CARDIAC ANATOMY
This innermost layer of the heart wall is composed of simple squamous epithelium and is continuous with the endothelial lining of the blood vessels.
What is the endocardium?
This node in the right atrial wall serves as the heart's natural pacemaker by generating impulses approximately 75 times per minute.
What is the sinoatrial node?
This term describes the volume of blood remaining in each ventricle after the contraction phase of the cardiac cycle is complete.
What is end systolic volume?
This middle layer of the blood vessel wall, composed of smooth muscle and elastin, is the primary site of vasoconstriction and vasodilation.
What is the tunica media?
These sensory receptors, located in the carotid sinuses and aortic arch, detect changes in blood pressure and transmit signals to the cardiovascular center.
What are baroreceptors?
These structures anchor the cusps of the atrioventricular valves to the papillary muscles to prevent the valves from everting into the atria during contraction.
What are chordae tendineae?
These specialized connecting junctions contain gap junctions that electrically couple adjacent cells, allowing the heart to function as a single coordinated unit.
What are intercalated discs?
The first heart sound, known as "lub," is produced when these specific valves close at the beginning of ventricular systole.
What are the atrioventricular valves?
Of the three sources of peripheral resistance, this specific variable has the greatest influence because resistance varies inversely with its fourth power.
What is blood vessel diameter or radius?
This hormonal system is initiated by the release of renin from the kidneys to stabilize arterial blood pressure when it declines.
What is the renin-angiotensin-aldosterone mechanism?
If the left coronary artery is occluded, these two specific regions of the heart will experience a deficiency in blood delivery.
What are the interventricular septum and the anterior ventricular walls?
In an electrocardiogram, this specific wave represents the depolarization of the SA node and the subsequent contraction of the atria.
What is the P wave?
According to the Frank-Starling law, an increase in this factor—the amount of blood returning to the heart—leads to an increase in stroke volume.
What is venous return?
This physiological calculation, which propels blood to the tissues, is determined by adding the diastolic pressure to one-third of the pulse pressure.
What is mean arterial pressure?
This "sucking" pressure is created by nondiffusible plasma proteins pulling water back into the capillary from the interstitial space.
What is capillary colloid osmotic pressure or oncotic pressure?
The left ventricle wall is three times thicker than the right ventricle wall due to this primary difference in the resistance of their respective circuits.
What is the high friction of the systemic circuit compared to the low pressure of the pulmonary circuit?
During the pacemaker potential, the interior of the cell becomes more positive because these specific channels are open while potassium channels are closed.
What are slow sodium channels?
During the isovolumetric contraction phase of the cardiac cycle, all heart valves are closed, meaning this physiological variable remains constant while pressure rises.
What is ventricular volume?
These small-diameter vessels are known as "resistance vessels" because their frequent changes in diameter are the major determinants of peripheral resistance.
What are arterioles?
Net filtration occurs at the arterial end of a capillary bed because this outward force exceeds the inward capillary colloid osmotic pressure.
What is capillary hydrostatic pressure?
Inflammation of the pericardium results in this diagnostic creaking sound heard with a stethoscope as membrane surfaces become roughened.
What is a pericardial friction rub?
This specific 0.1-second event in the intrinsic conduction system ensures the atria finish their contraction before the ventricles begin to contract.
What is the delay at the atrioventricular node?
This specific aortic pressure event occurs during isovolumetric relaxation as backflow rebounds off the closed aortic semilunar valve cusps.
What is the dicrotic notch?
Blood flow is mathematically defined as being directly proportional to the pressure gradient and inversely proportional to this source of friction.
What is peripheral resistance?
This clinical condition, caused by low levels of plasma proteins from liver disease or malnutrition, results in edema by hindering fluid return to the blood.
What is hypoproteinemia?