Chapter 43 The Circulatory System
Insects, open circulatory system
Vertebrates, closed circulatory system
Double circulation
1. Pulmonary circuit: passes through lungs. Low pressure
2. Systemic circulation: goes to body tissues. High pressure
Right side of heart: deoxygenated => goes to lungs
Left side of heart: oxygenated => goes to tissues
Necessary for decrease in blood pressure as blood moves through the lungs
- Deoxygenated blood: Vena cava => Right atrium => (Bicuspid valve) => Right ventricle
=> Pulmonary artery => (Pulmonary valve)
- Lungs
- Oxygenated blood: Pulmonary vein => Left atrium => (Tricuspid valve) => Left
ventricle => Aorta => (Aortic valve)
- Body tissues
, Cardiac cycle: one complete diastole and one complete systole. Less than 1 sec
- Diastole: relaxed. Blood flows into atria when atria and ventricles are relaxed, then
both atria contract simultaneously. Lowest pressure
- Systole: both ventricles contract simultaneously. Peak pressure
Systole
C ardiac cycle=
Diastole
Superior and inferior vena cava
Atrioventricular valves:
- Bicuspid: right side of heart
- Tricuspid: left side of heart
Semi-lunar valves
- Pulmonary valve: Pulmonary artery
- Aortic valve: Aorta
Insects, open circulatory system
Vertebrates, closed circulatory system
Double circulation
1. Pulmonary circuit: passes through lungs. Low pressure
2. Systemic circulation: goes to body tissues. High pressure
Right side of heart: deoxygenated => goes to lungs
Left side of heart: oxygenated => goes to tissues
Necessary for decrease in blood pressure as blood moves through the lungs
- Deoxygenated blood: Vena cava => Right atrium => (Bicuspid valve) => Right ventricle
=> Pulmonary artery => (Pulmonary valve)
- Lungs
- Oxygenated blood: Pulmonary vein => Left atrium => (Tricuspid valve) => Left
ventricle => Aorta => (Aortic valve)
- Body tissues
, Cardiac cycle: one complete diastole and one complete systole. Less than 1 sec
- Diastole: relaxed. Blood flows into atria when atria and ventricles are relaxed, then
both atria contract simultaneously. Lowest pressure
- Systole: both ventricles contract simultaneously. Peak pressure
Systole
C ardiac cycle=
Diastole
Superior and inferior vena cava
Atrioventricular valves:
- Bicuspid: right side of heart
- Tricuspid: left side of heart
Semi-lunar valves
- Pulmonary valve: Pulmonary artery
- Aortic valve: Aorta
