Unit 10 - Endocrine System.pdf

Essentials of Human Anatomy & Physiology Thirteenth Edition Chapter 9 The Endocrine System Lecture Presentation by Patty Bostw...

Essentials of Human Anatomy & Physiology Thirteenth Edition Chapter 9 The Endocrine System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College Copyright © 2021 Pearson Education, Inc. All Rights Reserved Interaction of Endocrine & Nervous System The endocrine system works closely with the nervous system to maintain homeostasis. They both work to communicate and coordinate body activities. – Nervous system uses Neurotransmitters as it’s chemical messengers – Endocrine System uses Hormones as it’s chemical messengers. The glands in the Endocrine System are considered “effectors” so their secretion of hormones are often under direction from the nervous system.  Endocrine System: Hormones The endocrine system is made up of cells, tissues, and organs called endocrine glands, that secrete hormones into the blood Hormones – Chemical substances secreted in one part of the body that have an effect on another part of the body – Diffuse into the bloodstream and body fluids to act on specific target cells some distance away Target cells – cells with a specific receptor for a hormone – Binding of the hormone will either initiate or inhibit selective cell activities  Endocrine System: Hormones Hormones control several major processes in the body: –Reproduction –Growth and development –Mobilization of body defenses –Maintenance of much of homeostasis –Regulation of metabolism ***Endocrinology is the study of hormones and endocrine organs*** **Most hormones (except for a few) work under negative feedback to maintain homeostasis**** The Chemistry of Hormones Hormones are classified chemically as: 1) Amino acid-based Hormones, which includes: ▪ Proteins ▪ Peptides ▪ Amines 2)Steroid Hormones —made from cholesterol 3) Prostaglandins—made from highly active lipids that act as local hormones  Hormones and Target Cells **Hormones and receptors have specific shapes! Lock and Key configuration.** Recall: Endocrine and Exocrine Glands (3 Differences!) The body has 2 major types of glands: Exocrine glands - secretes substances into ducts, outside the internal environment or into hollow organs – Have ducts – Secrete Substances i.e. Sweat, mucus, oil, tears, or enzymes/digestive juices – Have an immediate effect where they are secreted Endocrine glands - secrete hormones into the blood and body fluids to affect target cells – No ducts – Secrete Hormones which act as chemical messengers – Travel to have an effect elsewhere in the body at their target cells  Endocrine Glands of the Body Major endocrine glands include: Hypothalamus Pituitary gland Pineal gland Thyroid gland Parathyroid glands Thymus Adrenal glands Pancreas Gonads (testes and ovaries) Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Other Endocrine Cells in the Body Specialized cells in various other organs can also produce hormones, but are part of other organ systems: (which we won’t discuss) Stomach Small intestine Kidneys Brain Atria of the Heart Placenta Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Hypothalamus (THE BOSS!) The hypothalamus maintains homeostasis by regulating a wide variety of visceral activities and by linking the endocrine system with the nervous system: – Regulates heart rate and arterial blood pressure – Regulates body temperature, water and electrolyte balance, hunger and body weight – Controls movements and secretions of the digestive tract. – Helps to regulate sleep and wakefulness. – Stimulates the anterior pituitary gland to produce hormones – Stimulates the posterior pituitary gland to secrete stored hormones the Hypothalamus produced The Pituitary Gland and Hypothalamus Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Pituitary Gland The pituitary gland is attached to the hypothalamus by a stalk called the infundibulum which includes a portal vein system that links the 2: – Anterior pituitary makes its own hormones when stimulated by hypothalamus hormones. – Posterior pituitary stores hormones made by hypothalamus ▪ Oxytocin and ADH Hypothalamus and Pituitary Gland Hypothalamus Anterior pituitary Posterior pituitary  Control of the Pituitary by the Hypothalamus Anterior pituitary control: – Releasing and inhibiting hormones from the hypothalamus control the secretion from the anterior pituitary – Hormones are carried in the bloodstream by hypophyseal portal veins – anterior pituitary cells are then either: stimulated to release (with Releasing Hormones) or inhibited to stop releasing their hormone (with Inhibitory Hormones) Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Control of the Pituitary by the Hypothalamus Posterior pituitary control: – The posterior pituitary stores 2 hormones made by the hypothalamus ▪ Oxytocin & ADH – The posterior pituitary releases these hormones into the blood in response to nerve impulses from the hypothalamus Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 9.5 Hormones of the Anterior Pituitary and Their Major Target Organs 6 Hormones of the Anterior Pituitary Gland 1. Growth Hormone (GH) Stimulates body cells to grow and reproduce. It also speeds the rate at which cells use carbohydrates and fats GH imbalances: – Pituitary dwarfism: Due to GH deficiency during childhood – Gigantism: Due to GH over-secretion during childhood – Acromegaly: Due to GH over-secretion in adulthood  Growth Hormone Imbalances Pituitary Dwarfism vs Gigantism Gigantism- Andre the Giant 7’4”, 520lbs A woman who developed Acromegaly from a Pituitary Tumor later in life Sultan Kosen,is the tallest living man at 8’3”  6 Hormones of the Anterior Pituitary 2. Prolactin Gland Promotes milk production following the birth of an infant. Requires a suckling stimulus (from baby or breast pump) – An example of **positive feedback** 3. Adrenocorticotropic hormone (ACTH) Controls the secretion of certain hormones from the adrenal cortex – Mainly controls cortisol secretion from the adrenal gland **Stress can increase ACTH secretion and therefore increase cortisol levels**  6 Hormones of the Anterior Pituitary Gland 4. Thyroid Stimulating Hormone (stimulated first by TRH from Hypothalamus) Controls the secretion of hormones (T3 & T4) from the thyroid gland Copyright © McGraw-Hill Education. Permission required for reproduction or display.  6 Hormones of the Anterior Pituitary Gland 5. Follicle-stimulating hormone (FSH) FSH in females: – responsible for the development of egg-containing follicles in ovaries – stimulates follicular cells to secrete estrogen FSH in males: – stimulates production of sperm cells 6. Luteinizing Hormone (LH) – Promotes secretion of sex hormones (i.e. testosterone in males) – plays a major role in releasing an egg cell in females (the ovulation hormone!) 2 Hormones Stored in the Posterior Pituitary Gland 1. Antidiuretic Hormone Causes the kidneys to conserve water, and reduces amount of water excreted in the urine – In conditions of dehydration ADH causes vasoconstriction of blood vessels, which helps to maintain blood pressure 2. Oxytocin Involved in uterine contractions – another example of positive feedback Also involved in emotional bonding, love, empathy, and feeling socially connected. – Animals that bond with humans – like dogs – produce more oxytocin than other animals  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Positive STIMULUS Oxytocin from the EFFECTOR Feedback fetus’s and mother’s hypothalamus......stimulates placenta to make prostaglandins. EFFECTOR Hypothalamus...stimulates uterus to contract. CONTROL CENTER STIMULUS Fetus’s hypothalamus and mother’s hypothalamus Prostaglandins stimulate both secrete oxytocin. more frequent and intense contractions of uterus. Placenta EFFECTOR Uterine contractions cause the fetal head to push against the cervix, making the cervix stretch STIMULUS and dilate. Dilating cervix stimulates the hypothalamus to secrete more oxytocin (positive feedback). Structure of the Thyroid Gland The thyroid gland is located below the larynx Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Thyroid Hormones: Thyroxine (T4) and Triiodothyronine (T3) The 2 hormones have similar actions; they regulate metabolism of carbohydrates, lipids and proteins – T3 is the more potent hormone compared to T4 They increase the rate at which cells release energy from carbohydrates, enhance protein synthesis, and stimulate the breakdown and mobilization of lipids Iodine is needed by the follicular cells to make thyroid hormones  Thyroid Disorders Hypothyroidism: (Low T3, T4) – Underactivity of the thyroid gland – Causes low metabolic rate, fatigue and weight gain in adults – In infants, causes Cretinism: poor growth and bone formation, abnormal mental development, sluggishness Hyperthyroidism: (High T3 and T4) – Overactivity of the thyroid gland – Causes high metabolic rate, restlessness, overeating in adults – May lead to eye protrusion (exophthalmia) Depending on cause of disease, either hypothyroidism or hyperthyroidism may lead to formation of a Goiter, an enlarged thyroid that appears as a bulge in the neck Goiters  Calcitonin Extrafollicular cells of the thyroid secrete calcitonin, a hormone which lowers blood calcium levels and phosphate ions when they are too high – Calcitonin increases calcium deposition in bones (stimulates osteoblasts to remove it from the blood and store it in the bone tissue) – Increases calcium excretion by the kidneys into urine (Pee it out) Calcitonin secretion is regulated by the blood concentration of calcium and chemoreceptors. – when blood calcium levels are high, calcitonin is secreted  The Parathyroid Glands The 4 tiny parathyroids are located on posterior of thyroid gland Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Parathyroid Glands Parathyroid Hormone (PTH): PTH increases blood calcium ion concentration and phosphate ion concentration PTH stimulates specialized bone cells (osteoclasts) to releases calcium into the blood and the kidneys to conserve (reabsorb) calcium PTH secretion is regulated by the blood concentration of calcium and chemoreceptors – when blood calcium levels are low, PTH is secreted  Blood Calcium Disorders Tetany – abnormal muscle stimulation and involuntary muscle contractions caused by low concentrations of blood calcium (Hypocalcemia). Often presents as spasms of the wrist and thumb and sometimes in the feet. Kidney stones - caused by high concentrations of blood calcium (Hypercalcemia). The blood gets filtered by the kidney. The calcium deposits can form stones which either stay in the kidney itself or get stuck in the the ureter on its way to the bladder. Hormonal Control of the Level of Calcium Ions in the Blood Structure of the Pancreas Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Hormones of the Pancreas The pancreas secretes hormones as an endocrine gland, and digestive juice into the digestive tract as an exocrine gland Glucagon: – Increases the blood level of glucose, by stimulating the breakdown of glycogen and the conversion of noncarbohydrates into glucose by the liver – Secreted when blood glucose levels are low Insulin: – Decreases the blood level of glucose by stimulating the liver to form glycogen, promotes facilitated diffusion of glucose into cells, increases protein synthesis, & stimulates adipose cells to store fat – Secreted when blood glucose levels are high Regulation of the Blood Glucose Level by Pancreatic Hormones (Negative Feedback) Control of Blood Glucose by Insulin & Glucagon Copyright © McGraw-Hill Education. Permission required for reproduction or display. BioFlix : Homeostasis of Blood Glucose Levels https://mediaplayer.pearsoncmg.com/assets/loMS4qosEmL53haP3z1Z_eWMupIkyIFv  Diabetes A metabolic disease due to lack of insulin or the inability of cells to recognize insulin. 3 Types: 1) Type 1 diabetes mellitus is an autoimmune disorder destroying the pancreas cells, causing insulin production to either decrease or stop – Treatment: regular insulin injections, insulin pump, meal planning, daily exercise, testing blood sugar regularly (test strips or CGM machine) 2) Type 2 diabetes mellitus is when insulin is being produced but is not recognized by the target cells, so it stays in the blood and can’t get into the cells. – Treatment: diet, exercise, weight management, medications 3) Gestational Diabetes – Insulin resistance in the mother induced by pregnancy. Blood sugar travels through placenta to baby and can cause growth and development issues with the baby. (i.e. abnormally large baby)  Diabetes Common Signs & Symptoms pf Diabetes: – Frequent urination – Increased thirst – Increased feelings of hunger – Blurry vision – Cuts bruises that are slow to heal – Extreme Fatigue, tiredness Concerns with uncontrolled Diabetes: – High blood glucose harms eyes, heart, kidneys, peripheral nerves, brain so many secondary diseases are possible. – Reduced healing of wounds due to poor circulation (amputation possible in severe cases) – Glucose entry into body cells is impaired, fatigue, coma, and death can occur (in extreme cases)  Diabetes Common Laboratory Tests associated with Diabetes Mellitus include: – Fasting Plasma Glucose Test – HbA1C Test (estimates blood sugar levels over past 3 month) – Random Glucose Test – Oral Glucose Tolerance Test (drink a sugary drink wait 2hrs then test glucose levels)  Pineal Gland and Thymus Pineal Gland The pineal gland, near the upper portion of the thalamus, secretes melatonin, which is involved in the regulation of circadian rhythms of the body. It is released at night Thymus The thymus, lying between the lungs under the sternum, secretes thymosins that affect production and differentiation of T lymphocytes that are important in immunity. The gland is the largest in children and shrinks with age  Adrenal Glands The adrenal glands sit on top of the kidneys, enclosed in a layer of adipose and connective tissues 1. Epinephrine and 2. Norepinephrine are secreted by the adrenal medulla (inner core) into the blood stream 3. Cortisol is a stress hormone secreted by the adrenal cortex (outer core) 4. Aldosterone from adrenal cortex helps regulate Na+ and K+ balance. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 9.8 Microscopic Structure of the Adrenal Gland  Hormonal Responses to Stress Responses to stress are designed to maintain homeostasis The stress response has 2 stages: the “alarm” stage and the “resistance” stage The Alarm Stage involves the immediate "fight or flight" responses of epinephrine and norepinephrine (SHORT TERM RESPONSE TO STRESS) Actions of Epinephrine and Norepinephrine – Increases blood glucose and fatty acids – Increases heart rate, breathing rate, blood pressure – Dilates air passages – Sends more blood to skeletal muscles, and less to skin and digestive organs  The Stress Response Copyright © McGraw-Hill Education. Permission required for reproduction or display. Short-term “fight or flight” or alarm stage Blood glucose increases. Long-term adjustment or resistance stage Blood glycerol and fatty acids increase. Heart rate increases. Blood concentration of amino acids increases. Blood pressure increases. Release of fatty acids increases. Air passages dilate. Glucose formed from noncarbohydrates— Pupils dilate. Blood flow redistributes. amino acids (from proteins) and glycerol (from fats)—Increases. Copyright © McGraw-Hill Education. Permission required for reproduction or display. ©McGraw-Hill Education.  Responses to Stress In the Resistance Stage there is increased cortisol secretion from the adrenal cortex (LONGER TERM REPSONSE TO STRESS) Actions of Cortisol from the adrenal cortex: – Regulates glucose metabolism – Influences the metabolism of protein and fat – Inhibits protein synthesis, which increases blood amino acids – Promotes fatty acid release from adipose tissue, increasing use of fatty acids for energy and decreasing use of glucose – Causes liver cells to produce glucose from noncarbohydrates, to increase blood glucose (increased blood sugar) Long term stress can be harmful: – Decreases lymphocytes, which lowers resistance to infections and some cancers – Increases risk of high blood pressure, atherosclerosis, and GI ulcers Gonads The gonads (ovaries and testes) are responsible for: – Producing sex cells (sperm and egg cells) – Producing sex hormones – Ovaries produce Estrogen and progesterone – Testes produce testosterone **We will learn more about these structures later in the Reproductive System Lecture*** Gonads Ovaries – Female gonads located in the pelvic cavity – Produce ova, or eggs – Produce two groups of steroid hormones 1. Estrogens 2. Progesterone Testes – Male gonads suspended outside the pelvic cavity – Produce sperm – Produce androgens, such as testosterone Ovary Hormones Estrogens – Stimulate the development of secondary female characteristics – Mature the female reproductive organs With progesterone, estrogens also: – Promote breast development – Regulate menstrual cycle Progesterone – Acts with estrogen to bring about the menstrual cycle – Helps in the implantation of an embryo in the uterus – Helps prepare breasts for lactation Testes Hormones The Testes produce several androgens. Testosterone is the most important androgen ▪ Responsible for adult male secondary sex characteristics ▪ Promotes growth and maturation of male reproductive system ▪ Required for sperm cell production Medical Use of Hormones Hormones are extracted from animal tissue, manufactured in the lab, or genetically engineered and administered is many situations. Some of these include: –Growth hormone –Insulin –Adrenal steroids –Epinephrine (adrenaline) –Thyroid hormones (Synthroid) –Oxytocin (Pitocin) –Androgens –Estrogen and progesterone (birth control, creams, etc.) Endocrine Glands and their Hormones Endocrine Glands and their Hormones Endocrine Glands and their Hormones Endocrine Glands and their Hormones