Tuesday, July 8, 2008

- Excitability and Membrane Electropotential .

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

, 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

electric current e.g,
  • Muscle cells .
  • Nerve cells (neurons) .
  • Glandular cells.
*There are 3 types of muscles :

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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