Transmembrane proteins, specifically channel proteins, make this possible. Charged particles, which are hydrophilic by definition, cannot pass through the cell membrane without assistance ( Figure 12.17). The cell membrane is a phospholipid bilayer, so only substances that can pass directly through the hydrophobic core can diffuse through unaided. Both of the cells make use of the cell membrane to regulate ion movement between the extracellular fluid and cytosol.Īs you learned in the chapter on cells, the cell membrane is primarily responsible for regulating what can cross the membrane and what stays on only one side. For skeletal muscles to contract, based on excitation–contraction coupling, requires input from a neuron. Previously, this was shown to be a part of how muscle cells work. Most cells in the body make use of charged particles, ions, to build up a charge across the cell membrane. Looking at the way these signals work in more variable circumstances involves a look at graded potentials, which will be covered in the next section. The basis of this communication is the action potential, which demonstrates how changes in the membrane can constitute a signal. To understand how neurons are able to communicate, it is necessary to describe the role of an excitable membrane in generating these signals. The functions of the nervous system-sensation, integration, and response-depend on the functions of the neurons underlying these pathways. Describe the changes that occur to the membrane that result in the action potential.Describe the components of the membrane that establish the resting membrane potential.
By the end of this section, you will be able to:
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