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An example of upregulation is the response of liver cells exposed to such xenobiotic molecules as dioxin. In this situation, the cells increase their production of cytochrome P450 enzymes, which in turn increases degradation of these dioxin molecules. Downregulation or upregulation of an RNA or protein may also arise by an epigenetic alteration ...
Aquaporins are "the plumbing system for cells". Water moves through cells in an organized way, most rapidly in tissues that have aquaporin water channels. [28] For many years, scientists assumed that water leaked through the cell membrane, and some water does. However, this did not explain how water could move so quickly through some cells. [28]
Up-regulation is a process which occurs within a cell triggered by a signal (originating internal or external to the cell), which results in increased expression of one or more genes and as a result the proteins encoded by those genes. Conversely, down-regulation is a process resulting in decreased gene and corresponding protein expression.
Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell. Water can enter the cell by diffusion through the cell membrane or through selective membrane channels called aquaporins, which greatly facilitate the flow of water. [ 1 ]
The remainder binds with haemoglobin in red blood cells, is carried to the lungs, and exhaled. [11] H 2 O also diffuses out of the cell into the bloodstream, from where it is excreted in the form of perspiration, water vapour in the breath, or urine from the kidneys.
Extrinsic regulation is made by signals from the niche, where stem cells are found, which is able to promote quiescent state and cell cycle activation in somatic stem cells. [63] Asymmetric division is characteristic of somatic stem cells, maintaining the reservoir of stem cells in the tissue and production of specialized cells of the same. [64]
Neural top–down control of physiology concerns the direct regulation by the brain of physiological functions (in addition to smooth muscle and glandular ones). Cellular functions include the immune system’s production of T-lymphocytes and antibodies, and nonimmune related homeostatic functions such as liver gluconeogenesis, sodium reabsorption, osmoregulation, and brown adipose tissue ...
The stage in which water flows into the CV is called diastole. The contraction of the contractile vacuole and the expulsion of water out of the cell is called systole. Water always flows first from outside the cell into the cytoplasm, and is only then moved from the cytoplasm into the contractile vacuole for expulsion. Species that possess a ...