November 7th

Cardiac Muscle Characteristics

Involuntary and homogeneous, resembling Type I muscle fibers; highly oxidative with abundant mitochondria and high caloric density; contracts as one unit.

Desmosomes

Structural junctions in cardiac muscle that hold cells together.

Intercalated Discs

Structures in cardiac muscle that facilitate communication and contraction between cardiac cells.

Gap Junctions

Components of cardiac muscle that permit the passage of ions and electrical impulses between cells.

Sinoatrial Node (SA Node)

The primary pacemaker of the heart, located in the upper right atrium, setting a baseline heart rate of about 100 beats per minute and establishing sinus rhythm.

Atrioventricular Node (AV Node)

Delays electrical conduction from the atria to ventricles by approximately 1300ths of a second, allowing for complete ventricular filling.

Atrial Kick

The complete filling of the ventricles before contraction, facilitated by the delay from the AV Node.

Purkinje Fibers

Transmit impulses quickly through the ventricles, essential for synchronized ventricular contraction.

Cardiac Cycle

Comprises two phases: Systole (contraction and ejection) and Diastole (filling).

Diastole

The period of heart filling, characterized by low pressure, allowing for optimal filling of the heart.

Systole

The period of heart contraction and blood ejection, characterized by high pressure as blood is pushed out.

Normal Blood Pressure at Rest

Less than 120/80 mmHg.

Ejection Fraction

A key measurement of heart health, defined as Stroke \, Volume \, / \, End \, Diastolic \, Volume. Normal at rest is about 60%.

Stroke Volume

The volume of blood pumped per beat, calculated as End \, Diastolic \, Volume \, - \, End \, Systolic \, Volume. Defined by End Diastolic Volume and End Systolic Volume.

End Diastolic Volume

The amount of blood in the ventricles at the end of diastole, which should be high for effective pumping.

End Systolic Volume

The amount of blood remaining in the ventricles after contraction, which should be low to indicate efficient pumping.

Torsional Control

Describes the twisting motion of the heart that enhances filling of the ventricles during diastole, aiding blood flow from atria to ventricles.

Cardiac Muscle Characteristics

Involuntary, homogeneous muscle fibers closely resembling Type I muscle fibers, highly oxidative (aerobic metabolism), abundant mitochondria, and high caloric density.

Desmosomes

Structural junctions in cardiac muscle that hold cells together.

Intercalated Discs

Structural features in cardiac muscle that facilitate communication and contraction between cardiac cells.

Gap Junctions

Structures in cardiac muscle that permit the passage of ions and electrical impulses between cells.

Sinoatrial Node (SA Node)

The primary pacemaker of the heart, located in the upper right atrium, setting a baseline heart rate of about 100 beats per minute and establishing sinus rhythm.

Atrioventricular Node (AV Node)

Delays electrical conduction from the atria to ventricles by approximately 1300ths of a second, allowing for complete ventricular filling (atrial kick).

Purkinje Fibers

Transmit impulses quickly through the ventricles, allowing for rapid and synchronized ventricular contraction.

Diastole

The period of heart filling, characterized by low pressure, allowing for optimal passive and active filling of the heart.

Systole

The period of heart contraction and blood ejection, characterized by high pressure as blood is pushed out to systemic and pulmonary circulation.

Normal Blood Pressure (rest)

Less than 120/80 mmHg at rest.

Acute Effects of Exercise on Blood Pressure

Systolic pressure increases due to higher stroke volume and demand for oxygenated blood, while diastolic pressure may remain the same or slightly decrease due to vasodilation.

Chronic Effects of Regular Exercise

Resting blood pressure tends to decrease, and overall cardiovascular fitness, oxygen delivery, and metabolic capabilities improve.

Ejection Fraction

A key measurement of heart health, calculated as Stroke Volume / End Diastolic Volume . Normal at rest is about 60% and can improve with exercise.

Stroke Volume

The volume of blood pumped per beat, determined by End Diastolic Volume and End Systolic Volume. Calculated as Stroke Volume = End Diastolic Volume - End Systolic Volume .

End Diastolic Volume

The amount of blood in the ventricles at the end of diastole (should be high for effective pumping).

End Systolic Volume

The amount of blood remaining in the ventricles after contraction (should be low to indicate efficient pumping).

Torsional Control (Diastolic Suction)