Each artery and vein consists of three layers: an inner lining of ______(i)________ endothelium, the tunica intima, a middle layer of __________(ii)__________ and _________(iii)_______ fibres, the tunica madia, and an external layer of _________(iv)__________ tissue with __________(v)__________ fibres, the tunica externa.

Options

A. `|{:(" (i)"," (ii)"," (iii)"," (iv)"," (v)"),("squamous","smooth muscles","collagen","connective","elastic"):}|`
B. `|{:(" (i)"," (ii)"," (iii)"," (iv)"," (v)"),("squamous","smooth muscles","elastic","connective","collagen"):}|`
C. `|{:(" (i)"," (ii)"," (iii)"," (iv)"," (v)"),("squamous","connective","collagen","smooth muscles","elastic"):}|`
D. `|{:(" (i)"," (ii)"," (iii)"," (iv)"," (v)"),("squamous","connective","elastic","smooth muscles","collagen"):}|`

Answer

To answer the question regarding the structure of arteries and veins, we need to fill in the blanks with the appropriate terms that describe the layers of these blood vessels.

1. **Identify the layers of arteries and veins**:
- The innermost layer is called the **tunica intima**, which consists of endothelial cells.
- The middle layer is known as the **tunica media**, which is primarily made up of **smooth muscle** and **elastic** fibers.
- The outermost layer is called the **tunica externa** (or tunica adventitia), which consists of **connective** tissue and **collagen** fibers.

2. **Fill in the blanks**:
- (i) Endothelium
- (ii) Smooth muscle
- (iii) Elastic
- (iv) Connective
- (v) Collagen

So, the completed statement would be:
"Each artery and vein consists of three layers: an inner lining of **endothelium** (i), the tunica intima, a middle layer of **smooth muscle** (ii) and **elastic** (iii) fibres, the tunica media, and an external layer of **connective** (iv) tissue with **collagen** (v) fibres, the tunica externa."