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15 Flashcards in this deck.
The heart is a muscular organ located in the thoracic cavity, nestled between the lungs. It consists of four chambers: two upper chambers called atria and two lower chambers known as ventricles. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins.
Blood flows from the atria to the ventricles through the atrioventricular valves—the tricuspid valve on the right and the mitral (bicuspid) valve on the left. The ventricles then pump blood out of the heart: the right ventricle sends deoxygenated blood to the lungs through the pulmonary artery, and the left ventricle dispatches oxygenated blood to the rest of the body via the aorta.
The heart contains four main valves that ensure unidirectional blood flow:
The heart's pumping action is regulated by its electrical conduction system, which coordinates the contraction and relaxation of the heart muscles. The primary components include:
The cardiac cycle consists of two main phases: diastole and systole. During diastole, the heart muscles relax, allowing the chambers to fill with blood. Systole involves the contraction of the heart muscles, pumping blood out of the chambers.
The efficiency of the heart can be measured by parameters such as cardiac output ($CO$), which is the volume of blood pumped by each ventricle per minute. It is calculated using the formula:
$$CO = SV \times HR$$
where $SV$ is stroke volume (the amount of blood pumped per beat) and $HR$ is heart rate (beats per minute).
The circulatory system comprises two primary pathways: systemic circulation and pulmonary circulation.
The heart itself requires a constant supply of oxygen and nutrients, which it receives through the coronary arteries. These arteries branch off from the aorta and encircle the heart muscle. Any blockage in these arteries can lead to conditions such as myocardial infarction (heart attack).
Maintaining heart health is crucial for overall well-being. Common cardiovascular diseases include:
The autonomic nervous system regulates heart rate and force of contraction through sympathetic and parasympathetic inputs. The sympathetic nervous system increases heart rate and contractility during stress or physical activity, while the parasympathetic system decreases heart rate during rest.
Aspect | Systemic Circulation | Pulmonary Circulation |
---|---|---|
Function | Delivers oxygenated blood to body tissues and returns deoxygenated blood to the heart. | Transfers deoxygenated blood to the lungs and brings oxygenated blood back to the heart. |
Pathway | Left ventricle → Aorta → Body → Superior & Inferior Vena Cavae → Right atrium. | Right ventricle → Pulmonary artery → Lungs → Pulmonary veins → Left atrium. |
Pressure | High pressure to facilitate blood flow throughout the body. | Lower pressure as it only needs to pump blood to the nearby lungs. |
Vessels | Arteries, veins, and capillaries throughout the body. | Pulmonary arteries and veins connecting the heart and lungs. |
1. Mnemonic for Heart Valves: "Try Pass Mickey's Aorta" stands for Tricuspid, Pulmonary, Mitral, Aortic valves.
2. Visual Aids: Use diagrams of the heart to visualize chamber locations and blood flow pathways.
3. Understand, Don’t Memorize: Grasp the functional differences between systemic and pulmonary circulation to apply knowledge effectively in exams.
4. Practice ECG Interpretations: Familiarize yourself with ECG patterns to strengthen understanding of the electrical conduction system.
1. The human heart creates enough pressure when it pumps to squirt blood up to 30 feet.
2.. A heart beats approximately 100,000 times each day, circulating about 5.5 liters of blood every minute.
3. The electrical impulses that trigger each heartbeat can be seen on an electrocardiogram (ECG), a tool commonly used in medical diagnostics.
Mistake 1: Confusing systemic and pulmonary circulation.
Incorrect: Thinking systemic circulation carries deoxygenated blood.
Correct: Remember that systemic circulation transports oxygenated blood to the body.
Mistake 2: Misidentifying heart valves.
Incorrect: Mixing up the tricuspid and mitral valves.
Correct: Use mnemonics like "Try Pass Mickey's Aorta" to remember Tricuspid, Pulmonary, Mitral, Aortic valves.
Mistake 3: Overlooking the role of the SA node.
Incorrect: Ignoring how the SA node initiates heartbeats.
Correct: Understand that the SA node is the natural pacemaker regulating heart rhythm.