6.2 The blood system

Essential idea: The blood system continuously transports substances to cells and simultaneously collects waste products.

The image above shows a capillary in adipose tissue. You can clearly see the red blood cells in the capillary lumen. Pores in the capillary wall allows plasma to leak into surrounding tissues facilitating the exchange of substances with body tissues.

Understandings, applications and skills

6.2.U1	Arteries convey blood at high pressure from the ventricles to the tissues of the body.
6.2.U2	Arteries have muscle cells and elastic fibres in their walls.
6.2.U3	The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
6.2.U4	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.
6.2.U5	Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
6.2.U6	Valves in veins and the heart ensure circulation of blood by preventing backflow.
6.2.U7	There is a separate circulation for the lungs.
6.2.U8	The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
6.2.U9	The sinoatrial node acts as a pacemaker.
6.2.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.
6.2.U11	The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.
6.2.U12	Epinephrine increases the heart rate to prepare for vigorous physical activity.
6.2.A1	William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.
6.2.A2	Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
6.2.A3	Causes and consequences of occlusion of the coronary arteries.
6.2.S1	Identification of blood vessels as arteries, capillaries or veins from the structure of their walls.
6.2.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.

[Text in square brackets indicates guidance notes]

Starters

Circulatory System Rap (Pump it Up!)
A musical introduction to the circulatory system by Mr W.

Circulatory System Musical Quiz (Heart Quiz)
Later in the topic you can use this quiz to test your understanding of heart structure. Thanks again to Mr W.

More interactive quizzes and flashcards on the circulatory system by Mr W use can use to check your understanding.

Presentation and notes

The presentation is designed to help your understanding.

Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.

Use the Cornell style template to collate your own notes for Topic 6.2 - The blood system.

Quick Quiz

Quick quiz Use the BioK Quick Quiz on 6.1 The blood system (as directed) to check your understanding of the topic.

Weblinks

Heart anatomy
Blood flow through the human heart by Sumanas Inc.
Anatomy of the heart by Orthosports
Anatomy of the heart by WISC online

Nature of science

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)

Theory of knowledge

Our current understanding is that emotions are the product of activity in the brain rather than the heart. Is knowledge based on science more valid than knowledge based on intuition?

Below are links to two articles looking at this issue from two perspectives. Read both and discuss:

The video below from Ben Goldacre talks in part about the danger of relying on intuition versus evidence based science to decide on which drugs doctors should prescribe.