Introduction to Blood | Plasma, Buffy Coat & Hematocrit

Summary

This video provides an insightful overview of red blood cells (RBCs), explaining their crucial role in transporting oxygen and carbon dioxide throughout the body. It covers the structure of RBCs, including their size, flexibility, and the presence of hemoglobin that binds gases. The video also explains the concept of hematocrit, the recycling process of old RBCs, and the breakdown of hemoglobin. With a focus on the importance of RBCs in cellular respiration and energy production, it emphasizes how these cells are essential for sustaining life.

Takeaways

• 😀 Hematocrit measures the percentage of whole blood made up of red blood cells (RBCs).
• 😀 In males, the hematocrit value is typically around 47% ± 5%, while in females it's around 42% ± 5%.
• 😀 RBCs are essential for carrying oxygen to tissues and carbon dioxide away from them, supporting cellular respiration and waste elimination.
• 😀 An average RBC count is about 5 million per microliter of blood, each carrying large amounts of oxygen and carbon dioxide.
• 😀 RBCs are about 8 micrometers long and 2 micrometers thick, and their flexibility allows them to fit through the smallest capillaries.
• 😀 RBCs lack organelles and a nucleus, which limits their ability to produce new proteins, resulting in a lifespan of around 120 days.
• 😀 As RBCs age, they lose flexibility and are filtered out by organs like the spleen, where they are broken down and recycled.
• 😀 The breakdown of RBCs involves recycling iron and globin (amino acids), while the heme is converted into bilirubin, which colors urine and feces.
• 😀 Hemoglobin inside RBCs binds to oxygen and carbon dioxide, with each molecule capable of carrying four oxygen molecules.
• 😀 A single RBC contains about 250 million hemoglobin molecules, meaning it can carry approximately 1 billion oxygen molecules.
• 😀 The iron in the heme group of hemoglobin is essential for oxygen binding and is key to the RBC's oxygen-carrying capacity.

Q & A

What is hematocrit and why is it important?

Hematocrit is a test that measures the percentage of blood volume made up of red blood cells (RBCs). It's important because it helps assess how well oxygen is being transported in the body. A typical hematocrit for males is about 47% (±5%) and for females about 42% (±5%).

What is the average lifespan of a red blood cell (RBC)?

The average lifespan of a red blood cell is about 120 days. After this period, old or damaged RBCs are removed by the spleen and liver.

How do red blood cells transport oxygen and carbon dioxide?

Red blood cells transport oxygen and carbon dioxide through hemoglobin. Hemoglobin binds oxygen in the lungs and carries it to tissues, and it also binds carbon dioxide to transport it back to the lungs for exhalation.

Why is the shape of red blood cells important?

The biconcave shape of red blood cells is important because it allows them to be extremely flexible. This flexibility is crucial for navigating through narrow capillaries in a single file, ensuring efficient oxygen delivery and carbon dioxide removal.

What happens to red blood cells when they age or become damaged?

As red blood cells age or become damaged, their shape becomes less flexible, and they are eventually trapped and destroyed in the spleen or liver. Their components, like iron and globin, are recycled, and the heme is broken down into bilirubin.

How much hemoglobin does each red blood cell contain?

Each red blood cell contains about 250 million hemoglobin molecules. Hemoglobin plays a crucial role in carrying oxygen and carbon dioxide within the RBC.

What is the function of the iron ion in hemoglobin?

The iron ion (Fe2+) in hemoglobin binds to oxygen, allowing hemoglobin to carry oxygen from the lungs to tissues and organs. Each hemoglobin molecule can bind up to four oxygen molecules.

How many oxygen molecules can one red blood cell carry?

One red blood cell can carry approximately 1 billion oxygen molecules. This is due to the large amount of hemoglobin present in each RBC, with each hemoglobin molecule binding four oxygen molecules.

Why do red blood cells not have organelles like a nucleus?

Red blood cells lack organelles, including a nucleus, because this allows them to have more space to store hemoglobin, which is essential for their function of oxygen and carbon dioxide transport. Without a nucleus, they also can't create new proteins, limiting their lifespan to about 120 days.

What does the breakdown of hemoglobin produce and how does it affect the body?

The breakdown of hemoglobin produces bilirubin, which is excreted through urine and stool. Bilirubin is what gives urine its yellow color and stool its brown color. The recycling of RBC components ensures the body can reuse valuable nutrients like iron and amino acids.