Excitability and Membrane Electropotential
Excitability of cells and tissues is a basic function of life.
Also known as irritability, it is the ability of cells to respond to
stimuli, excitability is necessary for the functioning of nerves,
muscles, and hormones, among other things.
The basis for the excitability of cells is their ion distribution, and
the distribution of ions and molecules is determined by transport
mechanisms associated with their plasma membrane structure.
This structure permits and regulates various forms of ionic
and molecular transport.
*The stimuli are classified into two types:-
1-electrical. (galvanic ,faradric)
2-chemical.( ions , chemical transmitters,gases,……etc)
* Excitable cells are those that can be stimulated to create a
tiny electric current e.g,
- Muscle cells .
- Nerve cells (neurons) .
- Glandular cells.
each muscle has a structural & functional unit
which is muscle fiber ( cell):-
1- skeletal muscle ….. skeletal muscle fiber.
2- cardiac muscle…… cardiac muscle fiber.
3- smooth muscle …..smooth muscle fiber.
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