The blood system

Double circulatory system

Explore the circulatory system in: human.biodigital > Anatomy by systems > Cardiovascular system

Heart structure

Labeled drawing of the human heart for IB biology:

Blood vessels

Atherosclerosis

Heartbeat and cardiac cycle: sinoatrial node

Regulation of the heart rate (medulla and epinephrine)

6.2 The Blood System - Common Subtopic (10%)

Focus more on these understandings, applications and skills:

• 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
• Capillaries have permeable walls that allow exchange of material 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
• The heart beat is initiated by a group of specialised 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
• Identification of blood vessels as arteries, capillaries or veins from the structure of their walls
• 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

Example of common questions:

• Identify and label the heart structure, as well as blood vessels
• Outline the differences between arteries, veins and capillaries.
• Describe the cardiac cycle.
• Outline the role of pacemaker.