Skip to main content

Can You See A Blood Cell With The Naked Eye?

Blood cell

Yes!
Blue field entoptic phenomenonYou need to look at a bright blue light such as the sky. After a moment, you will see a dance of translucent dots just outside the center of the vision. The dots are short-lived, visible for a second or less, traveling short distances along seemingly random, curvy paths and brighter than the background. If the eye is stopped, the points are still moving around. The dots are white blood cells moving in the capillaries in front of the retina of the eye.

capillariesWhy does this happen? Blue light is well absorbed by the red blood cells that fill the capillaries. The eye and brain "edit out" the shadow lines of the capillaries, partially by dark adaptation of the photoreceptors lying the capillaries. The white blood cells, which are much rarer than the red ones and do not absorb blue light, create gaps in the blood column, and these gaps appear as bright dots. This is called the blue field entoptic phenomenon. Most people are able to see this phenomenon. However, it is rather weak, and many people don’t notice it until asked to pay attention. This phenomenon is used to measure blood flow in the capillaries of the retina, known as Blue field entoptoscope.

Comments

Popular posts from this blog

Musa Ingens - The Tallest Banana Plant in the World

W hen we hear the word “Banana,” it reminds us an edible fruit with tiny seed or seedless, grow on the banana plant (herb). Have you ever heard of Musa Ingens, the giant banana? It is a rare banana species that can reach surprising sizes.

When NASA’s Mars Mission Failed For Stupid Reason

A ll human beings make mistakes, and NASA is no exception. It is important to learn from this mistake that highlighted the importance of physical units and how they can affect our real life. This is the story of one of the failed mission of NASA.

The Death of Richard Parker And Cannibalism - Shipwreck Case (1884)

T he English yacht Mignonette was a 19.43 net tonnage, a 52-foot cruiser built in 1867. It was an inshore boat, not made for long voyages. In 1883, she was purchased as a leisure vessel by Australian lawyer John Henry Want. The yacht could only reasonably be transported to Australia by sailing, but she was a small vessel and the prospect of a 24,000-km voyage hampered Want's initial attempts to find a suitable crew. She finally set sail for Sydney from Southampton on 19 May 1884 with a crew of four: Tom Dudley, the captain; Edwin Stephens; Edmund Brooks; and Richard Parker, the cabin boy. Parker was 17 years old and an inexperienced seaman. O n 5 July, the yacht was running before a gale, around 2,600 km northwest of the Cape of Good Hope. Though the weather was by no means extreme and the vessel was not in any difficulties, Dudley gave the order to heave to so that the crew could enjoy a good night's sleep. As the manoeuvre was completed, and Parker was sent below to pr