Studied by 3 peopleDescribe the location and the position of the heart.
It is in the mediastinum, which is the central compartment of the chest. It is positioned slightly to the left of the midline of the chest, between the lungs, behind the sternum (breastbone), and above the diaphragm.
Base of the heart.
Is broader and connects to major blood vessels.
Apex of the heart.
Is pointed and rests on the diaphragm.
Name the four chambers of the heart.
Left and Right Atria/ Left and Right Ventricle
Systemic Circuit
The left ventricle pumps oxygenated blood into this circuit, supplying the body's tissues and organs. It receives a larger volume of blood compared to the pulmonary circuit.
Pulmonary Circuit
The right ventricle pumps deoxygenated blood into this circuit where it is oxygenated in the lungs. It receives a smaller volume of blood compared to the systemic circuit.
Define mediastinum.
The central compartment of the thoracic cavity, located between the lungs. It contains various structures such as the heart, major blood vessels, esophagus, trachea, thymus, and lymph nodes.
Describe the heart’s location in the body.
Located in the thoracic cavity, specifically in the mediastinum, between the lungs. It is tilted slightly to the left side of the chest.
Why can cardiac tamponade be a life-threatening condition?
It involves the accumulation of fluid or blood in the pericardial sac, which compresses the heart and impairs its ability to pump blood effectively. This leads to decreased cardiac output, reduced oxygen supply to vital organs, and potentially fatal consequences such as shock, organ failure, and cardiac arrest.
Why can pericarditis be a life-threatening condition?
Can cause arrhythmias or inflammation of the heart valves, further increasing the risk of life-threatening complications.
What is arrhythmias?
Abnormal heart rhythms that can occur when the electrical signals in the heart are disrupted. This can cause the heart to beat too fast, too slow, or irregularly.
From superficial to deep, name the layers of the heart wall.
Pericardium, Myocardium, then Endocardium.
Describe the tissue layers of the pericardium.
Fibrous pericardium: It is the tough outer layer made of dense connective tissue that protects the heart and anchors it to surrounding structures.
Parietal pericardium: It is the middle layer composed of a serous membrane that produces a lubricating fluid to reduce friction between the heart and surrounding structures.
Visceral pericardium (epicardium): It is the innermost layer that directly covers the heart and is also composed of a serous membrane.
Why is it important that cardiac tissue contain many mitochondria and capillaries?
To generate ATP, the energy currency of cells, for continuous contraction; ensures efficient oxygen and nutrient supply to meet the high metabolic demands of the heart.
The anterior view of the heart is dominated by which chambers?
It is dominated by the four chambers with boundaries of sulci, auricles, and the ligamentum arteriosum.
The posterior view of the heart is dominated by which chambers?
It is dominated by the four chambers with boundaries of sulci and great blood vessles.
Which structures collect blood from the myocardium and into which heart chamber does this blood flow?
Cardiac veins; into the right atrium of the heart.
Coronary sulcus.
Encircles the heart and separates the atria from the ventricles.
Anterior interventricular sulcus.
Runs along the anterior surface of the heart and marks the boundary between the right and left ventricles.
Posterior interventricular sulcus.
Located on the posterior surface of the heart and separates the right and left ventricles.
Describe the areas of the heart supplied by the right and left coronary arteries?
The right coronary artery supplies blood to the right atrium, right ventricle, and the bottom portion of the left ventricle. The left coronary artery supplies blood to the left atrium, left ventricle, and the septum of the heart.
Anterior cardiac veins.
Drain blood from the anterior surface of the heart. They ultimately empty into the right atrium of the heart.
Posterior vein of the left ventricle.
Drains blood from the posterior part of the left ventricle and carries it back to the coronary sinus, which then returns the blood to the right atrium.
Arteries of the heart.
Right Coronary Artery
Marginal Arteries
Posterior Interventricular Artery
Left Coronary Artery
Circumflex Artery
Anterior Interventricular Artery (Left Descending Artery)
Veins of the heart.
Coronary Veins (anterior)
Anterior Cardiac Veins
Great Cardiac Vein
Coronary Veins (posterior)
Great Cardiac Vein
Posterior Vein of Left Ventricle
Middle Cardiac Vein
Small Cardiac Vein- vein circling around right atrium into the coronary sinus
Coronary Sinus- thick vein going into the right atrium
Describe what happens to blood flow in elastic rebound.
Pressure in vessel decreases causing the aortic walls to recoil pushing blood in both directions. Forward into the systemic circuit and backwards into coronary arteritis.
Why is the left ventricle more muscular than the right ventricle?
It needs to pump blood to the entire body, while the right ventricle only needs to pump blood to the lungs.
Damage to the semilunar valve on the right side of the heart would affect blood flow to which vessel?
Pulmonary trunk.
Define cardiac regurgitation.
A condition where the heart's valves do not close properly, leading to the backward flow of blood.
Describe the structural and functional roles of the cardiac skeleton.
Structurally- provides support and anchorage for the heart valves, helping to maintain their proper alignment and prevent their overstretching. It also separates the atria from the ventricles, ensuring the proper flow of blood through the heart chambers.
Functionally- acts as an electrical insulator, preventing the direct spread of electrical impulses between the atria and ventricles. Also helps to maintain the integrity of the heart's structure, preventing excessive stretching and distortion during the cardiac cycle.
What do semilunar valves prevent?
The backflow of blood from the arteries into the ventricles of the heart.
Arteriosclerosis.
The thickening and hardening of the arterial walls, affects the small arteries and arterioles, can increase the risk of various cardiovascular diseases, including heart attack and stroke.
Atherosclerosis.
The buildup of plaque in the arteries, leading to narrowing and hardening of the arteries. It is a progressive disease that can restrict blood flow and increase the risk of heart attacks, strokes, and other cardiovascular problems, is believed to involve a combination of factors such as high cholesterol, high blood pressure, smoking, and inflammation.
What is coronary ischemia?
A condition where there is a reduced blood flow to the heart muscle due to a partial or complete blockage in the coronary arteries.
Describe the purpose of a stent.
To treat narrow or blocked arteries to restore blood flow by keeping the artery open and preventing it from becoming blocked again.
Define cardiac cycle.
The sequence of events that occur during one complete heartbeat, including the contraction and relaxation of the heart chambers. It consists of systole and diastole phases of the atria and ventricles, allowing blood to be pumped throughout the body.
Give the alternate term for heart contraction.
Systole.
Give the alternate term for heart relaxation.
Diastole.
Compare the duration of atrial and ventricular systole at a representative heart rate of 75bpm.
The duration of atrial systole is approximately 0.1 seconds (100 msec), while the duration of ventricular systole is approximately 0.27 seconds (270 msec).
List the phases of the cardiac cycle.
Atrial Contraction (Atrial Systole)
Isovolumetric Contraction (Ventricular Systole)
Ventricular Ejection (Ventricular Systole)
Isovolumetric Relaxation (Ventricular Diastole)
Rapid Ventricular Filling (Ventricular Diastole)
Reduced Ventricular Filling (Ventricular Diastole)
What are the two phases of ventricular systole?
Isovolumetric contraction and ventricular ejection.
Is the heart always pumping blood when pressure in the left ventricle is rising?
No, when pressure in the left ventricle first rises, the heart is contracting but no blood is leaving the heart.
Why does tetany not occur in cardiac muscle?
The cells have a longer refractory period compared to skeletal muscle cells. This prevents sustained contraction and allows the heart to relax and refill with blood between contractions.
List the three stages of an action potential in a cardiac muscle cell.
Depolarization: During this stage, the cell membrane becomes more permeable to sodium ions, causing an influx of sodium into the cell. This leads to a rapid depolarization of the membrane.
Plateau Phase: In this stage, the cell membrane remains depolarized due to a balance between the influx of calcium ions and the efflux of potassium ions. This prolonged depolarization helps in the contraction of the cardiac muscle.
Repolarization: During this stage, the cell membrane becomes more permeable to potassium ions, leading to an efflux of potassium out of the cell. This restores the membrane potential to its resting state.
Describe slow calcium channels and the significance of their activity.
The significance of their activity lies in their role in regulating muscle contraction, neurotransmitter release, hormone secretion, and gene expression. They play a crucial role in cardiac function, as they contribute to the initiation and maintenance of the cardiac action potential.
Define autorhythmicity.
The ability of certain cells to generate spontaneous electrical impulses at regular intervals without external stimulation.
If the cells of the SA node failed to function, how would the heart rate be affected?
The heart rate would than be controlled by the AV node and would be affected it by slowing down or becoming irregular.
Why is it important for impulses from the atria to be delayed at the AV node before they pass into the ventricles?
To allow the atria to fully contract and empty their blood into the ventricles before the ventricles contract. This ensures efficient filling of the ventricles and optimal blood flow throughout the body.
Define electrocardiogram.
A medical test that records the electrical activity of the heart. It measures the electrical signals generated by the heart as it beats, providing information about the heart's rhythm, rate, and overall health.
List the important features of the ECG and indicate what each represents (draw it out).
P wave: Represents atrial depolarization.
QRS complex: Represents ventricular depolarization. Cannot be seen, but atrial repolarization occurs too.
T wave: Represents ventricular repolarization.
P-R interval: Represents the time it takes for the electrical signal to travel from the atria to the ventricles.
Q-T interval: Represents the time it takes for ventricular depolarization and repolarization.
Why is ventricular fibrillation fatal?
It disrupts the normal electrical signals in the heart, causing the ventricles to quiver instead of contracting effectively. This leads to a rapid and irregular heartbeat, preventing the heart from pumping blood effectively to the body and vital organs.
Bradycardia.
An abnormally slow heart rate, typically less than 60 beats per minute.
Tachycardia.
An abnormally fast heart rate, typically exceeding 100 beats per minute.
Describe the sites and actions of the cardioinhibitory and cardioacceleratory centers.
Both are located in the medulla oblongata. Cardioinhibitory are parasympathetic and decrease heart rate. Cardioacceleratory are sympathetic and increase heart rate.
Caffeine has effects on conducting cells and contractile cells similar to NE. What effect would drinking large amounts of caffeine have on the heart rate?
It would increase the heart rate.
Define end-diastolic volume (EDV) and end systolic volume (ESV).
EDV is the maximum volume of blood in the ventricles at the end of relaxation, while ESV is the minimum volume of blood in the ventricles at the end of contraction.
What effect would an increase in venous return have on stroke volume?
It would cause an increase in stroke volume.
What affect would an increase in sympathetic stimulation of the heart have on the end-systolic volume (ESV)?
It would lead to a decrease in end-systolic volume (ESV).
Define heart failure.
The inability of the heart to pump enough blood to meet the body's needs. It occurs when the heart muscles become weakened or damaged, leading to reduced cardiac output. Can be caused by various factors, including coronary artery disease, high blood pressure, heart valve disorders, and cardiomyopathy.
Compute the stroke volume of the ESV is 40ml and EDV is 125ml.
The stroke volume (SV) can be calculated by subtracting the end-systolic volume (ESV) from the end-diastolic volume (EDV).
SV = EDV - ESV;
SV = 125ml - 40ml SV = 85ml
Note
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