tailieunhanh - Ebook Wheater's functional histology - A text and colour atlas (6th edition): Part 2

(BQ) Part 2 book "Wheater's functional histology - A text and colour atlas" presents the following contents: Circulatory  system, skin, skeletal tissues, immune system, respiratory system, oral tissues, gastrointestinal tract, liver and pancreas, urinary system, endocrine system, male reproductive system, female reproductive system, central nervous system, special sense organs. | PART III ORGAN SYSTEMS 8. Circulatory 9. 10. Skeletal 11. Immune 12. Respiratory 13. Oral 14. Gastrointestinal 15. Liver and 16. Urinary 17. Endocrine 18. Male reproductive 19. Female reproductive 20. Central nervous 21. Special sense The heart 8 Circulatory system I INTRODUCTION The circulatory system mediates continuous movement of all body fluids its principal functions being the transport of oxygen and nutrients to the tissues as well as transport of carbon dioxide and metabolic waste products from the tissues. The circulatory system is also involved in temperature regulation and the distribution of molecules . hormones and cells . those of the immune system . The circulatory system has two functional components the blood vascular system and the lymph vascular system. The blood circulatory system comprises a circuit of vessels through which blood flow is initiated by continuous action of a central muscular pump the heart. The arterial system provides a distribution network to the peripheral microcirculation the capillaries and postcapillary venules the main sites of interchange of gas and metabolite molecules between the tissues and the blood. The venous system carries blood from the capillary system back to the heart. The lymph vascular system is a network of drainage vessels for returning excess extravascular fluid the lymph to the blood circulatory system and for transporting lymph to the lymph nodes for immunological screening see Ch. 11 . The lymphatic system has no central pump but there is an intrinsic pumping system effected by contractile smooth muscle fibres in the lymph vessel walls combined with a valve system preventing backflow. The whole circulatory system has a common basic structure An inner lining the tunica intima comprising a single layer of extremely flattened epithelial cells .