Ch.19- The Heart

• What carries oxygenated blood?


  an artery moving blood from the heart to a muscle

  
• What is the function of lymph node?

  filter debris from intracellular spaces
• What is the function of the spleen?


  filter blood and help fight infections
• What is the most abundant cells?

  red blood cells
• What is the pacemaker of the heart?


  sinoatrial node (SA node)

  
• What is the function of the circulatory system?

  transport hormones
• A closed system of the heart and blood vessels

  The heart pumps blood, and the blood vessels allow blood to circulate to all parts of the body
• Functions of the car


  Transport oxygen, nutrients, cell wastes, hormones to and from cells
• Anatomy of the heart


  Size of a human fist, weighing less than a pound

  Located in the thoracic cavity, between the lungs in the inferior mediastinum (medial section of the thoracic cavity)
• Apex (pointed region)


  is directed toward left hip and rests on diaphragm
• Base (area where great blood vessels emerge)

  Points toward right shoulder
• Coverings of the heart:


  • Double-walled sac

  • Is loose and superficial

  • Serous membrane is deep to the fibrous pericardium and composed of two layers:

  1. Parietal pericardium

  2. Visceral pericardium
• Parietal p


  outer layer of the pericardium
• visceral pericardium


  next to heart; also known as the epicardium
• Serous fluid fills the space between the layers of pericardium called the

  pericardial cavity
• Walls of the heart: Ep


  Outside layer; the visceral pericardium
• Walls of the Heart: Myo


  middle layer, contracts, mostly cardiac muscle
• Walls of the Heart: E


  Inner layer known as endothelium
• Four chambers of the heart

  right atrium, right ventricle, left atrium, left ventricle
• Atria(right


  -Superior receiving chambers

  -Assist with filling the ventricles

  -Blood enters under low pressure from veins of the body
• Ventricles(right


  -Inferior discharging chambers

  -Thick-walled pumps of the heart

  -During contraction, blood is propelled into circulation
• Pulmonary circulation


  blood flows from the right side of the heart to the lungs and back to the left side of the heart
• Blood is pumped out of the


  right side through the pulmonary trunk, which splits into pulmonary arteries and takes oxygen-poor blood to lungs
• Oxygen-rich blood returns to the heart from the


  lungs via pulmonary veins
• Interatrial


  separates the two atria longitudinally
• Interventricular


  separates the two ventricles longitudinally
• The heart functions as a double pump

  Arteries carry blood away from the heart; veins carry blood toward the heart.
• Double pump


  right side works as pulmonary circuit pump;

  left side works as systemic circuit pump
• Systemic C


  Oxygen-rich blood returned to the left side of the heart is pumped out into the aorta
• Blood circulates to


  systemic arteries and to all body tissues
• Left ventricle has thicker walls because....

  it pumps blood to the body through the systemic circuit
• Oxygen-poor blood returns to the

  right atrium via systemic veins, which empty blood into the superior or inferior vena cava
• Heart Va


  allow blood to flow in only one direction to prevent backflow
• atrioventricular valves


  between atria and ventricles
• Atrioventricular (AV) valves: Left AV valve


  bicuspid (mitral) valve
• Atrioventricular (AV) valves: Right AV valve

  tricuspid valve
• Semilunar valves


  -between ventricle and artery

  -Pulmonary semilunar valve

  -Aortic semilunar valve
• AV valves


  -Chordae tendineae anchor the cusps to the walls of the ventricles

  -Open during heart relaxation, when blood passively fills the chambers

  -Closed during ventricular contraction
• Semilunar valves


  closed during heart relaxation and open during ventricular contraction
• Valves open and close in resp


  pressure changes in the heart