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In excitable cells, the other possible states are graded membrane potentials (of variable amplitude), and action potentials, which are large, all-or-nothing rises in membrane potential that usually follow a fixed time course. Excitable cells include neurons, muscle cells, and some secretory cells in glands. Even in other types of cells, however ...
Voltage-gated calcium channels (VGCCs), also known as voltage-dependent calcium channels (VDCCs), are a group of voltage-gated ion channels found in the membrane of excitable cells (e.g. muscle, glial cells, neurons) with a permeability to the calcium ion Ca 2+.
However, the main excitable cell is the neuron, which also has the simplest mechanism for the action potential. [citation needed] Neurons are electrically excitable cells composed, in general, of one or more dendrites, a single soma, a single axon and one or more axon terminals. Dendrites are cellular projections whose primary function is to ...
In electrically excitable cells, such as skeletal and cardiac muscles and neurons, membrane depolarization leads to a Ca 2+ transient with cytosolic Ca 2+ concentration reaching around 1 μM. [39] Mitochondria are capable of sequestering and storing some of that Ca 2+.
A classic example of a syncytium is the formation of skeletal muscle.Large skeletal muscle fibers form by the fusion of thousands of individual muscle cells. The multinucleated arrangement is important in pathologic states such as myopathy, where focal necrosis (death) of a portion of a skeletal muscle fiber does not result in necrosis of the adjacent sections of that same skeletal muscle ...
Electrotonic potentials which decrease the membrane potential are called inhibitory postsynaptic potentials (IPSPs). They hyperpolarize the membrane and make it harder for a cell to have an action potential. IPSPs are associated with Cl − entering the cell or K + leaving the cell. IPSPs can interact with EPSPs to "cancel out" their effect.
The cell membrane of a cardiac muscle cell has several specialized regions, which may include the intercalated disc, and transverse tubules. The cell membrane is covered by a lamina coat which is approximately 50 nm wide. The laminar coat is separable into two layers; the lamina densa and lamina lucida.
The cell membrane has different lipid and protein compositions in distinct types of cells and may have therefore specific names for certain cell types. Sarcolemma in muscle cells: Sarcolemma is the name given to the cell membrane of muscle cells. [46] Although the sarcolemma is similar to other cell membranes, it has other functions that set it ...