The Divine Being must have made us with immense complexity and difficulty. According to the Bible, God loved us so much that he made us appearย toย like him.
Unlike plants and other basic organisms, our body is complicated due to its numerous parts and functions.
Because of their function and importance in our bodies, our veins and capillaries areย some of the most fascinating aspects of our bodies.ย
Key Takeaways
- Veins transport deoxygenated blood from the body to the heart.
- Capillaries facilitate the exchange of nutrients, oxygen, and waste between blood and tissues.
- Veins have thicker walls and valves to prevent backflow, while capillaries have thin walls for efficient diffusion.
Veinsย vsย Capillariesย
Capillaries are the smallest blood vessels in the body responsible for the exchange of oxygen, nutrients, and waste products between the blood and the tissues. Veins are blood vessels that carry blood back to the heart from the bodyโs tissues. They are larger in diameter than capillaries.

Veins are more easily identified becauseย veinsโฏwhich are closer to the surface ofย theย skin or do not have accompanying arteries are much more apparent, veins are easier to spot.
Further veins include pulmonary veins, which carry oxygenated blood from the lungs to the heart, and systemic veins, which carry deoxygenated blood towards the heart and run from the legs to the neck and arms.ย
A capillary is a small blood vessel that is 5 to 10ย micrometresย in size. The tunica intima, a narrow wall of basic squamous endothelial cells, seems to be the only component of capillaries.
They transmit blood here between the arterioles and venules, the smallest blood arteries in the body. Between such micro-vessels as well as the interstitial fluid which surrounds them, a variety of chemicals are exchanged.ย
Comparison Table
Parameters of Comparisonย | Veinsย ย | Capillaries |
---|---|---|
Definitionย | Veins are just the tubes that drain deoxygenated blood back to the heart as part of the circulatory system.ย | Capillaries are fine-branching blood arteries that connect arterioles and venules to create a network.ย |
Diameterย | In comparison, the diameter is larger.ย | The diameter is approximately 8ย micrometres.ย |
Formationย | The wall is made up of multiple layers of cells.ย | A single cell thickens the wall.ย |
Branchesย | Veins are not branched.ย | A capillary bed is a heavily branching network.ย |
Workย | Deoxygenated blood is drained to the heart.ย | Allow oxygen, nutrients, and metabolic wastes to flow freely between the blood and extracellular fluid.ย |
What areย Veins?ย
Those blood channels that convey deoxygenated blood back to the heartย areย known as veins. Deoxygenated blood as well as other metabolic wastes, are gathered in the venules during microvasculature.
Venules are small blood vesselsย thatย thus develop from veins.
The veins are pumped with deoxygenated blood. Blood pressure of the blood is lower than blood pressure in the arteries.
Contraction is the primary force that drives blood through veins. Blood cannot flow backwards through veins because of valves.
Blood capillaries make up the walls of a vein. Sinceย superficial veins are closer to the skinโs surface and do not have accompanying arteries, they are more visible.ย
ย The tunica adventitia, tunica media, and tunica intima are the 3 sections that make up the vein wall.
The tunica adventitia is indeed a layer of connective tissue that forms the strong external covering of the vein.
The tunica medium is made of a thin, smooth muscle layer and a fine endothelial tunica intima lining.
These tubes convey blood intoย theย bodyโs main vein, the vena cava.ย
Bothย theย superior vena cava and the inferior vena cava send blood into the heartโs right atrium.ย

What areย Capillaries?ย
Capillaries are a network of fine-branching blood arteries that form a network by connecting arterioles and veins. Theyโre spotted nearย metabolizingย cells in organs and tissues.
Just one file of blood vessels may pass through it at a time since capillaries have a size of 5-10 m. Basic squamous epithelium forms the capillary lining.
Endothelial cells as well as a basement membrane, build the wall as a result.
The primary function of capillaries is to allow chemicals to move between both the blood and the tissueโs extracellular matrix. Arterioles are blood vessels that transport oxygen to the bodyโs capillaries.
The capillaries bed is the architecture in the tissue that is supported by capillaries. Interstitial fluid is the fluid that passes from blood to extracellular fluid via the capillary wall.
Oxygen, nutrients, ions, and water make up the interstitial fluid.ย
Carbon dioxide and urea, for illustration, move from the extracellular fluid to the circulatory. Microcirculation is the term for this.
Continuous, fenestrated, and sinusoidal blood capillaries are indeed the 3 types of blood capillaries found in the human body.
A continuous endothelial cell layer lines the capillary lumen in continuous capillaries. Skeletal tissues, skin, gonads, & fingers all have this capillary type.
The intercellular gap allows only water & ions to flow through. The endothelial cells of fenestrated capillaries have small pores with a size of 60-80 nm.
The fenestrations allow ions and small proteins to flow through. Endocrine glands, pancreas, stomach, and kidney glomeruli all have fenestrated capillaries.ย
Main Differences Betweenย Veinsย andย Capillariesย ย
- Capillaries are fine-branching blood arteries that create a network by connecting arterioles and venules, whereas veins are merely tubes that return deoxygenated blood to the heart as part of the systemic circulation.ย
- The diameterย of veins isย larger,ย whereasย theย diameterย of capillaries isย approximately 8ย micrometres.ย
- The wallย of veinsย is made up of multiple layers of cells,ย whereas in capillaries,ย thickensย ofย the wallย isย aย single cell.ย
- Veins are not branched; a capillary bed is a heavily branchedย network.ย
- Capillaries allow oxygen, nutrition, and toxins from the body to freely pass between the blood and extracellular fluid, whereas veins transport deoxygenated blood back to the heart.ย

- https://link.springer.com/article/10.1007/BF00410688
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3630377/
Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.