Transport Systems

Transport Systems What type of organisms have transport systems? Why do organisms need a transport system?

Insects Insects don't have veins or arteries, They do have circulatory systems. An open circulatory system. Insect blood (hemolymph), flows freely through the body cavity and makes direct contact with organs and tissues.

A single blood vessel runs along the dorsal side of the insect, from the head to the abdomen. In the abdomen, the vessel divides into chambers and functions as the insect heart Perforations in the heart wall (ostia) allow hemolymph to enter the chambers from the body cavity. Muscle contractions push the hemolymph from one chamber to the next, moving it forward toward the thorax and head.

Insect blood is only about 10% hemocytes (blood cells); most of the hemolymph is watery plasma. The insect circulation system does not carry oxygen, so the blood does not contain red blood cells as ours does. Hemolymph is usually green or yellow in colour.

Closed circulatory Systems Closed circulatory systems are more efficient than open ones Closed system consists of arteries, veins, and capillaries. Capillaries surround the organs, making sure that all cells have an equal opportunity for nourishment and removal of their waste products

Earthworms One of the simplest types of closed circulatory systems is found in annelids such as the earthworm. Earthworms have two main blood vessels -- a dorsal and a ventral vessel -- which carry blood towards the head or the tail, respectively. Blood is moved along the dorsal vessel by waves of contraction in the wall of the vessel.

In the anterior region of the worm, there are five pairs of vessels, which we loosely term "hearts," that connect the dorsal and the ventral vessels. These connecting vessels function as rudimentary hearts and force the blood into the ventral vessel. Since the outer covering (the epidermis) of the earthworm is so thin moist, there is ample opportunity for exchange of gases, making this relatively inefficient system possible

Earthworm Quiz Have a go at this quiz!