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A ctenidium is shaped like a comb or a feather, with a central part from which many filaments or plate-like structures protrude, lined up in a row. Some aquatic gastropods possess a single row of filaments on their ctenidium, known as the monopectinate condition, [ 3 ] and others have a pair of filament rows, known as the bipectinate or ...
The anus is also on the right side of the body, so that waste matter is efficiently carried away. Bipectinate gills have to be supported by membranes, and these can become fouled with debris and sediment, restricting such gastropods to relatively clean-water environments, such as water flowing over solid rock.
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary ...
It is about 5 mm thick, and is formed by an aggregation of the smooth (involuntary) circular muscle fibers of the rectum. [citation needed] The internal anal sphincter aids the sphincter ani externus to occlude the anal aperture and aids in the expulsion of the feces. Its action is entirely involuntary. It is normally in a state of continuous ...
At the anus, there are two anal sphincters which control the exit of feces from the body, the internal anal sphincter and external anal sphincter. The inner sphincter is involuntary and the outer is voluntary. The microscopic precapillary sphincters function to control the blood flow into each capillary in response to local metabolic activity. [1]
Pages in category "Respiratory system anatomy" The following 19 pages are in this category, out of 19 total. This list may not reflect recent changes. A.
The digestive system usually has the following parts: buccal mass (including the mouth, pharynx, and retractor muscles of the pharynx) and salivary glands with salivary ducts; oesophagus and oesophagal crop; stomach, also known as the gastric pouch; digestive gland, also known as the hepatopancreas; intestine; rectum and anus
It is present in a continuous fashion from the esophagus to the upper rectum (the exact nomenclature of the rectum's muscle layers is still being debated). A discontinuous muscularis mucosae–like muscle layer is present in the urinary tract , from the renal pelvis to the bladder ; as it is discontinuous, it should not be regarded as a true ...