6.2: The blood system
Teaching time: 4 hours Practical time: 2 hours for a heart dissection and for investigating the elasticity of arteries.
key vocabulary
prior learning & retrieval practice
Review 2.8 cellular respiration
Review 2.3 carbohydrates and lipids
William Harvey - TOK link
NoS: Theories are regarded as uncertain—William Harvey overturned theories developed by the ancient Greek philosopher Galen on movement of blood in the body. (1.9)
A1: William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.
Exercise 1: Watch this video and answer the following questions:
Who was Galen and what did he propose?
How did William Harvey challenge Galen’s ideas?
Why were William Harvey’s ideas rejected by the scientific community?
Why were his ideas eventually accepted?
The blood system and blood vessels
Essential idea: The blood system continuously transports substances to cells and simultaneously collects waste products.
Exercise 2: Watch this video and connect-extend-challenge
The blood vessels: Function
U1: Arteries convey blood at high pressure from the ventricles to the tissues of the body.
U4: Blood flows through tissues in capillaries.
U5: Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
Exercise 3: Construct a table with three columns and four rows. In the top row, write, blood vessel, structure and function. In the first column, under blood vessel, write the names of the body's three blood vessels.
Exercise 4: Describe the function of the blood vessels in the relevant row.
The blood vessels: Structure
U2: Arteries have muscle cells and elastic fibres in their walls.
U3: The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
U4: Capillaries have permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary.
U6: Valves in veins and the heart ensure circulation of blood by preventing backflow.
Exercise 5: Complete the structure column of your table
S1: Identification of blood vessels as arteries, capillaries or veins from the structure of their walls.
Exercise 6: Complete Quizlet "Learn" and "Match"
The structure of the heart
S2: 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.
Exercise 7: Complete Quizlet "Learn" and "Match"
A2: Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
Exercise 8: Sketch and annotate a graph of the changes of pressure in the left atrium, ventricle an d aorta of the cardiac cycle.
U7: There is a separate circulation for the lungs.
Exercise 9: Describe the two circulatory systems in the human body and outline how each is connect to the heart.
Control of the heart beat
U8: The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
U9: The sinoatrial node acts as a pacemaker.
U10: 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.
Exercise 10: Explain how the heart beat is controlled by the pacemaker.
U11: The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.
U12: Epinephrine increases the heart rate to prepare for vigorous physical activity.
Exercise 11: Explain how the heart beat can be influenced by the nervous and endocrine system.
A3: Causes and consequences of occlusion of the coronary arteries.
Exercise 12: Create a table to show the causes and consequences of occlusion in the coronary arteries.
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