Heart

• Cardiovascular system 

  – Heart

  – Blood

  – Blood vessels

  § The heart

  – Beats approximately 100,000 times each day 

  – Pumping about 8000 liters of blood per day
• Anatomy of the Heart

  • Pulmonary circuit
  • Carries blood to and from gas exchange surfaces of lungs
  • right ventricle pumps blood out to lungs, then back to the left ventricle of the heart
  • Systemic circuit
  • Carries blood to and from the rest of the body
  • left ventricle pumpds blood out to the rest of the body, returns on the right side of the heart
  • Each circuit begins and ends at the heart
  • Blood travels through these circuits in sequence
• Cardivoascular System

  • artery: blood carried away from the heart
  • returns via pulmonary veins from lungs
  • aorta, leaves left ventricle, distribute blood to rest of the body
  • arteries transition to capillaries then to veins to return the blood to the heart
• Types of blood vessels

  • Arteries
  • Carry blood away from heart
  • Veins
  • Return blood to heart
  • Capillaries (exchange vessels)
  • Interconnect smallest arteries and smallest veins
  • Exchange dissolved gases, nutrients, and wastes between blood and surrounding tissues
• Four chambers of the heart 

  • Right atrium
  • Receives blood from systemic circuit 
  • Right ventricle
  • Pumps blood into pulmonary circuit (lungs)
  • Left atrium
  • Receives blood from pulmonary circuit (lungs)
  • Left ventricle
  • Pumps blood into systemic circuit
• Heart

  – Great vessels connect at base (superior)

  – Pointed tip is apex (inferior)

  – Sits between two pleural cavities in mediastinum

  – heart sits in thoracic cacity
• Pericardium

  • Surrounds heart
  • Outer fibrous pericardium 
  • Inner serous pericardium
  • Outer parietal layer
  • Inner visceral layer (epicardium)
  • Pericardial cavity
  • Between parietal and visceral layers
  • Contains pericardial fluid
• Pulmonary veins and arteries***

  • pulmonary veins look like arteries because they are oxygenated
  • pulmonary artery is carrying deoxygenated blood to the lung to return to left side of the heart
• Pericarditis

  • Caused by pathogens in pericardium
  • Inflamed pericardial surfaces rub against each other
  • Producing distinctive scratching sound 
  • May cause cardiac tamponade
  • Restricted movement of the heart
  • Due to excess fluid in pericardial cavity
• Superficial anatomy of the heart 

  • Two thin-walled atria
  • Each with an expandable outer auricle
  • Sulci (grooves)
  • Contain fat and blood vessels
  • Coronary sulcus
  • Marks border between atria and ventricles
  • Anterior interventricular sulcus and posterior interventricular sulcus
  • Mark boundary between left and right ventricles
• Position and Superficial Anatomy of Heart

  • Under sternum: CPR on sternum, compressing on ventricular aspect
  • Blood through superior vena cava into right atrium then right ventricle tricuspid valve, fills and eject blood into left or right pulmonary artery, to lungs pick up oxygen then through pulmonary vein into left atrium
  • Into left ventricle, when it is full squeezes and contracts to push blood through aorta
  • upper branches of aorta: left common carotid artery and left subclavian artery branches up, supply brain and upper limbs
  • descending aorta: goes down through abdomin, behind heart
• Heart wall consists of three distinct layers

  • Visceral layer of serous pericardium (epicardium)
  • Covers surface of heart
  • Covered by parietal layer of serous pericardium
  • Myocardium
  • Cardiac muscle tissue
  • Endocardium
  • Covers inner surfaces of heart
  • Simple squamous epithelium and areolar tissue
• Cardiac muscle

  • Atrial musculature forms bands that wrap around the atria in a figure-eight pattern
  • Ventricular musculature forms bands that spiral around the ventricles
• Internal anatomy and organization

  • Chambers of heart are separated by muscular partitions (septa)
  • Interatrial septum (thinner)
  • Separates atria
  • Interventricular septum
  • Separates ventricles
  • Much thicker than interatrial septum (left ventricle wall muscle need to be much thicker to pump blood to the entire body)
• Anatomy of the Heart

  • Atrioventricular (AV) valves
  • Tricuspid and mitral valves
  • Folds of fibrous tissue that extend into openings between atria and ventricles
  • Permit blood flow in one direction
  • From left atrium to left ventricle
  • From right atrium to right ventricle
  • Semilunar valves
  • Pulmonary and aortic valves
  • Prevent backflow of blood into ventricles
• Right atrium receives blood from

  •  Superior vena cava
  • Carries blood from head, neck, upper limbs, and chest
  • Inferior vena cava
  • Carries blood from trunk, viscera, and lower limbs
• Right atrium

  • Foramen ovale
  • Before birth, is an opening through interatrial septum
  • Connects the two atria of fetal heart
  • Closes at birth, eventually forming fossa ovalis when the babies lung's start to work
• Blood flows from right atrium to right ventricle

  • Tricuspid valve (right atrioventricular valve)
  • Has three cusps
  • Prevents backflow of blood
  • Free edges of valve attach to chordae tendineae from papillary muscles of ventricle
  • Prevent valve from opening backward
• Right ventricle

  • Trabeculae carneae
  • Muscular ridges on internal surface (of both ventricles)
  • Moderator band
  • Muscular ridge that delivers stimulus for contraction to papillary muscles
• Sectional Anatomy of Heart

  • Papillary muscles and chordae tendineae support the mitral valve and tricuspid valve
  • when someone has a heart attack, if their papillary muscles are affected and become necrosed, this person will likely die from the heart attack because valves are not functioning ends
• Conus arteriosus

  • At superior end of right ventricle
  • Ends at pulmonary valve
  • Three semilunar cusps
  • Leads to pulmonary trunk
  • Start of pulmonary circuit
  • Divides into left and right pulmonary arteries
• Left atrium

  • Receives blood from left and right pulmonary veins (oxygenated)
  • Blood passes to left ventricle through mitral valve (left atrioventricular valve or bicuspid valve)
  • Two cusps
• Left ventricle

  • Similar to right ventricle but does not have moderator band
  • Blood leaves left ventricle through aortic valve into ascending aorta
  • Aortic sinuses
  • Saclike expansions at base of ascending aorta
  • Ascending aorta turns to become aortic arch
  • Becomes descending aorta
• Compared to left ventricle, the right ventricle

  • Holds and pumps the same amount of blood
  • Has thinner walls
  • Develops less pressure
  • Is more pouch-shaped than round
• Heart valves

  • Prevent backflow of blood
  • Atrioventricular (AV) valves
  • Between atria and ventricles
  • When ventricles contract,
  • Blood pressure closes valves
  • Papillary muscles contract and tense chordae tendineae
  • Prevents regurgitation (backflow) of blood into atria
• Semilunar valves

  • Pulmonary and aortic valves
  • Prevent backflow of blood into ventricles
  • No muscular braces
  • Valvular heart disease (VHD)
  • Deterioration of valve function
  • May develop after carditis (inflammation of heart)
  • May result from rheumatic fever (inflammatory autoimmune response to streptococcal bacteria)
• Heart valves and blood flow

  • ventricles are relaxed, the tricuspid and mitral valves are open and the aortic and pulmonary valves are closed
  • just before the heart pumps, left atrium will squeeze and contract to push a little more blood into the ventricle, will get ready to eject blood
  • When the ventricles are contracting, the tricuspid and mitral valves are closed and the aortic and pulmonary valves are open
  • pulling leaflets down so they don’t bulge backwards into atrium and leak
• Coronary circulation

  • Supplies blood to muscle tissue of heart
  • Coronary arteries
  • Originate at aortic sinuses
  • Elevated blood pressure and elastic rebound of aorta maintain blood flow through coronary arteries
• Right coronary artery

  • Supplies blood to
  • Right atrium
  • Portions of both ventricles
  • Portions of electrical conducting system of heart
  • Gives rise to
  • Marginal arteries
  • Posterior interventricular artery
• Left coronary artery

  • Supplies blood to
  • Left ventricle
  • Left atrium
  • Interventricular septum
  • Gives rise to
  • Circumflex artery (lateral wall)
  • Anterior interventricular artery (front wall)
• Anatomy of the Heart

  • Coronary artery disease (CAD)
  • Areas of partial or complete blockage of coronary circulation
  • Cardiac muscle cells need a constant supply of oxygen and nutrients
  • Reduction in blood flow to heart muscle reduces cardiac performance
  • Coronary ischemia
  • Reduced circulatory supply from partial or complete blockage of coronary arteries
• Coronary artery disease

  • Usual cause is formation of a fatty deposit, oratherosclerotic plaque, in wall of coronary vessel
  • The plaque, or an associated thrombus (clot), narrows passageway and reduces blood flow
  • Spasms in smooth muscles of vessel wall can further decrease or stop blood flow
• Plaque vessels

  • as our vessels expand and contract, these plaques can crack, and our body does regularly as if there is a hole and clots the hole, but if it floods the hole in this case, it floods the cardiac vessel solid so the heart distal to the clot get no blood supply
• Angina pectoris

  • Commonly one of the first symptoms of CAD
  • A temporary ischemia develops when workload of heart increases
  • Individual may feel comfortable at rest
  • Exertion or emotional stress can produce sensations of pressure, chest constriction, and pain
  • Pain may radiate from sternal area to arms, back, and neck
• Myocardial infarction (MI), or heart attack

  • Part of coronary circulation becomes blocked
  • Cardiac muscle cells die from lack of oxygen
  • Death of affected tissue creates a nonfunctional area known as an infarct
  • Most commonly results from severe CAD
  • Coronary thrombosis
  • Thrombus formation at a plaque
  • Most common cause of an MI
• Myocardial infarction

  • Consequences depend on site and nature of circulatory blockage
  • If near the start of one of the coronary arteries
  • Damage will be widespread and heart may stop beating
  • If blockage involves small arterial branch
  • Individual may survive the immediate crisis
  • But may have complications such as reduced contractility and cardiac arrhythmias
• Myocardial infarction

  • Causes intense, persistent pain, even at rest
  • Pain is not always felt
  • May go undiagnosed and untreated
  • Often diagnosed with ECG and blood studies
  • Damaged myocardial cells release enzymes into circulation
  • Cardiac troponin T
  • Cardiac troponin I
  • A form of creatinine phosphokinase, CK-MB
• Treatment of CAD and myocardial infarction

  • About 25% of MI patients die before obtaining medical assistance
  • 65% of MI deaths among people under age 50 occur within an hour
• Risk factor modification

  • Stop smoking
  • Treat high blood pressure
  • Adjust diet to lower cholesterol and promote weight loss
  • Reduce stress
  • Increase physical activity
• Drug treatments are used to

  • Reduce coagulation (e.g., aspirin and coumadin)
  • Block sympathetic stimulation (propranolol or metoprolol)
  • Cause vasodilation (e.g., nitroglycerin)
  • Block calcium ion movement into muscle cells (calciumion channel blockers)
  • Relieve pain and help dissolve clots (in MI)