Physiology II NUR 104 PDF

PHYSIOLOGY II NUR 104 2 CREDIT HOURS LECTURER: PETER OSEI 1  LEARNING OUTCOMES By the end of the course, the students will: Describe the mechanism of muscle contraction; State the hormonal secretions of the glands of the endocrine system; Describe...

PHYSIOLOGY II NUR 104 2 CREDIT HOURS LECTURER: PETER OSEI 1  LEARNING OUTCOMES By the end of the course, the students will: Describe the mechanism of muscle contraction; State the hormonal secretions of the glands of the endocrine system; Describe the mechanism of urine formation; Explain the transmission of impulses in the nervous system; Outline the physiology of the special senses – sight, hearing, taste, touch and smell; Discuss the functions of the male and female reproductive system. 3  Course Content Unit 1: Urinary System: Fluid and electrolyte balance; Kidney; Nephrons and functions; Formation of urine; Disorders of renal function Unit 2: Reproductive System: Functions of female reproductive system; Male reproductive system and function; Some problems of both female and male reproductive system Unit 3: Endocrine System: Hypothalamus; Pituitary glands and hormones; Thyroid gland and hormones; Adrenal gland and hormones; Pancreas and hormones Unit 4: Gonads (glands) and hormones: Some disorders of endocrine system 4  Course Content (Cont’d) Unit 5: Nervous System: Autonomic nerves and function; Motor and sensory nerve Unit 6: Special Sensory Organs: Physiology of sight; Physiology of hearing; Sensation of taste; Sensation of smell; Tactile sensation; Some clinical problems of the nervous system and special senses Unit 7: Musculoskeletal System: Physiology of muscle contraction; Physiology of smooth muscles; Chemistry of skeletal muscles including energy source; Some disorders of musculoskeletal system 5  STUDENTS’ EVALUATION BSc. Nursing and BSc. Comm. H. Nursing BSc. Midwifery Continuous Assessment (40 %) Continuous Assessment (25 %) Assignments, Presentation, Quiz and Assignments, Presentation, Quiz and Attendance – 20 % Attendance – 10 % Mid-semester examination – 20 % Mid-semester examination – 15 % End of Semester Examination – 60 % End of Semester Examination – 75 % TOTAL 100 % TOTAL 100 % 6  GRADING SYSTEMS: BSc. Nursing and BSc. Comm. H. Nursing BSc. Midwifery A = 80 – 100 A+ = 80 – 100 B+ = 75 – 79 A = 70 – 79.99 B = 70 – 74 B+ = 65 – 69.99 C+ = 65 – 69 B = 60 – 64.99 C = 60 – 64 C+ = 55 – 59.99 D+ = 55 – 59 C = 50 – 54.99 D = 50 – 54 D+ = 45 – 49.99 E = 00 – 49 D = 40 – 44.99 F = 00 – 39.99 7  Reading List Amerman, E. (2006). Exercises for the Anatomy & Physiology Laboratory. 6th ed. Englewood, CO: Morton Publishing Company Graff, K. Van De Graff, (1995).Concept of human anatomy & physiology. 4th ed. New York. McGraw-Hill Companies Inc. Gunstream, S.E (1992). Anatomy and physiology: a text-workbook. New York: W.M.C. Brown Publishers. Hall, J.E. (2011). Guyton and Hall textbook of Medical physiology. 12th ed. Sounders, U.S.A. Martin, T. R. et al. (1998). Essentials of human anatomy and physiology.6th ed. New York: McGraw-Hill Companies, Inc. Saladin, K. S. (2010). Anatomy & Physiology. The unity of form and function. 5th ed. New York:McGraw-Hill Higher Education. 8  Reading List (Cont’d) Seeley, R. R; Stephens, T. D (2005). Essentials of anatomy and physiology. 5th ed. Boston: McGraw-Hill. Singh, Inderbir (2005). Anatomy and physiology for nurses. New Delhi: Jaypee Brothers medical publishers. Starr, c. & Macmillan, B. (2010). Human Biology. 8th ed. Bookslock, Belmont, U.S.A. Van De Graaff, K., Morton, D., & Crawley, J. (2010). A Photographic Atlas for the Anatomy and Physiology Laboratory. 6th ed., Englewood, CO., Morton Publishing Company. 9 Instructor and Office Hours Instructor: Peter Osei (MPhil) Office: Block D, Third floor, Room 703 Office Hours: By appointment Telephone: 0242519481 or 0509531356 Email: [email protected] 10 The Urinary System 11  Organs of the Urinary system Kidneys Ureters Urinary bladder Urethra 12  Functions of the Urinary System Elimination of waste products Regulate aspects of – Nitrogenous wastes homeostasis – Toxins – Water balance – Drugs – Electrolytes – Acid-base balance – Blood pressure – RBC production – Activation of vit.D 13  Location of the Kidneys Against the dorsal body wall The right kidney is slightly lower than the left Attached to ureters, renal blood vessels, and nerves at renal hilus At top each kidney is an adrenal gland 14  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 15  Regions of the Kidney Renal cortex – outer region Renal medulla – inside the cortex Renal pelvis – inner collecting tube 16  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 17 Blood Flow in the Kidneys 18 19  NEPHRONS The nephron is the tiny filtering structure in the kidneys. The structural & functional units of the kidneys Responsible for forming urine Main structures of the nephrons – Glomerulus – Renal tubule Each kidney contains more than a million tiny filtering nephrons that help clean the blood. 20  FUNCTIONS OF THE NEPHRON Regulation of fluid-balance The elimination of nitrogenous wastes The removal of other substances from the blood The maintenance of acid-base balance 21 Nephron anatomy 22  Glomerulus A specialized capillary bed Attached to arterioles on both sides (maintains high pressure) – Large afferent arteriole – Narrow efferent arteriole Figure 15.3c 23  Glomerulus Capillaries are covered with podocytes from the renal tubule The glomerulus sits within a glomerular capsule (the first part of the renal tubule) Figure 15.3c 24  Renal Tubule Glomerular (Bowman’s) capsule Proximal convoluted tubule Loop of Henle Distal convoluted tubule 25  Types of Nephrons Cortical nephrons – Located entirely in the cortex – Includes most nephrons Juxtamedullary nephrons – Found at the boundary of the cortex and medulla 26 27 28 29 30 31  Urine Formation Processes Filtration Reabsorption Secretion Figure 15.4 32  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 33  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 34  Materials Not Reabsorbed Nitrogenous waste products – Urea – Uric acid – Creatinine Excess water 35  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 36 Formation of Urine 37 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 38  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 39  Urinary Bladder Smooth, collapsible, muscular sac Temporarily stores urine Figure 15.6 40  Urinary Bladder Trigone – three openings – Two from the ureters – One to the urethrea Figure 15.6 41  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 42  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) 43 Female Urethra 44  Male Urethra 45  Sphincters  Internal  Smooth muscle  Autonomic (Automatic)  Controlled by spinal cord 46  Sphincters  External  Skeletal muscle  Cerebral control  Micturition  Expel urine from bladder 47  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 48  Urethra Gender Differences Function – Females – only carries urine – Males – carries urine and is a passageway for sperm cells 49  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 50  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 51  Distribution of Body Fluid Intracellular fluid (inside cells) Extracellular fluid (outside cells) – Interstitial fluid – Blood plasma 52  The Link Between Water and Salt 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 53  Maintaining Water Balance 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 54  Maintaining Water Balance Dilute urine is produced if water intake is excessive Less urine (concentrated) is produced if large amounts of water are lost Proper concentrations of various electrolytes must be present 55 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 rennin-angiotensin mechanism Cells in the kidneys and hypothalamus are active monitors 56 Blood composition depends on: 1. Diet 2. Cellular metabolism 3. Urine output How the kidneys manage blood composition: 1. Excretion of nitrogenous wastes 2. Water/electrolyte balance of the blood 3. Ensuring proper blood pH 57 THE CONTINUOUS MIXING OF BODY FLUIDS 58  Water and Salt Electrolytes: are charged particles (ions) that allow reactions requiring electrical charge to take place Cell membrane stability Muscle contraction Nerve impulse Body electrolytes include: Sodium (Na⁺) Potassium (K⁺) Calcium (Ca2⁺) Magnesium (Mg2⁺) 59  THE THIRST MECHANISM Osmoreceptors: cells in the hypothalamus – Activated by small changes in blood composition Results in a dry mouth Reinforces the drive to drink water 60 Hormonal Regulation of Water Intake/Output Hormones regulate reabsorption of water and electrolytes by the kidneys – Antidiuretic hormone (ADH) Hypothalamus tells posterior pituitary to release ADH prevents excessive water loss in the urine increases water reabsorption – Aldosterone (produced by adrenal cortex) increases sodium and water reabsorption; decreases potassium reabsorption 61  THE Renin-angiotensin mechanism Regulates blood pressure – The juxtaglomerular (JG) apparatus of the renal tubules sense drop in BP or solute concentration Causes release of the enzyme renin into blood Renin produces angiotensin II – Acts directly on the blood vessels to vasoconstrict The goal is to reduce filtrate volume 62  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 63 Maintaining Acid-Base Balance in Blood Most acid-base balance is maintained by the kidneys Urine pH varies from 4.5 to 8.0 Other acid-base controlling systems – Blood buffers – Respiration 64  Control of pH by the kidneys When blood pH rises (basic): – Bicarbonate ions are excreted – Hydrogen ions are retained by kidney tubules When blood pH falls (acidic): – Bicarbonate ions are reabsorbed – Hydrogen ions are secreted 65  Developmental Aspects of the Urinary System Functional kidneys are developed by the third month Urinary system of a newborn – Bladder is small; urine cannot be concentrated Control of the voluntary urethral sphincter starts until age 18 months Urinary infections are the only common problems before old age 66  Aging and the Urinary System There is a progressive decline in urinary function The bladder shrinks with aging Urinary retention is common in males 67  ASSIGNMENT 1 Describe the disorders of renal function 68 DISORDERS OF RENAL FUNCTION 69  Kidney Sites Susceptible to Renal Disease General: Renal medulla: – Low oxygen environment: Ischemia Glomerulus: – Structure predisposes it to immune complex deposition and complement fixation Tubules: “Post-Renal” Structures (ureters, bladder) – Malformations, Obstruction, Masses (i.e. cancer) 70  CATEGORIZATION Generalized Site of Disease: – Prerenal: Inadequate renal blood flow – Intrarenal: Nephron damage – Postrenal: Obstruction, Structural defects Site of Renal Lesion (Intrarenal) – Glomerulopathy Nephritic: Nephrotic: – Tubulointerstitial Disease Etiologic Factors: Infection, Diabetes, etc. 71  DISORDERS OF RENAL FUNCTION Some disorders of the renal function include the following Diabetic nephropathy Kidney stones Glomerulonephritis Renal Failure Diabetes Insipidus Urinary tract infections (UTI's) 72  Diabetic nephropathy Also known as Kimmelstiel-Wilson syndrome and intercapillary glomerulonephritis Is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nodular glomerulosclerosis. It is due to longstanding diabetes mellitus, and is a prime cause for dialysis in many Western countries. 73  Kidney stones Also known as nephrolithiases, urolithiases or renal calculi, are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. They vary in size from as small as a grain of sand to as large as a golf ball. Kidney stones typically leave the body in the urine stream; if they grow relatively large before passing (on the order of millimeters), obstruction of a ureter and distention with urine can cause severe pain most commonly felt in the flank, lower abdomen and groin. Kidney stones are unrelated to gallstones. 74  Pyelonephritis When an infection of the renal pelvis and calices, called pyelitis, spreads to involve the rest of the kidney as well, the result is pyelonephritis. It usually results from the spread of fecal bacterium Escherichia coli from the anal region superiorly through the urinary tract. In severe cases, the kidney swells and scars, abscesses form, and the renal pelvis fills with pus (discharge). Left untreated, the infected kidney may be severely damaged, but administration of antibiotics usually achieve a total cure. 75  Glomerulonephritis Inflammation of the glomerular can be caused by immunologic abnormalities, drugs or toxins, vascular disorders, and systemic diseases. Glomerulonephritis can be classified as diffuse proliferative, focal proliferative , membranous etc. Two major changes in the urine are distinctive of glomerulonephritis: hematuria and proteinuria with albumin as the major protein. There is also a decrease in urine as there is GFR (glomerular filtration rate). Renal failure is associated with oliguria (less than 400 ml of urine output per day). 76  Renal Failure Uremia is a syndrome of renal failure and includes elevated blood urea and creatinine levels. Acute renal failure can be reversed if diagnosed early. Acute renal failure can be caused by reduced renal blood flow,, damaged kidney, and obstruction to the outflow of urine. Diagnostic tests include BUN and plasma creatinine level tests. It is considered to be chronic renal failure if the decline of renal function to less than 25%. 77  Diabetes Insipidus This is caused by the deficiency of or decrease of ADH. The person with (DI) has the inability to concentrate their urine in water restriction, in turn they will void up 3 to 20 liters/day. There are two forms of (DI), neurogenic, and nephrogenic.  In nephrogenic (DI), the kidneys do not respond to ADH.  Usually the nephrogenic (DI) is characterized by the impairment of the urine concentrating capability of the kidney along with concentration of water. 78 The cause may be a genetic trait, electrolyte disorder, or side effect of drugs such as, lithium. In the neurogenic (DI), it is usually caused by head injury near the hypophysisal tract. 79  Urinary tract infections (UTI's) The second most common type of bacterial infections seen by health care providers is UTI's. Out of all the bacteria that colonize and cause urinary tract infections, the big gun is Escherichia coli. In the hospital indwelling catheters and straight catheterizing predispose the opportunity for urinary tract infections. In females there are three stages in life that predispose urinary tract infections, that is menarche, manipulation between intercourse, and menopause. 80  However, a small of men and children will get urinary tract infections. In men it is usually due to the prostate gland growth which usually occurs in older age men. In children it can occur 3% to 5% in girls and 1% in boys, In uncircumcised boys, it is more common than circumcised ones ; in girls it may be the result of onset of toilet training 81 Dialysis and Kidney Transplant 82  Generally, humans can live normally with just one kidney. Only when the amount of functioning kidney tissue is greatly diminished will renal failure develop. If renal function is impaired, various forms of medications are used, while others are contraindicated. Provided that treatment begun early, it may be possible to reverse chronic kidney failure due to diabetes or high blood pressure. 83  If creatinine clearance (a measure of renal function) has fallen very low ("end-stage renal failure"), or if the renal dysfunction leads to severe symptoms, dialysis is commenced. Dialysis is a medical procedure, performed in various different forms, where the blood is filtered outside of the body. Kidney transplantation is the only cure for end stage renal failure; dialysis, is a supportive treatment; a form of "buying time" to bridge the inevitable wait for a suitable organ. The first successful kidney transplant was announced on March 4, 1954 at Peter Bent Brigham Hospital in Boston. 84  The surgery was performed by Dr. Joseph E. Murray, who was awarded the Nobel Prize in Medicine in 1990 for this feat. There are two types of kidney transplants: living donor transplant and a cadaveric (dead donor) transplant. When a kidney from a living donor, usually a blood relative, is transplanted into the patient's body, the donor's blood group and tissue type must be judged compatible with the patient's, and extensive medical tests are done to determine the health of the donor. 85  Before a cadaveric donor's organs can be transplanted, a series of medical tests have to be done to determine if the organs are healthy. Also, in some countries, the family of the donor must give its consent for the organ donation. In both cases, the recipient of the new organ needs to take drugs to suppress their immune system to help prevent their body from rejecting the new kidney 86 Diuretics 87  A diuretic (colloquially called a water pill) is any drug that elevates the rate of bodily urine excretion (diuresis). Diuretics also decrease the extracellular fluid (ECF) volume, and are primarily used to produce a negative extracellular fluid balance. Caffeine, cranberry juice and alcohol are all weak diuretics. 88  Diuretics alleviate the symptoms of these diseases by causing sodium and water loss through the urine. As urine is produced by the kidney, sodium and water – which cause edema related to the disease – move into the blood to replace the volume lost as urine, thereby reducing the pathological edema Some diuretics, such as acetazolamide, help to make the urine more alkaline and are helpful in increasing excretion of substances such as aspirin in cases of overdose or poisoning The antihypertensive actions of some diuretics (thiazides and loop diuretics in particular) are independent of their diuretic effect. 89  That is, the reduction in blood pressure is not due to decreased blood volume resulting from increased urine production, but occurs through other mechanisms and at lower doses than that required to produce diuresis. Indapamide was specifically designed with this is mind, and has a larger therapeutic window for hypertension (without pronounced diuresis) than most other diuretics. Chemically, diuretics are a diverse group of compounds that either stimulate or inhibit various hormones that naturally occur in the body to regulate urine production by the kidneys. Alcohol produces diuresis through modulation of the vasopressin system. 90  THE REPRODUCTIVE SYSTEM 91  Introduction Male and female reproductive systems – Function together to produce offspring – Female reproductive system nurtures developing offspring – Produce important hormones 92  Male Reproductive System Testes Scrotum – sac that holds the – Primary organs testes Develop in the abdominal pelvic cavity of fetus Seminiferous tubules Descend into scrotal sac shortly – On top of testes before or after birth – Filled with spermatogenic cells – Produce the male sex cells that produce sperm cells (sperm) Interstitial cells produce – Produce the male hormone testosterone testosterone 93  Sperm Cells Head Tail – Nucleus with 23 – Flagellum that propels chromosomes sperm forward – Acrosome – enzyme-filled sac Helps sperm penetrate ovum Midpiece – Mitochrondria that generate cell’s energy 95  Male Internal Accessory Organs Epididymis Seminal vesicle – Sits on top of each testis – Secrete Fluid rich in sugar used to make energy – Receives spermatids from seminiferous Prostaglandins – stimulate muscular tubules contractions in female to propel sperm – Spermatids become sperm cells forward – Seminal fluid Vas deferens Released into vas deferens just before ejaculation – Tube connected to epididymis 60% of semen volume – Carries sperm cells to urethra 97  Male Internal Accessory Organs (cont.) Prostate gland Bulbourethral (Cowper’s) glands – Surrounds urethra – Produce a mucus-like fluid Secreted just before ejaculation – Produces and secretes a milky, alkaline Lubricates end of penis fluid into urethra just before ejaculation – Fluid protects sperm in the acidic Semen environment of the vagina – Alkaline mixture Nutrients – 40% of semen Prostoglandins – 1.5 to 5.0 ml per ejaculate – Sperm count of 40 to 250 million/mL 98  Male External Accessory Organs Scrotum Penis – Shaft – Holds testes away from body Erectile tissues surround urethra – Glans penis – Temperature 1° below body Cone-shaped structure on end of penis temperature – Prepuce – Lined with serous membrane Skin covering glans penis in uncircumcised males that secrets fluid – Functions Testes move freely Deliver sperm Urination 99  Erection, Orgasm, and Ejaculation Erection – Parasympathetic nervous system stimulates erectile tissue – Becomes engorged with blood Orgasm – Sperm cells propelled out of testes into urethra – Secretions from accessory organs also released into urethra Ejaculation – Semen is forced out of urethra – Sympathetic nerves then stimulate erectile tissue to release blood – Penis returns to flaccid state 100  Male Reproductive Hormones Hypothalamus –Gonadotropin-releasing hormone (GnRH) Stimulates anterior pituitary to release –Follicle-stimulating hormone (FSH) – initiates spermatogenesis –Luteinizing hormone (LH) – stimulates interstitial cells in the testes to produce testosterone –Testosterone Secondary sex characteristics Maturation of male reproductive organs Regulated by negative feedback 101 102 The male reproductive system: This system is simpler than the female reproductive system. A. Scrotum: a sac located outside of the abdominal cavity, made up of a thin layer of smooth and skeletal muscle and skin. It is divided into left and right by a septum to form different compartments for the testicles. The scrotum keeps the testicles outside the body so they can be 3 degrees cooler than normal core temperature. The muscles of the scrotum contract to bring the testicles closer to the body in cooler conditions. In warm conditions they relax to allow the skin to stretch and maximize cooling. 103 B. Testes: Oval shape organs made up of thousands of seminiferous tubules where the sperm is produced. It responds to follicle stimulating hormone that signals sperm production. When the sperm is in its last stages of maturation it moves to the epididymis. 1. Gross anatomy: about 1 x 4 inches, complete surrounded by a fibrous capsule and partially enclosed by a serous membrane that develop when the testes traveled outside the body into the scrotum. The fibrous capsule divides the testicles into wedge-like compartments called lobules that are filled with seminiferous tubules. They are innervated by an abundant about of visceral sensory nerves that make them very sensitive to pain. The high sensitivity serves for protection and in sexual arousal. 104 105  2.Seminiferous tubules and spermatogenesis: The seminiferous tubules consist of a thick stratified epithelium surrounding a lumen. The epithelium has spermatogenic cells that mature into sperm. At puberty the seminiferous tubules begin to produce about 400 million sperm. The spermatogenic cells are protect by a blood-testis barrier that keep the cells from activating the immune system. 106  Spermatogenesis These are the stages involved in sperm formation. Stage 1: formation of spermatocytes: spermatogonia divide by mitosis to produce two daughter cells, one remains in the germ line (to continue regeneration of more spermatogonia) and the other one goes on to become sperm. Stage 2: Meiosis: this is a reduction division that takes a cell through two rounds of division. At the end four genetically distinctive cells (spermatids) are created which will each mature into a sperm. Stage 3: Spermiogenesis: spermatids mature into sperm, the cell develops a long flagella, a mid piece with high mitochondria count, and a “head” filled with DNA (the nucleus). At the tip of the head lies a sac filled with digestive enzymes called the acrosome. Other cells in the testicles perform jobs like assisting the cells to mature and exit the scrotum (referred to as nurse cells), produce male androgen (like testosterone), and muscular cells that cause tiny contractions to push the sperm out of the testes. When sperm leaves the seminiferous tubules it travels down the 107 efferent tubules towards the epididymis. 108 109 110 111 Summary of Spermatogenesis Spermatogonia (46 chromosomes) Mitosis – makes primary spermatocytes Undergo meiosis  two secondary spermatocytes Divides – two spermatids = 4 spermatids Develop flagella to become mature sperm cells with 23 chromosomes 112  Reproductive duct system in males This section discusses the tubules through which sperm travel to exit the body. 1. Epididymis: organ that arches over the posterior lateral side of the testis. If you uncoil the epididymis, it can be as long as 6meters or 20 feet. During the twenty days the sperm spend here they complete maturation and gain the ability to swim and fertilize. During ejaculation smooth muscle contracts to send mature sperm to the ductus deferns. 2. Ductus deferens: also known as the vas deference. It runs superior to the testicles, enters the abdominopelvic cavity, runs posterior to the bladder, passes by the seminal vesicle, form the ampulla and ejaculatory duct, and finally leads into the prostatic urethra. 3. Spermatic cords: a tube of fascia holding blood vessels, nerves, and the ductus deference. 4. Urethra: the urethra in men carries both sperm and urine. During ejaculation the sphincter muscles close off the bladder so urine is not released into the semen. The urethra is divided into the prostatic urethra (section passing through prostrate gland), the membranous urethra (urogenital diaphragm) and the spongy urethra (penile). Urethral glands along the spongy urethra secrete a lubricating 113 solution before ejaculation. 114 115 116 117  Accessory glands: These glands produce substances that increases the chances of sperm survival once it is outside the body. These secretions in addition to sperm form semen. 1. Seminal vesicles: paired glands located posterior to the bladder. During ejaculation smooth muscle contract to help secrete a fluid that contains fructose (sugar), nutrients, prostagladins to stimulate the urethra to contract, substances that suppress the immune system against sperm in females, enzymes the enhance sperm mobility, and enzymes that thicken the ejaculate. 2. Prostate gland: the size of a chestnut, also has smooth muscle that contracts to assist in the release of prostatic secretion. This is a milky white fluid that has substances to enhance sperm mobility and thicken ejaculate. It is susceptible to tumors and sexually transmitted diseases (STDs). 3. Bulbourethral glands: secrete a mucus substances that lubricates and 118 neutralizes the acid from urine in the male urethra.  Penis Designed to deliver semen into the female reproductive tract. It originates at the root, expends through the body, and ends at the glans penis. Skin around the glans penis is called prepuce The penis contains erectile bodies: corpora spongiosum, corpora cavernosa, and others consisting of smooth muscle and connective tissue. It is a spongy network surrounded by a high amount of blood vessels that dilate during arousal and engorge the spongy tissues with blood. The veins that normally drain the penis are pressured shut by the expanding spongy tissue. The parasymphatetic branch causes the penis to become erect by stimulating vasodilation. The symphatetic branch cause ejaculation by stimulating contraction of smooth muscle along the reproductive tract. 119 120  Diseases and Disorders of the Male Reproductive System Disease/Disorder Description Benign prostatic Nonmalignant enlargement of the prostate gland; hypertrophy (BPH) common in older men Epididymitis Inflammation of an epididymis; usually starts as an urinary tract infection Impotence or erectile Disorder in which erection cannot be achieved or dysfunction (ED) maintained; about 50% of males between 40 and 70 have some degree of ED 121  Diseases and Disorders of the Male Reproductive System Disease/Disorder Description Prostate cancer Most common form of cancer in men over 40; risks of developing it increase with age Prostatitis Inflammation of the prostate gland; may be acute or chronic Testicular cancer Malignant growth in one or both testicles; more common in males 15–30 years; more aggressive malignancy 122 Female Reproductive System 123  Female Reproductive System Ovaries (2) – Primary sex organs produce Sex cells called ova Hormones estrogen and progesterone – Located in the pelvic cavity – Medulla Inner area; contains nerves, lymphatic vessels, and blood vessels – Cortex Outer area; contains ovarian follicles – Covered by epithelial and dense connective tissues 124 Female Reproductive System 125  Ovum Formation (cont.) Primordial follicles develop before Oogenesis is the process of ovum birth and contain formation – A primary oocyte or immature ovum – At puberty, primary oocytes are (born with maximum number) stimulated to continue meiosis Becomes 1 polar body (a – Follicular cells nonfunctional cell) and A secondary oocyte – Secondary oocyte released during ovulation – If fertilized, the oocyte divides to form a mature, fertilized ovum 126  Female Internal Accessory Organs Fallopian tube – oviduct – Infundibulum and fimbriae Fringed, expanded end of fallopian tube near ovary Function to “catch” an ovum – Muscular tube Lined with mucous membrane and cilia Propels ovum toward uterus 127  Female Internal Accessory Organs (cont.) Uterus – Wall of uterus – Hollow, muscular organ Endometrium – Receives embryo and – Innermost lining sustains its development – Vascular – Tubular glands – – Divisions mucus Fundus – domed upper Myometrium portion – Middle, thick, Body – main portion muscular layer Cervix – narrow, lower Perimetrium section extending into vagina – Thin layer covering (cervical orifice) the myometrium – Secretes serous fluid to coat and 128 protect uterus  Female Internal Accessory Organs (cont.) Vagina – Tubular, muscular organ – Extends from uterus to outside body (vaginal introitus) – Muscular folds – rugae – enable expansion Receive erect penis Passage for delivery of offspring and uterine secretions – Wall Innermost mucosal layer Middle muscular layer Outer fibrous layer 129 Internal Female Organs 130  External Accessory Organs Mammary glands – Secretion of milk – Structures Nipple – Oxytocin induces lactiferous ducts to deliver milk through openings Areola – pigmented area around nipple Alveolar glands – within mammary glands – Make milk when stimulated by prolactin 131 Mammary glands 132  External Genitalia Collectively known as the vulva (often incorrectly referred to as the vagina) Labia majora (analogous to the scrotum) – Rounded folds of adipose tissue and skin – Protect other external reproductive organs Labia minora – Folds of skin between labia majora – Very vascular – Merge to form hood over clitoris – Vestibule – space enclosed by labia minora Bartholin’s glands secrete mucus during sexual arousal 133  External Genitalia (cont.) Clitoris (analogous to the penis) – Anterior to urethral meatus – Contains female erectile tissue – Rich in sensory nerves Perineum – Between vagina and anus – Area for episiotomy, if needed, during birth process 134 External Genitalia (cont.) 135 136  Erection, Lubrication, and Orgasm Nervous stimulation – Clitoris becomes erect – Bartholin’s glands activate – lubrication – Vagina elongates Orgasm – Sufficient stimulation of clitoris – Walls of uterus and fallopian tubes contract to propel sperm up tubes 137  The ovaries The size of an almond, this paired organ is suspended by mesenteries and ligaments. It is surrounded by a fibrous capsule and can be divided into a cortex and medulla. The cortex houses the developing ova and the medulla holds vascular tissue. The ovary is the site of oogenesis and female sex hormone production. It responds to follicle-stimulating hormone that signals the maturation of an ovum. Typically only one egg is released from an ovary every month, the ovaries alternate in releasing the egg. Every time an egg is released the ovaries become scarred. Hormones that affect the menstrual cycle and female sex organs are also released by the ovaries; estrogen and progesterone. 138 The ovaries 139  Ovarian cycle This concerns the changes in the ovary during the menstrual cycle. Females are born with all the potential ova they can produce in a life time. These are called the primordial follicles which consist of a single immature oocyte and a single layer of follicular cells. These cells respond to FSH and being the maturation of an oocyte. Follicular phase: during the first two weeks of the menstrual cycle one follicle matures up until the stage when it is able to release an oocyte. Other primordial follicles may get activated but die out along the way. The primordial follicle becomes the primary follicle and continues to develop until it becomes the vesicular follicle. At this point the oocyte is surrounded by follicle cells that form a fluid filled cavity. 140 141  Ovulation (midpoint) phase: at about the mid cycle LH is release to signal the follicle to rupture and release the oocyte from the ovary. The ovum is surrounded by a group of cells that continue to nourish it, they are called the corona radiata. When the egg cell is released it enters the peritoneal cavity but is swept into the fallopian/uterine tubes by fimbriae. Luteal phase: after ovulation and during the last two weeks of the cycle, the follicle that held the oocyte becomes the corpus luteum, it is now considered an endocrine gland that releases progesterone. If no implantation occurs it becomes the corpus albicans (now scar tissue). 142 143  Oogenesis While in men spermatogenesis happens in about a month, in females oogenesis takes several years. During fetal development oocytes undergo meiosis I, but do not complete it; at this point they are called primary oocytes. At ovulation the primary oocyte completes meiosis I and begins meiosis II which is completed only if fertilization occurs. At the completion of meiosis II the oocyte is called an ovum. 144 145  Uterine tubes Also called fallopian tubes, they take the oocyte and provide a site for fertilization. The tube is lined with ciliated epithelium that gently guides the oocyte towards the uterus. There are also peristaltic waves caused by smooth muscle contraction to aide the movement of the oocyte. There are also non-ciliated cells that nourish the oocyte or embryo on its way to the uterus. Sometimes a fertilized egg can implant in a uterine tube and cause a life threatening ectopic pregnancy. 146  The uterus A thick muscular pouch about the size of a pear that lies in the pelvic cavity superior to the bladder. The function of the uterus is to receive an embryo and provide an environment for its development. During pregnancy it stretches to accommodate the growth of the fetus. When there is no pregnancy the cavity within the uterus is small. The opening of the uterus is at the cervix, during child birth it dilates to allow the child to pass by. The cervix tissue may become infected by a virus called HPV human papilloma virus. It can cause abnormal tissue growth including cervical caner. The purpose of pap-smears is to check the cervical tissue for147 abnormal growth. 1. Supports of the uterus: The uterus, cervix, and vagina are supported by ligaments and mesenteries. Most uterine support is provided by muscles of the pelvic floor. Sometimes these muscles are torn during child birth and the unsupported uterus results in a prolapsed uterus. In this condition the tip of the cervix protrudes through the opening of the external vagina. 2. Uterine wall: composed of three layers: – perimetrium (outer= serous membrane), – myometrium (middle= layers of smooth muscle), and – endometrium (inner= simple columnar epithelium). The thick layer called stratum functionalis (above myometrium) undergoes most of the changes during the uterine cycle. 148  Uterine cycle Also called the menstrual cycle. It relates to changes occurring in the endometrium of the uterus that are induced by female sex hormones. It involves the following phases: – Menstrual phase – Proliferative phase – Secretory phase 149  Menstrual phase Days 1-5 During this phase, the endometrium is shed. 150  Proliferative phase Days 6-14 During this phase, the endometrium builds a new stratum functionalis as it responds to rising estrogen levels. As the layer thickens, glands release a clear sticky mucus secretion that assist the sperm in finding the egg. 151  Secretory phase Days 15-28 During this point the stratum functionalis is highly vascularized and there is secretion of glycoproteins to support a developing embryo in case fertilization occur. These changes are a response to progesterone released by the corpus luteum in the ovary. If there is no fertilization the progesterone levels drop signaling changes that cause death of the stratum functionalis. The arteries constrict cutting out blood supply and suddenly open again but the weak capillaries fragment and the menstrual phase begins again. 152 153 154 Uterine cycle 155 156 157  The vagina Also known as the birth canal. It is the opening that leads into the cervix and is located anterior to the anus but posterior to the clitoris and urethral opening. The vagina is also the site where sperm is deposited. This canal is very flexible and it composed of three layers: adventitia, muscularis, and mucosa. It also has ruggae to stimulate the penis during intercourse and stretch out during childbirth. The mucosa is made up of stratified squamous epithelium. It secretes glycogen to maintain healthy beneficial bacteria that produce lactic acid. This creates an acidic environment that is not beneficial to other bacteria or sperm. 158 Disease/Disorder Description Breast cancer Uncontrolled growth of abnormal cells in the breast Cervical cancer Uncontrolled growth of abnormal cells in the cervix Cervicitis Inflammation of the cervix usually due to an infection Dysmenorrhea Condition with severe menstrual cramps that limit normal activities 159 Endometriosis Tissues of uterine lining growing outside of the uterus Fibrocystic breast Abnormal cystic tissue in the breast; size varies disease related to menstrual cycle; common in 60% of women between 30 and 50 Fibroids Benign tumors in the uterine wall. Ovarian cancer Uncontrolled growth of abnormal cells in the ovary 160 Premenstrual Collection of symptoms occurring just syndrome (PMS) before a menstrual period Vaginitis/ Inflammation of the vulvovaginitis vagina/inflammation of vagina and vulva; both associated with abnormal vaginal discharge Uterine Uncontrolled growth of abnormal cells (endometrial) in the uterus. cancer 161 ENDOCRINE SYSTEM 162 Endocrine glands are scattered throughout the body, many of them with no apparent connection to each other. 163  The endocrine system The system broadcasts its hormonal messages to essentially all cells by secretion into blood and fluid that surrounds cells. Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond. 164 Principal functions of the endocrine system Maintenance of the internal environment in the body (maintaining the optimum biochemical environment). Integration and regulation of growth and development. Control, maintenance and instigation of sexual reproduction, including gametogenesis, coitus, fertilization, fetal growth and development and nourishment of the newborn. 165  Regulation of hormone secretion Sensing and signaling: a biological need is sensed, the endocrine system sends out a signal to a target cell whose action addresses the biological need. Key features of this stimulus response system are: receipt of stimulus synthesis and secretion of hormone delivery of hormone to target cell evoking target cell response degradation of hormone 166  Control of Endocrine Activity The physiologic effects of hormones depend largely on their concentration in blood and extracellular fluid. Almost inevitably, disease results when hormone concentrations are either too high or too low, and precise control over circulating concentrations of hormones is therefore crucial. 167  Control of Endocrine Activity The concentration of hormone as seen by target cells is determined by three factors: Rate of production Rate of delivery Rate of degradation and elimination 168  Control of Endocrine Activity Rate of production: Synthesis and secretion of hormones are the most highly regulated aspect of endocrine control. Such control is mediated by positive and negative feedback circuit. 169  Control of Endocrine Activity Rate of delivery: An example of this effect is blood flow to a target organ or group of target cells - high blood flow delivers more hormone than low blood flow. 170  Control of Endocrine Activity Rate of degradation and elimination: Hormones, like all biomolecules, have characteristic rates of decay, and are metabolized and excreted from the body through several routes. Shutting off secretion of a hormone that has a very short half-life causes circulating hormone concentration to fall, but if a hormone's biological half-life is long, effective concentrations persist for some time after secretion ceases. 171  Feedback Control of Hormone Production Feedback loops are used extensively to regulate secretion of hormones in the hypothalamic-pituitary axis. An important example of a negative feedback loop is seen in control of thyroid hormone secretion 172 Inputs to endocrine cells 173 Hypothalamus 174  Hypothalamus Part of brain Regulates ANS, emotions, feeding/satiety, thirst, body temperature, etc. Hormones related to these functions “Releasing hormones” Axonal transport to posterior lobe 175  Hypothalamus The hypothalamus, which is attached to the posterior pituitary, is the link between the central nervous system and the endocrine system. The hypothalamus controls the secretions of the pituitary gland. The activities of the hypothalamus are influenced by hormone levels and other substances in the blood and by sensory information collected by the central nervous system. The hypothalamus contains the cell bodies of neurosecretory cells whose axons extend into the posterior pituitary. 176  Hypothalamus Hormones are made in the cell bodies of the hypothalamus and stored in the axons entering the posterior pituitary. When the cell bodies are stimulated, the axons in the posterior pituitary release the hormones into the blood. The hypothalamus has indirect control of the anterior pituitary. The hypothalamus produces a specific releasing hormone that controls the secretion of each anterior pituitary hormone. 177  Anterior Pituitary “Releasing” hormones regulate AP aka adeno hypo physis “glands” “under” “growth” All proteins TSH (thryoid stimulating hormone/thyrotropin) ACTH (adrenocorticotropic hormone) FSH (gonadotropin) LH (gonadotropin) Tropins/tropic hormones GH (growth hormone) Prolactin-releasing H 178 Anterior Pituitary 179 180  Anterior P. Homeostatic Imbalances Growth hormone (GH or hGH) Promotes mitosis, cell division Elongation of long bones, etc. Healing of wounds Lack of hGH retards growth Hypersecretion in youth produces giantism Hyposecretion in childhood produces pituitary dwarfism Hypersecretion in adult produces acromegaly 181  Posterior Pituitary Axonal transport to Posterior Pituitary aka neuro hypo physis “nerve” “under” “growth” Hypothalamic cell bodies synthesize oxytocin ADH 182  Pituitary—Posterior lobe Oxytocin Stimulates smooth muscle contraction of uterus & mammary glands. Antidiuretic H. Stimulates water reabsorption in collecting ducts. Stimulates vasoconstriction (vasopressin) Lack  diabetes insipidus 183 Posterior Pituitary Homeostatic Imbalances ADH Hyposecretion produces diabetes insipidus “tasteless” Excessive thirst and urination central or neurogenic DI gestagenic or gestational DI nephrogenic DI dipsogenic DI Diabetes Insipidus Foundation, Inc. 184 185  Thyroid Gland Location in neck Inferior to larynx Anterior & lateral to trachea Composed of follicles Follicle cells produce thyroglobulin Thyroxin (T4) Triiodothyronine (T3) Both “thyroid hormone”, body’s major metabolic hormone Parafollicular/ C cells Calcitonin Decreases blood Ca2+ by depositing it in bones 186  Homeostatic imbalances Hypothyroidism results Myxedema (in adults) Goiter—low levels of iodine Cretinism (in children) Hyperthyroidism results Graves disease 187  Parathyroid Glands Four small glands embedded in posterior of thyroid Parathyroid hormone (PTH) Stimulates osteoclasts to free Ca2+ from bone Stimulates Ca2+ uptake from intestine & kindey 188  Parathyroid Homeostatic Imbalances Severe hyperparathyroidism causes massive bone destruction If blood Ca2+ fall too low, neurons become overactive, resulting in tetany 189 Feedback Loop Negative feedback in calcium homeostasis. A rise in blood Ca2+ causes release of calcitonin from the thyroid gland, promoting Ca2+ deposition in bone and reducing reabsorption in kidneys. A drop in blood Ca2+ causes the parathyroid gland to produce parathyroid hormone (PTH), stimulating the release of Ca2+ from bone. PTH also promotes reabsorption of Ca2+ in kidneys and uptake of Ca2+ 190 in intestines.  Adrenal Glands One on top of each kidney Cortex Corticosteroid glandular Medulla Catecholamines neurohormonal Epinephrine Norepinephrine 191  Adrenal Cortex Cortex Activity stimulated by ACTH Controls prolonged responses by secreting corticosteroids. Mineralcorticoids Aldosterone regulate salt and water balance Glucocorticoids Cortisol regulate glucose metabolism and the immune system. Gonadocorticoids Androgens Estrogens 192  Adrenal Cortex Imbalances Hypersecretion leads to Cushing’s disease ACTH-releasing tumors or side effects of corticoid drugs. Hyposecretion leads to Addison’s Disease Deficits in glucocorticoids and mineralcorticoids 193  Adrenal Medulla Medulla The adrenal medulla mediates short–term responses by secreting catecholamine hormones. Cells are modified neurons (lack axons) Epinephrine (adrenaline) Norepinephrine (noreadrenaline) enable a rapid ( fight-or-flight ) responses to stress by increasing blood glucose and blood pressure and directing blood to the heart, brain, and skeletal muscles. 194 195  Pancreas Consists of two major types of secretory tissues which reflects its dual function Exocrine gland secretes digestive juice localized in the acinar cells Endocrine gland releases hormones localized in the islet cells (islets of Langerhans) 196  Pancreatic Islets “About a million” embedded in pancreas Control centers for blood glucose Insulin from beta cells Glucagon from alpha cells 197 Insulin Glucagon 198  Islets of Langerhans Insulin stimulates glucose uptake, glycogenesis Glucagon stimulates glycogenolysis, glucose release from liver (vs gluconeogenesis) 199 Feedback Loop A rise in blood glucose causes release of insulin from beta cells the pancreas, promoting glucose uptake in cells and storage as glycogen in the liver. A fall in blood glucose stimulates alpha cells in the pancreas to secrete glucagon, which causes the liver to break down glycogen and release glucose. 200 Pancreas Homeostatic Imbalances: Diabetes mellitus Symptoms: Polyuria Polydipsia Polyphagia 201  Gonads Ovaries Estrogens Progesterone Testes Testosterone 202  Pineal gland Melatonin Inhibits early puberty Day/night cycles Timing of sleep, body temperature, appetite Secretes melatonin during darkness Participates in setting the body’s clock Melatonin is a potent antioxidant Melatonin is high when young and is reduced as we age 203  Thymus Thymus gland Thymopoietins, thymic factor, thymosins Influence development of T lymphocytes 204  Non-Endocrine Gland Hormones Stomach (gastrin) Small intestine (duodenumintesetinal gastrin, secretin, cholecystokinin) Heart (atrial natriuretic peptide) Kidneys (erythropoietin, active vitamin D3) Adipose tissue (leptid, resistin) Skin Placenta (human chorionic gonadotropin, human placental lactogen, relaxin) 205 Functions regulated by the Endocrine System Growth Healing Water balance & Blood Pressure Calcium Metabolism Energy Metabolism Stress Regulation of other Endocrine Organs 206 Growth Growth hormone-releasing hormone Human growth hormone (hGH) Thyrotropin (TSH) Thyroxine & triiodothyronine Calcitonin Somatostatin (GHIH) 207 Healing Growth hormone-releasing hormone Human growth hormone (hGH) Thyrotropin (TSH) Thyroxine & triiodothyronine Calcitonin Glucagon, Insulin Erythropoietin 208 Water balance & Blood pressure ADH Aldosterone Angiotensin II Atrial natriuretic H. Epinephrine 209 Calcium Metabolism Calcitonin Parathyroid H. (PTH) Estrogens/androgens Growth hormone 210 Energy Metabolism Thyroxine & triiodothyronine Thyroid-stimulating H. (thyrotropin, TSH) Epinephrine & norepinephrine Insulin Glucagon Adrenocorticotropic H. (ACTH) Cortisol 211 Stress Epinephrine & norepinephrine T4 &T3 ACTH Cortisol 212 Common Diseases and Disorders of the Endocrine System Causes Increased productions of the growth hormone or a tumor. Signs and Symptoms Enlargement of skull, and hands and feet bones Thickening of the skin Headache, fatigue, pain, weight gain, heart disease Treatment Medications to decrease growth hormone production Radiation therapy Surgery 213 Common Diseases and Disorders of the Endocrine System (cont.) Causes Specific causes unknown but may be due to cancer, or an autoimmune dysfunction Signs and Symptoms Weakness, fatigue, dizziness, weight loss, muscle pain, vomiting, diarrhea and dehydration Treatment Corticosteriods Medications or hormones to balance sodium and potassium levels 214 Common Diseases and Disorders of the Endocrine System (cont.) Causes Excessive production of ACTH (adrenal gland tumor) Long-term use of steriods Signs and Symptoms Round or full face, hump of fat between the shoulders, fatigue, thin arms and legs with large abdomen, high blood pressure, high blood glucose levels Treatment Lifestyle changes Radiation and surgery for tumor removal 215 Common Diseases and Disorders of the Endocrine System (cont.) Causes Decreased or absent production of insulin by the pancreas Obesity, high blood pressure, pregnancy, high cholesterol levels Signs and Symptoms High blood glucose levels, excessive thirst, frequent urination, increased appetite, blurred vision, slow wound healing, weight loss, foot problems, impotence in men Treatment Insulin (injection and oral tablets) Lifestyle changes Complications Kidney disease, blindness, atherosclerosis, amputations 216 Common Diseases and Disorders of the Endocrine System (cont.) Causes Underproduction of the growth hormone Trauma to pituitary gland or pituitary tumor Signs and Symptoms Short height, abnormal facial features, cleft lip or palate, delayed puberty, headache, frequent urination, thirst Treatment Administer supplemental growth hormone 217 Common Diseases and Disorders of the Endocrine System (cont.) Causes Overproduction of the growth hormone or a pituitary tumor Signs and Symptoms Very tall height, delayed sexual maturity, thick facial bones, thick skin, weakness, vision problems Treatment Medications to decrease growth hormone levels Radiation therapy or surgery for tumor 218 Common Diseases and Disorders of the Endocrine System (cont.) Causes Over production of thyroid hormones Also considered an autoimmune disorder Signs and Symptoms Exophthalmos, goiter, insomnia, weight loss, muscle weakness, increased appetite, vision problems, increased heart rate Treatment Medications Radiation and surgery to the thyroid gland 219 Common Diseases and Disorders of the Endocrine System (cont.) Causes Removal of the thyroid gland, neck radiation treatments and obesity Signs and Symptoms Weakness, fatigue, weight gain, depression, dry skin, general body aches, pale or yellow skin, slow heart rate, enlarged heart, coma Treatment Supplemental thyroid hormones Close monitoring of thyroid hormone levels 220  Apply Your Knowledge A patient enters the medical office with complaints of fatigue and body aches. You notice that the patient’s arms are thin and the abdomen appears enlarged. The physician states to you “ This looks like a case of hypercortisolism.” You realize this refers to which of the following diseases? a. Cushing’s disease b. Addison’s disease c. Diabetes mellitus 221 SENSES 222  Introduction to Senses Senses are the physiological methods of perception. Sense is a faculty by which outside stimuli are perceived. Our senses are split into two different groups. Exteroceptors: detect stimulation from the outsides of our body. For example smell, taste,and equilibrium. Interoceptors: receive stimulation from the inside of our bodies. For instance, blood pressure dropping, changes in the gluclose and Ph levels. 223  Introduction to Senses There are generally five senses; Sight (eye), hearing (ear), touch (skin), smell (nose), taste (tongue). However, it is generally agreed that there are at least seven different senses in humans, and a minimum of two more observed in other organisms. Sense can also differ from one person to the next. has to do with how the brain interprets the stimuli that are received. all have specialized sensory receptors that collect and transmit information to specific areas of the brain. 224 General Properties of Sensory Systems Stimulus Internal External Energy source Receptors Sense organs Transducer Afferent pathway CNS integration Perception 225 General Properties of Sensory Systems 226 Figure 10-4: Sensory pathways Classification of Receptors Somatic Senses – Sensations of touch, pressure, vibration, warmth, cold, pain and detection of body positions and movements Free Nerve Endings – The simplest type, having no structural specializations; examples include receptors for pain, temp. itch and tickle Special Senses – taste, smell, vision, hearing and equilibrium 227 Classification by Location 1. Exteroceptors – Located at or near the surface of the body; provide information about the external environment. 2. Interoceptors – Located in the blood vessels and viscera to provide info about internal conditions 3. Proprioceptors – Located in tendons, muscles, joints and the internal ear - Provide info about body position, muscle tension and the position and activity of our joints. 228 Classification by Stimulus 1. Mechanoreceptors – They detect mechanical pressure or stretching; related to touch, pressure, vibration, proprioception, hearing, equilibrium and blood pressure. 2. Thermoceptors – They detect changes in temperature. 229 Classification by Stimulus Cont’d 3. Nociceptors – They detect stimuli that cause physical or chemical damage to tissues. 4. Chemoreceptors – They detect chemicals in the mouth (taste), nose (smell) and body fluids. 230  Comparison of General and Special Senses General Senses Special Senses Include somatic sensations Include smell, taste, vision, (tactile, thermal, pain, and hearing and equilibrium. proprioceptive) and Anatomically distinct visceral sensations. structures and Scattered throughout the concentrated in specific body. locations in the head. Simple structures. Complex neural pathway. 231 SPECIAL SENSES 232  SENSE OF SMELL: OLFACTION Olfactory epithelium contains 10-100 million receptors. Olfactory receptor- a bipolar neuron with cilia called olfactory hairs. - Respond to chemical stimulation of an odorant molecule. Supporting cells- provide support and nourishment. Basal cells- replace olfactory receptors. 233 Olfactory Epithelium and Olfactory Receptors 234 Olfactory Epithelium and Olfactory Receptors (cont’d) 235 Olfactory Epithelium and Olfactory Receptors (cont’d) 236  PHYSIOLOGY OF SMELL The physiology of smell in humans begins in the nasal cavity. There, a huge number of receptors (over 40 million) are located in the upper roof of the cavity. The receptors have cilia projections that stick out into the cavity space. These increase the surface area and the sensitivity of the receptors. One reason for the receptor sensitivity concerns the mechanics of airflow in the nasal cavity. The air rushes in quickly (at about 250 milliliters per second) and is turbulent. Thus, not all of a particular odor will have a chance to contact a receptor. So, a receptor must be able to swiftly detect a low concentration of a molecule. The olfactory receptor cells are replaced every three to four weeks. The receptors are responsible for detecting a large number of odours (about 2,000, depending on the individual). A group of genes is known to encode proteins associated with the receptors that may function in the specific detection of an odor. There may be upwards of2371,000 very specific odor receptors.  PHYSIOLOGY OF SMELL (cont’d) Odors reach a receptor by diffusing through the air and physically contacting the receptor. Surrounding the cilia is a mucous membrane. It is into this membrane that an odor dissolves. The binding of an odor molecule to a receptor stimulates the activation of a protein called the G-protein and the release of calcium from the receptor membrane. These events begin the process whereby an electrical potential is generated. The potential constitutes the signal that is sent off to the brain. A signal is relayed to the anterior olfactory nucleus, which is essentially a collection point for the receptor signals. The signals are then routed to a region of the brain responsible for the processing of the information. This region is known as the primary olfactory cortex. Following the stimulation of a receptor, the odor molecule is rapidly destroyed and the stimulation ended. This frees the receptor for stimulation by another odor molecule. In this way the sensitivity of the smell sensory system is maintained. Dogs have a much greater sense of smell than humans. Their receptors have almost 20 times the surface area as human receptors, and there are 100 times more receptors per 238 square centimeter in a dog's nasal cavity than in a humans. SENSE OF TASTE: GUSTATION 239  Anatomy of Taste Buds and Papillae Taste bud - made of three types of epithelial cells: supporting cells, gustatory receptor cells and basal cells. About 50 gustatory cells per taste bud. Each one has a gustatory hair that projects through the taste pore. Taste buds are found in the papillae. Three types of papillae: vallate (circumvallate), fungiform and foliate. 240 241 Gustation: Sense of Taste, cont’d 242  Physiology of Gustation Five types of taste: sour, sweet, bitter, salty and umami. Tastant dissolves in saliva → plasma membrane of gustatory hair→ receptor potential→ nerve impulse via cranial nerves VII, IX and X→ medulla→ thalamus→ primary gustatory area of the cerebral cortex. 243 Gustatory Pathway 244 SENSE OF VISION OR SIGHT Visible light: 400-700 nm. 245 Accessory Structures of the Eye Eyelids or palpebrae Eyelashes and eyebrows Extrinsic eye muscles 246 Accessory Structures of the Eye 247 The Lacrimal Apparatus Tears from the lacrimal apparatus- lacrimal glands→ excretory lacrimal ducts→ lacrimal puncta→ lacrimal canals→ nasolacrimal sac→ nasolacrimal duct. 248 Anatomy of the Eyeball 249  Wall of the Eyeball Three layers: Fibrous tunic- outer layer Sclera “white” of the eye Cornea-transparent coat Vascular tunic or uvea- middle layer Choroid Ciliary body consists of ciliary processes and ciliary muscle Iris Retina- inner layer Optic disc Macula lutea- fovea centralis 250 Responses of the Pupil to Light Pupil is an opening in the center of the iris. Contraction of the circular muscles of the iris causes constriction of the pupil. Contraction of the radial muscles causes dilation of the pupil. 251  Interior of the Eyeball Lens- lack blood vessels, consists of a capsule with proteins (crystalline) in layers; transparent. Lens divides the eyeball into two cavities: anterior and posterior. Anterior cavity- further divided into anterior and posterior chambers. Both are filled with aqueous humor. Posterior cavity (vitreous chamber)-filled with vitreous body. 252 Cavities of the Eyeball 253 Refraction of Light Rays Refraction is the bending of light rays. The cornea and lens refract light rays. 254 Accommodation and the Near Point of Vision Increase in the curvature of the lens for near vision is called Accommodation. Near point of vision is the minimum distance from the eye that an object can be clearly focused. 255  Refraction Abnormalities and their Correction Nearsightedness (myopia)- close objects seen clearly. Image is focused in front of the retina. Correction- use of concave lens. Farsightedness (hyperopia)- distant objects seen clearly. Image is focused behind the retina. Correction- use of convex lens. 256 257  Rods and Cones Named after the shapes of their outer segments. Rod Cones - three types: red, green and blue. Outer segment- contains photopigments. Transduction of light energy into receptor potential occurs here. Inner segment- contains the nucleus, Golgi complex and mitochondria. 258  Structure of Rod and Cone Photoreceptors 259  Photopigments Two parts: opsin (four types, three in the cones and one in the rod) retinal (light absorbing part). Rhodopsin - photopigment in rods. Cone photopigments - three types. Absorption of light by a photopigment → structural changes. 260  Rod disc in outer segment Rhodopsin molecule Light Disc cis- membrane retinal Bleaching and 4 Cis-retinal binds to opsin (regeneration) opsin 1 Isomerization of retinal Regeneration of cis- Colored photopigment trans- (rhodopsin) retinal Photopigment retinal trans- opsin retinal opsin 3 Retinal 2 Trans-retinal isomerase separates converts trans- from opsin to cis-retinal opsin (bleaching) 261 Colorless products  Bleaching and Regeneration of Photopigment 1. Isomerization: In darkness, retinal has a bent shape called cis-retinal. Absorption of photon causes straightening of the retinal (trans-retinal). 2. Bleaching: trans-retinal separates from opsin. 3. Regeneration: trans-retinal→ cis-retinal. 262  Light and Dark Adaptation Light adaptation: Dark → light. Faster. Dark adaptation: Light →dark. Slow. Cones regenerate rapidly whereas rhodopsin regenerates more slowly. 263 Operation of Rod Photoreceptors 264  Color Blindness and Night Blindness Color blindness- inherited inability to distinguish between certain colors. Result from the absence of one of the three types of cones. Most common type: red-green color blindness. Night blindness or Nyctalopia- vitamin A deficiency. 265  Processing of Visual Input Receptor potential in rods and cones→ graded potentials in bipolar neurons and horizontal cells→ nerve impulses in ganglion cells→ optic nerve→ optic chiasm→ optic tract→ thalamus→ primary visual area of cerebral cortex in occipital lobe. 266  Visual Pathway Visual field of Visual field of left eye right eye Temporal Nasal Nasal Temporal half half half half Left eye Right eye Nasal retina Temporal Nasal Temporal retina 1 retina retina 3 1 3 4 Optic 4 2 tract 2 Midbrain Midbrain 5 5 Lateral geniculate nucleus of the thalamus Optic 6 Optic radiations 6 radiations Primary visual area of cerebral cortex (area 17) in occipital lobe Left eye and its pathways Right eye and its pathways 267  Physiology of Sight Sight begins when light rays from an object enter the eye through the cornea; the cornea is actually responsible for about sixty percent of the eyeball’s light-ray-bending capability. The cornea’s refractive power bends the light rays in such a way that they pass freely through the pupil, the size-changing hole in the iris. The iris, works like a shutter in a camera. It has the ability to enlarge and shrink, depending on how much light the environment is sending into the pupil. After passing through the iris, the light rays strike the eye’s crystalline lens. This clear, flexible structure works much like the lens in a camera – shortening and lengthening its width in order to focus light rays properly. 268  Physiology of Sight, cont’d In a normal eyeball, after exiting the back of the lens, the light rays pass through the vitreous; the vitreous humor helps the eye hold its spherical shape. Finally, the light rays land and come to a sharp focusing point on the retina, which is responsible for capturing all of the light rays, processing them into light impulses through millions of tiny nerve endings, then sending these light impulses through over a million nerve fibers to the optic nerve. The optic nerve is sort of like an extension of the brain. The light impulses travel through this nerve fiber to the brain, where they are interpreted as an image. 269  SENSE OF HEARING AND BALANCING The ear is the organ of hearing and balancing 270  Anatomy of the Ear Three main regions: External (outer) ear- auricle or pinna, external auditory canal, and tympanic membrane. Ceruminous glands- Middle ear- auditory ossicles: malleus, incus and stapes. Auditory (eustachian) tube. Internal (inner) ear- Labyrinth: bony and membranous. Bony labyrinth- perilymph and membranous labyrinth- endolymph. Oval window and round window- membranous regions. 271 Anatomy of the Ear 272 The Middle Ear and the Auditory Ossicles 273 The Internal Ear 274  The Internal Ear Three parts: the semicircular canals, the vestibule (both contain receptors for equilibrium) and the cochlea (contains receptors for hearing). Semicircular canals: anterior, posterior and lateral. Ampulla- Vestibule consists of two sacs: utricle and saccule. 275 Semicircular Canals, Vestibule and Cochlea 276  Semicircular Canals, Vestibule and Cochlea 277  Cochlea Snail-shaped. Section through the cochlea shows three channels: cochlear duct, scala vestibuli and scala tympani. Helicotrema Vestibular membrane Basilar membrane Spiral organ or Organ of Corti- hair cells. 278  Physiology of Hearing Audible sound range: 20-20,000 Hz. Sound waves→ auricle→ external auditory canal→ tympanic membrane→ malleus→ incus→ stapes→ oval window→ perilymph of the scala vestibuli→ vestibular membrane→ endolymph in the cochlear duct→ basilar membrane →hair cells against tectorial membrane → bending of hair cell stereocilia→ receptor potential→ nerve impulse. 279 Events in the Malleus Incus Stapes vibrating in oval window Helicotrema Cochlea Stimulation Sound waves Perilymph of Auditory Receptors 3 4 7 8 Scala tympani Scala 5 vestibuli 6 Basilar 1 2 9 membrane External auditory 8 canal Spiral organ (organ of Corti) Tectorial membrane Vestibular membrane Cochlear duct (contains endolymph) Tympanic membrane Secondary tympanic membrane vibrating in round window Middle ear Auditory tube 280 The Auditory Pathway 281  Physiology of Equilibrium Two types of equilibrium: Static- maintenance of the body position relative to the force of gravity. Dynamic- maintenance of body position (mainly head) in response to rotational acceleration and deceleration. Receptors for equilibrium are hair cells in the utricle, saccule and semicircular canals and are collectively called vestibular apparatus. 282 Location and Structure of Receptors in the Maculae 283  Otolithic Organs: Saccule and Utricle Macula- small thickened regions within the saccule and utricle. Sensory structures for static equilibrium. Also detect linear acceleration and deceleration. Contain hair cells and supporting cells. Stereocilia and kinocilium together called hair bundle. Otolithic membrane rests on the hair cells and contain otoliths. 284  Physiology of Equilibrium, cont’d Tilting of the head forward→ sliding of the otolithic membrane bending the hair bundles→ receptor potential→ vestibular branch of the vestibulocochlear nerve. 285 Location and Structure of the Semicircular Ducts 286  Semicircular Ducts Crista, a small elevation in the ampulla contain hair cells and supporting cells. Cupula, a mass of gelatinous material covering the crista. Head movement→ semicircular ducts and hair cells move with it→ hair bundles bend→ receptor potential→ nerve impu