Practise mammalian circulation questions by tracing heart vessels, identifying blood cells and vessels, and explaining capillary exchange and tissue fluid.
Hummingbirds are the smallest of birds and are found in the Americas. Some species migrate hundreds of kilometres between warmer overwintering areas and summer breeding grounds. Like mammals, birds maintain a constant body temperature.
Hummingbirds have a high requirement for sugars because they have a very high metabolic rate. Fig. 3.1 shows a hummingbird feeding on nectar, one of their main food sources.
Fig. 3.1
In birds such as hummingbirds:
- blood is kept within vessels
- for each complete circuit of the body, blood passes through the heart twice.
State the term used to describe this type of circulatory system.
Complete Table 3.1 to show the names and functions of the main blood vessels associated with the heart of mammals.
Table 3.1
The mammalian circulatory system is adapted for the long-distance transport of the respiratory gases, oxygen and carbon dioxide.
The system is described as a closed double circulation.
Name:
- the two different circulations of the double circulatory system of mammals
- the main vein returning deoxygenated blood to the heart.
In a closed circulation, blood is kept within vessels at all times.
Name the type of blood vessel that connects capillaries and veins.
During one cardiac cycle:
- blood enters the heart from the lungs and from the rest of the body
- blood leaves the heart to be transported to the lungs and to the rest of the body.
Name the blood vessels entering the heart that bring blood from the rest of the body.