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Haas, J. As urine make its way to the ureters, the stretching of the ureter's smooth muscle results in peristaltic contractile waves that help move the urine into the bladder. Once the urine is in the bladder, the bladder's unique anatomy allows for efficient storage of urine. The bladder is essentially a muscular sac with three layers. Its three layers are similar to the ureter except that the muscular layer has muscle fibers organized in inner and outer longitudinal layers and a middle circular layer. The muscular layer is also known as the detrusor muscle.
Two of the openings are where the distal portions of the ureters insert, and the other opening is the orifice for the urethra. The urethra is a thin-walled muscular tube that function to drain urine out of the bladder. Its mucosa lining consists of mostly pseudostratified columnar epithelium through the proximal portion has transitional epithelial tissue. The thickening of the detrusor muscle at the bladder-urethra junction forms the internal urethral sphincter which has an autonomic nervous system control.
The urethra has an additional function for males as it transports semen. In males, the urethra is approximately Micturition process entails contraction of the detrusor muscle and relaxation of the internal and external urethral sphincter. The process is slightly different based on age. Children younger than three years old have the micturition process coordinated by the spinal reflex. It starts with urine accumulation in the bladder that stretches the detrusor muscle causing activation of stretch receptors. The stretch sensation is carried by the visceral afferent to the sacral region of the spinal cord where it synapses with the interneuron that excites the parasympathetic neurons and inhibits the sympathetic neurons.
The visceral afferent impulse concurrently decreases the firing of the somatic efferent that normally keeps the external urethral sphincter closed allowing reflexive urine output. However, after the age of 3, there is an override of reflexive urination where there is conscious control of the external urethral sphincter.
Excretion urography and plain X-ray examination are important in the diagnosis of renal stone disease. Mesangial and endothelial cells in the glomerulus secrete prostaglandins and exhibit phagocytosis. The number of glomeruli and their tubules decrease with age. However, these studies were all underpowered and of too short a duration to allow firm conclusions on the renoprotective effect of SST analogues. Or filter your current search. Protein Families.
Low bladder volume activates the pontine storage center which activates the sympathetic nervous system and inhibits the parasympathetic nervous system cumulatively allowing accumulation of urine in the bladder. The renal system pathologies have a wide range of clinical presentations. Emphysematous urinary tract infections, chronic kidney disease, nephrolithiasis, and urinary incontinence in men and women are topics of discussion below. Escherichia coli and Klebsiella pneumoniae commonly cause emphysematous UTI although Proteus , Enterococcus , Pseudomonas , Clostridium , and Candida spp can be part of the causative organism.
Laboratory testing can reveal elevated serum creatinine, pyuria, leukocytosis, and hyperglycemia. Chronic kidney diseases are not uncommon. Approximately Clinical manifestations include edema and hypertension although some patients can be asymptomatic. Laboratory testings are essential in the diagnosis of CKD.
An increase in serum creatinine and urea concentration are very common findings. Hyperphosphatemia, hyperkalemia, hypocalcemia, elevated parathyroid hormone, and metabolic acidosis may also be present in the lab findings. When CKD is suspected, ultrasound, urinalysis with microscopy, and albumin to creatinine ratio are necessary. Ultrasound will help rule out any form of obstruction. Urinalysis can also help rule out interstitial nephritis when sterile pyuria is negative. If there is no evidence of renovascular disease as a causative factor, a kidney biopsy might be conducted, then evaluation for renal replacement therapy can be done.
Nephrolithiasis is another pathology commonly seen in the renal system. Nephrolithiasis is the presence of crystallized calcium, magnesium, cystine, or uric acid in the renal system. Calcium stone has two forms: calcium oxalate which is the most common and the calcium phosphate. Hematuria is also a common symptom seen in nephrolithiasis. As the diagnosis of nephrolithiasis is under consideration, other possible pathologies need to be ruled out.
For instance, pyelonephritis frequently presents with flank pain, although it also presents with a fever, which is not usually present with nephrolithiasis. Ectopic pregnancy can be mistaken for renal colic. In this case, a renal and pelvic ultrasound can help to clarify.
Pain management should also commence. If urosepsis is present, emergent decompression should be conducted. If urosepsis is absent, the size of the stone should undergo evaluation. Observation, symptomatic treatment, alpha-blocker, and urine straining is appropriate for patients with a stone size of less than 10 mm. Extracorporeal shock wave lithotripsy or ureteroscopy can potentially help patients with stones greater than 10 mm. Urinary incontinence is also a common renal pathology. It is an involuntary leakage of urine. There are four types of incontinence: urgency incontinence, stress incontinence, mixed incontinence, and incontinence due to incomplete bladder emptying.
In men, 11 to 34 percent of men older than 65 years have urinary incontinence. Stress urinary incontinence in men is commonly known to be caused by poor urethral sphincter function.
The common presentation for overflow incontinence is nocturnal enuresis due to pelvic floor relaxation that usually occurs at night in combination with a full bladder. Management of urinary incontinence usually starts with lifestyle interventions such as dietary change, weight loss, and pelvic floor muscle exercise. If these lifestyle interventions are not improving the condition, then alpha-blockers can be started.
Many other drugs can be used, such as an antimuscarinic or beta-adrenergic agonist, and duloxetine. Approximately 50 percent of adult women experience urinary incontinence. Stress incontinence is the most common type of urinary incontinence in women between age 45 to 49 years. Intrinsic sphincter insufficiency is another factor that leads to stress incontinence in women, and it is mostly as a result of multiple pelvic or incontinence surgeries.
Detrusor contractility decreases with age and a decrease in estrogen has been found to play a role. Management of urinary incontinence in women is very similar to men where lifestyle intervention is started first before pharmacological therapy. Surgical intervention might be necessary. To access free multiple choice questions on this topic, click here.
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National Center for Biotechnology Information , U. StatPearls [Internet]. Search term. Affiliations 1 Central Michigan University. Introduction The renal system consists of the kidney, ureters, and the urethra.
Renal physiology (Latin rēnēs, "kidneys") is the study of the physiology of the kidney. This encompasses all functions of the kidney, including maintenance of. Normal kidney physiology: This illustration demonstrates the normal kidney physiology, showing where some types of diuretics act, and what they do.
Mechanism Glomerular Filtration Glomerular filtration is the initial process in urine production. Clinical Significance The renal system pathologies have a wide range of clinical presentations. Questions To access free multiple choice questions on this topic, click here. References 1. Uetani N, Bouchard M. Plumbing in the embryo: developmental defects of the urinary tracts.
A junior faculty member serves as the review officer to organize the deadlines, assign all reviewers, and coordinate the written and post-review comments to the trainee under review. SMART panel is a training mechanism to gain experience for all the trainees in peer-review processes as well as to aid in pre-submission reviews for the trainees. For more information on the programs hosted by the Cardio-Renal Physiology and Medicine group, please see the links under each opportunity.