the secretion of estrogen from the ovarian follicle • Controlled by GnRH from the hypothalamus • Decreased by inhibin from the ovary or testes

  20. LH: Luteinizing hormone • Gonadotropic hormone • *Causes ovulation in women • The follicle then becomes the corpus luteum which secretes progesterone and estrogen • *Stimulates the testes to produce testosterone • Also controlled by GnRH from the hypothalamus

  21. Thyroid gland • Front and sides of trachea, below larynx • Produce and secrete • Thyroxin (T4) • Triiodothyronine (T3) • Calcitonin • *Iodine is necessary for the synthesis of T3 & T4

  22. Thyroxin and T3 • Same functions • Regulation of energy production • Increases cell respiration of all foods • Increases energy and heat production • Protein synthesis • Needed for normal physical and mental development

  23. Thyroid disorders • Goiter: not enough dietary iodine • Hypothyroidism: • *Infant – Cretinism • physical and mental retardation • *Adult – Myxedema • Lethargy, dry skin, weight gain, feels cold, slow heart rate

  24. *Grave’s disease Weight loss, increased appetite, increased sweating, fast heart rate, warm, fatigued, exopthalmos (protrusion of the eyes) Hyperthyroidism

  25. Control of thyroid hormone secretion • Slow metabolic rate sensed by hypothalamus • TRH secreted by hypothalamus negative • TSH secreted by anterior pituitary feedback • T3 & T4 secreted by thyroid • Increased metabolic rate

  26. Calcitonin • *Produced and secreted by the thyroid gland • Decreases the reabsorption of calcium from the bones to the blood (*Keeps calcium in bones, decreases blood calcium) • Secreted in response to hypercalcemia

  27. Parathyroid glands (4) • 2 on the back of each side of the thyroid gland • *Produce and secrete PTH(parathyroid hormone) • PTH increases the reabsorption of Calcium and Phosphorus from the bones to the blood • Also increases absorption of calcium and phosphorus from the small intestine (requires vit D) • *BOTH increase blood calcium and phosphorus levels (needed for blood clotting, muscle and nerve function) • Secretion stimulated by hypocalcemia • Antagonist to calcitonin!!

  28. ULQ of abdominal cavity Exocrine & Endocrine functions! Exocrine (into duodenum) Amylase Lipase Tripsin Bicarbonate juice Endocrine Insulin Decreases blood glucose Glucagon Increases blood glucose Pancreas

  29. Glucagon • *Alpha cells of the Islets of Langerhans • In response to low blood sugar (hypoglycemia) • *Secreted between meals • *Increases blood glucose level • Stimulates liver to release glucose from glycogen (Glycogenolysis) • Stimulates the production of glucose from amino acids (Gluconeogenesis) • Stimulates the use of fats and amino acids for energy

  30. Insulin • *Beta cells of the islets of Langerhans • *Secreted in response to hyperglycemia • After a meal • *Lowers blood sugar level • *Increase transport of glucose into cells • Liver synthesizes glycogen (Glycogenesis) • Other cells utilize glucose for energy

  31. Diabetes mellitus • Type 1 IDDM: Insulin dependent Diabetes mellitus • Juvenile onset • Destruction of the beta cells may be caused by an autoimmune response, or a virus • Genetic predisposition • Insulin injections (pump) • Type2 NIIDM: Non-insulin dependent Diabetes mellitus • Adult onset • Associated with obesity • May be controlled with diet, exercise, and medication • Type 3 Gestational diabetes: Pregnancy • All expectant mothers are tested at about 7 months

  32. Diabetes mellitus • Symptoms • Polydipsia • Polyuria • Hyperglycemia • Long-term effects • Vascular damage • Poor circulation in extremities, retina, kidneys • Gangrene, blindness, hemodialysis & transplant • Atherosclerosis (esp. Type 2) • Increase risk of heart attack and stroke

  33. Ketoacidosis • If patient forgets to take insulin • Glucose is not available to cells • Fats and proteins used for energy • Ketones produced as wastes (acidic) • May progress to coma and death

  34. Adrenal glands • 2 Suprarenal • *1 on top of each kidney • Nothing to do with function of kidneys • 2 parts • Inner: adrenal medulla • Outer: adrenal cortex • Function independently

  35. *Adrenal medulla (inner) • Catchecholamines • *Epinephrine (adrenalin) and Norepinephrine • Mimic the sympathetic nervous system • Secreted in stressful situations • *Norepinephrine causes vasoconstriction ( BP) • *Epinephrine (adrenalin) • Increases heart rate & force of contraction • Vasoconstriction • Dialates bronchioles, decreases peristalsis, stimulates glycogenolysis • Sympathetic impulses from the hypothalamus cause secretions

  36. Adrenal cortex – steroid hormones • Mineralocorticoids (aldosterone) • *Glucocorticoids (cortisol) • Sex hormones: • Estrogens and androgens • In small amounts in both sexes

  37. Aldosterone • Most abundant mineralocorticoid • *Increases the reabsorption of sodium and the excretion of potassium by the kidneys • Increases Na in the blood • Increases K in the urine • Increases water retention • Water follows sodium • *Increases BP!

  38. Renin-Angiotensin • Low BP activates • Causes the secretion of aldosterone and vasoconstriction • Increasing BP

  39. Cortisol • A glucocorticoid released under control of ACTH, and CRH

  40. “Glucose sparing effect” • Increases the use of fats and amino acids for energy (gluconeogenesis) • Conserves glucose for use by the brain • Secreted in times of stress • Fear, anger, exercise, hunger, disease, physical injury • *Anti-inflammatory • Cortisol stabilizes the membrane of the lysosome and the effects of histamine • Decreases the immune response

  41. Disorders associated with the adrenal cortex • *Cushings • Hypersecretions of cortisol • *Addisons • Hyposecretion of aldosterone and cortisol

  42. Ovaries • Within the pelvic cavity • One on each side of the uterus • Produce and secrete • Estrogen • Progesterone • Inhibin

  43. *Secreted by follicle cells (ovary) *Stimulated by FSH from anterior pituitary & GnRH from the hypothalamus *Stimulates the growth of the endometrium of the uterus, and *with FSH the maturation of the ovum Secondary sex characteristics Growth of mammary glands, growth of uterus, deposition of fat on hips and thighs, closure of the epiphyseal discs, lowers blood cholesterol and triglycerides Estrogen

  44. Progesterone • After the mature ovum is released from the ovary, the follicle becomes the corpus luteum • *Corpus luteum now secretes progesterone and estrogen • *Stimulated by LH from the anterior pituitary and GnRH form the hypothalamus • *Furthers the growth of the endometrium (increases vascularity), and storage of glycogen • Secretory cells in the mammary glands also develop under progesterone

  45. Estrogen and progesterone are also secreted by the placenta Estrogen & Progesterone

  46. Inhibin • Corpus luteum also secretes inhibin • *Decreases the secretion of FSH and GnRH • Negative feedback!

  47. Testes • Located in the scrotum • Secrete testosterone and inhibin

  48. Steroid hormone Secreted by interstitial cells of the testes Stimulus for secretion is LH from anterior pituitary Functions *Promotes maturation of sperm (along with LH) Secondary sex characteristics Secondary sex characteristics Growth of reproductive organs, facial, body hair, growth of larynx and deepening of voice, growth of skeletal muscle, closure of the epiphyseal discs Testosterone

  49. Inhibin • Increased testosterone stimulates the release of inhibin • *Inhibin decreases the secretion of FSH by the anterior pituitary gland • Maintains spermatogenesis at a constant rate

  50. Melatonin • Produced by the pineal gland • Located in the 3rd ventricle of the brain • Secreted most in darkness • *Stimulates the onset of sleep • Retina signals the hypothalamus • In other mammals, melatonin regulates seasonal reproductive cycles

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