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Pinacocytes are part of the epithelium in sponges. They play a role in movement (contracting and stretching), cell adhesion, signaling, phagocytosis, and polarity. [ 2 ] Pinacocytes are filled with mesohyl which is a gel like substance that helps maintain the shape and structure of the sponge.
The Porifera phylum contains all sponges which are characterized by the small pores on the outer layer, which take in water. The cells in the sponge walls filter food from the water. Whatever is not uptaken by the sponge is pumped through the body out of a large opening.
In the small intestine, the larger part of digestion takes place and this is helped by the secretions of bile, pancreatic juice and intestinal juice. The intestinal walls are lined with villi, and their epithelial cells are covered with numerous microvilli to improve the absorption of nutrients by increasing the surface area of the intestine ...
The first stage, the cephalic phase of digestion, begins with secretions from gastric glands in response to the sight and smell of food. This stage includes the mechanical breakdown of food by chewing, and the chemical breakdown by digestive enzymes, that takes place in the mouth.
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus.The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines.
Sponges are hermaphrodites, producing both egg and sperm. Sperm is released from one sponge and brought in through the ostia of another sponge. Once the sperm reaches the body cavity it is fertilized and develops into a free-swimming larvae. The free-swimming larvae are released out the osculum and will eventually settle and attach elsewhere. [6]
Intracellular digestion is divided into heterophagic digestion and autophagic digestion. [3] These two types take place in the lysosome and they both have very specific functions. [3] Heterophagic intracellular digestion has an important job which is to break down all molecules that are brought into a cell by endocytosis. [3]
Gastrin is a hormone produced by enteroendocrine G cells in the pyloric glands. [1] All three of these stimulate parietal cells to secrete hydrochloric acid and intrinsic factor. The chief cells secrete pepsinogen in response to gastrin and especially Ach, and ACh also stimulates mucus secretion. [1]