Measuring the Human Heart - Heartbeat, Blood Pressure, and Cardiac Output | Visible Body

Visible Body

6 Jul 202303:34

Summary

TLDRThis video explores the mechanics of the human heart, focusing on heartbeat, blood pressure, and cardiac output. It explains the heart's size, weight, and the two phases of a heartbeat—systole and diastole. Viewers learn about how blood pressure is measured, the function of heart valves, and how cardiac output is calculated based on stroke volume and heart rate. The video emphasizes the importance of these metrics in understanding heart function and encourages using interactive 3D models to explore circulatory system anatomy.

Takeaways

💪 The human heart is a powerful organ, weighing around 300 grams, and is about the size of a fist.
🧔 Typically, an adult male's heart is larger than that of an adult female.
💓 The average resting heart rate is about 72 beats per minute.
🫀 The heartbeat results from the contraction and relaxation of the ventricles, the heart's lower chambers.
🔄 The heartbeat has two phases: systole (ventricles contract) and diastole (ventricles relax).
🔊 The sound of the heartbeat comes from the closing of the heart's valves during systole and diastole.
📊 Blood pressure is measured with two numbers: systolic pressure (when ventricles contract) and diastolic pressure (when ventricles relax).
🩸 The average systolic pressure is around 120 mmHg, while the average diastolic pressure is around 70 mmHg.
📏 Blood pressure is measured in millimeters of mercury (mmHg) using a sphygmomanometer.
🚴 Cardiac output, the volume of blood the heart pumps per minute, is calculated by multiplying stroke volume (average 70 mL) by heart rate (average 72 beats per minute), resulting in 5.4 liters per minute.

Q & A

What is the average weight of an adult human heart?
-The average adult human heart weighs around 300 grams, which is less than a pound.
How does the size of a male's heart compare to a female's heart?
-Typically, the heart of an adult male is slightly larger than the heart of an adult female.
How many times does the average human heart beat per minute at rest?
-The average human heart beats around 72 times per minute at rest.
What are the two phases of the heartbeat?
-The two phases of the heartbeat are systole, when the ventricles contract and pump blood out, and diastole, when the ventricles relax and fill with blood.
What causes the heartbeat sound?
-The heartbeat sound is caused by the closing of the heart's valves. During systole, the mitral and tricuspid valves close, while during diastole, the semilunar valves close.
How is blood pressure measured and what do the two numbers represent?
-Blood pressure is measured using two numbers. The systolic pressure represents the highest pressure when the ventricles contract, while the diastolic pressure represents the lowest pressure when the ventricles relax.
What is the average systolic and diastolic blood pressure?
-The average systolic pressure is around 120 millimeters of mercury, and the average diastolic pressure is around 70 millimeters of mercury.
What unit is used to measure blood pressure?
-Blood pressure is measured in millimeters of mercury (mmHg), which is a manometric unit used to measure force applied by a liquid.
How is cardiac output calculated?
-Cardiac output is calculated by multiplying the stroke volume (amount of blood pumped per beat) by the number of heartbeats per minute. For example, with a stroke volume of 70 milliliters and a heart rate of 72 beats per minute, the cardiac output would be 5040 milliliters, or 5.4 liters per minute.
How does cardiac output change with physical activity?
-Cardiac output increases with a higher heart rate, which is required during increased physical activity to supply more oxygenated blood to the body.

Outlines

00:00

🔍 Understanding the Heartbeat and Circulatory System

This introduction sets the stage for exploring the anatomy and function of the heart. It teases the learning journey ahead, involving the exploration of heartbeat, blood pressure, and cardiac output using 3D visuals and models. Before diving into details, it touches upon the heart's impressive power relative to its small size, comparing the weight of the average adult heart (around 300 grams) to the size of a fist, while noting the slight size difference between male and female hearts.

💓 What Makes Your Heartbeat?

This section focuses on the heart's rhythmic beating and how it circulates blood. It explains that the average human heart beats around 72 times per minute at rest. The heartbeat is powered by the contraction and relaxation of the ventricles, the heart’s lower chambers. These two phases of the heartbeat are introduced: systole (when the ventricles contract and pump blood) and diastole (when the ventricles relax).

🔊 The Sound of Your Heartbeat

The paragraph dives into the mechanics behind the sounds of a heartbeat. It describes how the closing of heart valves produces the characteristic sounds. During systole, the mitral and tricuspid valves close, while the semilunar valves open to allow blood out. During diastole, the semilunar valves close, and the mitral and tricuspid valves open to let blood flow into the ventricles from the atria.

📊 Blood Pressure: Understanding the Numbers

Blood pressure is explained here in terms of systolic and diastolic measurements. Systolic pressure is the maximum pressure on artery walls during the contraction of the heart's ventricles, with an average of 120 mmHg. Diastolic pressure measures the lowest pressure during ventricular relaxation, with an average of 70 mmHg. These numbers reflect the force exerted by blood against vessel walls.

🧪 What Are Millimeters of Mercury?

This part clarifies how blood pressure is measured. Blood pressure is recorded using a device called a sphygmomanometer and is measured in millimeters of mercury (mmHg). It explains that one millimeter of mercury represents the pressure exerted by a one-millimeter-high column of mercury, providing a standard for measuring the force of blood against arterial walls.

📈 Cardiac Output: Calculating Heart Efficiency

Cardiac output refers to the volume of blood the ventricles pump per minute. The calculation requires knowing the stroke volume (the amount of blood pumped with each heartbeat) and the heart rate (beats per minute). The average stroke volume is 70 milliliters, and multiplying this by an average heart rate of 72 bpm gives a cardiac output of 5.4 liters per minute. This value increases during physical activity due to the need for higher blood flow.

🖥️ Learning More with Visible Body Courseware

This final paragraph encourages the use of visual and interactive resources, such as the Visible Body Courseware, for learning about the circulatory system. It highlights the value of these tools for both teaching and studying human anatomy and physiology, inviting learners to explore more through the provided platform.

Mindmap

Keywords

💡Heart

The heart is the central organ of the circulatory system responsible for pumping blood throughout the body. In the video, the heart is described as a 'Powerhouse' that weighs around 300 grams and is about the size of a fist. It plays a crucial role in the discussion of heartbeat, blood pressure, and cardiac output.

💡Heartbeat

The heartbeat refers to the rhythmic contraction and relaxation of the heart muscles, specifically the ventricles. It is what you can feel and hear, typically beating 72 times per minute at rest. The video explores how the heartbeat drives blood through the heart and the body, focusing on its two phases: systole and diastole.

💡Systole

Systole is the phase of the heartbeat when the ventricles contract and pump blood out of the heart. The mitral and tricuspid valves close during systole, while the semilunar valves open. The video uses this phase to explain how blood is forced through the body, generating blood pressure.

💡Diastole

Diastole is the phase of the heartbeat when the ventricles relax and the heart fills with blood. During this phase, the semilunar valves close, and the mitral and tricuspid valves open. The video contrasts diastole with systole to show the complete cycle of the heartbeat.

💡Ventricles

Ventricles are the lower chambers of the heart that pump blood out to the body and lungs. The video emphasizes the contraction and relaxation of the ventricles during systole and diastole, explaining how these movements drive blood circulation and generate the heartbeat sound.

💡Blood pressure

Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels. The video explains how blood pressure is measured using two values: systolic and diastolic pressure, with 120/70 mmHg being the average. Blood pressure increases when the ventricles contract and decreases when they relax.

💡Systolic pressure

Systolic pressure is the higher value in blood pressure measurements, indicating the pressure in the arteries when the ventricles contract. In the video, an average systolic pressure of 120 mmHg is given as a normal measurement, which represents the maximum force during heartbeat.

💡Diastolic pressure

Diastolic pressure is the lower value in blood pressure readings, representing the pressure in the arteries when the heart's ventricles are relaxed. The video gives an average diastolic pressure of 70 mmHg, showing how the heart maintains blood flow even during its resting phase.

💡Cardiac output

Cardiac output is the amount of blood pumped by the ventricles per minute. The video explains how cardiac output is calculated by multiplying the stroke volume (amount of blood per beat) by the heart rate (beats per minute). The example in the video gives a cardiac output of 5.4 liters per minute, highlighting how the heart adjusts during physical activity.

💡Stroke volume

Stroke volume is the amount of blood ejected by the heart with each beat. The video mentions an average stroke volume of 70 milliliters and shows how this value is used, along with heart rate, to calculate cardiac output. Stroke volume varies depending on physical demands placed on the body.

Highlights

The average adult human heart weighs around 300 grams and is approximately the size of a fist.

At rest, the average human heart beats around 72 times per minute.

The heartbeat is caused by the contracting and relaxing of the heart's lower chambers, the ventricles.

A heartbeat has two phases: systole, when the ventricles contract, and diastole, when the ventricles relax.

During systole, the mitral and tricuspid valves close, and the semilunar valves open to allow blood to leave the heart.

During diastole, the semilunar valves close, and the mitral and tricuspid valves open, allowing blood to flow into the ventricles.

Blood pressure is measured using two numbers: systolic and diastolic pressures.

Systolic pressure measures the highest pressure on the artery walls when the ventricles contract; the average systolic pressure is 120 mmHg.

Diastolic pressure measures the lowest pressure when the ventricles relax; the average diastolic pressure is 70 mmHg.

Blood pressure is measured using a sphygmomanometer in millimeters of mercury, which refers to the amount of pressure exerted by a one-millimeter column of mercury.

Cardiac output refers to how much blood the ventricles pump per minute.

Cardiac output is calculated by multiplying the stroke volume by the number of heartbeats per minute.

The average stroke volume is 70 milliliters, and multiplying this by 72 beats per minute results in a cardiac output of 5.4 liters per minute.

Cardiac output increases with physical activity as the heart rate rises.

Visible Body Courseware offers interactive 3D visuals and tools to learn and teach about the anatomy and physiology of the circulatory system.