Exam 3

• Purposes of the cardiorespiratory system

  Transport O2 and nutrients to tissues

  Removal of CO2 wastes from tissues

  Regulation of body temperature
• Two major adjustments of blood flow during exercise

  -increased cardiac output

  -redistribution of blood from inactive organs to active muscle
• arteries and arterioles


  carry blood away from the heart
• capillaries


  Exchange of O2, CO2, and nutrients with tissues
• veins and venules


  carry blood toward the heart
• pulmonary circuit is on the _____ side of the heart

  right

  -pumps deoxygenated blood to the lungs via pulmonary arteries

  -returns oxygenated blood to the left side of the heart via pulmonary veins
• systemic circuit is on the _______ side of the heart

  left

  -pumps oxygenated blood to the whole body via arteries

  -returns deoxygenated blood to the right side of the heart
• the heart wall is composed of the... (3)


  epicardium

  myocardium

  endocardium

  
• How does the myocardium receive its blood supply?

  coronary arteries
• myocardial infarction (MI)


  Blockage in coronary blood flow results in cell damage

  Exercise training protects against heart damage during MI
• heart muscle vs skeleton muscle (pt 1)

  
• heart muscle vs skeleton muscle (pt 2)

  
• systole


  -contraction phase

  -ejection of blood

  -approximately 2/3 blood is ejected from ventricles per beat
• diastole


  -relaxation phase

  -filling with blood
• at rest, the diastolic time is ________ than the systolic time

  longer
• how does exercise affect the duration of both systole and diastole

  makes them shorter
• pressure changes during diastole

  -pressure in ventricles is low

  -filling with blood from atria

  -AV valves open when the ventricle < atrial
• pressure changes during systole

  -Pressure in ventricles rises

  -Blood ejected in pulmonary and systemic circulation

  -Semilunar valves open when ventricular P > aortic P
• what is the first heart sound?

  closing of AV valves
• what is the second heart sound?

  closing of aortic and pulmonary valves
• what is pulse pressure?

  difference between systolic and diastolic pressure
• What is mean arterial pressure (MAP)?

  average pressure in the arteries throughout the cardiac cycle
• hypertension


  high blood pressure 140/90 or higher
• hypertension is a risk factor for...

  Left ventricular hypertrophy

  Atherosclerosis and heart attack

  Kidney damage

  Stroke
• determinants of mean arterial pressure (MAP)

  cardiac output

  total vascular resistance
• short term regulation of MAP

  Sympathetic nervous system

  Baroreceptors in aorta and carotid arteries

  -increase in BP = decreased SNS activity

  -decrease in BP = increased SNS activity
• long term regulation of MAP

  kidneys via control of blood volume
• factors that influence BP

  -Blood volume increases

  -HR increases

  -SV increases

  -Blood viscosity increases

  -Peripheral resistance increases

  
• components of cardiac conduction system

  SA node

  AV node

  Bundle of His

  Purkinje fibers
• Sinoartial node (SA node)


  pacemaker, initiates depolarization
• Atrioventricular node (AV node)


  -passes depolarization to ventricles

  -brief delay to allow for ventricular filling
• Bundle Branches


  connect atria to left and right ventricle
• Purkinje fibers


  spread wave of depolarization throughout ventricles
• Steps of conduction system of heart

  1. action potentials originate in SA node and travel across the wall of the atrium from the SA node to the AV node

  2. action potentials pass through the AV node and along the AV bundle, which extends from the AV node, through the fibrous skeleton, into the interventricular system

  3. the AV bundle divides into right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches

  4. action potentials are carried by the purkinje fibers from the bundle branches to the ventricular walls

  
• Electrocardiogram (ECG)


  A recording of the electrical activity of the heart

  -P wave: atrial depolarization

  -QRS complex: ventricular depolarization and atrial repolarization

  -T wave: ventricular repolarization

  
• ST segment depression may indicate...

  myocardial ischemia
• Atherosclerosis


  -fatty plaque that narrows coronary arteries

  -reduces blood flow to myocardium (myocardial ischemia)
• what do heart sounds reflect?

  changes in intraventricular pressure and opening/closing of heart valves
• where is the beginning of systole on ECG?

  QRS complex
• where is the beginning of diastole on ECG?

  T wave