8.5 Micturition and urinary tract disorders
5 min read•august 14, 2024
The urinary system plays a crucial role in maintaining our body's balance. This section dives into micturition, the process of urination, and common urinary tract disorders. We'll explore how our brain and nerves control function and what happens when things go wrong.
and kidney failure are serious issues that can impact our health. We'll look at the causes, symptoms, and treatments for these conditions, as well as life-saving options like and kidney transplants for those with severe kidney problems.
Micturition and Bladder Control
Neural Control of Micturition
Top images from around the web for Neural Control of Micturition
Diagnosis and Management of Neurogenic Bladder Dysfunction View original
Is this image relevant?
Spinal cord and neural connections for the bladder, allowing micturition and storage (8 ... View original
Is this image relevant?
Urodynamics: How the brain controls urination | eLife View original
Is this image relevant?
Diagnosis and Management of Neurogenic Bladder Dysfunction View original
Is this image relevant?
Spinal cord and neural connections for the bladder, allowing micturition and storage (8 ... View original
Is this image relevant?
1 of 3
Top images from around the web for Neural Control of Micturition
Diagnosis and Management of Neurogenic Bladder Dysfunction View original
Is this image relevant?
Spinal cord and neural connections for the bladder, allowing micturition and storage (8 ... View original
Is this image relevant?
Urodynamics: How the brain controls urination | eLife View original
Is this image relevant?
Diagnosis and Management of Neurogenic Bladder Dysfunction View original
Is this image relevant?
Spinal cord and neural connections for the bladder, allowing micturition and storage (8 ... View original
Is this image relevant?
1 of 3
- Micturition, or urination, empties the bladder of urine through the coordination of the detrusor muscle in the bladder wall and the internal and external urethral sphincters
- The , a spinal reflex, initiates when the stretched bladder wall triggers the detrusor muscle to contract and the internal urethral sphincter to relax, allowing urine to flow out of the bladder
- The pontine micturition center in the brainstem coordinates the micturition reflex by sending signals to the spinal cord to stimulate the detrusor muscle and relax the internal urethral sphincter
- The cerebral cortex mediates voluntary control of micturition, overriding the micturition reflex and allowing for conscious control of the external urethral sphincter
Disorders of Micturition
- Damage to the nervous system (spinal cord injury, multiple sclerosis) or obstruction of the urinary tract (benign prostatic hyperplasia) can result in disorders of micturition
- occurs when nerve damage disrupts the communication between the brain and the bladder, leading to problems with bladder control and emptying
- happens when the bladder becomes overly full and urine leaks out involuntarily, often due to an obstruction or weak bladder muscles
- involves urine leakage during physical activities that increase abdominal pressure (coughing, sneezing, lifting heavy objects)
- is characterized by a sudden, intense urge to urinate followed by involuntary bladder contractions and urine leakage, often caused by overactive bladder muscles
Urinary Tract Infections
Common UTIs and Their Causes
- Urinary tract infections (UTIs) result from bacterial invasion of the urinary tract, most commonly by Escherichia coli (E. coli) from the digestive tract
- , an infection of the bladder, causes frequent, painful urination and sometimes blood in the urine, occurring more often in women due to their shorter
- , a kidney infection, presents with flank pain, fever, and nausea, resulting from untreated cystitis or bacterial spread through the bloodstream
- Sexual activity, use of spermicides or diaphragms, and anatomical abnormalities of the urinary tract that impede urine flow increase the risk of developing UTIs
Diagnosis and Treatment of UTIs
- and urine culture are typically used to diagnose UTIs by detecting the presence of bacteria, white blood cells, and other abnormalities in the urine
- Dipstick tests can quickly screen for signs of infection, such as nitrites and leukocyte esterase, but a urine culture is needed to identify the specific bacterial pathogen
- Antibiotics targeted to the specific bacterial pathogen are the mainstay of treatment for UTIs, with the choice of antibiotic depending on the location and severity of the infection
- Drinking plenty of fluids, urinating frequently, and practicing good hygiene (wiping from front to back after using the bathroom) can help prevent recurrent UTIs
- In some cases, long-term, low-dose antibiotic prophylaxis may be recommended for individuals with frequent, recurrent UTIs to prevent future infections
Renal Failure Pathophysiology
Acute Renal Failure
- results from sudden insults to the kidneys (ischemia, toxins, urinary tract obstruction) and is characterized by a rapid decline in glomerular filtration rate and accumulation of nitrogenous waste products in the blood
- Prerenal causes of acute renal failure include conditions that reduce blood flow to the kidneys, such as hypovolemia, heart failure, and sepsis
- Intrarenal causes involve direct damage to the kidney tissue, such as acute tubular necrosis, glomerulonephritis, and interstitial nephritis
- Postrenal causes obstruct the flow of urine out of the kidneys, such as kidney stones, benign prostatic hyperplasia, and tumors compressing the ureters
- Treatment of acute renal failure aims to address the underlying cause, provide supportive care (fluid and electrolyte management), and prevent complications until kidney function recovers
Chronic Renal Failure and End-Stage Renal Disease
- develops gradually over months to years due to progressive loss of nephrons and decline in kidney function, resulting from conditions like diabetes, hypertension, and glomerulonephritis
- As chronic renal failure progresses, the kidneys become less able to maintain fluid and electrolyte balance, regulate blood pressure, and produce erythropoietin and active vitamin D
- (ESRD) is the final stage of chronic renal failure, with kidney function at less than 10% of normal capacity, requiring dialysis or for survival
- Clinical manifestations of renal failure include fatigue, nausea, vomiting, anorexia, edema, hypertension, anemia, and electrolyte imbalances (hyperkalemia, metabolic acidosis)
- Management of chronic renal failure focuses on slowing the progression of kidney damage, treating complications, and preparing for renal replacement therapy (dialysis or transplantation) when needed
Dialysis and Transplantation for ESRD
Principles of Dialysis
- Dialysis filters waste products and excess fluid from the blood when the kidneys can no longer do so effectively, with two main types: hemodialysis and peritoneal dialysis
- Hemodialysis circulates the patient's blood through an external machine with a semipermeable membrane, allowing waste products and excess fluid to diffuse out of the blood while retaining essential molecules (proteins, blood cells)
- Peritoneal dialysis uses the patient's peritoneal membrane as a natural filter by infusing a sterile solution into the abdominal cavity, allowing waste products and excess fluid to diffuse into the solution, which is then drained out
- Dialysis access is established through an arteriovenous fistula, arteriovenous graft, or central venous catheter for hemodialysis, and a peritoneal dialysis catheter for peritoneal dialysis
- Complications of dialysis include infection, thrombosis, and cardiovascular disease, requiring close monitoring and management
Kidney Transplantation
- Kidney transplantation is a surgical procedure in which a healthy kidney from a living or deceased donor is transplanted into a patient with ESRD, providing a better quality of life and longer survival compared to dialysis
- Immunosuppressive medications are required after transplantation to prevent rejection of the transplanted kidney by the recipient's immune system, but can have significant side effects
- Potential complications of kidney transplantation include infection, malignancy, cardiovascular disease, and graft failure
- Eligibility for kidney transplantation depends on factors such as age, overall health, and ability to adhere to a complex medical regimen
- The success of kidney transplantation has improved over time with advances in surgical techniques, immunosuppressive medications, and post-transplant care, but the demand for donor kidneys continues to exceed the supply
Key Terms to Review (30)
Acute renal failure: Acute renal failure, also known as acute kidney injury (AKI), is a sudden loss of kidney function that occurs over hours to days. This condition can lead to the accumulation of waste products in the blood, electrolyte imbalances, and disturbances in fluid balance. Understanding acute renal failure is crucial, especially in relation to urinary tract disorders and the micturition process, as it can severely affect how the body processes and eliminates waste.
Anticholinergics: Anticholinergics are a class of drugs that block the action of acetylcholine, a neurotransmitter involved in many bodily functions, including muscle contraction and signaling in the nervous system. These medications are often used to treat various conditions, including overactive bladder and urinary tract disorders, by inhibiting involuntary muscle contractions and reducing secretions.
Autonomic control: Autonomic control refers to the regulation of involuntary physiological functions by the autonomic nervous system, which operates without conscious thought. This system manages critical bodily functions such as heart rate, digestion, and micturition, ensuring homeostasis and responding to internal and external stimuli. It plays a significant role in processes like micturition by coordinating the actions of various muscles and organs involved in urination.
Biofeedback therapy: Biofeedback therapy is a technique that teaches individuals to control physiological processes by providing real-time data about their bodily functions, such as heart rate, muscle tension, and skin temperature. This method empowers patients to become more aware of their body’s responses and can help manage various conditions, including those related to micturition and urinary tract disorders.
Bladder: The bladder is a hollow muscular organ that stores urine before it is excreted from the body. It plays a crucial role in the urinary system, allowing for the temporary retention of urine until the body signals that it is time to release it. The bladder's ability to stretch and contract is vital for proper micturition, making it a key player in urinary tract function and disorders.
Bladder Compliance: Bladder compliance refers to the ability of the bladder to stretch and accommodate varying volumes of urine without significantly increasing internal pressure. This property is essential for normal bladder function, allowing for the storage of urine without discomfort and facilitating effective micturition when necessary.
Chronic renal failure: Chronic renal failure, also known as chronic kidney disease, is a long-term condition in which the kidneys gradually lose their ability to function effectively over time. This impairment can lead to the accumulation of waste products in the blood, disrupting the body’s balance of fluids and electrolytes. The condition is often associated with other health issues, such as diabetes and hypertension, and can significantly impact micturition and urinary tract function.
Cystitis: Cystitis is the inflammation of the bladder, often caused by a urinary tract infection (UTI). This condition can lead to symptoms such as frequent urination, urgency, and pelvic discomfort, which can significantly impact an individual's quality of life. Understanding cystitis is essential for recognizing the broader implications of urinary tract disorders and their effects on normal micturition processes.
Cystoscopy: Cystoscopy is a medical procedure that involves the examination of the bladder and urethra using a thin, tube-like instrument called a cystoscope. This procedure allows healthcare providers to visualize the interior of the urinary tract, aiding in the diagnosis and treatment of various urinary tract disorders.
Detrusor Contraction: Detrusor contraction refers to the rhythmic contraction of the detrusor muscle, a smooth muscle layer of the bladder wall, which plays a critical role in the process of micturition. This contraction is essential for the expulsion of urine from the bladder during urination and is regulated by both the autonomic nervous system and various reflexes. Understanding detrusor contraction is vital in exploring urinary tract disorders, as abnormal contractions can lead to issues such as urinary incontinence or retention.
Dialysis: Dialysis is a medical procedure that removes waste products and excess fluid from the blood when the kidneys are unable to perform this function effectively. This process is crucial for individuals with kidney failure or severe kidney dysfunction, helping to maintain a proper balance of electrolytes and fluid in the body. The two main types of dialysis are hemodialysis and peritoneal dialysis, both of which play an important role in managing urinary tract disorders related to renal function.
End-stage renal disease: End-stage renal disease (ESRD) is the final stage of chronic kidney disease, where the kidneys are no longer able to function effectively and require dialysis or a kidney transplant for survival. At this point, the kidneys have lost about 90% of their ability to filter waste and excess fluids from the blood, leading to severe health complications if not managed. ESRD is closely linked to urinary tract disorders, as these conditions can contribute to the deterioration of kidney function over time.
John D. McAninch: John D. McAninch is a notable figure in the field of urology, particularly known for his contributions to understanding micturition and urinary tract disorders. His work emphasizes the intricate relationship between physiological processes of urination and various urological conditions, highlighting innovative approaches to diagnosis and treatment. McAninch’s research has helped shape current practices and enhance patient outcomes in urological health.
Kidney transplantation: Kidney transplantation is a surgical procedure that involves placing a healthy kidney from a donor into a person whose kidneys are no longer functioning properly. This procedure is crucial for patients with end-stage renal disease, as it can restore normal kidney function and significantly improve quality of life. Understanding kidney transplantation involves looking at its indications, complications, and its role in managing urinary tract disorders.
Micturition Reflex: The micturition reflex is a neural reflex that controls the process of urination, where the bladder contracts to expel urine from the body. This reflex is initiated when stretch receptors in the bladder wall are activated as it fills, sending signals to the brain that create the urge to urinate. It's a complex interaction involving both involuntary and voluntary control, essential for normal urinary function and regulation.
Nephrolithiasis: Nephrolithiasis refers to the formation of kidney stones, which are solid masses made of crystals that develop in the kidneys. These stones can vary in size and composition, leading to potential blockages in the urinary tract, causing pain and other urinary tract disorders. The presence of kidney stones can also impact the process of micturition, often resulting in complications such as hematuria or urinary obstruction.
Neurogenic Bladder: Neurogenic bladder is a medical condition where the bladder loses its normal function due to nerve damage, leading to issues with bladder control and urination. This condition often results from neurological disorders such as spinal cord injuries, multiple sclerosis, or stroke, which disrupt the communication between the bladder and the brain. Understanding neurogenic bladder is crucial for addressing micturition problems and urinary tract disorders, as it significantly impacts a person's ability to store and release urine effectively.
Overflow incontinence: Overflow incontinence is a type of urinary incontinence characterized by the involuntary leakage of urine due to an overfilled bladder that cannot empty properly. This condition often occurs when there is a blockage in the urinary tract or when the bladder's ability to contract is impaired, leading to frequent dribbling of urine and a feeling of fullness even after urination. It is commonly associated with underlying medical conditions that affect bladder function and can significantly impact an individual's quality of life.
Paul H. Stein: Paul H. Stein is a prominent figure in the field of urology, recognized for his contributions to understanding micturition and urinary tract disorders. His work has significantly influenced the diagnosis and management of various urinary conditions, showcasing the intricate relationship between physiology and clinical practice in urology.
Pyelonephritis: Pyelonephritis is a type of urinary tract infection that affects one or both kidneys, often caused by bacteria that ascend from the bladder. This condition can lead to inflammation and damage to the kidney tissue, which is critical for filtering waste from the blood. Understanding pyelonephritis is essential, as it can significantly impact kidney function and overall health if not treated promptly.
Somatic Innervation: Somatic innervation refers to the part of the peripheral nervous system that controls voluntary movements by sending signals to skeletal muscles. This process involves motor neurons that originate in the spinal cord and extend to muscle fibers, enabling conscious control over movements such as walking or grasping. It is crucial for integrating sensory feedback, allowing the body to respond appropriately to environmental stimuli.
Specific Gravity: Specific gravity is a measure of the density of a substance compared to the density of water. It helps in assessing the concentration of solutes in bodily fluids, particularly urine, and can be an important indicator of various health conditions.
Stress incontinence: Stress incontinence is a common condition characterized by the involuntary leakage of urine during physical activities that increase abdominal pressure, such as coughing, sneezing, laughing, or exercising. This condition occurs when the pelvic floor muscles and the urethral sphincter are weakened, leading to a lack of support for the bladder. It is often linked to factors like childbirth, aging, and hormonal changes, particularly in women, which can affect the urinary system and micturition process.
Urethra: The urethra is a tube that connects the urinary bladder to the outside of the body, allowing for the excretion of urine. It plays a crucial role in both the urinary and reproductive systems, as it also serves as a conduit for semen in males. The structure and function of the urethra are essential for understanding both micturition processes and male reproductive anatomy.
Urge incontinence: Urge incontinence is a type of urinary incontinence characterized by a sudden, intense urge to urinate followed by involuntary leakage of urine. This condition often stems from an overactive bladder, where the bladder muscles contract too frequently, leading to unexpected episodes of urination. It can significantly impact a person's quality of life and is linked to various underlying conditions affecting the urinary tract.
Urinalysis: Urinalysis is a laboratory examination of urine that helps diagnose various medical conditions by analyzing its physical, chemical, and microscopic properties. This process not only aids in assessing kidney function and detecting diseases but also provides critical insights into fluid, electrolyte, and acid-base balance in the body, as well as identifying potential urinary tract disorders.
Urinary incontinence: Urinary incontinence is the involuntary loss of urine, which can occur due to various factors such as weakened pelvic muscles, neurological disorders, or urinary tract infections. This condition affects individuals of all ages but is more prevalent in older adults and can significantly impact quality of life. It is important to understand the different types, causes, and treatments associated with urinary incontinence to effectively manage and support those affected by this condition.
Urinary sphincter relaxation: Urinary sphincter relaxation refers to the process where the muscles surrounding the urethra, specifically the internal and external urinary sphincters, relax to allow the passage of urine from the bladder. This process is crucial during micturition, as it works in tandem with bladder contraction to enable urination and is also involved in various urinary tract disorders.
Urinary tract infections: Urinary tract infections (UTIs) are infections that affect any part of the urinary system, including the kidneys, bladder, ureters, and urethra. These infections are often caused by bacteria entering the urinary tract, leading to symptoms such as pain during urination, frequent urges to urinate, and cloudy urine. UTIs are a common health issue and can lead to complications if not treated properly.
Urodynamic studies: Urodynamic studies are a series of tests designed to evaluate how well the bladder and urethra are functioning. These tests help identify issues related to urine storage and flow, which can be crucial in diagnosing various urinary tract disorders, including incontinence and obstruction. By measuring pressure and volume changes during bladder filling and emptying, healthcare providers can gain insights into underlying conditions affecting the urinary system.