Chapter
2
The Circulation System
Blood Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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The Blood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Composition of the Blood . . . . . . . . . . . . . . . . . . . . . . . . |
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The Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Oxygen Carriage . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Carriage of Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . . . . |
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The Circulation System . . . . . . . . . . . . . . . . . . . . . . . . . . |
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What Can Go Wrong . . . . . . . . . . . . . . . . . . . . . . . . . . |
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System Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Factors Predisposing to Heart Attack . . . . . . . . . . . . . . . . . . . . |
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Insufficient Oxygen Carried . . . . . . . . . . . . . . . . . . . . . . . . |
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24 |
Carbon Monoxide |
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Smoking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Blood Pressure |
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Pressoreceptors and their Function Maintaining Blood Pressure . . . . . . . . . . |
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Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Donating Blood and Aircrew |
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Pulmonary Embolism . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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The Circulation System |
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System Circulation The 2
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The Circulation System |
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Blood Circulation
The circulatory system of the human body consists of two parts. The pulmonary system takes de-oxygenated blood from the heart to the lungs for gaseous exchange and returns oxygenated blood to the heart. From there the systemic system delivers oxygen rich blood to all tissues of the body to allow metabolization to occur and returns the de-oxygenated blood to the heart.
The Blood
Blood consists of a liquid, the plasma, and a number of different types of cells which are necessary for the healthy functioning of the human body. The functions of the circulatory system and the blood contained therein are to:
•carry oxygen to, and carbon dioxide from, the various tissues and organs of the body.
•carry nutrients to tissues and remove waste products from these tissues.
•carry chemical messengers, such as hormones including adrenaline, to regulate the actions and secretions of various organs.
•transport certain cells which can attack and destroy invading micro-organisms, bacteria, enabling the body to resist disease.
•assist in temperature control of the body. Vasoconstriction of the exterior blood vessels will take place if the body is subjected to cold and vasodilation will take place if the body is subjected to heat.
Composition of the Blood
The plasma, a pale straw coloured medium, is the liquid part of the blood. As well as carrying the various blood cells it delivers digested food products such as glucose and amino acids, dissolved proteins, various hormones and enzymes. The plasma contains sodium chloride.
The blood cells are of three types:
•Red blood cells contain haemoglobin and carry oxygen to the cells and tissues of the body. The red cells do not have nuclei and thereby make more room for haemoglobin.
•White blood cells are of various types; they resemble amoebae and have large nuclei to engulf and destroy invading bacteria. Their main function is the defence against disease. They produce antibodies to fight bacteria and antitoxins to neutralize the toxins produced by bacteria.
•Platelets are the smallest of the blood cells and assist in the blood clotting process.
The Circulation System 2
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System Circulation The 2
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