6.2 The blood system

IB Syllabus Statements

Understandings:

Arteries convey blood at high pressure from the ventricles to the tissues of the body.
Arteries have muscle cells and elastic fibres in their walls.
The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
Blood flows through tissues in capillaries. Capillaries have permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary.
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
Valves in veins and the heart ensure circulation of blood by preventing backflow.
There is a separate circulation for the lungs.
The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
The sinoatrial node acts as a pacemaker.
The sinoatrial node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles.
The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.
Epinephrine increases the heart rate to prepare for vigorous physical activity.

Applications and skills:
Application: William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.
Application: Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
Application: Causes and consequences of occlusion of the coronary arteries.
Skill: Identification of blood vessels as arteries, capillaries or veins from the structure of their walls.
Skill: Recognition of the chambers and valves of the heart and the blood vessels connected to it in dissected hearts or in diagrams of heart structure.

What theories developed by Greek philosopher Galen, were overturned by William Harvey?
Where do arteries move blood to and from, and at what kind of pressure?
What do arteries have in their walls and what is their importance?
Explain the importance of capillaries having permeable walls.
Where do veins move blood to and from, and at what kind of pressure?
Explain the role of valves in veins and the heart.
Compare the circulation of blood from the heart to the circulation for the lungs.
Explain how a heart beat is initiated.
How does the sinoatrial node act as a pacemaker to stimulate contractions, and how are they propagated through the heart?
Explain how the heart rate may be increased or decreased.
What is the role of epinephrine?
What has been a benefit of understanding the structure of the cardiovascular system?
What important discovery was made by William Harvey?
Outline the pressure changes in the left atrium, left ventricle, and aorta during the cardiac cycle.
Explain the causes and consequences of occlusion of the coronary arteries.
Explain how you would identify blood vessels as arteries, capillaries, or veins, from the structure of their walls.
Explain how you would identify the chambers and valves of the heart and the blood vessels connected to it, in dissected hearts or in diagrams of the heart.