Chapter 16 Lecture Outline See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright 2016 McGraw-Hill Education. Permission required for reproduction or display. 1
Endocrine System 2
Points to ponder What is the endocrine system? Compare and contrast exocrine and endocrine glands. What are steroid and peptide hormones? Name the major glands and their functions in the endocrine system. What is diabetes (type 1 and 2) and how might you prevent type 1? How do the endocrine and nervous systems work with the rest of the systems in the body to maintain homeostasis? 3
16.1 Endocrine Glands Endocrine system Mostly comprised of glands Secretes hormones that move through the bloodstream to target cells Results in a slow but a prolonged response 4
16.1 Endocrine Glands Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hypothalamus Pituitary Gland Posterior pituitary Anterior pituitary Parathyroids parathyroid glands (posterior surface of thyroid) Thymus Thyroid Pancreas Adrenal Gland Adrenal cortex Gonads Testes Ovaries testis (male) Figure 16.2 The endocrine system. ovary (female) 5
16.1 Endocrine Glands What is a target cell? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. nontarget cell receptors target cells hormone capillary Figure 16.3 Hormones target specific cells. 6
16.1 Endocrine Glands Exocrine vs. endocrine glands Exocrine glands secrete their products into ducts that carry these products to other organs or outside the body. Endocrine glands secrete their products directly into the bloodstream. 7
16.1 Endocrine Glands What are hormones? Hormones are chemical signals that promote communication between cells, body parts, and even individuals. 8
16.1 Endocrine Glands What are hormones? Hormones Prostaglandins are local hormones that affect neighboring cells and thus are not carried in the bloodstream. Pheromones are chemical signals that influence the behavior of other individuals. 9
16.1 Endocrine Glands What are hormones? Peptide hormones bind to a receptor in the plasma membrane causing the formation of camp which activates a cascade of enzymes. Steroid hormones are lipids that enter a cell and affect gene activity and thus protein synthesis. 10
16.1 Endocrine Glands Action of peptide hormones Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. capillary peptide hormone (first messenger) 1. Hormone binds to a receptor in the plasma membrane. activated enzyme receptor protein 2. Binding leads to activation of an enzyme that changes ATP to camp. Figure 16.4 Action of a peptide hormone. plasma membrane ATP 4. Many molecules of glycogen are broken down to glucose, which enters the bloodstream. camp (second messenger) 3. cam P activates an enzyme cascade. glycogen glucose (leaves cell and goes to blood) 11
16.1 Endocrine Glands Action of steroid hormones Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1. Hormone diffuses through plasma membrane because it is lipid soluble. steroid hormone plasma membrane cytoplasm nucleus 2. Hormone binds to receptor inside nucleus. DN A receptor protein mrna protein ribosome Figure 16.5 Action of a steroid hormone. 3. Hormone-receptor complex activates gene and synthesis of a specific mrna molecule follows. mrna 4. mrna moves to ribosomes, and protein synthesis occurs. 12
16.2 Hypothalamus and pituitary gland Major glands of the endocrine system 1. Hypothalamus 2. Posterior pituitary gland 3. Anterior pituitary gland 4. Thyroid gland 5. Parathyroid glands 6. Adrenal glands 7. Pancreas 8. Testes 9. Ovaries 10.Thymus 11.Pineal gland 13
16.2 Hypothalamus and Pituitary Gland 1. Hypothalamus Regulates internal environment through the autonomic nervous system Helps control heartbeat Helps control body temperature Helps control water balance Controls glandular secretions 14
16.2 Hypothalamus and Pituitary Gland 2. Posterior pituitary gland Stores antidiuretic hormone (ADH) and oxytocin that are produced by the hypothalamus ADH regulates water balance by reabsorbing water into the bloodstream. Oxytocin causes uterine contractions during childbirth and allows milk to be released during nursing. 15
16.2 Hypothalamus and Pituitary Gland 3. Anterior pituitary gland Controlled by hypothalamic-releasing and hypothalamic-inhibiting hormones 16
16.2 Hypothalamus and Pituitary Gland 3. Anterior pituitary gland Hormones produced by the anterior pituitary 1. Thyroid-stimulating hormone (TSH) stimulates the thyroid to produce thyroid hormones. 2. Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce cortisol. 3. Gonadotropic hormones stimulate gonads to produce sex cells and hormones. 17
16.2 Hypothalamus and Pituitary Gland 3. Anterior pituitary gland 4. Prolactin (PRL) stimulates mammary glands to develop and produce milk only after childbirth. 5. Melanocyte-stimulating hormone (MSH) causes skin-color changes in many fishes, amphibians, and reptiles having melanophores, special skin cells that produce color variations. 6. Growth hormone (GH) promotes skeletal and muscular growth. 18
16.2 Hypothalamus and Pituitary Gland The hypothalamus and pituitary Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. hypothalamus 1.Neurosecretory cells produce hypothalamic-releasing and hypothalamic-inhibiting hormones. 2. These hormones are secreted into a portal system. 1. Neurosecretory cells produce ADH and oxytocin. 2. These hormones move down axons to axon terminals. 3. When appropriate, ADH and oxytocin are secreted from axon terminals into the bloodstream. optic chiasm portal system 3. Each type of hypothalamic hormone either stimulates or inhibits production and secretion of an anterior pituitary hormone. 4. The anterior pituitary secretes its hormones into the bloodstream, which delivers them to specific cells, tissues, and glands. Posterior pituitary Anterior pituitary Thyroid: thyroid-stimulating hormone (TSH) Adrenal cortex: adrenocorticotropic hormone (ACTH) Figure 16.6 Hormones produced by the hypothalamus and pituitary. Kidney tubules: antidiuretic hormone (ADH) Smooth muscle in uterus: oxytocin Mammary glands: oxytocin Mammary glands: prolactin (PRL) Bones, tissues: growth hormone (GH) Ovaries, testes: gonadotropic hormones (FSH, LH) 19
16.2 Hypothalamus and Pituitary Gland What happens when the body produces too much or too little GH? Pituitary dwarfism too little GH is produced during childhood; results in small stature Gigantism too much GH is produced during childhood; results in poor health Acromegaly overproduction of GH as an adult; results in larger than normal feet, hands, and face 20
16.2 Hypothalamus and Pituitary Gland What happens when plentiful GH is produced during childhood? Figure 16.8 Growth hormone influences height. 21
16.2 Hypothalamus and Pituitary Gland What happens when GH is produced in high amounts during adulthood? Figure 16.9 Overproduction of growth hormone in adults leads to acromegaly. 22
16.3 Thyroid and Parathyroid Glands 4. Thyroid gland It is a large gland located below the larynx. Iodine is needed in the diet to allow the thyroid gland to produce its hormones. 23
16.3 Thyroid and Parathyroid Glands 4. Thyroid gland It produces thyroid hormone (TH) which regulates metabolism. calcitonin which helps lower blood Ca 2+ levels by stimulating the deposition of calcium in the bones. 24
16.3 Thyroid and Parathyroid Glands Thyroid abnormalities Simple goiter thyroid enlarges due to lack of iodine in the diet 25
16.3 Thyroid and Parathyroid Glands Thyroid abnormalities Hypothyroidism low blood levels of thyroid hormones A.Congenital hypothyroidism: thyroid does not develop properly and is characterized in a short, stocky person who may have mental retardation B.Myxedema: hypothyroidism in adults characterized by lethargy, weight gain, loss of hair, cold intolerance, and thick, puffy skin 26
16.3 Thyroid and Parathyroid Glands Thyroid abnormalities Hyperthyroidism excess thyroid hormones in the blood A.Exophthalimic goiter: characterized by enlargement of the thyroid gland, protrusion of the eyes, hyperactivity, and insomnia B.Thyroid tumor: can also cause hyperthyroidism 27
16.3 Thyroid and Parathyroid Glands Thyroid abnormalities Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. affected eye a. Simple goiter b. Congenital hypothyroidism c. Exophthalmic goiter a: Bruce Coleman, Inc./Alamy; b: Medical-on- Line/Alamy; c: Dr. P. Marazzi/Photo Researchers,Inc. Figure 16.10 Effects of insufficient dietary iodine, hypothyroidism, and hyperthyroidism. 28
16.3 Thyroid and Parathyroid Glands 5. Parathyroid glands Small glands embedded in the surface of the thyroid gland Produces parathyroid hormone (PTH) Causes blood Ca 2+ level to increase by promoting osteoclast activity Promotes reabsorption of Ca 2+ by the kidneys 29
16.3 Thyroid and Parathyroid Glands Regulation of blood calcium Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. calcitonin Thyroid gland secretes calcitonin into blood. Bones take up Ca 2+ from blood. Blood Ca 2+ lowers. Homeostasis (normal blood Ca 2+ ) Blood Ca 2+ rises. activated vitamin D Parathyroid glands release PTH into blood. parathyroid hormone (PTH) Figure 16.11 Blood calcium homeostasis. Intestines absorb Ca 2+ from digestive tract. Kidneys reabsorb Ca 2+ from kidney tubules. Bones release Ca 2+ into blood. 30
16.4 Adrenal Glands 6. Adrenal glands Glands that sit on top of the kidneys Two parts of each gland Adrenal medulla: controlled by the nervous system Adrenal cortex: portions are controlled by ACTH from the anterior pituitary 31
16.4 Adrenal Glands The adrenal glands Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. adrenal gland kidney adrenal cortex adrenal medulla connective tissue capsule zona glomerulosa adrenal cortex zona fasciculata (a) zona reticularis adrenal medulla (b) Figure 16.12 The adrenal glands. 32
16.4 Adrenal Glands Adrenal medulla Inner portion of the adrenal glands Hypothalamus initiates stimulation of hormone secretion in the adrenal medulla Produces hormones that allow a short-term response to stress ( fight or flight response) Epinephrine (adrenaline) Norepinephrine 33
16.4 Adrenal Glands Adrenal cortex Outer portion of the adrenal glands Produces hormones that provide a long-term response to stress 34
16.4 Adrenal Glands Adrenal cortex Two major types of hormones Glucocorticoids regulate carbohydrate, protein, and fat metabolism. suppress the body s inflammatory response. e.g., cortisol and cortisone 35
16.4 Adrenal Glands Adrenal cortex Mineralocorticoids regulate salt and water balance. e.g., aldosterone (targets the kidney) 36
16.4 Adrenal Glands Summary of the adrenal glands Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. stress hypothalamus path of nerve impulses Neurosecretory cells produce hypothalamicreleasing hormone. Stress Response: Long Term Glucocorticoids neuron cell body Protein and fat metabolism instead of glucose breakdown. spinal cord (cross section) sympathetic fibers epinephrine norepinephrine Anterior pituitary secretes ACTH. ACTH Reduction of inflammation; immune cells are suppressed. Mineralocorticoids Sodium ions and water are reabsorbed by kidney. Stress Response: Short Term Blood volume and pressure increase. Heartbeat and blood pressure increase. Blood glucose level rises. glucocorticoids Muscles become energized. adrenal medulla adrenal cortex mineralocorticoids Figure 16.13 Response of the adrenal medulla and the adrenal cortex to stress. 37
16.4 Adrenal Glands Adrenal glands can malfunction Addison disease hyposecretion of glucocorticoids by the adrenal cortex, characterized by bronzing of the skin Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Figure 16.15 Addison disease. b. a: Custom Medical Stock Photo; b: NMSB/Custom Medical Stock Photo 38
16.4 Adrenal Glands Adrenal glands can malfunction Cushing syndrome hypersecretion of glucocorticoids by the adrenal cortex, characterized by weight gain in the trunk of the body but not the arms and legs Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 16.16 Cushing syndrome. (both): Courtesy Shannon Halverson 39
16.5 Pancreas 7. Pancreas Fish-shaped organ behind the stomach Composed of two tissues Exocrine: produces and secretes digestive juices 40
16.5 Pancreas 7. Pancreas Endocrine (islets of Langerhans): produces and secretes hormones 1. Insulin secreted when blood glucose is high; stimulates the uptake of glucose by cells (muscle and liver) 2. Glucagon secreted when blood glucose is low; stimulates the breakdown of glycogen in the liver 41
16.5 Pancreas Regulation of blood glucose Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. inslin 80x B cells in pancreatic islet Liver stores glucose from blood as glycogen. Muscle cells store glycogen and build protein. After eating, pancreas secretes insulin into blood. Adipose tissue uses glucose from blood to form fat. Glucose level drops. Homeostasis (normal blood glucose) Glucose level rises. Between eating, pancreas secretes glucagon into blood. Liver breaks down glycogen to glucose. Glucose enters blood. A cells in 80x Pancreatic islet Figure 16.18 Blood glucose homeostasis. Adipose tissue breaks down fat. glucagon (both): Victor P. Eroschenko 42
16.5 Pancreas What is diabetes? It is the inability to control blood glucose levels. There are two types: type 1 and type 2. 25.8 million people in the US have diabetes. 43
16.5 Pancreas What is diabetes? General symptoms include frequent urination. unusual hunger and/or thirst. unexplained change in weight. blurred vision. sores that heal slowly or not at all. excessive fatigue. 44
16.5 Pancreas What is diabetes? Long-term effects are blindness, loss of limbs, nerve deterioration, kidney, and cardiovascular disease. 45
16.5 Pancreas Diabetes: Understanding the 2 types Type 1 It is normally early-onset. Type 1 is an autoimmune disorder that tends to run in families. Pancreatic cells are attacked and cannot produce insulin. Need insulin injections are needed. 46
16.5 Pancreas Diabetes: Understanding the 2 types Type 2 Type 2 is normally adult-onset and is the most common type. It tends to occur in obese, sedentary people. Cells do not respond to insulin. Usually diet and exercise are important for controlling this and may even prevent this. 47
16.6 Other Endocrine Glands 8. Testes Gonads found in males Produce androgens (e.g., testosterone) Stimulates growth of the penis and testes Responsible for male sex characteristics such as facial, underarm, and pubic hair Prompts the larynx and vocal cords to enlarge, resulting in a lower voice Promotes muscular strength 48
16.6 Other Endocrine Glands 9. Ovaries Gonads found in females Produce estrogen and progesterone Stimulate growth of the vagina and uterus Responsible for secondary sex characteristics such as female body hair, fat distribution, and breast development Responsible for egg maturation Regulate the uterine cycle 49
16.6 Other Endocrine Glands Hormones produced by the testes and ovaries Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stimulates the male secondary sex characteristics and maturation of sperm Stimulates the female secondary sex characteristics and maturation of eggs hypothalamus anterior pituitary testosterone FSH, LH FSH, LH estrogen and progesterone Figure 16.20 The hormones produced by the testes and the ovaries. testis ovary 50
16.6 Other Endocrine Glands 10. Thymus The thymus lies beneath the sternum. This gland is largest and most active during childhood. T lymphocytes mature here. It secretes hormones called thymosins that aid in differentiation of lymphocytes. 51
16.6 Other Endocrine Glands 11. Pineal gland Located in the brain Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Secretes melatonin that regulates the sleep/wake cycle (circadian rhythm) a. Experimental b. Winter May also regulate sexual development 6 P.M. 6 A.M. c. Summer The McGraw-Hill Companies, Inc./Evelyn Jo Johnson, photographer Figure 16.21 Melatonin production changes by season. 52
16.6 Other Endocrine Glands Hormones from other tissues Erythropoietin is secreted by the kidneys to increase red blood cell production. Leptin is produced by fat cells, and acts on the hypothalamus to give a feeling of being satiated. 53
16.6 Other Endocrine Glands Hormones from other tissues Prostaglandins Groups of potent chemicals that are not carried in the bloodstream work locally on neighboring cells. Some cause smooth muscle contraction. They have a major impact on reproductive organs. They have many other roles in the body. Aspirin and ibuprofen block the synthesis of these. 54
16.7 Hormones and Homeostasis Homeostasis The nervous and endocrine systems are important in maintaining homeostasis. The hypothalamus bridges regulatory functions of both systems. The nervous system is able to respond to changes in the external environment. 55
16.7 Hormones and Homeostasis How the nervous and endocrine systems work with other body systems Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The nervous and endocrine systems work together to maintain homeostasis The systems listed here in particular. also work with these two systems. Nervous and Endocrine Systems The nervous and endocrine systems coordinate the activities of the other systems. The brain receives sensory input and controls the activity of muscles and various glands. The endocrine system secretes hormones that influence the metabolism of cells, the growth and development of body parts, and homeostasis. Urinary System Cardiovascular System Nerves and epinephrine regulate contraction of the heart and constriction/dilation of blood vessels. Hormones regulate blood glucose and ion levels. Growth factors promote blood cell formation. Blood vessels transport hormones to target cells. Respiratory System The respiratory center in the brain regulates the breathing rate. The lungs carry on gas exchange for the benefit of all systems, including the nervous and endocrine systems. Nerves stimulate muscles that permit urination. Hormones (ADH and aldosterone) help kidneys regulate the water-salt balance and the acid-base balance of the blood. Digestive System Nerves stimulate smooth muscle and permit digestive tract movements. Hormones help regulate digestive juices that break down food to nutrients for neurons and glands. Muscular System Nerves stimulate muscles, whose contractions allow us to move out of danger. Androgens promote growth of skeletal muscles. Sensory receptors in muscles and joints send information to the brain. Muscles protect neurons and glands. Figure 16.22 The nervous system and endocrine system interact to control homeostasis. Reproductive System Nerves stimulate contractions that move gametes in ducts, and uterine contraction that occurs during childbirth. Sex hormones influence the development of the secondary sex characteristics. Integumentary System Nerves activate sweat glands and arrector pili muscles. Sensory receptors in skin send information to the brain about the external environment. Skin protects neurons and glands. Skeletal System Growth hormone and sex hormones regulate the size of the bones; parathyroid hormone and calcitonin regulate their Ca 2+ content and therefore bone strength. Bones protect nerves and glands. 56