What is the action potential of smooth muscle?
Smooth muscle action potentials are unique in that membrane potential acts to initiate or modulate contraction. As such, graded membrane response can become stimulated by multiple factors, including local humoral factors, circulating hormones, or mechanical stimulation like stretching of the cells.
Do smooth muscle cells conduct action potentials?
Depolarization of smooth muscle cells can activate voltage-dependent Ca2+ channels and generate Ca2+ action potentials.
What are the 12 steps of muscle contraction?
Terms in this set (12)
- Motor neuron sends action potential (nerve impulse) to the muscle.
- acetylcholine (ACh) release from vesicles on motor neuron.
- ACh binds to receptors on muscle membrane & activates 2nd action potential, now on muscle.
- Action potential opens active transport pumps of sarcoplasmic reticulum.
Why are there no action potentials in the smooth muscle?
In both instances, the transmitter substances cause depolarization of the smooth muscle membrane, and this in turn elicits contraction. Action potentials usually do not develop; the reason is that the fibers are too small to generate an action potential.
How is the action potential of a cell produced?
An action potential is essentially a brief REVERSAL of electric polarity of the cell membrane and is produced by VOLTAGE-gated ion channels. These channels are passageways for ions in and out of the cell, and as their names suggest, are regulated by membrane voltage.
What happens at the peak of the action potential?
At threshold, calcium channels open, calcium ions flow into the cell further DE-polarizing the membrane. This results in the rising phase of the action potential. At the peak of depolarization, potassium channels open, calcium channels inactivate, potassium ions leave the cell and the voltage returns to -60mV.
How long does a spike action potential last?
Typical spike action potentials, suchas those seen in skeletal muscle, occur in most types of unitary smooth muscle. The duration of this type of action potential is 10 to 50 milliseconds, as shown in Figure 8–4A.