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Thermodynamically the flow of substances from one compartment to another can occur in the direction of a concentration or electrochemical gradient or against it. If the exchange of substances occurs in the direction of the gradient, that is, in the direction of decreasing potential, there is no requirement for an input of energy from outside the system; if, however, the transport is against ...
The intracellular domain is responsible for the initiation of a cascade of chemical reactions which ultimately triggers the specific cellular function controlled by the receptor. Enzyme-linked receptors are transmembrane proteins with an extracellular domain responsible for binding a specific ligand and an intracellular domain with enzymatic or ...
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. [1]
This is usually to accumulate high concentrations of molecules that a cell needs, such as glucose or amino acids. If the process uses chemical energy, such as adenosine triphosphate (ATP), it is called primary active transport. Membrane transport proteins that are driven directly by the hydrolysis of ATP are referred to as ATPase pumps. [10]
Transcellular transport involves the transportation of solutes by a cell through a cell. [1] Transcellular transport can occur in three different ways active ...
Exocytosis (/ ˌ ɛ k s oʊ s aɪ ˈ t oʊ s ɪ s / [1] [2]) is a form of active transport and bulk transport in which a cell transports molecules (e.g., neurotransmitters and proteins) out of the cell (exo-+ cytosis). As an active transport mechanism, exocytosis requires the use of energy to transport material.
Cyclic AMP acts as second messenger in intracellular signal transduction and causes the organ to secrete a bicarbonate-rich fluid that flows into the intestine. Bicarbonate is a base that neutralizes the acid, thus establishing a pH favorable to the action of other digestive enzymes in the small intestine.
The tubular fluid is diluted because the cell's walls are water-impermeable and do not lose water as NaCl is actively reabsorbed. Thus, the TAL is an important segment of the TGF system, and its transport properties allow it to act as a key operator of the TGF system. [ 5 ]