Body Parts That Start With Y

The human body is a complex organized system made of billions of smaller structural parts – cells, tissues, and organs as parts of various systems that keep us alive.

Ten major body systems include the muscular, skeletal, endocrine, nervous, lymphatic, respiratory, cardiovascular, digestive, reproductive, and urinary systems.

All of the organs, cells, and tissues work together so arranged to keep your body accordingly moving and operating through all of the mentioned systems.

The tuned balance of your body depends on the organization, responsiveness, metabolism, reproduction, growth, proper management, digestion, respiration, and excretion of your systems.

With so many parts and details of the body, thousands of parts begin with every letter of the alphabet.

But only a handful start with the letter Y or the most uncommon letter for body parts.

In this article, we wish to focus on those parts and organs and explain their meanings and functions to help you understand your body better.

Some of which might be new information and knowledge for you.

We will begin with more common parts you might already know to those lesser known.

Body Parts That Start with the Letter Y

Yellow Marrow

Bone marrow is soft and fatty tissue inside your bones, vital for producing billions of blood cells and platelets.

It is a semi-solid tissue found in the spongy portion of your bones, also known as cancellous or a mesh-like structure with many pores.

The human bone is made of the cancellous or spongy part that contains the red marrow, compact bone, the hard exterior of the bone, and the yellow marrow inside.

Many blood vessels pass through the center of the bone, aligning with the yellow marrow.

Red marrow contains blood stem cells which can become red blood cells, platelets, or white blood cells.

Meanwhile, the yellow part is built from fat, keeping your bones sturdy and mobile.

Red blood cells get made of a unique protein called hemoglobin which carries oxygen from your lungs to other parts of your body.

White blood cells are rejuvenating cells of your immune system. They are responsible for protection against infections and other diseases.

And platelets are pieces of large cells that heal your wounds by slowing or stopping your bleeding.

Back to the yellow part of your bone – the result of fat in your organism is the yellow marrow.

This tissue stores lipids and other fats as energy for when your bones need it.

A newborn baby has more red marrow than yellow, but the ratio changes with age, depending on the prevalence of the hematopoietic cells versus fat cells.

Hematopoietic cells are called immature cells that can develop into various types of blood cells, depending on your diet, lifestyle, history of family illness, and so on.

These cells are also called blood stem cells.

In some circumstances, your body can reverse yellow marrow into red marrow to increase blood cell production, but it does not happen often.


Chromosomes are part of our DNA (as well as the DNA of animals, plants, and other life on the planet) and contain all of the genetic material of the said organism.

They have a threadlike structure made of protein and a single molecule of DNA located in the nucleus of the cells.

Chromosomes carry the parents’ genes from cell to cell, as the children inherit half of their chromosomes from their mother and a half from their father.

Humans have a total of 46 chromosomes in each cell, or 23 pairs.

The first 22 pairs are classified by size, as each chromosomic pair holds a part of your genetic profile.

The 23rd pair is called the s*x chromosomes, which determine the sex of the child even before birth.

Boys have the Y chromosome with one X chromosome, while girls have two X chromosomes.

If the Y chromosome is missing, the child is female.

The Y chromosome is present in mammals, some insects, and plants. The role of this chromosome is the same as it is in humans.

Passed down from father to son, it carries around 693 genes in a person.

Males with XYY or two Y chromosomes have Jacob syndrome due to the extra Y chromosome.

Some present symptoms are out-of-the-ordinary height where the male is taller than average, acne-prone skin, increased risk of learning disabilities, and weaker muscle tone.

The syndrome is not lethal, occurring in 1 out of 1,000 boys.

The X and Y chromosomes have evolved from a pair of identical chromosomes that changed over time to fit and give genders the characteristics we know today.

American geneticist Nettie Stevens identified the Y chromosome in 1905 during the mealworm study, the larval form of the yellow mealworm beetle.

She suggested during her study that chromosomes always existed in pairs and that the smaller X chromosome split in two for the Y chromosome to exist.

Before her discovery, scientists believed only the X chromosome determined s*x, but labeling the other half of the pair as the Y chromosome explained how we see sex through the presence or absence of the Y chromosome.

Yolk Sac

A lesser-known body part is the so-called yolk sac, or the structure that develops inside the uterus during the early stage of pregnancy.

While we have both Y and X chromosomes in males, the yolk sac occurs only in females during pregnancies, no matter the sex of the soon-to-be baby.

The yolk sac looks like a membrane attached to the embryo, providing it with food and necessary nourishment.

It can also help circulate gases between the said embryo and the mother.

Besides this, the yolk sac produces crucial cells that turn into various structures necessary for the well-being of the embryo, such as blood cells, the umbilical cord, and reproductive organs.

The yolk sac is at the frontal part of the embryo.

It is unknown when the yolk sac forms in the embryo, but it is one of the first elements seen within the gestational sac or the cavity of fluids surrounding the said embryo.

While you might not see much during your first ultrasound around six weeks after your last period, you might be able to see a 3- to 5-millimeter (around 0.1965 inches) circle that is the yolk sac.

This tiny circle holds the embryo’s nourishment until the placenta fully forms and takes over the necessary supplies.

The placenta provides oxygen and nutrients to a growing baby once the yolk sac disintegrates, and it works as an organ that attaches to the uterus walls. The placenta gets removed from the mother at birth.

There is a possibility that mothers do not see their yolk sac at the first ultrasound.

But it is not to worry, as you might have your dates wrong, and your pregnancy is not as far along as you thought.

The medical experts would send you back for another ultrasound a couple of weeks later.

And most times than not, the yolk sac would be visible at the next appointment.

An irregular shape, size, and movement of the visible yolk sac could indicate a problem with the pregnancy and foreshadow an eventual miscarriage.

But this information is available early in your pregnancy and does not exclude the possibility of future healthy pregnancies.

What matters the most is that the yolk sac is a positive sign the pregnancy began healthily and that the embryo is starting to develop as expected. A healthy baby is to follow.

The yolk sac ceases to exist after the creation of the placenta.

More Body Parts That Start With Y

Yellow eyes

Similar content:

Body Parts That Start With Z

Body Parts That Start With U

Body Parts That Start With T

Like and Share:

Related Posts