Urinary System Lecture 3 S23 PDF

Chapter 26 The Urinary System Part 3 July 2023 Dr. Kevin Tipper, ND VCMT EVALUATION OF KIDNEY FUNCTION Evaluation of Kidney Function General Characteristics of Normal U Normal Urine Characteristic Normal...

Chapter 26 The Urinary System Part 3 July 2023 Dr. Kevin Tipper, ND VCMT EVALUATION OF KIDNEY FUNCTION Evaluation of Kidney Function General Characteristics of Normal U Normal Urine Characteristic Normal Range Composition pH 4.5–8 (average: 6.0) Normal volume is about Specific gravity 1.003–1.030 1200 m L /day with an Osmotic 855–1335 concentration m Osm /L illi iters osmotic concentration of (osmolarity) illi ole iters 1000 m Osm /L illi ole Water content 93–97% Volume 700–2000 Changes in urine can be m L /day illi iters tested and measured to Color Pale yellow show abnormalities in the Odor Varies with urinary system or composition elsewhere Bacterial None (sterile) content Evaluation of Kidney Function Normal Urine Composition Water 95% of total urine volume Remaining 5%: Electrolytes Solutes derived from cellular metabolism urea from protein breakdown creatinine from creatine phosphate breakdown in mm. fibres uric acid from nucleic acid breakdown urobilinogen from hemoglobin breakdown Exogenous substances such as drugs Small quantities of fatty acids, pigments, enzymes and hormones Evaluation of Kidney Function Urinalysis sample of urine is taken and individual substances are analyzed Red blood cells: may indicate infection or kidney stones, but blood could be from other sources White blood cells: may indicate infection in urinary tract Nitrites: some bacteria convert nitrates to nitrites, could indicate infection Leukocyte esterase: indicates infection Proteins: may indicate kidney disease Glucose: may indicate diabetes mellitus Among other tests…. Evaluation of Kidney Function Urinalysis Evaluation of Kidney Function Blood Tests Blood Urea Nitrogen (BUN) measures blood nitrogen part of urea resulting from the catabolism and deamination of amino acids rises steeply with severe decreases in GFR that can happen with renal disease Plasma Creatinine measures plasma levels of creatinine result from the catabolism of creatine phosphate in skeletal muscle cells rises steeply with severe decreases in GFR that can happen with renal disease Used to estimate GFR (eGFR) Evaluation of Kidney Function Blood Tests Inulin Clearance measures volume of blood that is cleansed of inulin unit of time measures how efficiently the kidneys are removing inulin from the blood High renal clearance = efficient filtration and excretion Low renal clearance = inefficient filtration and excretion Inulin (plant polysaccharide) passes through the kidneys with no amount of inulin secreted or reabsorbed.  clearance rate = GFR (can be used clinically to determine GFR) Gold standard for estimating eGFR, but not always accessible in a clinical setting Evaluation of Kidney Function Blood Tests PAH Clearance measures the amount of plasma that passes through the kidneys in one minute (typically 650 mL/min) PAH (para-aminohippuric acid) is used to measure renal plasma flow b/c when administered via IV it is filtered and secreted in 1 single pass KIDNEY (RENAL) FAILURE Kidney Failure Occurs when the kidneys cannot filter wastes from blood and can no longer maintain homeostasis GFR drops too low Impairs all systems in the body, resulting in: Decrease in urine production Rise in blood pressure Anemia from decline in erythropoietin production Central nervous system problems (sleeplessness, seizures, delirium, and coma) © 2018 Pearson Education, Inc. Kidney Failure Chronic kidney failure Diabetes and hypertension are the most common causes Kidney function deteriorates gradually Associated problems accumulate over time Progression can be slowed, but the condition is not reversible Management involves restricted water, salt, and protein intake Reduces strain on urinary system by minimizing: Volume of urine produced Amount of nitrogenous waste generated Acidosis (a common problem with renal failure) can be countered by ingesting bicarbonate ions © 2018 Pearson Education, Inc. Kidney Failure Acute kidney injury (AKI) Kidney function deteriorates rapidly in just a few days May be impaired for weeks Sudden slowing or stopping of filtration caused by: Exposure to toxic drugs, renal ischemia, urinary obstruction, or trauma Allergic response to antibiotics or anesthetics in sensitized individuals Recovery of partial or complete function is possible if patients survive the initial incident © 2018 Pearson Education, Inc. Kidney Failure Dialysis Process of passive diffusion across a selectively permeable membrane Hemodialysis Uses an artificial membrane as an alternative to the kidney’s normal membrane around the glomerulus Regulates the composition of blood using a dialysis machine Membrane pores allow diffusion of ions, nutrients, and organic wastes, but not plasma proteins Dialysis fluid containing specific concentrations of solutes is run on the other side of the membrane © 2018 Pearson Education, Inc. Kidney Failure © 2018 Pearson Education, Inc. Kidney Failure Kidney failure treatment Dialysis relieves renal failure symptoms, but is not a cure Kidney transplant is the only real cure for severe renal failure Patient survival is more than 90 percent at 2 years after the transplant Close relative donor increases success rate Immunosuppressive drugs are necessary to reduce rejection of transplant © 2018 Pearson Education, Inc. THE URINARY TRACT The Urinary Tract The urinary tract is made up of: Ureters receive urine from the kidneys Conduct urine to the urinary bladder by gravity and peristalsis Urinary bladder receives and stores urine contraction of muscle in walls drives urination Urethra conducts urine from the bladder to outside the body In the penis, also conducts semen Functions: transports urine Stores urine eliminates urine © 2018 Pearson Education, Inc. The Urinary Tract Ureters transport urine from renal pelvis bladder Paired muscular tubes extending from the kidney to the urinary bladder (about 30 cm) Retroperitoneal and attached to the posterior abdominal wall The Urinary Tract Ureters 3 layers Mucosa transitional epithelium (urothelium) Muscularis 2 layers of smooth muscle for peristalsis Adventitia outer connective tissue layer anchors ureters to wall of peritoneum The Urinary Tract Urinary bladder Located posterior to pubic symphysis Filled by the ureters and drained by the urethra Dimensions vary with state of distension The bladder is outside the peritoneal cavity; it is subperitoneal Anchored to the pelvic and pubic bones by supporting ligaments Lateral umbilical ligaments Middle umbilical ligament © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder Rugae Folds in the bladder lining that disappear with expansion as the bladder fills Ureteric orifices Two (one for each ureter) on the posterior inferior surface Slit-like shape helps prevent backflow of urine into ureters with bladder contraction © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder internal urethral orifice Where urine leaves the bladder and enters the urethra Trigone Triangular area bounded by the two ureteral openings and the entrance to the urethra © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder Neck of the urinary bladder Surrounds the urethral opening Contains a muscular internal urethral sphincter (involuntary smooth muscle) © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder External urethral sphincter Located distal to prostate in males In females, located in similar location to males, at pelvic floor boundary Under voluntary control Must be voluntarily relaxed to permit urination © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder Contains mucosa, submucosa, muscularis, and connective tissue layers © 2018 Pearson Education, Inc. The Urinary Tract Urinary bladder Mucosa Contains rugae Lined with transitional epithelium (urothelium) Both allow for expansion to hold urine Muscularis layer has three layers Inner longitudinal layer Circular layer Outer longitudinal layer Collectively, the layers form the detrusor muscle © 2018 Pearson Education, Inc. The Urinary Tract The Urinary Tract Urethra Extends from the neck of the urinary bladder to the exterior of the body Different lengths and functions in males versus females Male urethra is longer and transports semen as well as urine © 2018 Pearson Education, Inc. The Urinary Tract Urethra Female Urinary Tract 4cm long Opens into orifice between clitoris & vagina Male Urinary Tract 20cm long also carries semen tube passes through prostate Three sections: prostatic urethra, membranous urethra, spongy urethra © 2018 Pearson Education, Inc. The Urinary Tract Urethra Lined with stratified epithelium that varies by location Transitional at the neck Stratified columnar at midpoint Stratified squamous near the external urethral orifice Thick, elastic lamina propria Longitudinal folds in the mucous membrane Mucin-secreting cells in the epithelial pockets © 2018 Pearson Education, Inc. URINATION The Micturition Reflex Urination Urine storage reflex Stretch receptors of urinary bladder wall distort as it fills Afferent impulses stimulate sympathetic stimulation to detrusor and stimulate contraction of internal urethral sphincter Pontine storage center decreases parasympathetic activity and increases somatic motor nerve activity of external urethral sphincter © 2018 Pearson Education, Inc. Urination Micturition reflex (urination) Coordinates the process of urination Involves both: Local reflex pathway Central pathway through the cerebral cortex © 2018 Pearson Education, Inc. Urination Micturition reflex Urine voiding reflex through pontine micturition center Afferent information of sensation of bladder fullness relayed to the thalamus Stretch receptors signal spinal cord & brain when volume 200-400ml Projection fibers relay the information to the cerebral cortex For voluntary relaxation of the external urethral sphincter Causes contraction of the detrusor muscle and relaxation of the internal urethral sphincter Since pressure is already increased, relaxing the sphincters leads to urination © 2018 Pearson Education, Inc. URINARY DISORDERS Urinary Disorders Primary signs of urinary disorders Change in volume and appearance of urine Polyuria Excessive urine production Results from hormonal or metabolic problems Possibly diabetes or glomerulonephritis Oliguria Reduced urine production (50–500 mL/day) Anuria Severely reduced urine production (0–50 mL/day) Oliguria and anuria indicate serious kidney problems and potential renal failure © 2018 Pearson Education, Inc. Urinary Disorders Primary signs of urinary disorders Change in frequency Increased urgency or frequency Can be from irritation of the lining of the ureters or urinary bladder UTI, prostatitis, diabetes, kidney stones, etc. Incontinence Inability to control urination voluntarily May involve periodic involuntary leakage (stress incontinence), inability to delay urination (urge incontinence), or continual trickle of urine from full bladder (overflow incontinence) © 2018 Pearson Education, Inc. Urinary Disorders Primary signs of urinary disorders Change in frequency Urinary retention Initially normal renal function Urination does not occur In males, commonly results from enlarged prostate gland and compression of prostatic urethra © 2018 Pearson Education, Inc. Urinary Disorders Primary signs of urinary disorders Pain Pain in the superior pubic region Associated with urinary bladder disorders Pain in the superior lumbar region or in the flank that radiates to the right or left upper quadrants Associated with kidney infections (pyelonephritis) Also associated with kidney stones (renal calculi) Dysuria Painful or difficult urination Can occur with cystitis or urethritis or urinary obstructions (possibly enlarged prostate in males) © 2018 Pearson Education, Inc. Urinary Disorders Clinical signs of urinary system disorders Fever Commonly develops when urinary system is infected with pathogens Cystitis (bladder infection)—usually low-grade fever Pyelonephritis (kidney infection) can produce very high fevers © 2018 Pearson Education, Inc.