Biology 107

Lecture Notes: Circulation I.

Reading: Chapter 42 in text.

Circulation in animals

· Transport systems functionally connect body cells with the organs of exchange

o Diffusion is too slow of a process to transport chemicals throughout the body of a large animal

· The presence of a circulatory system reduces the distance a substance must diffuse to enter or leave a cell.

· Most animals have either a gastrovascular cavity or a circulatory system for internal transport

· Open circulatory system :

· Closed circulatory system :

· Closed cardiovascular systems allow gill-breathing or lung-breathing

· The mammalian heart drives blood through pulmonary and systemic circuits

o Heart rate:

· Systole:

· Diastole:

o Cardiac output :

· Stroke volume:

· Maintaining the heart’s rhythmic beat

o Cardiac muscle cells are myogenic :

· sinoatrial (SA) node:

· atrioventricular (AV) node: