Double Circulation The need for a circulatory system All organisms need to transport materials to where they are needed inside their tissues Small organisms (or relatively inactive animals like jel...
Arteries Introduction to blood vessels The circulatory system of the human body contains several different types of blood vessel: Arteries Arterioles Capillaries Venules Veins Each type of blood ve...
Discovery of the Circulation of Blood NOS: Theories are regarded as uncertain; William Harvey overturned theories developed by the ancient Greek philosopher Galen on movement of blood in the body A...
Digestive System Diagram Human Digestive System The human digestive system includes the following: Glands - the salivary glands, and glands in the pancreas that produce digestive juices The stomach...
Methods of Absorption Digestion breaks down food into smaller, soluble molecules These products of digestion then pass from the lumen of the intestine into the blood They pass through the microvill...
Villi: Increasing the Surface Area The ileum (the second section of the small intestine) is adapted for absorption It is very long It has a highly folded surface It has millions of villi (singular ...
Introduction to Digestion The digestive system is an example of an organ system in which several organs work together to digest and absorb food Digestion is a process in which relatively large, ins...
Dichotomous Keys For anyone who doesn't specialise in studying a particular group of organisms, it can be very difficult to identify, or ID, a species when working in the field Correctly identifyin...
Cladistics & Reclassification The development of DNA sequencing technology means that classification can now be carried out on the basis of evolutionary relationship Organisms classified in thi...
