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Depolarization of the SA node, Action potentials of the myocardium & ANS effects

By: HWC, Views: 7626

• A typical contractile cell in the myocardium has a resting membrane potential. • The resting membrane potential of cells in the SA node is not fixed, and is known as the pacemaker potential. • The action potential of a healthy SA nodal cell has three parts: • Pacemaker potential: ...

Requirements for nervous signals

By: HWC, Views: 7678

• The function of neurons is to allow communication between cells, thereby maintaining homeostasis. • Electrical signals, called membrane potentials, travel along the membranes of the neurons. • Voltage variability and distance traveled determine the type of nervous signal. 1. Graded...

Action potentials - electrical characteristics and generation

By: HWC, Views: 7567

• An action potential is the nervous impulse or signal for long distance communication. Each action potential is generated at the cell's trigger zone. • Action potentials are considered an all-or-nothing phenomena because they are either generated or not. • The generation of an action...

Conduction of action potentials

By: HWC, Views: 7884

• Action potentials must be rapidly conducted over long distances in order for the nervous system to communicate with other cells. • Propagation of an action potential uses processes similar to those that generate the potential at the trigger zone. • a When a graded potential reaches ...

Summation - defined, spatial, temporal & AP generation or not

By: HWC, Views: 7646

If several presynaptic end bulbs release their neurotransmitter at about the same time, the combined effect may generate a nerve impulse due to summation Summation may be spatial or temporal • A typical neuron may have thousands of synapses. A corresponding number of postsynaptic membrane ...

Factors that affect conduction rates (myelination, axon diameter & temperature)

By: HWC, Views: 7854

• Several factors determine the rate of conduction of action potentials: • Myelination • Axon diameter • Temperature • The step-by-step depolarization of an axon is called continuous conduction and occurs along unmyelinated axons. • Neurons in the PNS have many axons that ...

Neurotransmission at chemical synapses & Excitory and inhibitory potentials

By: HWC, Views: 7646

• A series of events occur at chemical synapses in order to communicate with the adjacent cell. • The action potential arrives at the presynaptic membrane. • The depolarization phase of the action potential opens voltage gated Ca+ channels. • increased inflow of Ca+' into the cyto...

Graded potentials - electrical characteristics and types

By: HWC, Views: 7982

• A graded potential occurs when a gated channel is opened or closed, altering ion flow through the membrane. • Changes in ion and charge distributions cause voltage changes to the resting membrane potential. • The strength of the stimulus determines the number of gated channels affect...

Nervous pathway to the Neuromuscular (NMJ)

By: HWC, Views: 8257

• A nervous impulse, also called an action potential, starts from the brain or spinal cord to signal skeletal muscle cell contraction. Action potentials continue along a motor neuron to the muscle cell. • The signal to contract must cross a synapse - the neuromuscular junction (NMJ) - betwe...