cardio heart

• The cardiovascular system consists of the blood, the heart, and blood vessels

  
• Blood must be pumped continuously by the heart through the body's blood vessels for it to reach body cells and exchange materials with them
• The heart beats about 100,000 times every day, which adds up to about 35 million beats in a year, and approximately 2.5 billion times in an average lifetime
• The left side of the heart pumps blood through an estimated 100,000 km (60,000 mi) of blood vessels, which is equivalent to traveling around the earth's equator about three times
• The right side of the heart pumps blood through the lungs, enabling blood to pick up oxygen and unload carbon dioxide
• Even while you are sleeping, your heart pumps 30 times its own weight each minute, which amounts to about 5 liters (5.3 qt) to the lungs and the same volume to the rest of the body
• At this rate, your heart pumps more than about 14,000 liters (3600 gal) of blood in a day, or 5 million liters (1.3 million gal) in a year
• The heart contributes to homeostasis by pumping blood through blood vessels to the tissues of the body to deliver oxygen and nutrients and remove wastes
• Cardiology


  The scientific study of the normal heart and the diseases associated with it

  
• The heart is located in the mediastinum, with two-thirds of its mass to the left of the midline

  
• Mediastinum


  An anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs
• Surfaces of the heart

  • Anterior
  • Inferior
  • Right
  • Left
• Pericardium


  The membrane that surrounds and protects the heart
• Parts of the pericardium

  • Fibrous pericardium
  • Serous pericardium
• Fibrous pericardium


  Tough, inelastic, dense irregular connective tissue that resembles a bag and rests on and attaches to the diaphragm
• Serous pericardium


  A thinner, more delicate membrane that forms a double layer around the heart
• Parietal layer of serous pericardium


  Fused to the fibrous pericardium
• Visceral layer of serous pericardium (epicardium)


  One of the layers of the heart wall and adheres tightly to the surface of the heart
• Pericardial cavity


  The space that contains the few milliliters of pericardial fluid
• Layers of the heart wall

  Epicardium (external layer)<|>Myocardium (middle layer)<|>Endocardium (inner layer)
• Epicardium


  Composed of two tissue layers: the visceral layer of the serous pericardium and a variable layer of delicate fibroelastic tissue and adipose tissue
• Myocardium


  Responsible for the pumping action of the heart and composed of cardiac muscle tissue
• Endocardium


  A thin layer of endothelium overlying a thin layer of connective tissue that provides a smooth lining for the chambers of the heart and covers the valves of the heart
• Myocarditis is an inflammation of the myocardium that usually occurs as a complication of a viral infection, rheumatic fever, or exposure to radiation or certain chemicals or medications
• Endocarditis refers to an inflammation of the endocardium and typically involves the heart valves, most cases are caused by bacteria
• Pericarditis is inflammation of the pericardium, the most common type is acute pericarditis which begins suddenly and has no known cause in most cases but is sometimes linked to a viral infection
• Chronic pericarditis begins gradually and is long-lasting, in one form there is a buildup of pericardial fluid which can lead to cardiac tamponade, a life-threatening condition
• Cardiopulmonary resuscitation (CPR) is an emergency procedure for establishing a normal heartbeat and rate of breathing, hands-only CPR is the preferred method as it saves about 20% more lives than the standard method
• Hands-only CPR saves about 20% more lives than the standard method
• Hands-only CPR boosts the survival rate from 18% to 34% compared to the traditional method or none at all
• Hands-only CPR is easier for an emergency dispatcher to give instructions to frightened, nonmedical bystanders
• Public fear of contracting contagious diseases such as HIV, hepatitis, and tuberculosis continues to rise
• Bystanders are much more likely to perform hands-only CPR rather than treatment involving the standard method
• Standard CPR is still recommended for infants and children, as well as anyone who suffers from lack of oxygen, for example, victims of near-drowning, drug overdose, or carbon monoxide poisoning
• Fibrous skeleton of the heart


  Dense connective tissue that forms the fibrous skeleton of the heart

  
• Fibrous skeleton of the heart

  • Consists of four dense connective tissue rings that surround the valves of the heart, fuse with one another, and merge with the interventricular septum
  • Forms a structural foundation for the heart valves
  • Prevents overstretching of the valves as blood passes through them
  • Serves as a point of insertion for bundles of cardiac muscle fibers
  • Acts as an electrical insulator between the atria and ventricles
• Fibrous rings support the four valves of the heart and are fused to one another
• Operation of the Atrioventricular Valves


  1. When an AV valve is open, the rounded ends of the cusps project into the ventricle

  2. When the ventricles are relaxed, the papillary muscles are relaxed, the chordae tendineae are slack, and blood moves from a higher pressure in the atria to a lower pressure in the ventricles through open AV valves

  3. When the ventricles contract, the pressure of the blood drives the cusps upward until their edges meet and close the opening

  4. At the same time, the papillary muscles contract, which pulls on and tightens the chordae tendineae

  5. This prevents the valve cusps from everting (opening into the atria) in response to the high ventricular pressure
• If the AV valves or chordae tendineae are damaged, blood may regurgitate (flow back) into the atria when the ventricles contract
• Operation of the Semilunar Valves

  1. The aortic and pulmonary valves are known as the semilunar (SL) valves

  2. Each cusp attaches to the arterial wall by its convex outer margin

  3. The SL valves allow ejection of blood from the heart into arteries but prevent backflow of blood into the ventricles

  4. The free borders of the cusps project into the lumen of the artery

  5. When the ventricles contract, pressure builds up within the chambers

  6. The semilunar valves open when pressure in the ventricles exceeds the pressure in the arteries, permitting ejection of blood from the ventricles into the pulmonary trunk and aorta

  7. As the ventricles relax, blood starts to flow back toward the heart

  8. This backflowing blood fills the valve cusps, which causes the free edges of the semilunar valves to contact each other tightly and close the opening between the ventricle and artery