The Relationship between Atoms, Molecules and Cells

This paper tackles the relationship between atoms, molecules and cells, as well as the differences betweens organs and tissues, and the structure of organ systems. Moreover, it explains the anatomy and physiology of the skin and two of its structures  the epidermis and the dermis.

An atom is the fundamental piece of matter, which is anything that can be physically touched. Everything in the universe with the exception of energy is made up of matter, which means that everything in the universe is composed of atoms (Propulsion, n.d.). Only one type of atom makes up a material called a chemical element, or an element. An atom is the smallest particle of an element that still retains the qualities and characteristics of that element (Atoms and Elements, n.d.). Certain elements such as Calcium, Hydrogen, Oxygen, Nitrogen, Phosphorus and Sulfur make up all living matter. These are the elements found in bulk form and are considered essential for life. There are also some elements found in trace quantities in a great number of organisms and are very likely also essential for life  Calcium, Manganese, Iron, and Iodine. These elements almost always combine into biomolecules and provide for a huge variety of chemical structure as well as reactivity.

The biomolecules formed from the numerous combinations of the chemical elements essential for life are classified into nucleic acids, proteins, and polysaccharides (Biochemistry, n.d.) which are all found in biological cells. In short, these biomolecules are the ones that make up the cells and they function for storage and transfer of genetic information within the cell, the catalysis of biochemical reactions, the maintenance of the physical structure of the cell, intracellular transport, and protection.

The Differences between Organs and Tissues
Groups of cells with similar structure and function come together to form a tissue such as blood, muscles and nerves. Blood tissue, for example, contain a variety of cells RBC for carrying oxygen, WBC for protection and destruction of harmful bacteria, and platelets to facilitate clotting.

Tissues with similar function and structure group together to form a specialized body known as an organ such as the heart, the stomach and the brain.

The Organ System
The organ system is formed when various organs come together to perform a specific functions. One example of organ system in animals is the circulatory system which carries blood to every part of the body. The circulatory system is made up of the heart, the veins, the arteries, the capillaries and blood. The term system refers to a group of interrelated parts working together for a harmonious whole. There are actually 10 organ systems in the human body.

One of the organ systems is the skeletal system, made up of bones and cartilage, provides support for the body and protects the delicate internal organs. Second, the muscular system, made up of the skeletal, smooth and cardiac muscles, functions for support and movement. Third, the circulatory system, which was previously mentioned, transports nutrients, gases and hormones throughout the body. Fourth, the nervous system, composed of the brain, spinal cord, and peripheral nerves, relays electrical signals from the body to the brain. Fifth, the respiratory system, made up of the nose, trachea and lungs, provides gas exchange between the circulatory system and the environment. Sixth, the digestive system, made up of the mouth, esophagus, stomach and the intestines, has the role of breaking down food and the consequent absorption of nutrients for growth and maintenance of the body. Seventh, the excretory system, made up of kidneys, ureters, bladder, and urethra, functions for the filtering out of cellular wastes, excess water and toxins out of the circulatory system. Eighth, the endocrine system, made up of the endocrine glands, control and regulate growth and nutrient absorption throughout the body. Ninth, the reproductive system, which refers to the ovaries and related organs in females and the testes and related organs in males, has one function and that is to manufacture cells for the perpetuation of the species. Lastly, the lymphatic or immune system, made up of WBC, lymph nodes and vessels, and T- and B- cells, serves as the bodys defense against harmful microorganisms.

The Skin, the Epidermis and the Dermis
The skin is the largest organ of the body and it performs a number of different functions. These functions include thermoregulation, sensation, metabolic functions and protection. The two regions of the skin are the epidermis and the dermis. The most superficial layer of the skin is called the epidermis and it is considered the first barrier of protection from harmful substances.

The epidermis consists of cells called keratinocytes and five layers namely stratum germinativum, stratum spinosum, stratum granulosum, stratum lucidum, and the stratum corneum at the topmost. Other cells that make up the epidermis include the melanocytes, the Merkel cells, and the Langerhans cells. The keratinocytes, which make up around 95 of all the epidermal cells, typically function for holding the physical structure of the epidermis as well as the other types of cells and may even function as immunomodulaters.

The dermis, on the other hand, is the one responsible for thermoregulation and vascular support of the otherwise avascular epidermis. The dermis is typically composed of the papillary dermis and the reticular layer where one finds the fibroblasts responsible for the secretion of collagen, elastin and ground substance that provide support and elasticity to the skin. The papillary dermis houses the vascular networks that support the avascular epidermis and provide a thermoregulation network. There are also free sensory nerve endings in the highly sensitive areas of the papillary dermis. The reticular layer, aside from containing the fibroblasts that provide skin elasticity and strength, houses other epithelial structures such as the sweat and sebaceous glands as well as the hair follicles.


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