CARDIOVASCULAR SYSTEM - THE HEART
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I. Anatomy of the Heart
A. Size and location
1. Roughly, fist-sized and <1 pound
2. Mediastinum
B. Membranous Coverings of the Heart
1. Pericardium
a. Parietal pericardium -
b. Visceral pericardium (epicardium) -
c. Pericardial cavity -
d. Outer Fibrous Layer ("pericardial sac")
2. Pericarditis
C. Layers of the Heart Wall
1. Epicardium - (same as visceral pericardium)
2. Myocardium -
3. Endocardium -
D. Surface Anatomy of the Heart
1. Auricles
2. Coronary Sulcus (Atrioventricular sulcus or groove)
3. Interventricular Sulcus (or groove)
4. Base
5. Apex
E. Heart Chambers and Internal Anatomy
1. Atria
a. Interatrial septum
b. Fossa ovalis (foramen ovale in the fetus)
c. Pectinate muscle
d. Openings to Superior Vena Cava, Inferior Vena Cava and Coronary Sinus
2. Ventricles
a. Interventricular septum
b. Papillary muscles
c. Chordae tendinae
d. Trabeculae carnae
F. Heart Valves
1. Right chambers
a. Tricuspid valve (Right Atrioventricular (AV) valve)
b. Pulmonary semilunar valve
2. Left chambers
a. Bicuspid valve (Left AV valve or Mitral valve)
b. Aortic semilunar valve
3. Valve defects
a. Stenosis -
b. Mitral valve prolapse (MVP)
G. Cardiac muscle fibers (microscopic anatomy: review from BIO 1007!)
1. Cardiac muscle cells
a. Striations
b. Branched
c. 1-2 nuclei, lots of mitochondria
d. Intercalated discs with gap junctions
2. Functional syncytium -
H. Cardiac Skeleton
1. Fibrous CT
2. Fx:
I. Pathway of Blood Through the Heart
1. Pulmonary Circuit
2. Systemic Circuit
J. Blood Supply to the Heart
1. Coronary arteries
2. Cardiac (coronary) veins and coronary sinus
3. Angina pectoris -
4. Myocardial infarction (MI) -
5. CHF -
6. Visit the American Heart Association web site for statistics on heart disease: www.americanheart.org (link checked 1/14/07)
II. Cardiac Physiology
A. Differences Between Cardiac Muscle (C) and Skeletal Muscle (S)
1. All-or-none law
S : true at cellular level
C : true at organ level
2. Means of stimulation
S : external nervous stimulation manditory
C : autorhythmic cells
B. Intrinsic Conduction System and Automaticity (Autorhythmicity) of the Heart (Suggested activity: View the Intrinsic Conduction System section of the Interactive Physiology CD: Cardiovascular System section)
1. Autorhythmic cells - spontaneously depolarize
a. Sinoatrial (SA) node
b. Atrioventricular (AV) node
c. Atrioventricular bundle (bundle of His)
d Bundle branches
e. Purkinje fibers
2. Electrocardiography
a. Electrocardiograph - instrument used to measure the electrical activity of the heart
b. Electrocardiogram - the graphic recording given by the above instrument; also called an ECG or EKG
1. P wave -
2. QRS complex (wave) -
3. T wave -
3. Defects of the Conduction System
a. Arrhythmias -
b. Fibrillation -
c. Heart block -
C. Cardiac cycle *the changes that occur within the heart during contraction*
1. Systole -
2. Diastole -
Summary of Cardiac Cycle:
The series of events that occur within the heart during each heartbeat constitutes the cardiac cycle. We can describe these changes in terms of the pressure changes that occur within the atria and the ventricles and also by noting the blood volume present (within the ventricles). Let's list, in order, the changes that occur. We will start with the heart when it is at rest (diastole).
1. Atrial pressure (low). Blood flows --> atria --> ventricles. 70% of the total blood volume enters the ventricles passively at this time.
2. Atrial pressure (high). Atria contract (atrial systole) forcing the remaining 30% of the blood into the ventricles. *note: at the end of this period, the blood volume = the end diastolic volume (EDV~120mL).
3. The atria relax (atrial diastole) and then the ventricles contract (ventricular systole). AV valves start to bulge back into the atria. Papillary muscles prevent the valves from bulging too far. At this time, ventricular pressure >> atrial pressure (AV valves close)
4. Ventricular pressure during contraction >> Pressure of the great arteries This forces semilunar valves open. Blood leaves ventricles. As ventricular pressure falls, blood starts to flow back toward ventricles, but is stopped by the semilunar valve cusps. *note: at the end of this period, the volume of blood left in the ventricles after ventricular systole = the end systolic volume (ESV~50mL)
D. Heart sounds
1. Lub =
2. Dup =
3. Murmurs
E. Heart Dynamics
1. Cardiac Output (CO or Q)
CO (Q) = Stroke Volume (SV) x Heart Rate (HR)
a. Stroke volume (SV) -
b. EDV (preload) -
c. ESV -
d. Starling's Law of the Heart
e. SV = EDV - ESV
2. Factors Controlling Cardiac Output (View Interactive Physiology CD: Cardiovascular System)
a. Blood Volume Reflexes
1. Atrial or Bainbridge Reflex
a. Venous Return and Filling Time
i. Tachycardia -
ii. Bradycardia -
2. Frank-Starling Law of the Heart
E. Autonomic Effects on Heart Rate
1. Parasympathetic stimulation and ACh
2. Sympathetic stimulation and Norepinephrine
3. Epinephrine and Norepineprine from the Adrenal Medulla
F. Autonomic Effects on Stroke Volume
1. Epinephrine and Norepineprine
Are you ready to test your Heart knowledge? Click here and choose the "quizzes" link. (Link updated 1/14/07)
Last Updated 06/08/07