Hair is a structure unique to mammals, composed of the protein Keratin (which is also present in our nails and outer layer of skin). Under a microscope the outer layer of the hair shaft looks like roofing shingles. This is called the cuticle and consists of several layers of flat, thin cells. The inside layer of the hair is called the cortex and provides the mechanical strength that maintains the shape of the hair.

The eye is a specialized organ that detects light and converts it into neural signals that are interpreted by nerves and sent to the brain to form the images you see. The smallest object visible with the average eye that has 20/20 vision is 0.1mm in diameter.

Homo sapiens are bipedal primates with highly developed brains. A human's average height is between 1.5m to 1.8m. The average lifespan is 67 years, though this number varies greatly depending on the environment one lives in.

About the size of a clenched fist, the heart is a powerful muscle that pumps blood throughout the body's circulatory system. On average, the human heart beats 72 times per minute, or 2,600,000,000 beats throughout a person's lifetime.

An arteriole is a tiny blood vessel (almost 2000 times smaller than the heart itself) that branches off from arteries. As blood moves into this smaller space the pressure increases. Arterioles have strong flexible walls to withstand this extra force and can adjust blood flow to different part of the body.

Arterioles are structured in several layers. The inside has a lining (one cell thick) of epithelial cells; these appear like thin, flat plates that fit closely together to provide a smooth surface over which the blood can easily flow.

This single layer is approximately 1 micrometer thick. Over top of this is a lining of muscle that helps regulate blood pressure by expanding or contracting. The outer layer is fibrous tissue that provides support and elasticity to withstand blood pressure. This layer also helps anchor the arteriole to the surrounding tissues.

Red blood cells are produced in bone marrow, circulate in the blood, and carry oxygen throughout the body. They are flexible, squishy, and shaped a bit like doughnuts (without the hole in the centre). The average lifespan of a red blood cell is 100 to 120 days. One teaspoon (5mL) of healthy blood contains about 25 billion red blood cells - this means that at any one time the average adult human body (with 5L of blood) can contain around 25 trillion red blood cells.

The cytoskeleton refers to a cellular skeleton, made of protein, which is present in all cells. The cytoskeleton does the same thing for the cell as our skeleton does for our bodies. There are three types of cytoskeleton structures; microfilaments, intermediate filaments, and microtubules that range in diameter from 6nm to 23nm respectively. They can grow up to 1000 times longer than they are wide.

Also known as leukocytes, these cells play a key role in our immune system. They are the guardians of our body, defending against infectious disease and foreign materials. In the average healthy adult, 1% of the cells in our blood are white blood cells; this would be around 50 billion in 1 litre of blood. There are several different types of white blood cells, but all work together in the immune system to keep us healthy and strong.

Platelets, the smallest cells in blood, keep us from bleeding to death when we get cut. Chemical signals cause these normally-smooth cells to become spiky so they stick to each other and to the edges of the wound, form clots, and stop the blood flow. The average lifespan of a platelet is just 5 to 9 days. This means our bodies must produce about 100 billion platelets each day in order to constantly replace the dead cells.

The flu is a larger virus than the common cold, and it causes chills, fever, sore throat, weakness, fatigue, muscle pain, and sometimes vomiting and nausea. This can be a more severe disease in certain populations, especially when a new strain emerges.

DNA stands for deoxyribonucleic acid and is commonly referred to as the blueprint of life. This is because DNA contains the genetic instructions for the structure and function of all known living organisms. While DNA is only 2.5nm wide, it can be incredibly long. If the DNA from a single cell nucleus were stretched out, it would measure approximately 6 feet in length. If we took all of the DNA from every cell in one human being and laid it out end-to-end, it would reach to the moon and back 8,000 times!

Cholesterol, a type of fat, plays a role in forming cell membranes. Cholesterol is carried through the blood stream in particles containing hundreds of cholesterol molecules. These particles can form a sticky substance called plaque that thickens artery walls and can cause blood clots and heart attacks.

Red blood cells transport oxygen from lungs to body tissues using a protein called hemoglobin. One hemoglobin protein holds four iron atoms. These iron atoms give blood its red color. One red blood cell contains approximately 170 million hemoglobin molecules.

These ring-shaped structures form the links between hemoglobin and the oxygen it carries. When the iron atom in a heme group connects to an oxygen molecule, the entire hemoglobin protein changes shape to allow oxygen to bind to the other groups. Each hemoglobin protein can transport four oxygen molecules.

Atoms are the building blocks of all matter. Using nanotechnology, researchers are able to “see” atoms and have begun to even manipulate individual atoms. In biology, carbon is the backbone for most organic molecules and is a major building block. The human body consists of 65-90% water, but the solid portion of you is mostly carbon.

Two oxygen atoms link to form a molecule of oxygen gas, which makes up about 21% of the earth's atmosphere and is key to almost all biological processes on the planet. Humans use oxygen as fuel to carry out many processes in the body. Sugar is metabolized in our bodies with oxygen to produce water, carbon dioxide (CO2), and energy. We use that energy to build other organic molecules necessary to grow and function. In plants the process is reversed through photosynthesis. Research is underway to use nanotechnology to help mimic part of the photosynthetic process and split water into hydrogen and oxygen. These gases could be used to create clean energy.