Heart, Circulatory System PDF

Heart, Circulatory System Assistant Lecturer Ahmed Makki ‫أنا شيء يمكنك حمله بيدك‪ ،‬ولكنه يرى أكثر منك‪ ،‬وينقل كالمك لآلخرين‪،‬‬ ‫فما هو؟‬  Blood Vessels There are three main types of blood vessels:  Arteries  Veins  Capil...

Heart, Circulatory System Assistant Lecturer Ahmed Makki ‫أنا شيء يمكنك حمله بيدك‪ ،‬ولكنه يرى أكثر منك‪ ،‬وينقل كالمك لآلخرين‪،‬‬ ‫فما هو؟‬  Blood Vessels There are three main types of blood vessels:  Arteries  Veins  Capillaries  Arteries  Carry blood away from the heart  Thick muscular walls  Lots of elastic tissue in the wall  Relatively small lumen  Blood under high pressure  Blood flow rapid  Blood flows in pulses  No valves Veins  Carry blood back to the heart  Thin muscular walls  Little elastic tissue in the wall  Relatively large lumen  Blood under low pressure  Blood flow is slow  No pulse  Valves prevent backflow of blood  Capillaries  Link up arteries and veins in the tissues  No muscle  Wall made up of one cell thick endothelium  Pressure falls as blood passes along capillary  Blood flowing is slowing down  No pulse  No valves Small  lumen - just large enough for a red blood cell to squeeze through  Role of the kidney in regulating blood pressure: Healthy kidneys respond to a hormone called aldosterone which is produced in the adrenal glands, to help the body regulate blood pressure. Kidney damage and uncontrolled high blood pressure contribute to a negative spiral. As more arteries become blocked and stop functioning, the kidneys eventually fail.