Endocrine System Lecture Notes (Fall 2024) PDF

9/3/24 Overview of the Endocrine Organs © 2019 Pearson Education, Inc. Structure of the Hypothalamus and Pituitary Gland Hypothalamus...

9/3/24 Overview of the Endocrine Organs © 2019 Pearson Education, Inc. Structure of the Hypothalamus and Pituitary Gland Hypothalamus is part of the CNS, in the brain Anterior pituitary is made of hormone-secreting Posterior pituitary, glandular epithelium like hypothalamus, is made of nervous tissue © 2019 Pearson Education, Inc. 1  9/3/24 Hypothalamus produces NEUROHORMONES that reach (via neurons) the posterior pituitary where they are stored and then secreted by Posterior Pituitary The posterior pituitary gland does NOT produce hormones. It stores and then releases in the blood the neurohomones produced by the hypothalamus: OT = Oxytocin ADH = Antidiuretic hormone © 2019 Pearson Education, Inc. (also called Vasopressin) Contains osmodetectors that monitor solutes concentration in the blood. When [solutes] in blood increases => ADH ADH = vasopressin Example: ADH = Antidiuretic hormone (produced by Hypothalamus) ! increases the amount of water retained by the kidneys => decreases urine production Target organ: kidney What if lack (abnormal) of ADH secreted? © 2019 Pearson Education, Inc. 2  9/3/24 Hypothalamus produces NEUROHORMONES that reach (via neurons) the posterior pituitary where they are stored and then secreted by Posterior Pituitary The posterior pituitary gland does NOT produce hormones. It stores and then releases in the blood the neurohomones produced by the hypothalamus: OT = Oxytocin ADH = Antidiuretic hormone © 2019 Pearson Education, Inc. (also called Vasopressin) Hypothalamus also produces RELEASING HORMONES that regulates the production & secretion of hormones by Anterior Pituitary © 2019 Pearson Education, Inc. 3  9/3/24 Thyroid Growth Releasing Hormone Hormone Releasing Hormone Thyroid Growth Stimulating Hormone Hormone T3 / T4 Negative feedback by target glands onto hypothalamus & anterior pituitary HPT axis HPA axis HPG axis © 2019 Pearson Education, Inc. Effects of Growth Hormone (GH) GH is important during development. Hyper or hypo-secretion of GH / IGF during development can lead to gigantism, dwarfism… GH stimulates release of Insulin-like Growth Factor (IGF) by the liver, muscles, bones… GH and IGF are also important in adults (for muscles development & regulation of Acute GH increases available energy body mass). to promote overall body growth. © 2019 Pearson Education, Inc. 4  9/3/24 Regulation of Growth Hormone (GH) Release Somatostatin = growth hormone- inhibiting hormone Positive feedback © 2019 Pearson Education, Inc. Table 16.1 Hormones of the Hypothalamus and Pituitary Gland © 2019 Pearson Education, Inc. 5  9/3/24 REVIEW: Practice QUESTIONS [Learning Catalytics] Q1 Q2 © 2019 Pearson Education, Inc. Overview of the Endocrine Organs Thyroid hormones effects: 1) Regulation of metabolic rate & thermoregulation 2) Promotion of growth & devpt © 2019 Pearson Education, Inc. 3) Synergy with sympathetic nerv. syst. 6  9/3/24 Anatomy and Histology of the Thyroid Gland Parafollicular cells produce calcitonin, an hormone, working with parathyroid hormones iodine atoms The Thyroid follicles made of follicle cells that produce the thyroid hormones © 2019 Pearson Education, Inc. T3 & T4 are made of hydrophobic aa + iodine atoms (x3 or x4) Production of Thyroid Hormones (T3 and T4) © 2019 Pearson Education, Inc. 7  9/3/24 Regulation of Thyroid Hormone Production Reminder: Somatostatin (from hypothal.) also inhibits TSH secretion © 2019 Pearson Education, Inc. Disorders of Thyroid Hormones In both types it leads to a goiter Secretion Hyperthyroidism Hypothyroidism © 2019 Pearson Education, Inc. 8  9/3/24 Learning/Practice activity – POGIL 1 Cont. Part 3 Model 1 3 4 2 1 © 2019 Pearson Education, Inc. Disorders of Thyroid Hormones Secretion Hyperthyroidism (too much T3 & T4 produced) (due to immune system malfunction / production of TSH-like abnormal proteins – Graves Disease) ⇒ weight loss (due to increased metabolic rate) ⇒ heat intolerance (due to excessive heat production) ⇒ increase in blood pressure, heart rate (due to Sympathetic NS over-activity) Hypothyroidism (not enough T3 & T4 produced) (due to iodine deficiency in body (common in developing country), or destruction of thyroid gland by immune system) ⇒ effects opposite to that of hyperthyroidism © 2019 Pearson Education, Inc. 9  9/3/24 Overview of the Endocrine Organs © 2019 Pearson Education, Inc. Anatomy of the Parathyroid Glands Chief cells produce parathyroid hormone (PTH) -> regulate blood Ca2+ level © 2019 Pearson Education, Inc. 10  9/3/24 Regulation of blood calcium ions concentration by parathyroid hormone (PTH) and calcitonin Increases Indirectly Increases increases release of Ca2+ reabsorption from bones absorption of Chief cells of of Ca2+ by Ca2+ from diet parathyroid glands (PTH stimulates kidneys (not by small intestine detect the osteoclasts = lost in urine) (PTH activates “bone-destroying HYPOCALCEMIA cells) calcitriol in kidneys) LOW level of Ca2+ => PTH secreted © 2019 Pearson Education, Inc. Regulation of blood calcium ions concentration Parafollicular cells of by parathyroid hormone (PTH) and andcalcitonin calcitonin thyroid gland detect HIGH Ca2+ level = Increase HYPERCALCEMIA Increase Increase release of Ca2+ reabsorption absorption from bones Chief cells of of Ca2+ by of Ca2+ in parathyroid glands (osteoclasts are kidneys (not diet by small detect “bone-destroying cells) lost in urine) intestine HYPOCALCEMIA LOW level of Ca2+ => PTH secreted Calcitonin: -Inhibits the osteoclasts HIGH level of Ca2+ (-Stimulates the osteoblasts “bone-building cells”) => Calcitonin secreted © 2019 Pearson Education, Inc. 11  9/3/24 Thyroid and Parathyroid Hormones - Summary © 2019 Pearson Education, Inc. REVIEW: Practice QUESTIONS [Learning Catalytics] Q3 Q4 Q5 © 2019 Pearson Education, Inc. 12