Introduction

Introduction



Section contents



13. The blood 179

14. The heart and blood vessels 191

15. The circulation 209

16. The lymphatic system 223

17. The respiratory system 233


Section introduction


Two closely related systems, in both the anatomical and physiological sense, are covered in this section. These are the cardiovascular and respiratory systems and they, respectively, are responsible for circulating blood around the body and delivering oxygen to the blood and removing carbon dioxide. The lymphatic system, which also plays a key role in the defence of the body, is included here because it is responsible for removing excess fluid from the interstices of the peripheral tissues and returning it to the circulation.


The cardiovascular system is composed of the heart and the blood vessels and it is their collective action, with the heart working as a circulatory pump and the blood vessels as a closed transport system, which delivers blood to all the parts of the body. The blood is a tissue with several functions, including the transport of gases, defence against infection, clotting, distribution of heat and transport of nutrients. The gas transport and clotting functions are considered in this section.


Primarily, the respiratory system exchanges oxygen and carbon dioxide between atmospheric air and the blood. This is achieved mechanically in respiratory movements, which draw in atmospheric air and expel air rich in carbon dioxide. Air is mixed in the alveoli to produce alveolar air, and gas exchange between the blood and alveolar air takes place here by diffusion across the thin walls of the pulmonary capillaries and the alveolar membranes. These mechanisms are described.

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Jul 18, 2016 | Posted by in NURSING | Comments Off on Introduction

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