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T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the center of skeletal and cardiac muscle cells.With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration.
T tubule: transverse intracellular tubules invaginating from the cell membrane and surrounding the myofibrils of the T system of skeletal and cardiac muscle, serving as a pathway for the spread of electrical excitation within a muscle cell; Trachea: tubules forming the respiratory system of most insects and many arachnids
Early seed plants like ferns have spores and motile sperm that swim in a water medium, called zooidogamy. [18] The angiosperm pollen tube is simple, unbranched, and fast growing, however this is not the case for ancestral plants. In gymnosperms like Ginkgo biloba and cycadophyta, a haustorial pollen tube forms. The tube simply soaks up ...
Microtubule and tubulin metrics [1]. Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm [2] and have an inner diameter between 11 and 15 nm. [3]
The sodium-hydrogen antiporter's function is upregulated by Angiotensin II in the proximal convoluted tubule when the body needs to reabsorb sodium and excrete hydrogen. [34] Plants are sensitive to high amounts of salt, which can halt certain necessary functions of the eukaryotic organism, including photosynthesis. [31]
In plant anatomy, there are two main types of sieve elements. Companion cells and sieve cells originate from meristems, which are tissues that actively divide throughout a plant's lifetime. They are similar to the development of xylem, a water conducting tissue in plants whose main function is also transportation in the plant vascular system. [1]
Some plants also form smaller tubers or tubercules that act like seeds, producing small plants that resemble (in morphology and size) seedlings. Some stem tubers are long-lived, such as those of tuberous begonias , but many plants have tubers that survive only until the plants have fully leafed out, at which point the tuber is reduced to a ...
A lamella (pl.: lamellae) in biology refers to a thin layer, membrane or plate of tissue. [1] This is a very broad definition, and can refer to many different structures. Any thin layer of organic tissue can be called a lamella and there is a wide array of functions an individual layer can serve.