37 Questions
What causes typical repolarization of the cardiac cell?
Opening of K+ channels
Why does the long refractory period occur in the cardiac cycle?
To prevent premature contractions
Which component of the heart's electrical system fires the fastest without endocrine control?
SA node
What is the main function of the troponin in the cardiac muscle contraction process?
Allowing myosin and actin cross bridge formation
Which element is commonly used to record electrical signals of the heart in an abbreviated form?
Electrodes on the body
Where is the heart located in the body?
In the thoracic cavity
Which structure separates the heart from other structures?
Pericardium
What is the main function of the ventricles in the heart?
Pump blood out to the body or lungs
Which layer of the heart contains muscle cells, nerve fibers, and blood vessels?
Myocardium
What is the main function of the auricles in the heart?
Collect blood and push it into atria
Which blood vessel is unique in carrying deoxygenated blood?
Pulmonary artery
Which layer lines the chambers filled with blood and covers heart valves?
Endocardium
What is the main function of endothelins released by the endothelium?
Regulate growth patterns of cardiac muscle cells
Which structure divides the heart into chambers?
Septum
What is the function of the atrioventricular valves?
Separate atria from ventricles
Which valve closes due to papillary muscles?
Mitral valve
What ensures unidirectional blood flow in the heart?
Valves
Where do coronary arteries branch off from?
Aorta
What is the main function of the SA node in the heart?
Set the normal cardiac rhythm
What role do Purkinje fibers play in cardiac conduction?
Spread impulses around the ventricles
What happens during the plateau phase of cardiac contractile cells?
Ca++ channels close and Na+ channels are open
During which phase of the cardiac cycle does the P wave represent the depolarization of the atria?
Atrial systole
What is the main function of an artificial pacemaker?
Ensuring effective heart contractions
Which phase of the cardiac cycle is characterized by the pumping of blood into circulation?
Ventricular systole
What is the main function of an AED (Automated External Defibrillator)?
Correcting fibrillations
Which phase of the cardiac cycle signifies the relaxation of the ventricles and closing of semilunar valves?
Ventricular diastole
What does stroke volume represent in the cardiac cycle?
Amount of blood pushed out by ventricles
What is the normal range of Cardiac Output (CO) in liters per minute?
4 - 8 L/min
Which heart sound is associated with the closing of the atrioventricular valves?
S1
What causes heart murmurs according to the text?
Turbulent blood flow
What is the formula for Stroke Volume (SV) according to the text?
SV = EDV - ESV
Which nerve dominates the autonomic tone of the heart according to the text?
Vagus nerve
What does an increased level of thyroid hormone do to heart rate and contractility?
Increases heart rate and contractility
What can decrease heart rate according to the text?
Hypoxia (lack of O2)
At what point during cardiac development are the atrioventricular valves formed?
Between weeks 5 - 9
How does exercise impact Cardiac Output (CO) according to the text?
Increases CO by 4-8 times
What effect does sympathetic stimulation have on heart repolarization according to the text?
Shortens the repolarization period
Study Notes
Heart Anatomy
- The heart is a muscle that pumps 5.25 L of fluid per minute.
- It is located between the lungs in the mediastinum, separated from other structures by the pericardium.
- The heart sits in the pericardial cavity, with the base being superior and medial to the apex.
- The great veins (superior and inferior vena cava) and arteries (aorta and pulmonary trunk) attach at the base.
- The heart has a cardiac notch, a depression of the inferior lobe of the left lung.
Heart Structure
- The heart has 4 chambers: 2 atria and 2 ventricles.
- Atria are superior and collect blood, while ventricles are inferior and pump blood out to the body or lungs.
- The heart has 2 circuits: pulmonary and systemic.
- The right ventricle connects to the pulmonary trunk, and the left ventricle connects to the aorta.
- CO2 leaves and O2 enters in the pulmonary capillaries.
Heart Membranes and Layers
- The heart has 2 layers: fibrous and serous pericardium.
- The serous layer has 2 sublayers: parietal and visceral layers separated by the pericardial cavity.
- The cavity is filled with lubricating fluid.
- The visceral layer is called the epicardium and produces fluid.
Heart Features
- Auricles are thin-walled structures that can hold blood and empty into atria.
- Sulci are fat-filled grooves that contain coronary blood vessels.
Layers
- The epicardium is the most superficial layer.
- The myocardium is the middle, thickest layer, consisting of muscle cells, nerve fibers, and blood vessels.
- The endocardium is the innermost layer, lining the chambers filled with blood, covering heart valves, and continuous with the lining of blood vessels.
- The endothelium releases endothelins, which are strong vasoconstrictors and may regulate growth patterns of cardiac muscle cells.
Internal Structures
- Septum divides the heart into chambers and is a physical extension of the myocardium.
- Fossa ovalis is a depression in the interatrial septum, which was a foramen ovale (opening) while a fetus.
- Atrioventricular valves separate atria from ventricles, with tricuspid on the right and mitral or bicuspid on the left.
- Semilunar valves separate ventricles from blood vessels, with pulmonary and aortic valves.
Chambers
- Right atrium receives deoxygenated blood from the systemic circulation, contains pectinate muscles, and has a small contractile phase.
- Right ventricle receives deoxygenated blood from the right atrium and has chordae tendineae connected to 3 papillary muscles that close the tricuspid valve.
- Left atrium receives oxygenated blood from the pulmonary veins and has a small contractile phase (20%).
- Left ventricle receives oxygenated blood from the left atrium and has a thicker muscle, with no moderator band.
Valves
- Valves ensure unidirectional blood flow.
- Semilunar valves have no muscular attachments and make an audible sound as they close.
- Tricuspid and mitral valves close due to papillary muscles.
- Valve disorders are usually caused by inflammation.
Coronary Circulation
- Coronary circulation is cyclical and not continuous.
- Arteries branch off the aorta just superior to the semilunar valve.
- Coronary arteries bring blood to the myocardium and other components.
- Anastomosis is the interconnection of blood vessels to allow blood to flow even if there is a partial blockage in another branch.
- Coronary veins bring deoxygenated blood back to the right atrium.
Test your knowledge on cardiac physiology and the conduction system of the heart. Questions cover topics such as repolarization, refractory period, calcium ions, and the firing rates of different nodes in the heart.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
