Choose the correct option for the steps in regard to the process of micturition

Options

A. A -Stimulation of stretch receptors , B- Relaxation of muscles of urinary bladder ,C- Contraction of urethral sphincters
B. A-Stimulation of chemical receptors ,B-Contraction of muscles of urinary bladder ,C- Contraction of urethral sphinders
C. A- Stimulation of stretch receptors, B-Contraction ofmuscles of urinary bladder ,C- Relaxation of urethral sphincters
D. A-Stimulation of chemical receplors ,B- Contraction of muscies of urinary bladder, C-Relaxation of urethral sphincters

Answer

To solve the question regarding the steps involved in the process of micturition, we can break it down into a series of logical steps based on the physiological process involved:

### Step-by-Step Solution:

1. **Understanding Micturition**: Micturition is the process of expelling urine from the urinary bladder. It involves both voluntary and involuntary muscle actions and is regulated by the central nervous system.

2. **Filling of the Bladder**: As the bladder fills with urine (typically over 300-400 cc), the walls of the bladder stretch. This stretching is crucial for the next steps in the micturition process.

3. **Activation of Stretch Receptors**: The stretching of the bladder walls activates stretch receptors located in the transitional epithelium (also known as urothelium). These receptors send signals to the central nervous system indicating that the bladder is full.

4. **Central Nervous System Response**: Upon receiving signals from the stretch receptors, the central nervous system responds by sending motor signals back to the bladder. This response is crucial for the next phase of micturition.

5. **Contraction of Detrusor Muscle**: The motor signals from the central nervous system lead to the contraction of the detrusor muscles, which are the muscles of the bladder. This contraction is essential for pushing urine out of the bladder.

6. **Relaxation of Urethral Sphincter**: Simultaneously, the signals also cause the relaxation of the urethral sphincter. This relaxation allows urine to flow from the bladder through the urethra and out of the body.

7. **Urine Expulsion**: With the detrusor muscles contracted and the urethral sphincter relaxed, urine is expelled from the bladder, completing the micturition process.

### Conclusion:
Based on the steps outlined, the correct sequence of events in the micturition process is:
- Stimulation of the stretch receptors
- Contraction of the muscles of the urinary bladder (detrusor muscle)
- Relaxation of the urethral sphincter

Thus, the correct option for the steps in regard to the process of micturition is the third statement.

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