Practical lab 3 Flashcards
The 3 germ layers in early development of many animals.
Ectoderm, endoderm and mesoderm. These form the various tissues in early development of animals.
Endoderm
In innermost germ layers, lines the primitive gut and digestive tract. Also the outer-pocketing such as the liver and lungs of vertebrates.
Ectoderm
Covers the surface of the embryo, gives rise to the outer covering of the animal and in some phyla, the central nervous system
Mesoderm
The germ layer between the ectoderm and endoderm that forms muscles and most other organs between the gut and outer covering of the animal
Acoelomate body plan
The simplest body plan. (Seen in flatworms) There is no cavity between the digestive tract and outer body wall.
What is the “tube within a tube” arrangement?
When the internal organs of an animal is free floating within the fluid filled pseudocoelem.
Psuedocoelomate body plan
Seen in roundworms.
Have a fluid filled cavity called the pseudocoelem, located between the digestive tract and the outer body wall. Layer of mesoderm located underneath cell wall, none on organs.
Coelomate body plan
Seen in annelids and all other phyla
Have a body cavity, completely lined with mesoderm. Later of mesoderm underneath the body wall and surrounding organs.
2 layers of mesoderm and connect dorsally and centrally that suspend the internal organs in the coelom.
Functions of the body cavity
Fluid cushions the suspended organs which helps prevent injury
Allows internal organs to grow and move independently of the outer body wall.
Phylum Nematoda.
Consist of worms, and is one of the largest animal phyla.
Most nematodes are free-living
Have a body cavity called a pseudocoelem, and have a complete digestive tract.
Muscular pharynx
Acts as a pump to bring food from the mouth into the intestine
Digestive enzymes are produced by what?
The single layer of epithelial cells lining the intestine.
