Bye or Cell Trivia Quiz

Of all of the cells in the human body, 84% of them are red blood cells (RBCs). It follows that the typical human body creates 2.4 million of them per second! Red blood cells are also known as erythrocytes.

This word comes to us from two Greek words - erythros for "red" and kytos for "hollow vessel". RBCs take up oxygen in the lungs and transports it to the rest of the body where it is squeezed out in our capillaries, or tiny blood vessels for use in various areas. Each RBC circulates for approximately 100-120 days before the body kills it off and disposes of it through the body's waste-generating system.

The second most common cells are platelets, at 4.9% of the total in our bodies. Platelets are also called thrombocytes. Their main function is to react to bleeding from a blood vessel. When bleeding occurs, they immediately begin adhering to the cut. Unless the hole is too large, they stick together at the wound to form a clot that stops the bleeding.

Next comes our bone marrow cells. Out of all of our cells, 2.5% of them are bone marrow cells. Bone marrow can be found the centre of the bones. It is a semi-solid substance found mainly in the ribs, vertebrae, bones of the pelvis, and the breast bone in human bodies. Bone marrow is the location of haematopoiesis, or new blood cell production in the human body.

Of all of the cells in the human body, 2.1% are vascular endothelial cells. The vascular endothelium is the inner-most structure that coats the interior walls of arteries, capillaries and veins. It provides a barrier between the blood and tissues, and controls the flow of hormones, blood cells, platelets, and other fluids between the blood and other areas in the body.

The human body is made up of 1.5% of lymphocytes, or a type of white blood cell. Lymphocytes can be divided into three types of cells - T cells, B cells, and Natural Killers. T cells mature in the thymus, and B cells mature in the bone marrow.

Natural Killer cells are part of our innate immune system. All types of lymphocytes play a role in identifying pathogens, or cells that don't belong, then attacking and killing them before they do damage to our bodies.

The neurons and glia make up 0.6% of our cells. Neurons are the cells in the human body that conduct nerve impulses. Most neurons contain a cell body that has a nucleus, or the part of the cell that contains the chromosomes. This is surrounded in the cell body by cytoplasm, a fluid that protects the nucleus. Short extensions from the nucleus, that resemble small trees, are called dendrites. These receive signals from surrounding neurons.

Neurons also each have an axon, a longer hair-like extension that carries signals to other neurons. Glial cells are far more numerous than neurons, but are not capable of transmitting nerve impulses. Instead, they support, nourish, and protect the neurons.

Of all of the cells in the human body, 0.5% of them are epidermal cells. Our skin is made up of three layers. The two inner layers are the dermis and hypodermis. The epidermis, made up of epidermal cells, forms the outer layer of human skin. The epidermal cells help to provide a barrier between the environment and the inside of the body. This provides a certain level of protection against possible infections.

Epidermal cells also help to regulate how much water a body loses through sweating. The word "epidermis" comes to us from two words in Ancient Greek - "epi" meaning "over" or "upon", and "derma" meaning "skin".

Fat cells, or adipocytes, make up 0.2% of the cells in the human body. There are three types of adipocytes in humans. These are brown adipocytes, marrow adipocytes, and white adipocytes. Brown adipocytes are commonly known as "baby fat" and are used by infants and young children to maintain their body heat. Marrow adipocytes are found in human bones. Unfortunately, scientists do not really understand the function of this type of fat cell.

Despite making up only 0.2% of the total cells in human adults, the average number of white adipocytes is about 30 billion, with a weight of 30 lbs or 13.5 kg. Humans generally gain the number of white adipocytes until their mid-twenties when the total number of these cells levels off. If an adult who has never been obese then loses weight, the white adipocytes will typically decrease in size, but the absolute number of them will not change.

Dermal fibroblasts are interesting cells that make up 0.1% of the cells in the human body. The dermis is the layer of skin directly beneath the epidermis, or outermost layer of skin. Its main function is to provide connective tissue to the outer layer of skin, and to cushion the body from stress and strain. Dermal fibroblasts are specialized cells that are found in the dermis. They are responsible for creating connective tissues, and for helping the body to heal wounds.

The dermal fibroblasts are so effective in healing that scientists are attempting to generate them in the lab to assist with burn healing. When third degree burns occur, the entire dermal layer and all fibroblasts are destroyed. This means that the skin cannot heal, and scar tissue forms. If fibroblasts can be introduced, they may assist with sealing of the wound, and healing dermis.

Of all of the cells in the human body, 0.001% are muscle cells. There are three types of muscles cells. Cardiac muscle cells are found in the walls of the heart. They are an involuntary muscle, meaning that humans cannot control when or how often these cells contract.

Another involuntary muscle is the smooth muscle. These cells are found in hollow organs such as the stomach, intestines, bladder and uterus. They can also be found in the eye where they cause the pupils to dilate, and in the skin where they cause the hair to stand on end when one is exposed to the cold or a fright.

The smooth muscles are not connected to bones. On the other hand, skeletal muscle cells are connected to our bones. These cell types are responsible for all voluntary movements.

They can also be responsible for involuntary movements such as twitches, or movements during sleep.