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Questions and Answers
What indicates a potential urinary tract infection based on urinalysis?
What indicates a potential urinary tract infection based on urinalysis?
Which component contributes to 95% of total urine volume?
Which component contributes to 95% of total urine volume?
What condition might be indicated by the presence of proteins in urine?
What condition might be indicated by the presence of proteins in urine?
What is the significance of a specific gravity value in the range of 1.003–1.030?
What is the significance of a specific gravity value in the range of 1.003–1.030?
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Which of the following substances may indicate diabetes mellitus when found in urine?
Which of the following substances may indicate diabetes mellitus when found in urine?
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What does a normal urine osmotic concentration range between?
What does a normal urine osmotic concentration range between?
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What might a high volume of urine suggest?
What might a high volume of urine suggest?
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What does Blood Urea Nitrogen (BUN) primarily measure?
What does Blood Urea Nitrogen (BUN) primarily measure?
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What does a steep rise in plasma creatinine levels indicate?
What does a steep rise in plasma creatinine levels indicate?
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Which method is considered the gold standard for estimating GFR?
Which method is considered the gold standard for estimating GFR?
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What does a high renal clearance of inulin indicate?
What does a high renal clearance of inulin indicate?
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What is the primary purpose of PAH clearance tests?
What is the primary purpose of PAH clearance tests?
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Which of the following conditions can result from kidney failure?
Which of the following conditions can result from kidney failure?
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What occurs when the GFR drops too low?
What occurs when the GFR drops too low?
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Which of the following is NOT a consequence of kidney failure?
Which of the following is NOT a consequence of kidney failure?
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What are the most common causes of chronic kidney failure?
What are the most common causes of chronic kidney failure?
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What is a characteristic of acute kidney injury (AKI)?
What is a characteristic of acute kidney injury (AKI)?
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Which method is used to manage chronic kidney failure?
Which method is used to manage chronic kidney failure?
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How does hemodialysis function?
How does hemodialysis function?
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What is true regarding kidney transplants?
What is true regarding kidney transplants?
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What is a potential treatment for acidosis in renal failure?
What is a potential treatment for acidosis in renal failure?
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Which statement about dialysis is correct?
Which statement about dialysis is correct?
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What can cause acute kidney injury (AKI)?
What can cause acute kidney injury (AKI)?
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What is the primary function of the ureters?
What is the primary function of the ureters?
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Which layer of the ureters is responsible for peristalsis?
Which layer of the ureters is responsible for peristalsis?
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What role do the rugae in the urinary bladder serve?
What role do the rugae in the urinary bladder serve?
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Where is the internal urethral orifice located?
Where is the internal urethral orifice located?
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What anatomical feature helps prevent the backflow of urine into the ureters during bladder contraction?
What anatomical feature helps prevent the backflow of urine into the ureters during bladder contraction?
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Which ligaments anchor the bladder to the pelvic and pubic bones?
Which ligaments anchor the bladder to the pelvic and pubic bones?
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What is the main function of the urinary bladder?
What is the main function of the urinary bladder?
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What defines the trigone of the urinary bladder?
What defines the trigone of the urinary bladder?
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What physiological response occurs as the urinary bladder fills with urine?
What physiological response occurs as the urinary bladder fills with urine?
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Which part of the nervous system is primarily activated during the micturition reflex?
Which part of the nervous system is primarily activated during the micturition reflex?
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What volume of urine in the bladder typically signals the brain to begin the process of urination?
What volume of urine in the bladder typically signals the brain to begin the process of urination?
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Which condition is characterized by excessively high urine production?
Which condition is characterized by excessively high urine production?
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What serious condition may oliguria and anuria indicate?
What serious condition may oliguria and anuria indicate?
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What effect does the micturition reflex have on the detrusor muscle?
What effect does the micturition reflex have on the detrusor muscle?
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What could increased urinary frequency indicate?
What could increased urinary frequency indicate?
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How does the pontine storage center influence the storage of urine?
How does the pontine storage center influence the storage of urine?
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What type of muscle is the internal urethral sphincter composed of?
What type of muscle is the internal urethral sphincter composed of?
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Which structure surrounds the urethral opening and serves as a muscular sphincter?
Which structure surrounds the urethral opening and serves as a muscular sphincter?
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Which section of the male urethra passes through the prostate?
Which section of the male urethra passes through the prostate?
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What is the primary function of the external urethral sphincter in both males and females?
What is the primary function of the external urethral sphincter in both males and females?
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How long is the female urethra compared to the male urethra?
How long is the female urethra compared to the male urethra?
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What type of epithelium lines the female urinary tract near the external urethral orifice?
What type of epithelium lines the female urinary tract near the external urethral orifice?
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Which layer of the urinary bladder is responsible for its contractions during urination?
Which layer of the urinary bladder is responsible for its contractions during urination?
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What is the primary role of the mucosa in the urinary bladder?
What is the primary role of the mucosa in the urinary bladder?
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Study Notes
Urinary System Evaluation Part 3
- Normal Urine Composition: Normal urine volume is approximately 1200 mL per day, with an osmotic concentration of 1000 mOsm/L.
- Changes in urine composition can indicate abnormalities in the urinary system or elsewhere.
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General Characteristics of Normal Urine:
- pH range: 4.5-8 (average 6.0)
- Specific gravity range: 1.003-1.030
- Osmotic concentration (osmolarity) range: 855-1335 mOsm/L
- Water content range: 93-97%
- Volume range: 700-2000 mL/day
- Color: Pale yellow
- Odor: Varies with composition
- Bacterial content: None (sterile)
Normal Urine Composition (Detailed)
- Water: Makes up 95% of total urine volume.
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Remaining 5% (Electrolytes):
- Solutes derived from cellular metabolism (e.g., urea from protein breakdown, creatinine from creatine phosphate breakdown in muscle fibers, uric acid from nucleic acid breakdown, urobilinogen from hemoglobin breakdown)
- Exogenous substances (e.g., drugs, fatty acids, pigments, enzymes, hormones)
- Small quantities of other substances.
Urinalysis
- A sample of urine is analyzed to determine individual substances.
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Substances that can be analyzed:
- Red blood cells: May indicate infection or kidney stones but can be from other sources
- White blood cells: May indicate infection in the urinary tract
- Nitrites: Some bacteria convert nitrates to nitrites, indicating infection in the urinary tract
- Leukocyte esterase: Indicates infection in the urinary tract
- Proteins: May indicate kidney disease
- Glucose: May indicate diabetes mellitus
- Other substances
Blood Tests
- Blood Urea Nitrogen (BUN): Measures blood nitrogen, part of urea resulting from catabolism and deamination of amino acids. Levels may sharply increase with decreases in glomerular filtration rate (GFR) due to renal disease.
- Plasma Creatinine: Measures plasma levels of creatinine, a result of creatine phosphate catabolism in skeletal muscle. Levels sharply increase with decreases in GFR due to renal disease. Used to estimate GFR (eGFR).
- Inulin Clearance: Measures the volume of blood that is cleansed of inulin per unit of time, and measures kidney efficiency in removing inulin from the blood. High renal clearance indicates efficient filtration and excretion, while low renal clearance indicates inefficient filtration and excretion. It is considered a gold standard for GFR measurement.
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PAH Clearance: Measures the amount of plasma passing through the kidneys in a minute. (typically 650 mL/min)
- PAH (para-aminohippuric acid) is used to measure renal plasma flow, as it is completely filtered and secreted in a single pass.
Kidney (Renal) Failure
- Definition: Occurs when kidneys cannot adequately filter waste from blood and maintain homeostasis because GFR is too low.
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Consequences: Impairs all body systems, resulting in:
- Decreased urine output
- Rises in blood pressure
- Anemia due to decreased erythropoietin production
- Central nervous system problems (sleeplessness, seizures, delirium, coma)
Chronic Kidney Failure
- Causes: Diabetes and hypertension are the most common causes.
- Progression: Kidney function deteriorates gradually, and associated problems accumulate over time.
- Management: Reduced water, salt, and protein intake to reduce strain on the urinary system and minimize urine volume and the amount of nitrogenous waste generated. Acidosis (a common complication) can be addressed with bicarbonate.
Acute Kidney Injury (AKI)
- Definition: Rapid deterioration of kidney function over a few days to weeks.
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Causes: Sudden slowing or stopping of filtration, including:
- Exposure to toxic drugs
- Renal ischemia
- Urinary obstruction
- Trauma
- Allergic response to certain medications (antibiotics or anesthetics)
Dialysis
- Process: Passive diffusion across a selectively permeable membrane.
- Hemodialysis: Method of filtering waste and excess fluid from the blood using an artificial membrane.
Kidney Failure Treatment
- Dialysis: Relieves symptoms but is not a cure.
- Kidney Transplant: The only real cure for severe renal failure. Survival rates are over 90% at two years post-transplant, with closer relative donors having a higher success rate.
- Immunosuppressive drugs: Necessary to prevent transplant rejection.
The Urinary Tract
- Components: Ureters, bladder, urethra
- Ureters: Transport urine from kidneys to bladder via gravity and peristalsis; muscular tubes about 30 cm long, retroperitoneal.
- Bladder: Stores and receives urine; is subperitoneal, anchored to pelvic/pubic bones by ligaments. Mucosa shows rugae (folds) during filling to allow expansion, with two openings (ureteral orifices) on the posterior inferior surface to prevent backflow. It has three layers: mucosa, muscularis (detrusor muscle), and adventitia (outer CT). The internal urethral orifice is where the urine exits the bladder and enters the urethra.
- Urethra: Conducts urine from bladder to exterior; different lengths/functions in males (longer, passes through prostate) versus females. Lined with stratified epithelium (transitional at the neck, stratified columnar at midpoint, stratified squamous near the external orifice). Has a thick, elastic lamina propria, longitudinal folds in the mucous membrane, mucin-secreting cells. The external sphincter is under voluntary control.
Urination (Micturition Reflex)
- Storage Reflex: Stretch receptors in the bladder wall activate afferent fibers to the pontine storage center, which inhibits parasympathetic pathways and stimulates somatic motor nerves, thereby contracting the external urethral sphincter.
- Micturition Reflex: Coordinated process involving both a local reflex pathway and a central pathway through the brainstem and cerebral cortex. Afferent signals, relayed to the thalamus and cortex, provide conscious recognition of bladder fullness.
- Stretch receptors trigger local reflex pathway leading to detrusor muscle contraction and relaxation of internal urethral sphincter; voluntary relaxation of external sphincter initiates urination.
Urinary Disorders
- Primary signs: Changes in volume and appearance of urine, change in frequency, pain.
- Polyuria: Excessive urine production (hormonal/metabolic problems like diabetes, or glomerulonephritis)
- Oliguria: Reduced urine production (50-500 mL/day)
- Anuria: Severely reduced urine production (0-50 mL/day).
- Incontinence: Inability to control urination voluntarily.
- Urinary retention: Initially normal renal function, but urination doesn't occur. In males often due to enlarged prostate gland compressing prostatic urethra.
- Pain: Pain in superior pubic region (bladder/bladder disorders), lumbar region/flank (kidney infections/stones), associated with dysuria (painful/difficult urination).
- Fever: Indicates infection of the urinary system (cystitis, pyelonephritis).
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