Textbook Question
Normal urine should have which of the following properties? Circle all that apply.
a. Translucency
b. Yellowish pigment
c. Cloudy appearance
d. pH less than 4.5
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25. The Urinary System
Renal Physiology Step 1: Glomerular Filtration
2:31 minutesProblem 23
Textbook Question
While repairing a frayed utility wire, Kevin, an experienced lineman, slips and falls to the ground. Medical examination reveals a fracture of his lower spine and transection of the lumbar region of the spinal cord. How will Kevin's micturition be controlled from this point on? Will he ever again feel the need to void? Will there be dribbling of urine between voidings? Explain the reasoning behind all your responses.
Verified step by step guidance1
Step 1: Understand the anatomy involved. The lumbar region of the spinal cord controls lower body functions, including the bladder's micturition reflex, which involves both autonomic and somatic nervous system components.
Step 2: Recognize that a transection at the lumbar level disrupts communication between the brain and the lower spinal cord segments responsible for voluntary control of urination, leading to loss of voluntary control over micturition.
Step 3: Identify that the micturition reflex may still occur via spinal reflex arcs below the lesion, meaning the bladder can contract reflexively without brain input, but the sensation of bladder fullness (the need to void) will likely be lost because sensory signals cannot reach the brain.
Step 4: Understand that without voluntary control and proper coordination, incomplete emptying of the bladder can occur, causing dribbling of urine between voidings due to overflow incontinence or reflex bladder contractions.
Step 5: Summarize that Kevin will not feel the need to void consciously, micturition will be reflexive and uncoordinated, and dribbling of urine is expected due to loss of voluntary sphincter control and impaired bladder emptying.
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Video duration:
2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Anatomy and Function of the Lumbar Spinal Cord in Micturition
The lumbar spinal cord contains important neural circuits that control bladder function, including sympathetic and somatic pathways. Damage at this level disrupts communication between the brain and lower urinary tract, affecting voluntary and involuntary control of urination.
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Types of Neurogenic Bladder Resulting from Spinal Cord Injury
Spinal cord injuries can cause different bladder dysfunctions, such as areflexic (flaccid) or reflex (spastic) bladder, depending on the injury site. A lumbar transection typically leads to an areflexic bladder, causing loss of bladder contraction and impaired sensation, resulting in urinary retention and dribbling.
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Neural Control of Micturition and Sensory Feedback Mechanisms
Micturition is controlled by a complex interaction between sensory input from the bladder, spinal cord reflexes, and higher brain centers. After lumbar spinal cord transection, sensory signals about bladder fullness may not reach the brain, so the patient may not feel the urge to void, leading to incontinence and dribbling.
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