Apical surface is the name of the epithelial cell surface that faces the outside of an organ.
The edge of the epithelium that faces light or the outside environment is called the apical surface.
The apical surface of the epithelial cells, where the lumen of the vesicles and tubules are located, and the inner surface of the body cavities, form the interface between the extracellular and underlying tissues.
It has multiple functions, including absorption and excretion, immune surveillance, sensory conduction, and barrier formation.
These functions are activated by several specializations, including glycocalyx (it cushions and hydrates the apical membrane), apical plasma membrane lipids(it restricts flow of water and solutes), channels and receptors (it regulates active and passive transport and sense the presence of growth factors), cytokines, and mechanical stimuli (eg, tensile and shear stress).
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In order to move you need oxygen and water to form the energy to function. The frog is basically drinking water and doesn’t need to move while doing so. You only need to breath to allow your body to move.
Answer:
Different groups of bacteria help in the cycling of nitrogen , carbon and phosphorus by chemical fixing or releasing in environment.
Explanation:The ecosystem contains flow of energy and cycling of minerals.
In the cycling of minerals, the micro-organisms help in fixing atmospheric nutrients e.g., nitrogen fixation by some bacteria and release the nutrients to the environment by decomposition of organic matters.
Different groups of bacteria help in the cycling of nitrogen , carbon and phosphorus by chemical fixing or releasing in environment.
Explanation:
Membranes
Recall that phospholipids have a hydrophobic end and a hydrophilic end and that when placed in water they will orient themselves accordingly (5.11 pg 79). This is the basis for the plasma membrane of a cell. The cell membrane consists of a phospholipid bilayer with embedded proteins. We refer to the modern conceptual model of the cell membrane as the "fluid mosaic" model since the phospholipids are able to move about across the surface of the membrane (fluid) and the proteins are many and varied (mosaic) (5.12).
Attached to the some proteins and to some of the phospholipids are oligosaccharides (short polysaccharides). When a protein has an oligosaccharide attached it is called a glycoprotein. Glycolipids are phospholipids with the sugar chains added. These oligosaccharides are found on the outside of the membrane and are used in cell to cell recognition. They differ among species, among individuals and within individuals.
Membrane proteins can have a number of functions, such as transport proteins, enzymes (more on these shortly), receptor sites, cell adhesion, attachment to the cytoskeleton. (5.13)
The most important thing about membranes is that they regulate what moves in and out of a cell. The membrane is selectively permeable because substances do not cross it indiscriminately.
Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids. Ions such as H+ or Na+ cannot.
Transport proteins make passage possible for molecules and ions that would not be able to pass through a plain phospholipid bilayer. Some transport proteins have a hydrophilic tunnel through them which allows polar molecule or ions to pass. Others actually bind to the molecules and move them across the membrane. In either case transport proteins are very specific.
Passive Transport
