Chapter 13: The Cardiovascular System - Cardiac Function

A complete set of vocabulary flashcards covering the heart's anatomy, electrical conduction system, cardiac cycle phases, and the factors regulating cardiac output based on Chapter 13 lecture notes.

Heart

A muscular organ used to move blood through the vessels that also possesses sensory and endocrine functions for blood pressure and blood volume regulation.

Blood Vessels

The tubular conduit system for the blood that serves as sensory and effector organs for blood pressure regulation and blood distribution.

Blood

A fluid used to carry materials to and from cells and to transport hormones that facilitate communication between organs and systems.

Atria

The heart chambers that receive blood from the veins.

Ventricles

The muscular heart chambers responsible for pumping blood out to the lungs and systemic organs.

Pericardium

The protective sac around the heart consisting of a fibrous pericardium and a serous pericardium with parietal and visceral layers.

Myocardium

The core layer of the heart wall composed of muscle tissue responsible for contraction.

Endocardium

The inner lining of the heart wall that borders the heart chambers.

Epicardium

The visceral layer of the serous pericardium that forms the outermost layer of the heart wall.

Atrioventricular (AV) Valves

Valves (tricuspid on the right and bicuspid/mitral on the left) that open when ventricles are relaxed and close when ventricles contract to prevent backflow into the atria.

Semilunar Valves

Valves (aortic and pulmonary) that open during ventricular contraction and close during relaxation as blood in the arteries presses down against the cusps.

Chordae tendineae

Thread-like bands of fibrous tissue that attach the atrioventricular valve cusps to papillary muscles to prevent the valves from being pushed into the atria.

Papillary muscle

Muscles located in the ventricles that contract to tighten the chordae tendineae, preventing valve inversion during ventricular contraction.

Plasma

The liquid portion of whole blood, making up approximately $55\%$ of the total blood volume.

Buffy coat

The portion of whole blood containing leukocytes and platelets, representing less than $1\%$ of the whole blood volume.

Erythrocytes

Red blood cells (RBCs) that make up approximately $45\%$ of whole blood volume and feature a biconcave disc shape for flexibility and increased surface area.

Parallel Blood Flow

A circulatory arrangement ensuring that all organs receive the same quality of blood (nutrients and oxygen) and allowing for regional control of blood distribution.

Autorhythmic Cells

Specialized cardiac myocytes that establish the heart rhythm; they include pacemaker cells and conduction fibers.

Pacemaker Cells

Specialized cells concentrated in the Sinoatrial (SA) node and Atrioventricular (AV) node that spontaneously generate action potentials to establish heart rhythm.

Sinoatrial (SA) node

The primary pacemaker of the heart located in the right atrium that generates action potentials more quickly than the $AV$ node.

Conduction Fibers

Large diameter cardiac myocytes specialized to transmit action potentials rapidly through the heart's conduction system.

Myogenic activity

Contractile activity that originates within the muscle tissue itself, characteristic of the heart, rather than being triggered by nerves.

Neurogenic activity

Contractile activity triggered by nervous system signals, characteristic of skeletal muscle.

Electrocardiogram (ECG)

A non-invasive technique for recording the electrical activity of the heart generated by the spread of current through body fluids.

Einthoven’s Triangle

The configuration of Lead I, II, and III placed on the limbs to provide different electrical views of the heart's current direction.

P-wave

The ECG waveform representing atrial depolarization.

QRS complex

The ECG waveform representing ventricular depolarization.

T-wave

The ECG waveform representing ventricular repolarization.

Systole

The phase of the cardiac cycle characterized by ventricular contraction.

Diastole

The phase of the cardiac cycle characterized by ventricular relaxation.

Systolic Blood Pressure (SBP)

The maximal aortic pressure reached during systole as blood enters the aorta from the left ventricle.

Diastolic Blood Pressure (DBP)

The minimum aortic pressure reached during diastole as blood leaves the aorta and moves downstream.

Mean Arterial Pressure (MAP)

The average aortic pressure during a cardiac cycle, representing the overall driving force for blood to reach organs.

End-diastolic volume (EDV)

The maximum volume of blood in the ventricles at the end of the filling phase, approximately $130\,cm^3$ at rest.

End-systolic volume (ESV)

The minimum volume of blood remaining in the ventricles after contraction, approximately $60\,cm^3$ at rest.

Stroke Volume (SV)

The volume of blood ejected from a ventricle in a single beat, calculated as $SV = EDV - ESV$.

Ejection Fraction (EF)

The percentage of $EDV$ ejected from the heart during one cardiac cycle, calculated as $EF = \frac{SV}{EDV}$; a normal value is approximately $54\%$.

Cardiac Output (CO)

The rate at which a single ventricle pumps blood, calculated as $CO = HR \times SV$; a normal value is approximately $5.0\,dm^3\,min^{-1}$.

Vagus nerves

The parasympathetic nerves that provide inhibitory input to the pacemaker cells to slow the heart rate.

Starling’s Law of the Heart

The intrinsic mechanism stating that when venous return changes, the heart automatically adjusts its output by stretching the myocardium to a more ideal sarcomere length.

Preload

The load on the myocardium, determined by End Diastolic Pressure ($EDP$), that exists before the heart contracts.

Afterload

The amount of resistance or arterial pressure the heart must pump against to eject blood; it increases as Mean Arterial Pressure ($MAP$) increases.

Ventricular Contractility

The force of ventricular contraction at any given $EDV$, increased extrinsically by the sympathetic nervous system and circulating epinephrine.