The Endocrine System Tutorial Materials

The endocrine system: Study online at https://quizlet.com/_f15eco 1. Where do hormones act? pass into the bloodstream + act at distant targets 2. Where do neurotransmitters act? act over small nerve synapses 3. What is the hypothalamus? brain region controlling the pituitary gland 4. What does the thyroid gland affect? metabolism + growth in children 5. What does the pituitary gland do? secretes many different hormones, some of which affect other glands 6. What do parathyroids do? help regulate levels of calcium in the blood 7. What do adrenal glands do? help trigger the fight or flight response 8. What does the hypothalamus do? sends out various factors + talks to the pituitary gland 9. What is the pituitary gland divided into? - anterior - posterior 10. What is the hypophyseal portal system? a system of blood vessels connecting the hypothalamus to the anterior pituitary 11. What is hormone secretion from the ante- hypothalamic releasing facrior pituitary regulated by? tors from the hypothalamus 12. How do hypothalamic-releasing factors reach the anterior pituitary? through the bloodstream ( the hypophyseal portal system) 13. What does TRH do? - released from the hypothalamus - travels down the portal ves1 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco sels - reaches the pituitary - releases thyroid-stimulating hormone (TSH) which targets the thyroid gland - causes the secretion of thyroid hormone 14. What does corticotrophin-releasing factor - released from the hypothala(CRF) do? mus - travels down portal vessels - reaches the pituitary - releases adrenocorticotropic hormone (ACTH) which targets the adrenal cortex - causes the secretion of glucocorticoid 15. What does gonadotrophin-releasing hor- - released from the hypothalamone (GnRH) do (FSH)? mus - travels down the portal vessels - reaches the pituitary - releases FSH (follicle-stimulating hormone) which targets the ovaries/testes - causes sperm/ovary maturation 16. What does gonadotrophin-releasing hor- - released from the hypothalamone (GnRH) do (LH)? mus - travels down portal vessels - reaches pituitary - releases LH - which targets the ovaries/testes - causes ovulation + testosterone secretion 17. 2 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco What does the posterior pituitary consist nerve terminals which origiof? nate in the supraoptic + paraventricular nuclei (PVN) of the hypothalamus 18. What do the axons of the neurons in the posterior pituitary form? the hypothalamic-hypophyseal tract 19. Where do the axons of the neurons in pos- they terminate in close proxterior pituitary terminate? imity to the capillaries 20. What passes down the axons of the neu- - peptides synthesised in rons in posterior pituitary? the hypothalamic nuclei pass down these axons + into the posterior pituitary, where they are stored + eventually secreted 21. What receptors does ADH target? - targets Gs receptors in the distal kidney tubule + causes reabsorption of water - targets Gq receptors in vascular smooth muscle + causes vasoconstriction 22. What receptor does oxytocin target? targets Gq receptors in the myometrium + causes labour contractions 23. What does TSH bind to in TH biosynthesis? binds to the TSH receptor on the follicular cells of the thyroid 24. What does the binding of TSH to a TSH receptor in TH biosynthesis cause? increases the production of thyroglobulin made by the follicular cells 25. What happens to the thyroglobulin which it is released into the colloid is produced in TH biosynthesis? 26. What does TSH stimulate? 3 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco the uptake of iodide from the blood into the follicular cell 27. What does iodide use to get into the follic- uses a Na+/I- symporter ular cell in TH biosynthesis? 28. What does TSH increase the activity of? thyroperoxidase 29. What does thyroperoxidase do to iodide? - converts iodide into iodine - facilitates the incorporation of iodine onto the tyrosine's of thyroglobulin 30. What is thyroperoxidase responsible for coupling? - mono iodothyronine (MIT) with di-iodothyronine (DIT) to form tri-iodothyronine (T3) - DIT with DIT to form thyroxine (T4) 31. How does T3 enter the cell? through endocytosis 32. What separates the thyroglobulin from T3 proteases and T4? 33. What transports T4 and T3 to peripheral tissues? thyroxine binding globulin 34. Where is the majority of T4 found in the body? in circulation (there is a lot of T4 in the body) 35. Where is the majority of T3 found in the body? intracellular environment (there is a small amount of T3 in the body) 36. What happens to T3 and T4 once they have they cross the plasma membeen separated from thyroglobulin? brane of various cells which are being targeted 37. What happens to T4 in the cells that are being targeted? 4 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco T4 is always converted into T3 in the cell by 2 deiodinase (D2) located on the ER 38. What happens to T3 in the cells that are being targeted? T3 translocates to the nucleus, binds to the nuclear thyroid hormone receptor + complexes with the Retinoid X Receptor - this regulates gene transcription 39. What happens to the T3 bound to nuclear this complex binds to the thythyroid hormone that is complexed with roid hormone response eleRetinoid X Receptor? ment (TRE) + induces transcription 40. What are the effects of T3 + T4 on the body? - stimulate metabolism - caused increased oxygen - consumption - increased metabolic rate + regulation of growth + development 41. What causes cellular uptake of thyroid hormones? transmembrane transporters 42. What are the symptoms of hyperthyroidism? - high metabolic rate - increased in skin temperature - sweating - sensitivity to heat - tremor - tachycardia - increased appetite - weight loss 43. What are the 2 types of hyperthyroidism called? - diffuse toxic goitre (graves disease) - toxic nodular goite 5 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco 44. What is Graves' disease? an organ-specific auto-immune disease where thyroid-stimulating immunoglobulins are directed at the TSH receptor + so thyroxine secretion is increased 45. What is the main symptoms of Graves' dis- protruding eyeballs ease? 46. What is toxic nodular goitre caused by? a benign neoplasm/adenoma 47. What is hypothyroidism also known as? myxoedema 48. What are the symptoms of hypothyroidism? - low metabolic rate - slow speech - lethargy - bradycardia - sensitivity to cold - mental impairment - thickening of the skin 49. What is the hypothalamic pituitary adrenal main stress response system axis? 50. What is the adrenal cortex? the outer largest part of the adrenal glands 51. Where are the adrenal glands? above the kidneys 52. What are the layers of the adrenal cortex - capsule from outer to inner? - zona glomerulosa - zone fasciculata - zona reticularis - adrenal medulla 53. What does the zona glomerulosa do? 6 / 15 - produces mineralocorticoids such as aldosterone - affects tubular reabsorption of sodium ions, chloride ions The endocrine system: Study online at https://quizlet.com/_f15eco + potassium ions, excretion + osmotic retention of water (increases BP) 54. What does zona fasciculata do? - produces glucocorticoids such as hydrocortisone - controls metabolism + stress response - it is anti-inflammatory + immunosuppressive 55. What does adrenocorticotrophic hormone stimulates synthesis + release (ACTH) do? of glucocorticoids from the adrenal cortex (zona fasciculata) 56. What does the renin-angiotensin system mineralocorticoid release control? from the adrenal cortex (zona glomerulosa) 57. Where is angiotensinogen produced? in the liver 58. Where is renin produced? in the kidneys 59. What does renin do? converts angiotensinogen to angiotensin I 60. Where is Angiotensin Converting Enzyme in the kidneys (ACE) produced? 61. Where is ACE mainly sourced? on the surface of the pulmonary + renal endothelium 62. What ACE do? converts angiotensin I to angiotensin II 63. What is the endocrine pancreas? the endocrine tissue which is NOT under the control of the hypothalamus/pituitary 7 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco 64. What is insulin + where is it produced? a polypeptide hormone that is produced in beta cells within the islets of Langerhans of the endocrine pancreas 65. What does insulin do? important in regulating glucose levels + high blood sugar levels stimulate its secretion 66. What happens to insulin once it leaves pancreatic beta cells? - insulin enters the bloodstream - insulin binds to insulin receptors on insulin-responsive tissue (muscle, liver + fat) - this facilitates the uptake of glucose into insulin responsive tissue - blood glucose is consequently lowered 67. What is the insulin receptor a complex of? 2 alpha + 2 beta subunits 68. What are the alpha + beta subunits in the disulphide bridges insulin receptor held together by? 69. Describe the alpha subunits + beta subunits in insulin receptors: - the alpha subunits are extracellular - the beta subunits are transmembrane spanning proteins - the alpha subunits form the insulin binding site - the intracellular portion of the beta subunits possess intrinsic tyrosine kinase activity 70. What does insulin binding promote? - auto - phosphorylation of Tyr residues on the intracellular domains 71. What do phosphorylated Tyr residues do? 8 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco act as docking sites for a range of signalling proteins which relay the message from the activated receptor into the cell - such consequences include recruitment of glucose transport channels into the membrane 72. What happens to activated insulin recep- - occupied receptors aggretors? gate into clusters which are subsequently internalised into vesicles, resulting in downregulation - these receptors are recycled back to the plasma membrane 73. What are the immediate metabolic effects - recruiting glucose transport (short term actions) of activated insulin channels receptors? - increase in glucose uptake into cells - increase in glycogen synthesis - decrease in gluconeogenesis 74. What is glycogen synthesis? insulin converts glucose into glycogen 75. How do activated insulin receptors signal? via a series of signal transduction proteins 76. Where do activated insulin receptors sig- - signal to the nucleus to pronal to + what does this do? mote gene expression - to modulate the synthesis of key enzymes involved in the regulation of blood glucose - to promote cell growth + division 9 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco 77. What is type 2 diabetes associated with? both insulin resistance + impaired insulin secretion 78. What may precipitate elevated insulin lev- a diet high in sugars + carboels? hydrates 79. What happens to tissues which insulin ex- - they become unresponsive erts its upon? following the bombardment of their respective insulin receptors with elevated blood insulin levels - now resistant to the effects of insulin - glucose can no longer enter the cell - leading to a further rise in blood glucose 80. Why do tissues upon which insulin exerts due to downregulation of the its effects become unresponsive? insulin + impaired signalling mechanisms which recruit the transporter GLUT-4 81. What is downregulation of insulin? a loss of insulin receptors from the cell surface 82. What do pancreatic beta cells (which respond to elevations in blood glucose) do in an attempt to drive glucose uptake into cells? - produce yet more insulin which results in hyperinsulinemia - the beta cells become depleted of insulin (supply cannot keep up with demand) + impaired insulin secretion results 83. What is menstruation? - marks the beginning of the menstrual cycle - during which the superficial 10 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco layer of the endometrium is shed 84. What is the follicular phase? the endometrium regenerates after menstrual flow ceases 85. What does GnRH do? secreted from the hypothalamus + stimulates the anterior pituitary to release FSH + LH 86. What do FSH + LH do? act upon ovaries to promote the development of small groups of follicles each of which contains an ovum 87. What is the Graafian follicle? 1 follicle develops faster than the others to form this, which secretes oestrogen (the remainder degenerate) 88. What is oestrogen responsible for? - the endometrial regeneration at day 5,6 to mid cycle - the endometrium increases in thickness + vascularity 89. What happens at peak oestrogen levels? - there is a prolific cervical secretion of mucus (pH 8-9, alkaline) - rich in protein + carbohydrate which facilitates entry of the sperm 90. What does high endogenous oestrogen secretion just before mid-cycle cause? 91. What happens if fertilisation occurs? 11 / 15 - surge in LH secretion - this in turn causes rapid swelling + rupture of the Graafian follicle resulting in ovulation The endocrine system: Study online at https://quizlet.com/_f15eco the fertilised ovum passes down the fallopian tube to the uterus 92. What happens to the ruptured follicle in luteal phase? the ruptured follicle proliferates + develops into the corpus luteum, which secretes progesterone 93. What does progesterone do? - render endometrium - exerts a negative feedback on the hypothalamus + pituitary, thus decreasing the release of LH 94. What happens to cervical mucus in luteal cervical mucus is less welphase? coming to sperm 95. What happens if fertilisation + implantation do not occur? - progesterone secretion stops, triggering menstruation - the corpeus luteum continues to secrete progesterone which negatively feeds back to the hypothalamus + pituitary to prevent ovulation 96. Name some symptoms of menopause: - headache - weight gain - night sweats - palpitations - urinary incontinence 97. Describe what happens during perimenopause: - oestrogen decreases as ovaries run out of eggs - thickness of uterine lining varies according to hormone level - ovulation becomes irregular - progesterone not produced if ovulation doesn't occur 12 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco - periods become irregular - levels of FSH + LH increase - corpus luteum does not form so circulating levels of progesterone decline 98. Describe postmenopause: - very little oestrogen released - ovulation does not occur - progesterone is not produced - periods do not occur - uterine lining does not thicken 99. What effect does oestrogen have on bone - oestrogen protect bone density? mass + density through reducing the activity of osteoclasts - after menopause, there is age-related loss of bone density + increased frequency of fracture 100. Describe the effect of oestrogen on heart - oestrogen offers a protective disease after menopause: effect against heart disease - it is thought that oestrogen reduces levels of LDL cholesterol whilst raising HDL cholesterol - after the menopause, women experience the same frequency of cardiovascular disease as men 101. What is the polypeptide parathyroid hormone? - the main physiological regulator of Ca2+ in the blood - its secretion from parathyroid 13 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco chief cells is stimulated by a reduction in ionised Ca2+ in the plasma 102. When is PTH secretion inhibited? when plasma Ca2+ conc rises 103. What does PTH + calcium homeostasis stimulate the synthesis of? the synthesis of the biologically active form of vitamin D (calcitriol) in the kidney 104. What does PTH + calcium homeostasis en- reabsorption of Ca2+ from the hance reabsorption of? kidney distal tubules + enhancement of urinary phosphate excretion 105. What does PTH + calcium homeostasis cause mobilisation of? mobilisation of calcium ions + phosphate from bone through the stimulation of osteoclasts which increases bone resorption 106. What is bone resorption? the process by which osteoclasts break down the tissue in bones + release the minerals, resulting in a transfer of calcium from bone tissue to the blood 107. What calcium ions are important for? - cofactor for blood clotting 108. What is 98% of calcium in the form of? - in the form of crystals deposited on the protein matrix of bone - which provides its mechanical strength 109. Where is calcium found? - circulates in plasma partly bound to protein (50%) - the remainder is in the free ionised + active form which is 14 / 15 The endocrine system: Study online at https://quizlet.com/_f15eco maintained by actions of PTH + calcitriol 110. What is hyperparathyroidism? - without enough vitamin D/calcium your parathyroid glands compensate by producing too much PTH - this can lead to bone weakening (osteoporosis) + increased fracture risk 15 / 15