Mammals pump blood to the lungs for gas exchange, then back to the heart for pumping out to the systemic circulation. Contraction of the ventricle forces blood from the heart through an artery. There aretoplatelets in each milliliter of blood.
Trace the path of blood in the human body. Amphibians have a three-chambered heart with two atria and one ventricle.
The human heart will undergo over 3 billion contraction cycles, as shown in Figure 12, during a normal lifetime. Lymph nodes are small irregularly shaped masses through which lymph vessels flow. Begin with the aorta and name all major components of the circulatory system through which the blood passes before it returns to the aorta.
Figure 6. Simple animals, such as the hydra and planaria shown in Figure 1lack specialized organs such as hearts and blood vessels, instead using their skin as an exchange point for materials.
Occasional chest pain, angina pectoralis, can result during periods of stress or physical exertion. Blood pressure is measured in mm of mercury; healthy young adults should have pressure of ventricular systole of mm, and 80 mm at ventricular diastole. The Vascular System Back to Top Two main routes for circulation are the pulmonary to and from the lungs and the systemic to and from the body.
Fish pump blood from the heart to their gills, where gas exchange occurs, and then on to the rest of the body.