49.1
Why Do Animals Need a Circulatory
System? 1045
Some animals do not have circulatory
systems 1045
Open circulatory systems move tissue
fluid 1046
Closed circulatory systems circulate
blood through a system of blood vessels
1046
49.2 How Have Vertebrate Circulatory
Systems Evolved? 1047
Fish have two-chambered hearts 1047
Amphibians have three-chambered hearts
1048
Reptiles have exquisite control of
pulmonary and systemic circulation
1048
Birds and mammals have fully separated
pulmonary and systemic circuits 1049
49.3 How
Does the Mammalian Heart Function?
1050
Blood flows from right heart to lungs
to left heart to body 1050
The heartbeat originates in the cardiac
muscle 1052
A conduction system coordinates the
contraction of heart muscle 1053
Electrical properties of ventricular
muscles sustain heart contraction
1054
The ECG records the electrical activity
of the heart 1055
49.4
What Are the Properties of Blood and
Blood Vessels? 1055
Red blood cells transport respiratory
gases 1055
Platelets are essential for blood
clotting 1056
Plasma is a complex solution 1056
Blood circulates throughout the body
in a system of blood vessels 1057
Materials are exchanged in capillary
beds by filtration, osmosis, and diffusion
1057
Blood flows back to the heart through
veins 1059
Lymphatic vessels return tissue fluid
to the blood 1060
Vascular disease is a killer 1060
49.5 How
Is the Circulatory System Controlled
and Regulated? 1061
Autoregulation matches local blood
flow to local need 1061
Arterial pressure is controlled and
regulated by hormonal and neuronal
mechanisms 1061
Cardiovascular control in diving mammals
conserves oxygen 1063
