Final answer:
Blood is usually drawn from veins rather than arteries because veins are more accessible and less pressured, making it safer and less uncomfortable. Basic blood chemistry, such as oxygen and carbon dioxide levels, differs between venous and arterial blood due to their different roles in gas exchange. Blood pressure is higher in arteries, which is why pulses are measured in arteries, not veins.
Step-by-step explanation:
Why is Blood Drawn from Veins Instead of Arteries?
Blood is typically drawn from veins rather than arteries because veins are closer to the surface of the skin and have less pressure compared to arteries, making the procedure simpler and less painful. In addition, venous blood is less oxygenated and under lower pressure than arterial blood, which reduces the risk of bleeding and bruising.
Basic Blood Chemistry Differences Between Venous and Arterial Blood
Basic blood chemistry may differ between venous and arterial blood primarily due to the gas exchange that occurs in the lungs and tissues. Arterial blood is rich in oxygen and low in carbon dioxide as it leaves the lungs and is delivered to tissues, while venous blood is rich in carbon dioxide and other metabolic waste products as it returns to the heart. Differences are also present in pH levels, with arterial blood being slightly more alkaline.
Understanding the Blood Pressure in Arteries and Veins
Blood pressure is significantly higher in arteries than in veins due to the force exerted by the heart's contractions. Venous blood pressure is much lower, which is why when taking your pulse, you measure the arterial pulse as the heartbeat's force is transmitted along the arterial walls. Veins do not have a pulse because they do not experience this same direct pressure from the heartbeats.