Cardiovascular System: The Heart
Functions of the Heart
• Generating ______________ ______________
• ______________ blood
– Heart separates ______________ and ______________ circulations
• Ensuring ______________blood flow
– Heart valves ensure one-way flow
• ______________ blood supply
– Changes in ______________ rate and force match blood delivery to
changing ______________ needs
Size, Shape, Location of the Heart
• Size of a closed ______________
• Shape
– ______________: Blunt ______________ point of ______________
– Base: ______________ part at ______________ of end of cone
• Located in ______________ cavity
Heart Wall
• ______________ layers of tissue
– _________cardium: This serous membrane of ______________
______________ surface of heart
– ________cardium: Middle layer composed of ______________
______________cell and responsibility for heart ______________
– ________cardium: Smooth ______________ surface of heart
______________
External Anatomy
• ______________ chambers
– 2 atria
– 2 ______________
• Auricles
• Major ______________
– Superior ______________ ______________
– ______________ veins
• Major arteries
– ______________
– Pulmonary ______________
Heart Valves
• Atrioventricular
– ______________
– ______________ or mitral
• Semilunar
– ______________
– ______________
• Prevent blood from flowing ______________
Blood Flow Through Heart
1. What is another term for the bicuspid valve?
2. Write out the path of the blood starting at the superior vena cava and
inferior vena cava and back.
Systemic and Pulmonary Circulation
Write out the path of the blood starting in the right side of the heart and back.
Heart Skeleton
• Consists of plate of ______________ connective tissue between
______________ and ______________
• Fibrous ______________ around ______________ to support
• Serves as ______________ ______________ between atria and ventricles
• Provides site for ______________ attachment
Conducting System of Heart
Write out the path of the electrical stimulation from start to finish.
Refractory Period
• Absolute: ______________ muscle cell completely ______________ to
further stimulation
• Relative: Cell exhibits ______________ sensitivity to additional stimulation
• ______________ refractory period prevents tetanic ______________
Electrocardiogram
• ______________ potentials through ______________ during cardiac cycle
produces ______________ currents than can be measured
• Pattern
– P wave
• Atria ______________
– QRS complex
• Ventricle ______________
• Atria ______________
– T wave:
• Ventricle ______________
Cardiac Arrhythmias
• Tachycardia: Heart rate in excess of 100bpm
• Bradycardia: Heart rate less than 60 bpm
• Sinus arrhythmia: Heart rate varies 5% during respiratory cycle and up to
30% during deep respiration
• Premature atrial contractions: Occasional shortened intervals between one
contraction and succeeding, frequently occurs in healthy people
Cardiac Cycle
• Heart is two pumps that work together, right and left half
• Repetitive contraction (systole) and relaxation (diastole) of heart chambers
• Blood moves through circulatory system from areas of higher to lower
pressure.
– Contraction of heart produces the pressure
Heart Sounds
• First heart sound or “lubb”
– Atrioventricular valves and surrounding fluid vibrations as valves
close at beginning of ventricular systole
• Second heart sound or “dupp”
– Results from closure of aortic and pulmonary semilunar valves at
beginning of ventricular diastole, lasts longer
• Third heart sound (occasional)
– Caused by turbulent blood flow into ventricles and detected near end
of first one-third of diastole
Mean Arterial Pressure (MAP)
• Average blood pressure in aorta
• MAP=CO x PR
– CO is amount of blood pumped by heart per minute
• CO=SV x HR
– SV: Stroke volume of blood pumped during each heart
beat
– HR: Heart rate or number of times heart beats per
minute
• Cardiac reserve: Difference between CO at rest and maximum
CO
– PR is total resistance against which blood must be pumped
Factors Affecting MAP
Regulation of the Heart
• Intrinsic regulation: Results from normal functional characteristics, not on
neural or hormonal regulation
– Starling’s law of the heart
• Extrinsic regulation: Involves neural and hormonal control
– Parasympathetic stimulation
• Supplied by vagus nerve, decreases heart rate, acetylcholine
secreted
– Sympathetic stimulation
• Supplied by cardiac nerves, increases heart rate and force of
contraction, epinephrine and norepinephrine released
Heart Homeostasis
• Effect of blood pressure
– Baroreceptors monitor blood pressure
• Effect of pH, carbon dioxide, oxygen
– Chemoreceptors monitor
• Effect of extracellular ion concentration
– Increase or decrease in extracellular K+ decreases heart rate
• Effect of body temperature
– Heart rate increases when body temperature increases, heart rate
decreases when body temperature decreases
Effects of Aging on the Heart
• Gradual changes in heart function, minor under resting condition, more
significant during exercise
• Hypertrophy of left ventricle
• Maximum heart rate decreases
• Increased tendency for valves to function abnormally and arrhythmias to
occur
• Increased oxygen consumption required to pump same amount of blood
Cardiovascular System: The Heart
Functions of the Heart
•
Generating blood pressure
•
Routing blood
–
•
Ensuring one-way blood flow
–
•
Heart separates pulmonary and systemic circulations
Heart valves ensure one-way flow
Regulating blood supply
–
Changes in contraction rate and force match blood delivery to changing metabolic needs
Size, Shape, Location of the Heart
•
Size of a closed fist
•
Shape
•
–
Apex: Blunt rounded point of cone
–
Base: Flat part at opposite of end of cone
Located in thoracic cavity
Heart Wall
•
Three layers of tissue
–
Pericardium: This serous membrane of smooth outer surface of heart
–
Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart
contracting
–
Endocardium: Smooth inner surface of heart chambers
External Anatomy
•
•
Four chambers
–
2 atria
–
2 ventricles
Auricles
•
•
Major veins
–
Superior vena cava
–
Pulmonary veins
Major arteries
–
Aorta
–
Pulmonary trunk
Heart Valves
•
•
•
Atrioventricular
–
Tricuspid
–
Bicuspid or mitral
Semilunar
–
Aortic
–
Pulmonary
Prevent blood from flowing back
Blood Flow Through Heart
Systemic and Pulmonary Circulation
Heart Skeleton
•
Consists of plate of fibrous connective tissue between atria and ventricles
•
Fibrous rings around valves to support
•
Serves as electrical insulation between atria and ventricles
•
Provides site for muscle attachment
Conducting System of Heart
Refractory Period
•
Absolute: Cardiac muscle cell completely insensitive to further stimulation
•
Relative: Cell exhibits reduced sensitivity to additional stimulation
•
Long refractory period prevents tetanic contractions
Electrocardiogram
•
Action potentials through myocardium during cardiac cycle produces electric currents than can
be measured
•
Pattern
–
P wave
•
–
–
Atria depolarization
QRS complex
•
Ventricle depolarization
•
Atria repolarization
T wave:
•
Ventricle repolarization
Cardiac Arrhythmias
•
Tachycardia: Heart rate in excess of 100bpm
•
Bradycardia: Heart rate less than 60 bpm
•
Sinus arrhythmia: Heart rate varies 5% during respiratory cycle and up to 30% during deep
respiration
•
Premature atrial contractions: Occasional shortened intervals between one contraction and
succeeding, frequently occurs in healthy people
Cardiac Cycle
•
Heart is two pumps that work together, right and left half
•
Repetitive contraction (systole) and relaxation (diastole) of heart chambers
•
Blood moves through circulatory system from areas of higher to lower pressure.
–
Contraction of heart produces the pressure
Heart Sounds
•
First heart sound or “lubb”
–
•
Second heart sound or “dupp”
–
•
Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of
ventricular systole
Results from closure of aortic and pulmonary semilunar valves at beginning of
ventricular diastole, lasts longer
Third heart sound (occasional)
–
Caused by turbulent blood flow into ventricles and detected near end of first one-third
of diastole
Mean Arterial Pressure (MAP)
•
Average blood pressure in aorta
•
MAP=CO x PR
–
CO is amount of blood pumped by heart per minute
•
•
–
CO=SV x HR
–
SV: Stroke volume of blood pumped during each heart beat
–
HR: Heart rate or number of times heart beats per minute
Cardiac reserve: Difference between CO at rest and maximum CO
PR is total resistance against which blood must be pumped
Factors Affecting MAP
Regulation of the Heart
•
Intrinsic regulation: Results from normal functional characteristics, not on neural or hormonal
regulation
–
•
Starling’s law of the heart
Extrinsic regulation: Involves neural and hormonal control
–
Parasympathetic stimulation
•
–
Supplied by vagus nerve, decreases heart rate, acetylcholine secreted
Sympathetic stimulation
•
Supplied by cardiac nerves, increases heart rate and force of contraction,
epinephrine and norepinephrine released
Heart Homeostasis
•
Effect of blood pressure
–
•
Effect of pH, carbon dioxide, oxygen
–
•
Chemoreceptors monitor
Effect of extracellular ion concentration
–
•
Baroreceptors monitor blood pressure
Increase or decrease in extracellular K+ decreases heart rate
Effect of body temperature
–
Heart rate increases when body temperature increases, heart rate decreases when body
temperature decreases
Effects of Aging on the Heart
•
Gradual changes in heart function, minor under resting condition, more significant during
exercise
•
Hypertrophy of left ventricle
•
Maximum heart rate decreases
•
Increased tendency for valves to function abnormally and arrhythmias to occur
•
Increased oxygen consumption required to pump same amount of blood