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As an action potential (nerve impulse) travels down an axon there is a change in electric polarity across the membrane of the axon. In response to a signal from another neuron, sodium- (Na +) and potassium- (K +)–gated ion channels open and close as the membrane reaches its threshold potential. Na + channels open at the beginning of the ...
Dendrite. Structure of a typical chemical synapse. A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell.
Crying. Crying is the dropping of tears (or welling of tears in the eyes) in response to an emotional state or physical pain. Emotions that can lead to crying include sadness, anger, joy, and fear. Crying can also be caused by relief from a period of stress or anxiety, or as an empathetic response. The act of crying has been defined as "a ...
Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie perception and thought. They allow the nervous system to connect to and control other systems of the body. At a chemical synapse, one neuron releases neurotransmitter molecules into a small space (the ...
Allostasis. Allostasis (/ˌɑːloʊˈsteɪsɪs/) is a physiological mechanism of regulation in which an organism anticipates and adjusts its energy use according to environmental demands. First proposed by Peter Sterling and Joseph Eyer in 1988, the concept of allostasis shifts the focus away from the body maintaining a rigid internal set-point ...
The lacrimal gland is a compound tubuloacinar gland, it is made up of many lobules separated by connective tissue, each lobule contains many acini.The acini composed of large serous cells which, produce a watery serous secretion, serous cells are filled with lightly stained secretory granules and surrounded by well-developed myoepithelial cells and a sparse, vascular stroma.
In physiology, transduction is the translation of arriving stimulus into an action potential by a sensory receptor. It begins when stimulus changes the membrane potential of a sensory receptor. A sensory receptor converts the energy in a stimulus into an electrical signal. [1] Receptors are broadly split into two main categories: exteroceptors ...
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