Urinary System Notes PDF

Urinary System Fluid, Electrolyte, and Acid-Base Balance  LEARNING OUTCOMES Identify the organs of the urinary system and their functions. Identify the parts of a nephron and the functional significance of each Evaluate basic arterial blood gas analysis resu...

Urinary System Fluid, Electrolyte, and Acid-Base Balance  LEARNING OUTCOMES Identify the organs of the urinary system and their functions. Identify the parts of a nephron and the functional significance of each Evaluate basic arterial blood gas analysis results. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 2  Anatomy and Physiology, 1e Chapter 25: The Urinary System Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 3 Functions of the Urinary System Section 25.1 Learning Objective 25.1.1 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 4  Urinary System Functions Production, storage, and transportation of urine Filtration of blood and waste removal pH regulation of bodily fluids Blood pressure regulation Regulation of solute concentration in blood Stimulation of erythrocyte production Vitamin D synthesis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 5 Gross and Microscopic Anatomy of the Kidney Section 25.2 Learning Objectives 25.2.1–25.2.7 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 6  The Kidneys (Figure 25.1) Paired, retroperitoneal organs located on either side of the vertebral column Not within abdominal cavity Right kidney is slightly lower than left because it is displaced by the liver Protected by muscle, adipose, and ribs Adrenal glands located on superior margin Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 7 External Layers of the Kidneys (Figure 25.2) Fibrous capsule maintains shape of kidney Perinephric fat absorbs shock and provides protection Renal fascia anchors kidneys to posterior abdominal wall Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 8  Internal Anatomy (Figure 25.3A) Superficial renal cortex covers deeper renal medulla Renal medulla includes the renal pyramids and the renal columns Renal columns separate renal pyramids of medulla Also divide kidney into 6 to 8 renal lobes Renal papillae drain urine into minor calyces Minor calyces merge to form major calyces Major calyces merge to form renal pelvis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 9  The Renal Hilum (Figure 25.4) Located on medial side of each kidney Entry and exit site for structures that supply kidney Renal artery Renal vein Renal nerve Ureter Lymphatics Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 10  Nephrons and Blood Supply (Figure 25.5) Nephron—functional unit of kidney Arteries—renal, segmental, interlobar, arcuate, interlobular Nephron—afferent arterioles, glomeruli, efferent arterioles, peritubular capillaries Veins—interlobular, arcuate, interlobar, renal Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 11  Blood Flow in the Nephron (Figure 25.6) Afferent arterioles deliver blood to nephron Within nephron, glomerular capillaries filter blood Fenestrated capillaries Bloods exits via efferent arterioles Peritubular capillaries accomplish exchange of nutrients and wastes Vasa recta drains peritubular capillaries Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 12  Nephrons (Figure 25.7) Functional units of the kidney that make urine Two components Renal corpuscle Composed of glomerulus and glomerular capsule Tubular system Proximal convoluted tubule, nephron loop, distal convoluted tubule, collecting ducts Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 13  Renal Corpuscle (Figure 25.8) Responsible for filtration of blood Forms filtrate Composed of: Glomerulus = fenestrated capillary Glomerular capsule—captures filtrate Parietal layer made of simple squamous epithelium Visceral layer made of podocytes Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 14  The Glomerulus (Figure 25.9) A fenestrated capillary Fenestrations located in endothelium of glomerulus Allow additional volume of blood and larger substances to be filtered in same amount of time Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 15  Filtration Membrane (Figure 25.10) Limits filtration of blood cells, platelets and large plasma proteins Negative charge of membrane limits filtration of negatively charged molecules Composed of: Fenestrated endothelium of glomerulus Basement membrane Filtration slits formed by pedicels of podocytes Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 16  Tubular System (1 of 2) (Figure 25.11) Refines filtrate into urine Proximal convoluted tubule (PCT) Actively secretes and reabsorbs solutes Nephron loop Divided into descending limb and ascending limb Each limb has unique permeability for solute and water Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 17  Tubular System (2 of 2) Distal convoluted tubule (DCT) Farther away from renal corpuscle Reabsorbs and secretes fewer solutes and less water Collecting ducts Not part of nephron but can influence solute and water reabsorption Usually occurs under hormonal influences DCTs of several nephrons empty into the same collecting duct Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 18  Aquaporins (Figure 25.12) Membrane proteins that allow water through Water movement occurs via osmosis Water moves toward area of greater osmolarity Not all sections of renal tubule contain aquaporins Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 19  Renal Cortex versus Renal Medulla (Figure 25.13) Renal cortex Contains majority of nephron structures Glomeruli/renal corpuscles Most proximal and distal convoluted tubules Renal medulla Contains parts of nephron loops and collecting ducts Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20  Cortical versus Juxtamedullary Nephrons (Figure 25.14) Cortical nephrons are the majority of the nephrons in the kidney (85%) Renal corpuscles located closer to renal capsule Shorter nephron loops Juxtamedullary nephrons (15%) have renal corpuscles closer to medulla Longer nephron loops with vasa recta Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 21  Physiology of Urine Formation Section 25.3 Learning Objectives 25.3.1–25.3.11 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 22  Processes of Urine Formation Production of urine depends on three processes carried out by the kidneys: Filtration Accomplished by renal corpuscles Plasma is filtered by glomerulus to form filtrate Reabsorption and secretion Accomplished by renal tubule Reabsorption returns filtered materials to blood Secretion removes additional materials from blood into renal tubule Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 23  Glomerular Filtration Filtration occurs as plasma is filtered into capsular space Nonspecific process based on size Occurs via bulk driven by net filtration pressure (NFP) Influenced by glomerular hydrostatic pressure, blood colloid osmotic pressure, and capsular hydrostatic pressure Glomerular filtration rate (GFR)—volume of filtrate formed per minute by both kidneys Average is 80–140 mL/minute at rest Highly variable to due gender, age, diet, metabolism Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 24 The stages of kidney disease, also known as chronic kidney disease (CKD), are: Stage 1: Kidney damage, but normal or increased glomerular filtration rate (GFR) of 90 or higher Stage 2: Mild kidney damage, with a GFR of 60–89 Stage 3a: Moderate kidney damage, with a GFR of 45–59 Stage 3b: Moderate to severe kidney damage, with a GFR of 30–44 Stage 4: Severe kidney damage, with a GFR of 15–29 Stage 5: Kidney failure, with a GFR of less than 15 or dialysis  Pressures that Influence Glomerular Filtration (Figure 25.15) Glomerular hydrostatic pressure promotes filtration into the capsule Capsular hydrostatic pressure and blood colloid osmotic pressure promote movement into glomerulus Movement occurs in the direction of lower pressure Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 26  Influences on GFR GFR influenced by various factors Hypertension damages glomeruli and filtration membrane Larger openings allow filtration of additional solutes including plasma proteins Disease: Nephritis = inflammation of nephron May be caused by infection May harden and narrow the lumen of the tubules Interferes with flow of filtrate through tubule and decreases GFR Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 27  Tubular Reabsorption and Secretion Filtrate must be refined into urine by: Tubular reabsorption—filtered substances reabsorbed from tubules back into blood Tubular secretion—wastes secreted from blood into tubular fluid to become part of urine Most filtered materials are reabsorbed Materials not reabsorbed become part of urine Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 28 Reabsorption and Secretion Within Renal Tubule (Figure 25.17) Kidneys form ~180 liters of filtrate per day Most water and solutes are reabsorbed PCT, nephron loop, and DCT reabsorb most water Collecting ducts vary in amount of water reabsorbed Solutes reabsorbed at various points in tubule Molecules secreted become a part of urine Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 29  Substances Secreted or Reabsorbed in the Nephron (Table 25.1) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 30 Mechanisms of Reabsorption and Secretion Mechanisms include Simple diffusion, facilitated diffusion, primary active transport, secondary active transport, and osmosis If transport requires use of membrane channel or protein, it is subject to Specificity—can only transport specific molecules Transport maximum (Tmax)—maximal rate of transportation if all transporters occupied Competition—similar molecules may compete for transporter Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 31  Transportation Routes (Figure 25.18) Reabsorption may occur between tubular cells or through them Luminal surface = surface of cell that faces lumen of renal tubule Basolateral surface = surface that faces interstitial fluid/peritubular capillaries Different forms of transport used for each surface Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 32  Reabsorption and Secretion in PCT Most solute and water reabsorption occurs in PCT All glucose and amino acid reabsorption occurs in PCT Sodium, bicarbonate, and calcium reabsorption occurs too Sodium (Na+) symporters provide energy for secondary active transport of glucose and amino acids Diffuse through basolateral membrane after entering tubular cells Water passively follows solutes via osmosis Secretion of excess urea, ammonia, creatinine, and acid Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 33  Sodium Reabsorption (Figure 25.19) Luminal transport occurs via facilitated diffusion No energy input required Basolateral transport occurs via active transport Sodium ions are transported from low to high concentration Sodium-potassium pumps in basolateral surface Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 34  Reabsorption of Glucose and Water (Figure 25.20) Sodium symporters in luminal surface transport sodium and glucose into tubular cell Sodium moves across basolateral surface by sodium- potassium pumps; glucose by facilitated diffusion Amino acids reabsorbed in similar way As osmolarity of IF and blood increases, water reabsorbed by osmosis via aquaporins Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 35 Reabsorption of Bicarbonate (Figure 25.21) Sodium-hydrogen antiporter in luminal surface transports sodium ions into tubular cell and hydrogen ions into tubular lumen Carbonic anhydrase combines hydrogen and bicarbonate ions to form carbonic acid Carbonic acid dissociates to form carbon dioxide and water Carbon dioxide enters tubular cell and is converted back into bicarbonate for reabsorption Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 36  Reabsorption and Secretion in Nephron Loop Descending limb contains aquaporins for water reabsorption Ascending limb actively reabsorbs solute ions, especially Na+ and Cl- Builds osmotic gradient for water reabsorption from descending limb Countercurrent multiplier system As filtrate moves through nephron loop solute pumps in ascending multiply osmotic gradient to increase water reabsorption Structure of vasa recta allows nutrient and waste exchange without disruption of osmotic gradient Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 37  Descending and Ascending Nephron Loop (Figure 25.22B and 25.22C) Descending loop contains permanent aquaporins Osmolarity of tubular fluid increases as water moves into interstitium Thick ascending loop impermeable to water Symporters transport sodium and chloride ions into interstitium Osmolarity of tubular fluid decreases Creates osmotic gradient for movement of water Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 38 Epithelial Cells of Ascending Nephron Loop (Figure 25.23) Thick ascending limb transports solutes Sodium and chloride ions are transported into epithelial cell Movement of chloride ions builds up negative charge in interstitial fluid (IF) Attracts additional cations for reabsorption Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 39  Understanding the Countercurrent Multiplier (Figure 25.24) Actions of nephron loop referred to as countercurrent multiplier Multiplies osmolarity of IF Countercurrent multiplier train analogy Solutes pulled out from earlier cars Influences latter cars Creates osmotic gradient that pulls water from descending nephron loop Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 40  Reabsorption and Secretion in DCT Reabsorption varies according to physiological needs Sodium and chloride ion reabsorption occurs Water passively follows sodium and chloride Parathyroid hormone (PTH) will increase calcium reabsorption here Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 41  Juxtaglomerular Apparatus (1 of 2) Juxtaglomerular apparatus (JGA) regulates glomerular blood hydrostatic pressure Allows kidneys to autoregulate glomerular filtration rate (GFR) Composed of: Macula densa—cells in the DCT Regulates release of renin to control blood pressure Responds to elevated GFR by decreasing release of nitric oxide Lowers GFR as afferent arteriole constricts Juxtaglomerular (JG) cells—smooth muscle cells in afferent arteriole Respond to elevated GFR by constricting afferent arteriole to reduce GFR Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 42  Collecting Ducts and Recovery of Water Collecting ducts regulate urine volume, urine osmolarity, and blood osmolarity Principal cells – reabsorb sodium ions and secrete potassium ions Intercalated cells – reabsorb potassium and bicarbonate ions; secrete hydrogen ions Alters osmolarity of blood by varying reabsorption of water If blood is hyperosmotic, reabsorption of water increases If blood is hypoosmotic, reabsorption of water decreases Regulated by hormones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 43  Homeostasis and Control Over the Formation of Urine Section 25.4 Learning Objectives 25.4.1–25.4.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 44  Renin-Angiotensin-Aldosterone Pathway (Figure 25.26) Increases blood pressure to maintain GFR Renin released by JG cells when BP is low Converts angiotensinogen into angiotensin I Angiotensin I converted to angiotensin II by ACE in lungs Angiotensin II causes vasoconstriction and aldosterone release Aldosterone increases Na+ and water reabsorption Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 45  Antidiuretic Hormone (ADH) Increases water reabsorption by the kidney Promotes insertion of aquaporins in collecting duct Increased water reabsorption leads to higher blood pressure Vasoconstriction also leads to increased blood pressure Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 46  Natriuretic Hormones Main example is atrial natriuretic hormone (ANH) Stimulates excretion of sodium Excretion of sodium increases water loss in urine Leads to lower blood pressure Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 47 Hormones that Influence GFR and RBF (Table 25.2) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 48  Additional Endocrine Activities of the Kidney Section 25.5 Learning Objectives 25.5.1–25.5.3 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 49  Vitamin D Synthesis Vitamin D synthesized by skin in response to UV radiation Most active form of vitamin D is calcitriol Kidney coverts precursor from skin to calcitriol Aids in absorption of calcium from digestive tract and reabsorption of calcium by kidneys Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 50  Erythropoiesis Kidney releases erythropoietin (EPO) in response to hypoxemia EPO stimulates production of red blood cells Production occurs in red bone marrow Kidney damage may lead to anemia Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 51  Calcium Reabsorption DCT contains receptors for PTH PTH causes cells in DCT to upregulate calcium channels Increased calcium channels lead to increased reabsorption of calcium Active forms of vitamin D aids b transporting calcium to basolateral membrane for exocytosis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 52  Gross and Microscopic Anatomy of the Urinary Tract (Ureters, Urinary Bladder, and Urethra) Section 25.6 Learning Objectives 25.6.1–25.6.6 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 53  The Urinary Tract (Figure 25.27) Urine flows from kidneys to: Ureters Exit kidneys and transport urine to urinary bladder Urinary bladder Temporarily stores urine Urethra Allows urine to exit body Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 54  Ureters (Figure 25.28) Transport urine from kidneys to urinary bladder Retroperitoneal location Lined by transitional epithelium Urine moves through ureters by peristalsis and gravity Physiological sphincter prevents reflux of urine Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 55  Urinary Bladder (Figure 25.29) Receives urine via ureteral openings Stores urine until eliminated from body Lined by transitional epithelium Walls contain detrusor muscle Internal urethral orifice Surrounded by internal urethral sphincter, which is composed of smooth muscle and is involuntary External urethral sphincter is composed of skeletal muscle and is under voluntary control Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 56  Urinary Bladder and Urethra in Biological Females (Figure 25.30A) Urinary bladder anterior and inferior to uterus Uterus may compress bladder in pregnancy Shorter urethra increases risk of cystitis (urinary tract infection) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 57  Urinary Bladder and Urethra in Biological Males (Figure 25.30B) Urinary bladder located superior to prostate gland Enlargement of prostate gland may restrict flow of urine into urethra Longer urethra passes through prostate gland, floor of pelvis, and penis Longer urethra decreases risk of cystitis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 58  Micturition Reflex Proper term for urination Urine entering bladder causes distention (stretching) of bladder Parasympathetic stimulation causes detrusor muscle to contract Relaxation of internal urethral sphincter allows urine to flow into urethra External urethral sphincter is skeletal muscle Spinal reflex relaxes it to allow urine to continue to flow and exit urethra Control achieved during “potty training” Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 59  Nerves Involved in Urination (Figure 25.31) Pudendal nerve regulates voluntary micturition (urination) by regulating external urethral sphincter Pelvic and hypogastric nerves innervate urinary bladder Sympathetic hypogastric inhibits detrusor muscle contraction Parasympathetic pelvic increases contraction of detrusor muscle Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 60  The Male Urethra (Figure 25.32) Biological male urethra is substantially longer than biological female urethra Divided into three sections: Prostatic, membranous, and spongy urethra Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 61 Urine Characteristics and Elimination Section 25.7 Learning Objective 25.7.1 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 62  Characteristics of Urine (Table 25.3) Characteristics of urine change depending on factors like water intake, exercise, and nutrient intake pH range is 4.5–8.0 Glucose, blood, and protein not found in normal urine Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 63  Urinalysis Urinalysis—a test that evaluates materials found in urine Abnormal components of urine: Protein—usually indicates damage to filtration membrane Glucose—usually indicates diabetic condition Blood—indicates structural damage to urinary tract Leukocytes—indicates urinary tract infection Ketones—indicates body is using fat as energy source Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 64  Case Study Activity 1 Malcom is a diabetic. Unfortunately, he has forgotten to take his insulin. During class, Malcom became disoriented, passed out, and was rushed to the emergency department. A urinalysis revealed that his urine had an acidic pH, glucose, and ketones. Can you identify what caused Malcom to pass out? What is the term to indicate glucose present in urine? Explain the presence of ketones in Malcom’s urine. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 65  Case Study Activity 1 Answer Can you identify what caused Malcom to pass out? Without insulin, Malcom’s body could not metabolize glucose. His body began to metabolize lipids as an alternate source of energy, leading to formation of ketones and acid. The increased levels of acid, called acidosis, led to his loss of consciousness. What is the term to indicate glucose present in urine? Glucosuria Explain the presence of ketones in Malcom’s urine. Ketones are produced by the metabolism of lipids. As Malcom’s metabolism of lipids increased, more ketones were produced, and they ended up in his urine. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 66  Summary By the end of this chapter, you should be able to: Discuss the functions of the urinary system. Describe the anatomy of the organs in the urinary system. Discuss physiology of urine formation. Discuss hormonal regulation of urine production. Discuss the micturition reflex. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 67  Anatomy and Physiology, 1e Chapter 26: Fluid, Electrolyte, and Acid-Base Balance Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 68  Body Fluids and Fluid Compartments Section 26.1 Learning Objectives 26.1.1–26.1.5 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 69  Aqueous Solution Internal environment of the human body is an aqueous (watery) solution Water is the major solvent in the body Contains dissolved substances called solutes Proteins Carbohydrates Electrolytes—any mineral with a charge Na+, Cl−, K+, Ca++ Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 70  Water Movement in the Human Body Water moves between different body compartments via osmosis Movement of water is a result of osmotic gradients Moves from areas of lower solute concentration (high water concentration) to areas of higher solute concentration (low water concentration) Water will enter cells if water concentration is higher outside of cells Water will exit cells if water concentration is higher inside of cells Balance of solutes and water inside and outside of cells must be maintained Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 71  Body Water Content (Figure 26.2) Majority of body mass is water Varies with age: Infants ~75% of body mass is water Adults 50–60% of body mass is water Water content varies with location: Teeth and adipose 8–10% water Brain and kidneys 80–85% water Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 72  Fluid Compartments (Figure 26.3) Contain body fluids; separated from other compartments by a physical barrier Intracellular Fluid (ICF)—all fluid within cells Extracellular Fluid (ECF)—fluid that surrounds all cells Plasma and interstitial fluid (IF) are two major divisions of ECF Total body water—sum of ICF and ECF Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 73  Intracellular Fluid (Figure 26.4) Two-thirds of total water in human body Mainly cytosol and cytoplasm found in cells Regulated to maintain health of cells: Too much fluid causes cells to lyse Too little fluid causes cells to shrink Also lack water for chemical reactions Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 74  Extracellular Fluid One-third of total water in human body 20% of ECF is plasma 80% of ECF is interstitial fluid (IF) Includes cerebrospinal fluid (CSF), lymph, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, and aqueous humor Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 75  Total Body Water (TBW) The sum of intracellular fluid (ICF) and extracellular fluid (ECF) Varies from one individual to the next Hormones like estrogen increase water retention and increase TBW Progesterone promotes water loss in urine to decrease TBW Higher amounts of adipose tissue decrease TBW Adipose contains lipids and less water Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 76  Application: Edema Accumulation of excess water in tissues Can be caused by: Increased filtration or inadequate reabsorption by blood capillaries Impaired absorption of IF by lymphatic system Forms of edema include peripheral pitting edema and pulmonary edema Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 77  Composition of Bodily Fluids (Figure 26.5) Plasma and interstitial fluid (IF) are similar in composition Major difference is lower protein concentration in IF versus plasma ICF has higher concentration of potassium, phosphate, magnesium, and protein than ECF Bodily fluids are electrically neutral Maintained by sodium-potassium pumps Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 78 The Sodium-Potassium Pump (Figure 26.6) Maintains high levels of potassium and low levels of sodium in ICF Uses ATP to pump sodium out of cells Potassium enters cells Helps maintain electrical neutrality of bodily fluids Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 79  Fluid Movement Between Compartments (1 of 2) Hydrostatic and osmotic pressure gradients determine where fluid will move Hydrostatic pressure exerted by fluids Osmotic pressure exerted by solutes in fluids Movement occurs at capillaries If hydrostatic pressure is greater than osmotic pressure, fluid leaves capillary Amount of fluid filtered is proportional to size of gradient Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 80  Fluid Movement Between Compartments (2 of 2) Osmotic gradients draw fluid toward areas of higher solute concentration Water moves toward areas of greater solute concentration or lower water concentration Water moves between ICF and ECF due to osmosis Water will move between compartments to replace water that tissues have lost Occurs during sweating as water leaves blood to replace water lost by sweat glands May lead to dehydration Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 81  Capillary Exchange (Figure 26.7) Hydrostatic pressure is greater at arterial end of capillary Forces fluid from capillary into IF Hydrostatic pressure decreases at venous end Osmotic pressure dominates and IF enters capillary Exchange is uneven; excess IF is drained by lymphatic system Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 82  Plasma, Interstitial Fluid (IF), and Lymph (Figure 26.8) Plasma exits blood capillaries and becomes IF IF that is not reabsorbed enters lymphatics and becomes lymph Ultimately returned to the blood via subclavian veins This is analogous to water drainage system of a fountain Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 83  Sweating (Figure 26.9) Sweating influences water movement between compartments Water from IF enters gland to become part of sweat Water from blood moves into IF to replace lost water As more water is removed, dehydration may result Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 84  Solute Movement Between Compartments (Figure 26.10) Active transport can be used to move solutes against a concentration gradient Requires energy Passive mechanisms can be used to allow solutes to move down a concentration gradient Simple diffusion Facilitated diffusion Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 85  Water Balance Section 26.2 Learning Objectives 26.2.1–26.2.7 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 86  Regulation of Water Intake (1 of 2) (Figure 26.11) Water loss should be roughly balanced by water intake daily ~2.5L lost and ~2.5L taken in daily Water gained by ingestion (main method) and cellular respiration Water intake regulated by osmoreceptors in hypothalamus Stimulates thirst when blood osmolarity is high Releases ADH to conserve water Decreases salivation to conserve water and promote thirst Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 87  Regulation of Water Intake (2 of 2) (Figure 26.11) Blood volume also influences water intake Low blood volume leads to low blood pressure Detected by baroreceptors Stimulates release of hormones, angiotensin II and aldosterone to increase blood volume Angiotensin II stimulates thirst Aldosterone stimulates sodium and water reabsorption by kidney Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 88  Dehydration Results from inadequate fluid intake or excessive fluid loss May be due to excessive sweating, diarrhea, vomiting, or hemorrhage Leads to lack of water for metabolic reactions Decreased blood pressure and possible shock Severe dehydration (>10% total body water loss) is considered a medical emergency May lead to loss of consciousness, coma, or death Fast rehydration orally or via IV required Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 89  Diuresis Production of high volumes of urine Typically occurs when water intake is high or excessive Excess fluid is shed in urine Diuretics = medications that increase urine output Decrease blood volume and blood pressure Used to treat hypertension and congestive heart failure Alcohol functions as a diuretic by inhibiting ADH release Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 90  Water Intoxication Results from consumption of too much pure water Water without electrolytes Consuming pure water decreases osmolarity of ECF Leads to increased volume of fluids like CSF Manifests as intracranial edema The cranial cavity is unable to accommodate increased volume Pressure placed on brain and brainstem may become deadly Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 91  Regulation of Water Output Water is lost via urination (main method), defecation, evaporation, sweating, and exhalation Excessive water loss can lead to decreased blood pressure If blood pressure falls too low, body may go into shock Hypothalamus detects loss with osmoreceptors If blood osmolarity is too high, antidiuretic hormone (ADH) is released Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 92  Role of ADH (Figure 26.12) Antidiuretic Hormone (ADH) released in response to elevated blood osmolarity Promotes insertion of aquaporins in collecting ducts Allows kidneys to reabsorb additional water Also promotes vasoconstriction of arterioles Increases blood pressure Increases flow of blood to core organs to prevent shock Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 93  Electrolyte Balance Section 26.3 Learning Objectives 26.3.1–26.3.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 94  Role of Electrolytes The ions of the body aid in various functions: Transmission of action potentials Enzymatic function Urine formation Muscle contraction Release of hormones from endocrine glands pH regulation Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 95 Roles of the Big Six Ions (Table 26.1) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 96 Reference Values for the Big Six Ions (Table 26.2) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 97  Sodium Most common ion in ECF Plays a role in action potentials, urine formation, bodily fluid osmolarity, muscle contraction, and membrane transport Excess is cleared in urine Hyponatremia—low blood levels of sodium Hypernatremia—high blood levels of sodium Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 98  Potassium Most common ion in ICF Plays a role in resting membrane potential, action potentials, and muscle contraction Hypokalemia—low blood levels of potassium Hyperkalemia—high blood levels of potassium Can disrupt functioning of nervous system, heart, and skeletal muscles Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 99  Chloride Most common anion in ECF Plays a role in osmotic balance between ICF and ECF, electrical balance of ECF, and neuronal functioning Is also a component of hydrochloric acid in the stomach Hypochloremia—low blood levels of chloride Hyperchloremia—high blood levels of chloride Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 100  Bicarbonate Most common anion in blood Plays a role in buffering the pH of the bodily fluids Carbon dioxide is converted into bicarbonate for transport Conversion occurs in red bloods cells using the enzyme carbonic anhydrase Converted back into carbon dioxide in the lungs for exhalation Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 101  Calcium Mainly contained within bones and teeth Plays a role in muscle contraction, neurotransmitter release, enzyme activity, and blood clotting Absorbed via the intestine using active form of vitamin D Hypocalcemia—low blood levels of calcium Hypercalcemia—high blood levels of calcium Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 102  Phosphate Present in three ionic forms within the body Major component of ICF Component of the matrix of bone and teeth, phospholipids, ATP, nucleotides Plays a role in buffering body fluids Hypophosphatemia—low blood levels of phosphate Hyperphosphatemia—high blood levels of phosphate Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 103  Regulation of Sodium and Potassium (Figure 26.13) Homeostatic range maintained by kidneys Excess of either ion is released in urine Kidneys reabsorb more if the level of either ion is low Angiotensin II and aldosterone help the kidney regulate sodium and potassium levels in the blood Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 104  Regulation of Calcium and Phosphate (Figure 26.14) Regulated by hormones: Parathyroid hormone—increases blood calcium and decreases blood phosphate Stimulates osteoclasts to release calcium from bone matrix Calcitriol—most active form of Vitamin D Aids in calcium absorption in the intestine Calcitonin—decreases blood calcium levels Calcium removed from blood and incorporated into bony matrix Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 105  Acid-Base Balance Section 26.4 Learning Objectives 26.4.1–26.4.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 106  pH Scale (Figure 26.15) Maintaining acid-base balance is critical for physiological function Enzymes fail to function if balance not maintained pH scale is a measurement of the hydrogen ion (H+) concentration Blood pH range is 7.35–7.45 Buffers prevent rapid changes in pH Quickly donate hydrogen ions or remove them from solution Limited capacity Respiratory and urinary systems also help maintain acid-base balance Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 107  Protein Buffer Proteins can use amino acids to buffer pH Amino group can accept hydrogen ions if pH is too acidic Carboxyl group can donate hydrogen ions if pH is too alkaline Aids in buffering pH of blood and ICF Protein component of hemoglobin buffers red blood cells during formation of bicarbonate ions Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 108  Bicarbonate-Carbonic Acid Buffer Bicarbonate ions and carbonic acid provide buffering for blood and IF Bicarbonate ions can accept hydrogen ions when pH is too acidic Carbonic acid can donate hydrogen ions when pH is too alkaline Since bicarbonate ions can be converted into carbon dioxide, acid can be eliminated by exhalation Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 109  Respiratory Regulation of Acid-Base Balance (Figure 26.16) Changes in breathing can alter pH If pH is too acidic, hyperventilation occurs As carbon dioxide is exhaled, more carbonic acid is converted into CO2 and exhaled If pH is too alkaline, hypoventilation occurs Retained carbon dioxide is converted into hydrogen ions Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 110  Renal Regulation of Acid-Base Balance (Figure 26.17) Kidneys can alter secretion of hydrogen and reabsorption of bicarbonate ions If pH is too acidic, kidneys increase secretion of hydrogen ions and reabsorption of bicarbonate ions If pH is too alkaline, kidneys decrease secretion of hydrogen ions and reabsorption of bicarbonate ions Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 111 Acid-Base Homeostasis Section 26.5 Learning Objectives 26.5.1–26.5.5 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 112  pH Imbalances (Figure 26.18) Acidosis—blood pH below 7.35 May lead to suppression of nervous system activity, coma, shortness of breath, and arrhythmias Alkalosis—blood pH above 7.45 May lead to light-headedness, coma, tremors, and twitching Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 113  Metabolic Acidosis Occurs when blood pH is below 7.35 Due to loss of bicarbonate or intake of excess acid (hydrogen ion) Common causes include severe diarrhea, aspirin intoxication, and diabetic ketoacidosis – lactic acidosis from extreme exercise Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 114  Metabolic Alkalosis Occurs when blood pH is above 7.45 Due to presence of excess bicarbonate ions Usually due to loss of acid (hydrogen ions) Common causes include vomiting of stomach contents, antacid overdose or abuse, and gastric suctioning Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 115  Respiratory Acidosis Occurs when blood pH is below 7.35 Due to inadequate ventilation of the lungs Leads to increased carbon dioxide level in the blood As carbon dioxide is converted into bicarbonate ion, excess acid is produced Common causes include emphysema, pneumonia, and congestive heart failure Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 116  Respiratory Alkalosis Occurs when blood pH is above 7.45 Due to excessive ventilation of the lungs Usually hyperventilation Excessive exhalation of carbon dioxide leads to removal of hydrogen ions from blood Common causes include anxiety attacks, high altitude sickness, fever, and infections Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 117 Causes of Metabolic and Respiratory Acidosis and Alkalosis (Figure 26.19) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 118  Respiratory Compensation Adjustment in breathing rate in an attempt to correct pH imbalance Can compensate for metabolic imbalances within minutes Hyperventilation occurs for acidosis Hypoventilation occurs for alkalosis Limited ability to compensate Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 119  Metabolic Compensation Response of the kidneys to pH imbalances Aids in compensation of respiratory imbalances, but may take several hours to three days Acidosis Kidneys increase secretion of hydrogen ions and reabsorption of bicarbonate ions Alkalosis Kidneys decrease secretion of hydrogen and reabsorption of bicarbonate Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 120  Diagnosing pH Imbalances The clinical test used to diagnose pH imbalances is an arterial blood gas (ABG) Gives pH, partial pressure of carbon dioxide (pCO2), and bicarbonate level in the blood pH will allow you to determine if there is an acidosis or alkalosis pCO2 is used to determine if cause is respiratory Bicarbonate is used to determine if cause is metabolic Compensation mechanisms may complicate diagnosis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 121 Types of Acid-Base Imbalances (Table 26.3) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 122  Summary By the end of this chapter, you should be able to: Discuss the fluids of the human body. Discuss how fluids move between compartments of the body. List the roles of various ions in the human body. Discuss how the homeostasis of ions is maintained. Discuss buffers and how they aid in pH homeostasis. Discuss causes of pH imbalances and how the body compensates. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 123