To determine the amount of oxygen carried by venous blood, we can break down the information step by step:
### Step 1: Understand the Role of Blood
Blood is a vital fluid connective tissue that circulates throughout the body, transporting nutrients, gases, and waste products. One of its primary functions is the transport of oxygen.
**Hint:** Remember that blood is essential for transporting various substances, including gases like oxygen.
### Step 2: Identify the Components of Blood
Blood consists of several components, including red blood cells (RBCs), white blood cells, platelets, and plasma. The focus here is on red blood cells, which play a crucial role in oxygen transport.
**Hint:** Focus on the specific components of blood that are involved in gas exchange, particularly red blood cells.
### Step 3: Understand Hemoglobin's Function
Red blood cells contain hemoglobin, an iron-containing protein that binds oxygen. Hemoglobin can form a reversible bond with oxygen, allowing it to pick up oxygen in the lungs and release it in tissues where it is needed.
**Hint:** Hemoglobin is key to oxygen transport; think about how it interacts with oxygen in different parts of the body.
### Step 4: Quantify Oxygen Transport
Approximately 97% of the oxygen in the blood is transported bound to hemoglobin, forming a complex known as oxyhemoglobin. The remaining 2-3% of oxygen is transported dissolved in the plasma.
**Hint:** Consider the proportions of oxygen transport in blood; most is carried by hemoglobin.
### Step 5: Calculate Oxygen Content in Blood
In terms of volume, in 100 ml of oxygenated blood, about 15 ml of oxygen can be carried when hemoglobin is fully saturated. However, when discussing venous blood, it is essential to note that the oxygen content will be lower due to the delivery of oxygen to tissues.
**Hint:** Think about how the saturation of hemoglobin changes from arterial to venous blood.
### Step 6: Determine the Percentage of Oxygen in Blood
The total volume of oxygen in blood is approximately 5% of the total blood volume. This means that in venous blood, the oxygen content is about 5% of the total volume of blood.
**Hint:** Remember the percentage of blood volume that oxygen constitutes, as it helps in understanding the overall transport capacity.
### Conclusion
In summary, venous blood carries approximately 5% of its total volume as oxygen, primarily bound to hemoglobin. This is the correct answer regarding the amount of oxygen carried by venous blood.
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