Capillaries

Capillaries

  • Capillaries are tiny, thin-walled blood vessels that connect arterioles and venules, forming a network throughout the body's tissues. 
  • They are the site of exchange between the blood and tissues, allowing for the transfer of nutrients, gases, and waste products between the blood and cells. 
  • As blood passes through the capillaries in tissues, some water and small water-soluble substances move out into the spaces between the cells of tissues. 
  • This fluid, released from the capillaries, is called interstitial fluid or tissue fluid. 
  • Interstitial fluid contains water and dissolved substances, such as minerals, nutrients, gases, and waste products, similar to plasma. 
  • Tissue fluid serves as a medium for the exchange of nutrients, gases, and waste products between the blood and cells of tissues. 
  • It facilitates the delivery of oxygen and nutrients to cells and the removal of metabolic waste products, such as carbon dioxide and urea. 
  • An elaborate network of vessels called the lymphatic system collects tissue fluid from the interstitial spaces. 
  •  The fluid collected by the lymphatic system is called lymph. 
  •  Lymph is a colorless fluid containing specialized lymphocytes responsible for immune responses in the body. 
  • In addition to immune cells, lymph also carries nutrients, hormones, and waste products. 
  •  Fats are absorbed through lymph in specialized lymphatic vessels called lacteals, located in the intestinal villi of the small intestine. 
  • Lymphatic vessels transport absorbed fats, along with other nutrients, to the bloodstream for distribution throughout the body.