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Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 9 The Endocrine System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Endocrine System Second messenger system of the body Uses chemical messages (hormones) that are released into the blood Hormones are produced by specialized cells Cells secrete hormones into extracellular fluids Blood transfers hormones to target sites These hormones regulate the activity of other cells and several major processes Reproduction Growth and development Mobilization of body defenses Maintenance of much of homeostasis Regulation of metabolism Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.1 The Chemistry of Hormones Amino acid-based hormones Proteins Peptides Amines Steroids – made from cholesterol Prostaglandins – made from highly active lipids Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.3 Mechanisms of Hormone Action Hormones affect only certain tissues or organs (target cells or organs) Target cells must have specific protein receptors Hormone binding influences the working of the cells Slide 9.4 Effects Caused by Hormones Changes in plasma membrane permeability or electrical state Synthesis of proteins, such as enzymes Activation or inactivation of enzymes Stimulation of mitosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.5 Steroid Hormone Action Diffuse through the plasma membrane of target cells Enter the nucleus Bind to a specific protein within the nucleus Bind to specific sites on the cell’s DNA Activate genes that result in synthesis of new proteins Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.6 Nonsteroid Hormone Action Hormone binds to a membrane receptor Hormone does not enter the cell Sets off a series of reactions that activates an enzyme Catalyzes a reaction that produces a second messenger molecule Oversees additional intracellular changes to promote a specific response Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.8 Control of Hormone Release Hormone levels in the blood are maintained by negative feedback A stimulus or low hormone levels in the blood triggers the release of more hormone Hormone release stops once an appropriate level in the blood is reached Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.10 Humoral Stimuli of Endocrine Glands Endocrine glands are activated by other hormones Changing blood levels of certain ions stimulate hormone release Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.12 Neural Stimuli of Endocrine Glands Nerve impulses stimulate hormone release Most are under control of the sympathetic nervous system Figure 9.2c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.13 Pituitary - Hypothalamus Relationship Release of hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus Hypothlamus produces two hormones that are transorted to neurosecretory cells of the posterior pituitary The poterior pituitary is not strictly an endocrine gland, but does release hormones Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.21 Pituitary Gland Size of a grape Hangs by a stalk from the hypothalamus Protected by the sphenoid bone Has two functional lobes Anterior pituitary – glandular tissue Posterior pituitary – nervous tissue Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.15 Hormones of the Anterior Pituitary Six anterior pituitary hormones Two affect nonendocrine targets Four stimulate other endocrine glands (tropic hormones) Characteristics of all anterior pituitary hormones Proteins (or peptides) Act through secondmessenger systems Regulated by hormonal stimuli, mostly negative feedback Slide 9.16 Functions of Anterior Pituitary Hormones Growth Hormone (GH) General metabolic hormone Major effects are directed to growth of skeletal muscles and long bones Causes amino acids to be built into proteins Causes fats to be broken down for a source of energy Prolactin (PRL) Stimulates and maintains milk production following childbirth Function in males is unknown Adrenocorticotropic hormone (ACTH) Regulates endocrine activity of the adrenal cortex Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.19 Functions of Anterior Pituitary Hormones Thyroid-stimulating hormone (TSH) Influences growth and activity of the thyroid Gonadotropic hormones Regulate hormonal activity of the gonads Follicle-stimulating hormone (FSH) Stimulates follicle development in ovaries Stimulates sperm development in testes Gonadotropic hormones (continued) Luteinizing hormone (LH) Triggers ovulation Causes ruptured follicle to become the corpus luteum Stimulates testosterone production in males Referred to as interstitial cell-stimulating hormone (ICSH) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.20a Hormones of the Posterior Pituitary Oxytocin Stimulates contractions of the uterus during labor Causes milk ejection Antidiuretic hormone (ADH) Can inhibit urine production In large amounts, causes vasoconstriction leading to increased blood pressure (vasopressin) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.22 Thyroid Gland Found at the base of the throat Consists of two lobes and a connecting isthmus Produces two hormones: thyroid hormone and calcitonin Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.23a Thyroid hormone Major metabolic hormone Composed of two active iodine-containing hormones Thyroxine (T4) – secreted by thyroid follicles Triiodothyronine (T3) – conversion of T4 at target tissues Calcitonin Decreases blood calcium levels by causing its deposition on bone Antagonistic to parathyroid hormone Produced by C (parafollicular) cells Figure 9.9 Slide 9.25 Parathyroid Glands Tiny masses on the posterior of the thyroid Secrete parathyroid hormone Stimulate osterclasts to remove calcium from bone Stimulate the kidneys and intestine to absorb more calcium Raise calcium levels in the blood Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.26 Adrenal Glands Two glands Cortex – outer glandular region in three layers Medulla – inner neural tissue region Sits on top of the kidneys Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.27 Hormones of the Adrenal Cortex Mineralocorticoids (mainly aldosterone) Produced in outer adrenal cortex Regulate mineral content in blood, water, and electrolyte balance Target organ is the kidney Glucocorticoids (including cortisone and cortisol) Produced in the middle layer of the adrenal cortex Promote normal cell metabolism Help resist long-term stressors Released in response to increased blood levels of ACTH Sex hormones Produced in the inner layer of the adrenal cortex Androgens (male) and some estrogen (female) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.28a Hormones of the Adrenal Medulla Produces two similar hormones (catecholamines) Epinephrine Norepinephrine These hormones prepare the body to deal with shortterm stress Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.30 Pancreatic Islets The pancreas is a mixed gland The islets of the pancreas produce hormones Insulin – allows glucose to cross plasma membranes into cells from beta cells Glucagon – allows glucose to enter the blood from alpha cells These hormones are antagonists that maintain blood sugar homeostasis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.32a Pineal Gland Found on the third ventricle of the brain Secretes melatonin Helps establish the body’s wake and sleep cycles May have other as-yetunsubstantiated functions Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.34 Thymus Located posterior to the sternum Largest in infants and children Produces thymosin Matures some types of white blood cells Important in developing the immune system Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.35 Hormones of the Ovaries Estrogens Produced by Graafian follicles or the placenta Stimulates the development of secondary female characteristics Matures female reproductive organs Helps prepare the uterus to receive a fertilized egg Helps maintain pregnancy Prepares the breasts to produce milk Progesterone Produced by the corpus luteum Acts with estrogen to bring about the menstrual cycle Helps in the implantation of an embryo in the uterus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.36 Hormones of the Testes Interstitial cells of testes are hormone-producing 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 9.38 Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 15 The Urinary System Slides 15.1 – 15.20 Lecture Slides in PowerPoint by Jerry L. Cook Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Functions of the Urinary System Elimination of waste products Nitrogenous wastes Toxins Drugs Regulate aspects of homeostasis Water balance Electrolytes Acid-base balance in the blood Blood pressure Red blood cell production Activation of vitamin D Slide 15.1a Organs of the Urinary system Kidneys Ureters Urinary bladder Urethra Figure 15.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.2 Location of the Kidneys Against the dorsal body wall At the level of T12 to L3 The right kidney is slightly lower than the left Attached to ureters, renal blood vessels, and nerves at renal hilus Atop each kidney is an adrenal gland Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.3 Coverings of the Kidneys Renal capsule Surrounds each kidney Adipose capsule Surrounds the kidney Provides protection to the kidney Helps keep the kidney in its correct location Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.4 Regions of the Kidney Renal cortex – outer region Renal medulla – inside the cortex Renal pelvis – inner collecting tube Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 15.2b Slide 15.5 Kidney Structures Medullary pyramids – triangular regions of tissue in the medulla Renal columns – extensions of cortex-like material inward Calyces – cup-shaped structures that funnel urine towards the renal pelvis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.6 Nephrons The structural and functional units of the kidneys Responsible for forming urine Main structures of the nephrons include the glomerulus and renal tubule. Glomerulus A specialized capillary bed Attached to arterioles on both sides (maintains high pressure) Large afferent arteriole Narrow efferent arteriole Capillaries are covered with podocytes from the renal tubule The glomerulus sits within a glomerular capsule (the first part of the renal tubule) Slide 15.8 Peritubular Capillaries Arise from efferent arteriole of the glomerulus Normal, low pressure capillaries Attached to a venule Cling close to the renal tubule Reabsorb (reclaim) some substances from collecting tubes Slide 15.12 Urine Formation Processes Filtration Reabsorption Secretion Figure 15.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.13 Filtration Nonselective passive process Water and solutes smaller than proteins are forced through capillary walls Blood cells cannot pass out to the capillaries Filtrate is collected in the glomerular capsule and leaves via the renal tubule Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.14 Reabsorption The peritubular capillaries reabsorb several materials Some water Glucose Amino acids Ions Some reabsorption is passive, most is active Most reabsorption occurs in the proximal convoluted tubule Materials not reabsorbed include urea, uric acid, creatinine, and excess water Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.15 Secretion – Reabsorption in Reverse Some materials move from the peritubular capillaries into the renal tubules Hydrogen and potassium ions Creatinine Materials left in the renal tubule move toward the ureter Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.17 Characteristics of Urine Used for Medical Diagnosis Colored somewhat yellow due to the pigment urochrome (from the destruction of hemoglobin) and solutes Sterile Slightly aromatic Normal pH of around 6 Specific gravity of 1.001 to 1.035 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.19 Ureters Slender tubes attaching the kidney to the bladder Continuous with the renal pelvis Enter the posterior aspect of the bladder Runs behind the peritoneum Peristalsis aids gravity in urine transport Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.20 Urinary Bladder Smooth, collapsible, muscular sac Temporarily stores urine Trigone – three openings Two from the ureters One to the urethrea Urinary bladder wall Three layers of smooth muscle (detrusor muscle) Mucosa made of transitional epithelium Walls are thick and folded in an empty bladder Bladder can expand significantly without increasing internal pressure Slide 15.21a Urethra Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis Release of urine is controlled by two sphincters Internal urethral sphincter (involuntary) External urethral sphincter (voluntary) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.23 Urethra Gender Differences Length Females – 3–4 cm (1 inch) Males – 20 cm (8 inches) Location Females – along wall of the vagina Males – through the prostate and penis Function Females – only carries urine Males – carries urine and is a passageway for sperm cells Slide 15.24a Micturition (Voiding) Both sphincter muscles must open to allow voiding The internal urethral sphincter is relaxed after stretching of the bladder Activation is from an impulse sent to the spinal cord and then back via the pelvic splanchnic nerves The external urethral sphincter must be voluntarily relaxed Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.25 Maintaining Water Balance Normal amount of water in the human body Young adult females – 50% Young adult males – 60% Babies – 75% Old age – 45% Water is necessary for many body functions and levels must be maintained Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.26 Distribution of Body Fluid Intracellular fluid (inside cells) Extracellular fluid (outside cells) Interstitial fluid Blood plasma Figure 15.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.27 Maintaining Water Balance Changes in electrolyte balance causes water to move from one compartment to another Alters blood volume and blood pressure Can impair the activity of cells Water intake must equal water output Sources for water intake Ingested foods and fluids Water produced from metabolic processes Sources for water output Vaporization out of the lungs Lost in perspiration Leaves the body in the feces Urine production Dilute urine is produced if water intake is excessive Less urine (concentrated) is produced if large amounts of water are lost Slide 15.29 Proper concentrations of various electrolytes must be present Regulation of Water and Electrolyte Reabsorption Regulation is primarily by hormones Antidiuretic hormone (ADH) prevents excessive water loss in urine Aldosterone regulates sodium ion content of extracellular fluid Triggered by the renninangiotensin mechanism Cells in the kidneys and hypothalamus are active monitors Maintaining Acid-Base Balance in Blood Blood pH must remain between 7.35 and 7.45 to maintain homeostasis Alkalosis – pH above 7.45 Acidosis – pH below 7.35 Most ions originate as byproducts of cellular metabolism Most acid-base balance is maintained by the kidneys Other acid-base controlling systems Blood buffers Respiration Blood Buffers Molecules react to prevent dramatic changes in hydrogen ion (H+) concentrations Bind to H+ when pH drops Release H+ when pH rises Three major chemical buffer systems Bicarbonate buffer system Phosphate buffer system Protein buffer system Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.34 The Bicarbonate Buffer System Mixture of carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3) Bicarbonate ions (HCO3–) react with strong acids to change them to weak acids Carbonic acid dissociates in the presence of a strong base to form a weak base and water Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.35 Respiratory System Controls of AcidBase Balance Carbon dioxide in the blood is converted to bicarbonate ion and transported in the plasma Increases in hydrogen ion concentration produces more carbonic acid Excess hydrogen ion can be blown off with the release of carbon dioxide from the lungs Respiratory rate can rise and fall depending on changing blood pH Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.36 Renal Mechanisms of Acid-Base Balance Excrete bicarbonate ions if needed Conserve or generate new bicarbonate ions if needed Urine pH varies from 4.5 to 8.0 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 15.37