Cardiovascular System

• Cardiovascular system


  Makes sure that blood flows properly and blood is always oxygenated
• Pulmonary circulation


  Right side of heart is responsible, blood pumped from heart to lungs
• Systemic circulation


  Left side of the heart is responsible, has thicker muscle wall (has to do more work) blood pumped from heart to body
• Arteries


  Carry blood AWAY from the heart
• Blood vessels


  • Heart is pump blood, vessels are tubes, and the heart pumps blood around tubes
  • 2 pathways, they happen at the same time
• Generally arteries carry oxygenated blood EXCEPT PULMONARY ARTERY (carries deoxygenated blood to lungs)
• Smooth inside of blood vessels

  So the red blood vessels don't catch on the inside, it can flow smoothly, helps prevent plaque buildup
• Arteries


  • 3 layers, one layer in the middle is a thick wall, it is thick because it needs to be able to withstand the pressure
  • The walls of the arteries will allow the artery to expand and then rebound so it will help push the blood further
• Arterioles


  • Small arteries that are just visible to the eye
  • Middle layer has less elastic fibers
  • Consists mainly of circular muscle under involuntary control
  • When they contract, the diameter gets smaller- the muscles will relax so therefore gets bigger
• Vasoconstriction


  When muscles contract to make arterioles smaller
• Vasodilation


  When muscles relax to make arterioles bigger
• When arterioles are constricted

  Blood pressure will go up, flow rate increases, body temperature decreases
• When arterioles are dilated

  Blood pressure is lower, flow rate is lower, heat loss is bigger
• Capillaries


  • Microscopic, not made up of multiple layers like the arteries and arterioles, they are made of one layer of cells, more porous
  • Site of fluid / gas / nutrient exchange (diffusion)
  • Water can leak out of a capillary
• Venules


  Small veins, drain blood from capillary beds, carry blood TO heart, have valves to prevent the backflow of blood
• Veins


  • Has 3 layers, like arteries, but the middle layer is less muscular
  • Large blood vessels that carry blood towards the heart, usually carry deoxygenated blood
  • Acts as blood reservoir (more than 50% of the blood is in the veins)
  • Has thin walls because the blood is not under pressure in veins
• Valves in veins


  Allow blood to flow in one direction, prevent backflow
• Skeletal muscle contraction helps blood flow back to the heart in veins, as fluid pressure is very low to none in veins
• Coronary arteries and veins

  Supply the heart with blood (O2, nutrients) and removes wastes (CO2)
• When coronary arteries are blocked, blood can't reach region on heart tissue → the tissue will eventually die if block is not removed
• The heart will be weaker if there is a coronary artery blockage, as less blood will be pumped through the system
• Coronary arteries belong to the systemic circulatory system as they carry oxygenated blood
• Heart


  • Cone shaped muscular organ about the size of a fist
  • Myocardium (cardiac muscle tissue) is halfway between smooth and strict so it is flexible and strong
  • Pericardium is the outer thick membrane that secretes lubricant
• Heart chambers


  • Atria (smaller top chambers)
  • Ventricles (larger bottom chambers)
• Atrioventricular (AV) valves


  • Control the flow of blood flow between the atria and ventricles and prevent backflow
  • Tricuspid valve has 3 flaps or cusps
  • Bicuspid or mitral valve between left atrium and left ventricle
• Path of blood through the heart

  1. Blood deoxygenated → superior and inferior venae cavae bring blood to right atrium

  2. Right atrium contracts and pushes the blood to the right ventricle

  3. Right ventricle contracts and the blood goes up to the pulmonary trunk

  4. Pulmonary trunk divides into pulmonary arteries and those bring the blood to the lungs

  5. From the lungs, it transferred the blood to the pulmonary veins and from there back to the left atrium

  6. The left atrium contracts and blood is transferred to the left ventricle

  7. From left ventricle, blood goes to aorta

  8. Then blood is pushed to the arteries, arterioles, capillaries which will distribute blood to the rest of the body
• Heartbeat sounds


  • LUB: sound caused by atrioventricular valves closing when ventricles contract
  • DUB: sound caused by semilunar valves closing when ventricles are near empty and about to relax
• Heart murmurs


  Caused by problems with a valve closing
• Systole


  Contraction of the heart muscle
• Diastole


  Relaxation of the heart muscle
• Blood pressure


  Measured during systole and diastole, a healthy resting reading is 120/80 mm Hg
• Sinoatrial (SA) node


  Pacemaker of the heart, initiates the heartbeat by sending a signal every 0.85 seconds to make the atria contract
• Atrioventricular (AV) node


  Sends signals along the Purkinje fibers to the ventricles to contract
• Pulse


  The expanding and recoiling of arteries
• Hypotension


  Sustained low blood pressure
• Hypertension


  Sustained high blood pressure, usually associated with cardiovascular disease
• Atherosclerosis


  Thickening or hardening of arteries, due to saturated fats and cholesterol in the blood system, also causes plaque buildup
• Treatments for high blood pressure

  Beta blockers, vasodilators, diuretics
• Coronary arteries and veins

  Supply blood to the heart muscle itself
• Coronary heart diseases


  • If a coronary artery becomes plugged, a heart attack occurs
  • Atherosclerosis can occur in the coronary arteries, carotid arteries, aorta, and leg arteries