The human body is complex. To better take care of our body we need to understand its structure and its functions.
The human body is an organism made up of building blocks. The most basic of these building blocks are atoms. An atom is the smallest part of any element that cannot be further divided. It contains the chemical properties of that element. It is made up of a dense, central, positively charged nucleus which is surrounded by a system of electrons. Each atom is a building block and when combined with one or more atoms form a molecule.
A molecule is particle made up of group of atoms joined together by chemical bonds. These bonds are formed by the sharing or exchange of electrons. Simple molecules are then linked together to form macromolecules. Macromolecules are polymers or large molecules. DNA, RNA, lipids and proteins are examples of macromolecules which are vital to life forms on earth. These complex macromolecules become the building blocks to form membranes or organelles that make up living cells. The human body consists of many different types of molecules that form the working parts of the body, namely cells.
A cell is the fundamental unit of life. Varying chemical reactions take place within a cell that allows for the maintenance and reproduction of life to take place. Cells allow us to do the things we do every day. Each cell in the human body performs the same functions that our body performs as a whole, such as converting energy, digesting food, reproducing, excreting waste and breathing. A group of cells, alike in structure and function, that are joined together to perform specific functions are called tissues.
The body is made up of different types of cells. When cells group together and perform the same function, they form tissues. The body has four types of tissues: connective tissue which works to support body tissues and hold them together such as those in bones and blood; epithelial tissue is the tissue that lines the organs and covers the body; muscle tissue which allows movement to our body through contractions and expansions and nerve tissue which transmits electrical impulses and forms nerves.
A tissue is not to be mistaken for an organ. An organ is a party of the body made up of two or more tissues working in synchronization to perform specific and specialized bodily functions. A tissue is not specific to a single organ. All four types of tissues are present in most organs. The heart, skin, stomach, liver, and kidney are just some of the organs in our body.
When two or more specialized organs work together in harmony to achieve a common physiological function they form an organ system. The human body is made up of ten major organ systems that are working together so that the body may function as a whole. It is important to keep in mind that these organ systems to do not only exist and function individually but these organ systems have to work together to form the human body. Each system relies on the other systems to allow the body to function normally. The integumentary system is an example of an organ system. It protects the internal organs from damage, assures, hydration of tissues and organs, stores fat and produces vitamins and hormones needed by the body. The integumentary system is composed of the skin, hair, nails, sweat gland and sebaceous glands.
The skin is the largest organ in the body and is the main organ of the integumentary system. It is made up of several layers of tissues that are constantly undergoing self-shedding and regeneration. The skin performs various essential functions for the body. It protects us from the harmful ultraviolet rays of the sun. It provides protection for other organs and other body parts. Our skin contains a multitude of nerve endings that allows us to feel and helps us adapt to weather elements. The skin regulates our body temperature. The skin is made up of three main layers namely the epidermis, dermis and the hypodermis.
The epidermis is the cuticle or outermost layer of the skin. It consists of five main layers of tissues which are self-shedding and regenerating: Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum and Stratum Germinativum. The epidermis is insensitive as it does not have any blood vessels or nerve endings. It functions as a protective outer covering for our body against invasion and infection. The skin serves as the physical and chemical barrier to the interior body and the exterior environment. It protects us from harmful elements of the environment. The epidermis is the natural moisturizer of the skin.
The dermis or true skin is made up of two layers, the papillary and reticular layers, containing blood vessels, lymph vessels, hair follicles, sweat glands, sebaceous glands and nerve endings or pain and touch receptors. It is also known as the middle layer. The dermis supplies nutrients and oxygen to the skin, serves as a defence mechanism for the immune system against infections, regulates body temperature, provides elasticity to the skin and makes skin waterproof protecting it from growth of bacteria and fungi on the skin.
The hypodermis or subcutaneous layer of the skin lies between the dermis and principal tissues and organs. It is mostly made up of adipose tissue and is where most body fat is stored. It serves to secure the skin to the underlying surface, provides thermal protection and acts as a cushion from impacts to the skin.