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Autocrine signaling involves a cell secreting a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell itself. [13] This can be contrasted with paracrine signaling, intracrine signaling, or classical endocrine signaling.
A collection of nerves known as the sympathetic nervous system supply the heart as well as other organs. These nerves, when activated, encourage the heart to beat harder and faster. [28] The sympathetic nervous system uses noradrenaline, a catecholamine, as a chemical messenger or neurotransmitter, which can promote arrhythmias in those with ...
Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell. [1] This can be contrasted with paracrine signaling, intracrine signaling, or classical endocrine signaling.
An increase in heart rate is known as positive chronotropy. The parasympathetic nerves supplying the SA node (in particular the Vagus nerves) originate in the brain. These nerves release a neurotransmitter called acetylcholine (ACh). ACh binds to a receptor called an M2 muscarinic receptor, located on the SA node
The two main chemical messengers of the sympathoadrenal system are norepinephrine and epinephrine (also called noradrenaline and adrenaline respectively). These chemicals are created by the adrenal glands after receiving neuronal signals from the sympathetic nervous system. The different physiological effects of these chemicals depend on the ...
(A brief chemical gradient driven efflux of Na+ through the connexon at peak depolarization causes the conduction of cell to cell depolarization, not potassium.) [27] These connections allow for the rapid conduction of the action potential throughout the heart and are responsible for allowing all of the cells in the atria to contract together ...
The “spacing effect” refers to a phenomenon whereby learning, or the creation of a memory, occurs more effectively when information, or exposure to a stimulus, is spaced out.
The presence of such a gap suggested communication via chemical messengers traversing the synaptic cleft, and in 1921 German pharmacologist Otto Loewi confirmed that neurons can communicate by releasing chemicals. Through a series of experiments involving the vagus nerves of frogs, Loewi was able to manually slow the heart rate of frogs by ...