Six Different Levels of the Human Body: Level One and Two – ATOMS, MOLECULES, and CELLS
(Part one in a three part series)
Have you ever seen a science program about the planet earth and our solar system where they start with a close up of the earth and then pan out? Imagine starting at the surface of the earth and moving away. Next you see the continents, then the plant earth, then our solar system. Farther yet you see the Milky Way, then our galactic companions, then the local supercluster. You start at the microscopic level and finish at the macroscopic level. You can take that same concept and use it on the human body. Starting at the cellular level and reaching the final organism we call the human body. There are six levels that make up the human body, they are:
The Six Levels of the human body are:
1) The Chemical Level: consisting of atoms and molecules
2) The Cellular Level: consisting of a cell and its nucleus (organelle)
3) Tissue Level: such as muscle and connective tissue
4) Organ Level: example is the heart
5) The Body System level: There are 10 principles systems in our body. One example is the Central Nervous System (CNS).
6) The Organism Level: the human being.
In a Nutshell How all These Systems Work Together
The atom is the smallest amount of chemical elements and they combine to form molecules. The human body is 98 percent composed of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorous. Atoms and molecules bind together to build the basic building blocks of our body. Tissue is considered a group of closely related cells working together to perform a specific function. The four main tissues in our body are: 1) muscle tissue, 2) nervous tissue, 3) connective tissue, and 4) epithelial tissue. These tissues then organize themselves into organs such as the heart and the brain. Then the organs perform specific functions in our body’s system, and all these systems combined together form our human body.
Cells
Cells are the fundamental unit of life. Our bodies are composed of about 100 trillion cells of various forms and functions. Within our body, cells reproduce themselves and a new cell can only come into existence from a pre-existing cell. Cells within our body are constantly dying and being reproduced.
The Human Cell
I think that we all know from our Junior High Science classes that cells are made up of a plasma membrane and a nucleus. It is amazing what take place in our bodies when we start applying stresses such as exercise. For this reason I will go into more details about the cell and all of its working parts. Because we are all athletes to one degree or another we are interested in really understanding what is happening in our bodies (yes, even at the cellular level). Think of each cell as a living organism where each one has its own anatomy and physiology. This anatomy and physiology substructure of the cell is called organelles. The typical organelles that each cell contains are: Plasma Membrane, Nucleus, Ribosomes, Endoplasmic Reticulum, Golgi Apparatus, Lysosome, and Mitochondria. I will now explain each.
Plasma Membrane
The Plasma Membrane is also know as the Cell Membrane. The best way to picture the Plasma Membrane is to imaging an inflated balloon. The outer wall of the balloon would be considered the Plasma Membrane. This very complex structure is made up of mostly proteins and phospholipid bilayer. The phospholipid bilayer forms a double wall with proteins embedded in the bilayers. The cell membrane is made up of fatty acids which make up part of the phospholipid bilayer. The membrane makeup of fatty acids is very important to understand as an athlete because fats are an important part of our diets. Yes, although it is very important not to eat too much fats; we do need to eat to correct amount and correct kinds of fats since it is the essential building blocks for all cells. Fats are also important for athletes training to gain muscle mass and for long distance athletes. Their bodies metabolism burn a tremendous amount of fatty acids (See my article for details about Metabolism).
The Plasma Membrane can selectively allow the transportation of molecules through it. This basically means that the Plasma Membrane filters out undesirable compounds and has the ability to keep the desirable compounds it needs. As an athlete you should know that one of the desirable compounds it retains is insulin. Insulin is the hormone responsible for stimulating the uptake of glucose and amino acids across the Plasma Membrane. Insulin is very important in the metabolism of carbohydrates and fats, and important in the conversion of glucose to glycogen which lowers the blood glucose level.
Nucleus
The nucleus is the control center for the cells and one essential function is to initiate cell division.. The nucleus is considered to be a cell within a cell because it has its own membrane housing all of its genetic materials. The liquid that is between the Plasma Membrane and the Nuclear Membrane is called cytoplasm. As the control center, the nucleus initiates the production of substances that are needed by the cell. This intracellular signal causes certain chromosomes to produce exact copies of the gene sequence being activated. This material is then carried by the messenger RNA (Ribonucleic Acid). It is transported from the nucleus, through the nuclear membrane and into the cytoplasm. Once the RNA is in the cytoplasm it is like a template that is waiting to be copied. For the copying to occurs the RNA must connect with ribosomes.
Ribosomes are also organelles. Ribosomes travel along the messenger RNA strand to connect each point along the RNA with its corresponding transfer RNA which has an amino acid attached to it. I realize that this is a long discussion, but here is where it is important as an athlete to understand this process. Amino acids are strung together to form proteins, enzymes, etc. If your body is missing certain amino acids the protein chains cannot be completed. This is the main reason it is mandatory that you have adequate and effective protein intake as an athlete. If essential amino acid is lacking, protein synthesis can be reduced or actually temporarily stop.
Ribosomes
Ribosomes are very tiny spherical organelles that are made up of protein and RNA. Within a cell they are the most numerous organelle and are found scattered throughout the cell’s cytoplasm and also along the surface of another organelle; the endoplasmic reticulum. The main function of Ribosomes is to synthesize compounds for use outside of the cell.
Endoplasmic Reticulum (ER)
This organelle forms a network of intracellular canals within the cytoplasm. ER comes in two forms: rough and smooth. Ribosomes along with rough ER attach and is where proteins and other biomolecules can be transported through the ER’s canal network to other parts of the cell and outside the cell. The smooth ER are without ribosomes and its function is not clear.
Golgi Apparatus
Golgi Apparatus are stacks of tiny, oblong sacs embedded in the cytoplasm of the cell near the nucleus. Although it is not know for sure, it appears that the Golgi sacs are responsible for the synthesis of carbohydrate biomolecules. These carbohydrates are combined with the proteins made in the endoplasmic reticulum to form glycoproteins. The glycoproteins function as enzymes, hormones, antibodies, structural proteins, etc. As the amount of glycoprotein within the Golgi sac increases, the Golgi sac becomes inflated breaking away and transporting the glycoproteins out of the cell, into the bloodstream to be used by other cells.
Lysosome
Lysosomes are another sac-like structure. Their sacs contain and carry a variety of different enzymes which act as catalysts directing all major biomechanical reactions. These enzymes are able to breakdown all of the main components of the cell, such as proteins, fats, and nucleic acid. This material is then used to synthesize new biomolecules or for energy. Lysosomes also play a small role in destroying bacteria that may enter the cell.
Mitochondria
Although most of of probably never heard of the other organelles other than the nucleus, most of us have heard of Mitochondria. Simply, mitochondria is the powerhouse of the cell; its role is to generate energy. The enzymes that are critical for making ATP (adenosine triphosphate) exist in the mitochondria; and ATP stores its energy within the mitochondria. Within the mitochondria membrane, catabolic enzymes (catabolic is the breaking down of complex molecules into simpler ones) create the reactions within the cells that provide life-sustaining energy.
Mitochondria
Mitochondria’s powerhouse contains nutrients like glucose and fatty acids and they link together forming chemical bonds. When these chemical bonds are broken, energy is released. Within the mitochondria, this energy is trapped and stored in the ATP molecule which can then make use of it. So, the energy from glucose is transferred to the ATP molecule and the energy is in a form that the body can use.
Conclusion/Wrap-Up
All of the above organelle are the basic biological structure and main components of a cell. From an athlete’s concern, we know realize that all of our energy needs for the activities we do starts at the cellular level. Within the cell the plasma membrane retains insulin which is very important in the metabolism of carbohydrates and fats, and important in the conversion of glucose to glycogen which lowers the blood glucose level. We see that certain fats are essential for proper cell growth, function, and to feed our high metabolism. And that a eating lifestyle that is lacking in proteins can hamper the cells ability for amino acids to complete the protein chain robbing you body of this nutrient. Finally, we come to know that the mitochondria are the powerhouse of our cells fueling our muscles with the energy demands that we require for our physical activities.
