The bladder includes three types of muscle – the smooth muscle making up the bladder wall, the smooth muscle making up the internal sphincter, and the skeletal muscle of the external sphincter.
The sympathetic branch of the ANS causes relaxation of the bladder wall muscle and contraction of the internal sphincter. The PS has the opposite effect. What should cause relaxation of the bladder wall muscle by the ANS?
1. The pre-sympathetic ganglionic fiber should release:
My Answer: Acetylcholine
2. The post-ganglionic fiber should release:
My Answer: Norepinephrine
3. Consider the synapses on the bladder wall muscle (1) and the synapses on the internal sphincter (2) from the Sympathetic branch of the ANS.
A. The NT(s) at the two types of synapses is/are probably:
My Answer: Same, both release Acetylcholine
B. The receptors at the two types of synapses are probably:
My Answer: The same since both should release the same neurotransmitter?
4. What should neurotransmitter should cause relaxation of the external sphincter?
My Answer: Acetylcholine since the external sphincter is a skeletal muscle controlled by the somatic sensory system.