[A] Cardiovascular System Introduction

• Cells produced by hemopoietic tissues that usually enter the circulation

  peripheral or circulating blood
• Circulating blood is comprised of plasma and formed elements
• Fluid component and can be thought of as the ground substance of blood, a special connective tissue

  Plasma
• Containers for hemoglobin


  Red blood cells or erythrocytes
• Defend the body from infection and disease

  White blood cells or leucocytes
• Produce a cascade of chemical events leading to the formation of a clot, or thrombus

  Platelets
• Produced by platelets

  Clot or thrombus
• Major oxygen transport molecule

  Hemoglobin
• Absent in mammalian RBCs

  Nuclei
• Functions of circulating blood (RDNETWT):

  1. Respiration
  2. Disease Protection
  3. Nutrition
  4. Excretion
  5. Thermoregulation
  6. Water balance
  7. Transport of hormones
• Arteries carry blood away from the heart
• Veins carry blood toward the heart
• Capillaries are the tiny vessels that lie between arteries and veins
• Blood Vessel Cross Section:

  1. Tunica intima - endothelial cells
  2. Tunica media - smooth muscles, elastic fibers
  3. Tunica adventitia or externa - fibrous connective tissue
• Very small arteries and veins are called arterioles and venules
• In arterioles and venules, the tunica adventitia is thin, and the tunica media is composed of smooth muscle
• The pulse is created by the expansion of the arteries from sudden influx of blood from the heart
• Loss of elastic recoil in arteries can result in aneurysms
• Only 70% of blood goes back to the heart via the veins
• Prevent blood from flowing back in veins

  One way valves
• True or False: All veins have one way valves

  False
• Spider veins or varicose veins manifest as the dark blue appearance of the veins
• An embolus is a blockage that can travel to the heart, resulting in death
• Component of the cardiovascular system that regulates and supports cell metabolism intimately

  Microcirculation
• Regulates blood flow to the capillaries

  Precapillary sphincter
• A direct shunt running from the arterial to the venous side of circulation allows for major diversions of blood
• Shortcuts for circulation that can bypass some regions entirely

  Shunts
• Circulation pattern in which blood passes only once through the heart during each complete circuit

  Single circulation
• Single circulation cycle:

  Heart → Gills → Systemic tissues → Heart
• Double Circulation Cycle:

  Heart → Lungs → Heart → Systemic tissues → Heart
• The double circulation pattern is characterized by the addition of the pulmonary circuit