Fill in the blanks of the following paragraph using just two words – arteries and veins
___(a)___ carry oxygen-rich blood from the heart to all parts of the body and ___ (b)___ carry carbon dioxide-rich blood from all parts of the body back to the heart. ___ (c)___ have thin walls and __ (d)___ have thick elastic walls. Blood flows at high pressure in ___ (e)____. Valves are present in __ (f) ___ which allow blood to flow only towards the heart. __ (g)___ divide into smaller vessels. These vessels further divide into extremely thin tubes called capillaries. The capillaries join up to form __________ .

Explanation

To fill in the blanks of the paragraph using the words "arteries" and "veins," we can follow these steps:

1. **Identify the function of blood vessels**: The first blank asks for the type of blood vessel that carries oxygen-rich blood from the heart to the body. We know that this is the function of arteries.
- **Answer for (a)**: arteries

2. **Identify the blood type returning to the heart**: The second blank asks for the type of blood vessel that carries carbon dioxide-rich blood back to the heart. This is the function of veins.
- **Answer for (b)**: veins

...