Differentiate between artery and vein.

Explanation

To differentiate between arteries and veins, we can consider several key factors such as structure, function, blood flow direction, and location in the body. Here’s a step-by-step breakdown:

### Step 1: Definition
- **Arteries**: Blood vessels that carry oxygenated blood away from the heart to various parts of the body (except for the pulmonary artery, which carries deoxygenated blood to the lungs).
- **Veins**: Blood vessels that carry deoxygenated blood back to the heart (except for the pulmonary vein, which carries oxygenated blood from the lungs to the heart).

### Step 2: Structure
- **Arteries**: Have thick, muscular, and elastic walls to withstand high pressure as blood is pumped from the heart.
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