CARDIOVASCULAR

• Cardiovascular System


  • Arteries
  • Capillaries
  • Veins
  • Venules
• Arteries


  • Vessels that carry blood from the heart to the tissues
• Arteries


  Large arteries---> medium sized arteries---> small arteries---> arterioles
• Capillaries


  • Microscopic vessels where substances are exchanged between blood and tissues
• Basic exchange mechanism in Capillaries

  1. Diffusion

  2. Transcytosis
• Veins


  • Convey blood from the tissues back to the heart, have valves to prevent backflow of blood
• Venules


  Collect blood from the capillaries and drain into veins
• Diffusion


  Most important method of capillary exchange, exchange process for oxygen, carbon dioxide, glucose, amino acids, and hormones
• Transcytosis


  1. Substances in the blood plasma become enclosed within tiny vesicles

  2. Endocytosis: entrance of substances

  3. Exocytosis: exit of substances
• Hemodynamics


  • Blood flow
  • Cardiac output
• Blood flow is the volume of blood that flows through any tissue in a given period of time
• Cardiac output is the volume of blood that circulates through the systemic blood vessels each minute
• Two factors that influence cardiac output are blood pressure and resistance between blood and vessel wall
• Blood pressure


  • The hydrostatic pressure exerted by blood on the walls of blood vessels
• In a resting adult, blood pressure rises to about 120mmHg during systole (contraction) and drops to 80mmHg during diastole (relaxation)
• Resistance


  • Refers to opposition to blood flow principally as a result of friction between blood and the walls of blood vessels
• Resistance depends on average blood vessel radius, blood viscosity, and total length of blood vessel
• Venus return


  • The volume of blood flowing back to the heart from the systemic veins, depends on the pressure difference from the venules to the right ventricle
• Pulse is a travelling pressure wave created by the alternate expansion and recoil of elastic arteries after each systole of the left ventricle
• Normal resting pulse is 70-80 beats per minute
• Tachycardia is a rapid resting heart rate over 100 beats per minute
• Bradycardia indicates a slow resting heart or pulse rate, under 60 beats per minute