Chapter 10: Circulatory System

• Circulatory System


  • Moves blood throughout the body
  • Carries nutrients, oxygen, CO2, waste, and hormones
  • Distributes heat and maintains body fluid levels
  • Defends the body against invading microorganisms
• Your body has about 5.6 L of blood that circulates through the body three times a minute
• In one day, your blood travels a total of 19,000 km
• Arteries


  • Blood vessels that carry blood away from the heart
  • Made of thick, layered walls to hold high pressure
  • Outer and inner layers are primarily connective tissue
  • Middle layers are made of muscle fibres and elastic connective tissue
  • Stretch to accommodate the inrush of blood from heart contractions
  • Do not contain any valves
  • Supply their cells with nutrients and required materials
  • Elastic fibre walls recoil during relaxation phase
• Arterioles


  • Smaller blood vessels that blood from the arteries passes into
  • Much thinner walls than arteries
  • Made of elastic fibres and smooth muscles
  • Do not contain any valves
• Autonomic Nervous System


  • Part of the nervous system that controls the motor nerves regulating equilibrium and is not under conscious control
  • Regulates the diameter of the arterioles
  • Performs vasoconstriction and vasodilation
• Vasoconstriction


  The narrowing of blood vessels, allowing less blood to the tissues
• Vasodilation


  The widening of blood vessels, allowing more blood into the tissues
• Precapillary sphincter muscles regulate the movement of blood from the arterioles into capillaries
• Arterioles leading to capillaries open only when cells in that area require blood
• Atherosclerosis


  A degeneration of blood vessels caused by the accumulation of fat deposits in the inner wall
• Arteriosclerosis


  A group of disorders that cause the blood vessels to thicken, harden, and lose their elasticity
• Aneurysm


  A bulge in the weakened wall of a blood vessel, usually an artery
• Capillaries


  • Tiniest blood vessels
  • Composed of only a single layer of cells
  • Site of fluid and gas exchange between blood and body cells
  • Only two cells away from any one cell
  • Carry oxygenated blood to tissues
  • O2 diffuses from capillaries into tissues
  • Deoxygenated blood appears purple-blue as it leaves capillaries and enters venules
• Veins (& Venules)


  • Blood vessels that carry blood toward the heart
  • Venules merge into veins, which have larger diameter
  • Contain one-way valves to force blood to move back toward the heart
  • Skeletal muscles contract to push blood back to the heart
• The Heart


  • Muscular organ that pumps to circulate blood throughout the body
  • Surrounded by a fluid-filled membrane called the pericardium
• Septum


  Wall of muscle that separates the right and left sides of the heart
• Right Side of the Heart

  Receives deoxygenated blood from the body tissues and pumps it to the lungs
• Left Side of the Heart

  Receives oxygenated blood from the lungs and pumps it to the body tissues
• Pulmonary Circulatory System


  System of blood vessels that carries deoxygenated blood to the lungs and oxygenated blood back to the heart
• Systemic Circulatory System


  System of blood vessels that carries oxygenated blood to the tissues of the body and deoxygenated blood back to the heart
• Atrium (plural: atria)


  Thin-walled chamber of the heart that receives blood from the veins
• Ventricle


  Muscular, thick-walled chamber of the heart that delivers blood to the arteries and distant tissues
• Aorta


  Largest artery in the body; carries oxygenated blood away from the heart and into the tissues
• Superior and Inferior Vena Cava

  Carry deoxygenated blood from the body and empty into the right atrium of the heart
• Order of Circulation


  1. Deoxygenated blood returns to right atrium

  2. Right atrium pumps to right ventricle which pumps to lungs

  3. Oxygenated blood returns to left atrium

  4. Left atrium pumps to left ventricle and aorta
• Atrioventricular (AV) Valve


  Heart valve that prevents the backflow of blood from a ventricle into an atrium
• Semilunar Valve


  Valve that prevents the backflow of blood from the artery into a ventricle
• Coronary Artery


  Artery that supplies the cardiac muscle with oxygen and nutrients
• Cardiac Catheterization


  Procedure where a thin tube is threaded through a vessel to the heart to check for blockages
• Myogenic Muscle


  Muscle that contracts without external nerve stimulation
• Sinoatrial (SA) Node


  Small mass of tissue in the right atrium that originates the impulses stimulating the heartbeat
• Atrioventricular (AV) Node


  Small mass of tissue in the right atrioventricular region through which impulses from the sinoatrial node are passed to the ventricles
• Purkinje Fibre


  Nerve fibre that branches and carries electrical impulses throughout the ventricles
• Sympathetic Nervous System


  Division of the autonomic nervous system that prepares the body for stress
• Parasympathetic Nervous System


  Division of the autonomic nervous system that returns the body to normal resting levels following adjustments to stress
• Electrocardiograph


  Technology used to diagnose heart conditions by mapping the electrical field within the heart
• Electrocardiogram (ECG)


  Recording of the electrical impulses in the heart
• Heart Murmurs


  Gurgling sound caused by blood leaking past a closed heart valve due to an improper seal
• Diastole


  Relaxation (dilation) of the heart, during which the atria fill with blood