alimentary canal

Examples of alimentary canal in the following topics:

• Invertebrate Digestive Systems

  • Invertebrate digestive systems include a gastrovascular cavity with one opening or an alimentary canal with a true mouth and anus.
  • The alimentary canal is a more advanced digestive system than a gastrovascular cavity and carries out extracellular digestion.
  • Most other invertebrates like segmented worms (earthworms), arthropods (grasshoppers), and arachnids (spiders) have alimentary canals .
  • (b) An alimentary canal has two openings: a mouth for ingesting food and an anus for eliminating waste, as shown in this nematode.
  • Invertebrates like grasshoppers have alimentary canals with specialized compartments for digestion.

• Superphylum Lophotrochozoa

  • Animals belonging to superphylum Lophotrochozoa are protostomes: the blastopore (or the point of involution of the ectoderm or outer germ layer) becomes the mouth opening to the alimentary canal.

• Malpighian Tubules of Insects

  • They are usually found in pairs in the posterior regions of arthropod alimentary canals; the number of tubules varies with the species of insect.

• Digestive Systems

  • The digestive system consists of a group of organs that form a closed tube-like structure called the gastrointestinal tract (GI tract) or the alimentary canal .

• Phylum Annelida

  • Annelids possess a closed circulatory system of dorsal and ventral blood vessels that run parallel to the alimentary canal as well as capillaries that service individual tissues.

• Balance and Determining Equilibrium

  • Head position is sensed by the utricle and saccule, whereas head movement is sensed by the semicircular canals.
  • The semicircular canals are three ring-like extensions of the vestibule.
  • The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically.
  • Rotational movement of the head is encoded by the hair cells in the base of the semicircular canals.
  • The movement of two canals within a plane results in information about the direction in which the head is moving, and activation of all six canals can give a very precise indication of head movement in three dimensions.

• The Vestibular System

  • The fluid-filled semicircular canals are tubular loops set at oblique angles, arranged in three spatial planes.
  • The base of each canal has a swelling that contains a cluster of hair cells.
  • One canal lies horizontally, while the other two lie at about 45 degree angles to the horizontal axis.
  • Upon cessation of acceleration or deceleration, the movement of the fluid within the canals slows or stops.
  • Note that the canals are not sensitive to velocity itself, but to changes in velocity.

• Phylum Echinodermata

  • Echinoderms possess a unique ambulacral or water vascular system, consisting of a central ring canal and radial canals that extend along each arm .
  • From there, it passes into the stone canal, which moves water into the ring canal.
  • The ring canal connects the radial canals (there are five in a pentaradial animal), and the radial canals move water into the ampullae, which have tube feet through which the water moves.
  • These podocytes are connected by an internal system of canals to the madreporite.
  • Stone canal 5.

• Contractile Vacuoles in Microorganisms

  • In Paramecium, which, presumably, has the most-complex and highly-evolved CV, the vacuole is surrounded by several canals, which absorb water by osmosis from the cytoplasm.
  • After the canals fill with water, it is pumped into the vacuole.

• Transduction of Sound

  • The inner ear can be divided into three parts: the semicircular canals, the vestibule, and the cochlea, all of which are located in the temporal bone.
  • In the cross section of the cochlea (top right figure), note that in addition to the upper canal and lower canal, the cochlea also has a middle canal.