Micturition reflex

Definition

The micturition reflex is the process by which the urinary bladder is emptied. It involves both involuntary and voluntary muscle contractions regulated by neural circuits.

5 Must Know Facts For Your Next Test

1. Micturition reflex is initiated when stretch receptors in the bladder wall detect a certain level of fullness, sending signals to the spinal cord.
2. The internal urethral sphincter, controlled by the autonomic nervous system, relaxes as part of this reflex.
3. The external urethral sphincter, controlled voluntarily via the somatic nervous system, must be consciously relaxed to complete urination.
4. Bladder pressure increases as it fills with urine due to increased fluid volume, leading to activation of the micturition reflex.
5. Abnormalities in this reflex can lead to conditions such as urinary incontinence or urinary retention.

Review Questions

• What triggers the initiation of the micturition reflex?
• How do the internal and external urethral sphincters contribute differently to micturition?
• What role does bladder pressure play in initiating micturition?

Related terms

Hydrostatic Pressure:

The pressure exerted by a fluid at equilibrium due to gravity; important for understanding fluids in biological systems like blood and urine.

Autonomic Nervous System: A part of the peripheral nervous system that controls involuntary bodily functions such as heart rate, digestion, and respiratory rate.

Somatic Nervous System: \text{Part of the peripheral nervous system associated with voluntary control of body movements via skeletal muscles.}