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What will happen if the stretch receptors of the urinary bladder wall are totally removed?
A
There will be no micturition
B
Urine will continue to collect normally in bladder
C
Micturition will continue
D
Urine will not collect in the bladder
Detailed Solution
Urine formed by the nephrons is carried to the urinary bladder, where it is stored until a voluntary signal is given by the central nervous system.
This signal is initiated by the stretching of the bladder as it fills: the stretch receptors on the bladder wall send signals to the CNS.
The CNS then passes on motor messages that cause contraction of the smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter, releasing the urine. This is the micturition reflex.
If the stretch receptors are removed, the filling of the bladder is not signalled to the CNS, so the micturition reflex is not initiated.
On this reasoning the answer accepted in the key is that there will be no micturition.
Note: some books give 'Micturition will continue' (as an uncontrolled overflow) for this question; the key of the source PDF is retained here.
This signal is initiated by the stretching of the bladder as it fills: the stretch receptors on the bladder wall send signals to the CNS.
The CNS then passes on motor messages that cause contraction of the smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter, releasing the urine. This is the micturition reflex.
If the stretch receptors are removed, the filling of the bladder is not signalled to the CNS, so the micturition reflex is not initiated.
On this reasoning the answer accepted in the key is that there will be no micturition.
Note: some books give 'Micturition will continue' (as an uncontrolled overflow) for this question; the key of the source PDF is retained here.