diseases

• pericarditis: inflammation of the pericardium

  • roughs the serous membranes.making a creaking sound that can be heard
  • characterized by pain deep the sternum, can eventually lead to adhesions, inhibiting the heart to work properly
• cardiac tamponade: excess fluid from pericardial sac seeps into the heart and limits the ability to pump blood

  • treated by sticking a syringe in the heart and draining off excess fluid
• valvular stenosis: valve flaps become stiff and it forces the heart to work harder than necessary

  • makes it rempump the same blood over and over making the heart weaker over time
  • can be replaced with a mechanical valve or pig or cow valve
• angina pectoris: a thoracic pain that is caused by lack of blood delivery to the heart

  • can be from stress induced spasms of coronary arteries or increased physical demands of heart
  • myocardial cells are weakened by the lack of oxygen but they don't die
• myocardial infarction or heart attack: prolonged coronary blockage and cells die

  • dead tissue is replaced with non contractile scar tissues because tissue is amitotic
  • if a person will survive that depends on where the infarction happened
• Arrhythmias: irregular heart rhythms

  • Uncoordinated atrial and ventricular contractions
• Fibrillation: rapid, irregular contractions

  • Heart becomes useless for pumping blood, causing circulation to cease; may result in brain death

  Treatment: defibrillation interrupts chaotic twitching, giving heart “clean slate” to start regular, normal depolarizations
• Defective SA node may cause ectopic focus, an abnormal pacemaker that takes over pacing

  • If AV node takes over, it sets junctional rhythm at 40–60 beats/min
• Extrasystole (premature contraction): ectopic focus of small region of heart that triggers impulse before SA node can, causing delay in next impulse

  • Heart has longer time to fill, so next contraction is felt as thud as larger volume of blood is being pushed out
  • Can be from excessive caffeine or nicotine
• • If AV node is defective, may cause a heart block
  • Few impulses (partial block) or no impulses (total block) reach ventricles
  • Ventricles beat at their own intrinsic rate
  • Too slow to maintain adequate circulation
  • Treatment: artificial pacemaker, which couples atria and ventricles
• Heartbeat modified by ANS via cardiac centers in medulla oblongata
• • Cardioacceleratory center: sends signals through sympathetic trunk to increase both rate and force
  • Stimulates SA and AV nodes, heart muscle, and coronary arteries
• • Cardioinhibitory center: parasympathetic signals via vagus nerve to decrease rate
  • Inhibits SA and AV nodes via vagus nerves
• Hypocalcemia: depresses heart
• Hypercalcemia: increases HR and contractility
• Hyperkalemia: alters electrical activity, which can lead to heart block and cardiac arrest
• Hypokalemia: results in feeble heartbeat; arrhythmias
• Other factors that influence heart rate:

  • Age  
  • Fetus has fastest HR; declines with age
  • Gender
  • Females have faster HR than males
  • Exercise
  • Increases HR
  • Trained atheles can have slow HR
  • Body temperature
  • HR increases with increased body temperature
• • Tachycardia: abnormally fast heart rate (>100 beats/min)
  • If persistent, may lead to fibrillation
• • Bradycardia: heart rate slower than 60 beats/min
  • May result in grossly inadequate blood circulation in nonathletes
  • May be desirable result of endurance training
• • Congestive heart failure (CHF)
  • Progressive condition; CO is so low that blood circulation is inadequate to meet tissue needs
  • Reflects weakened myocardium caused by:
  • Coronary atherosclerosis: clogged arteries caused by fat buildup; impairs oxygen delivery to cardiac cells
  • Heart becomes hypoxic, contracts inefficiently
• • Persistent high blood pressure: aortic pressure >90 mmHg causes myocardium to exert more force
  • Chronic increased ESV causes myocardium hypertrophy and weakness
• Multiple myocardial infarcts: heart becomes weak as contractile cells are replaced with scar tissue
• • Dilated cardiomyopathy (DCM): ventricles stretch and become flabby, and myocardium deteriorates
  • Drug toxicity or chronic inflammation may play a role
• • Either side of heart can be affected:
  • Left-sided failure results in pulmonary congestion 
  • Blood backs up in lungs
  • Right-sided failure results in peripheral congestion
  • Blood pools in body organs, causing edema
• • Failure of either side ultimately weakens other side
  • Leads to decompensated, seriously weakened heart
  • Treatment: removal of fluid, drugs to reduce afterload and increase contractility
• • Heart Murmurs Usually indicate valve problems
  • Incompetent (or insufficient) valve: fails to close completely, allowing backflow of blood
  • Causes swishing sound as blood regurgitates backward from ventricle into atria
• • Stenotic valve: fails to open completely, restricting blood flow through valve
  • Causes high-pitched sound or clicking as blood is forced through narrow valve
• Heart murmurs: abnormal heart sounds heard when blood hits obstructions