Human Body: Anatomy, Physiology, and Homeostasis
Our body is an organism; therefore, our body is made of organs. These organs have a lot of tissues, tissues are made of billions of cells, cells are made of molecules, and molecules are made of atoms.
Body Components
- Atom: It is the smallest unit of a chemical element, which maintains its properties and cannot be broken by any chemical means. It consists of protons and neutrons with electrons orbiting this nucleus.
- Molecule: It is a set of atoms; it is the smallest particle that presents all the physical and chemical properties of a substance.
- Cell: They are the minimal unit of all living beings. They are constituted for membrane plasma, cytoplasm, and genetic material.
- Tissue: They are a set of cells in an organism that have a similar structure and function.
- Organ: It is a set of tissues that share functions and a structure and the same function.
- Anatomy: The science of the shape and structure of organisms and their parts.
- Physiology: The biological study of the functions of living organisms and their parts.
Homeostasis
This is the name that has all the processes within an organism’s body that keep it in stable conditions.
Organisms have mechanisms that can control:
- The amount of sugar
- Regulate the amount of water
- The temperature level
Thermoregulation Process
For our organism, it is important to keep the temperature steady. If the body gets warmer, it needs to cool down; when our body is cooler, it needs to warm up.
Enzymes
Enzymes help the body to get an optimum temperature at 37° Celsius.
Hypothermia
If the body is under too cold conditions, it does not operate effectively, and it could stop working. It begins with shivering and “goosebumps,” and if the body does not resist cold conditions, people could die.
Hyperthermia
If the organism is exposed to extreme hot conditions, the body gets a heat stroke. It begins with headaches and dizziness; if conditions stay, it may result in unconsciousness and coma.
Skin
The integumentary system contains the largest organ in the human body, the skin. It is also comprised of such extensions of the skin as hair and fingernails. The principal function of the skin is to protect the body’s delicate organs.
The functions of the skin to the homeostasis process are:
- Protection
- Regulate the body temperature
- Sensory reception
- Water balance
- Synthesis of vitamins and hormones
- Absorption of materials
The skin is made of three separate layers, each with its own particular function:
Epidermis
The epidermis is the outermost layer; here, cells are keratinized. The growth of skin takes place. This is the outermost layer of the skin. In this part of the skin, there are not blood vessels, but its deepest layer is supplied with lymph fluid. The epidermis layer is thickest in the palms and on the bottom of the feet. In the epidermis layer, you can find the melanin, which gives the pigments to the skin.
Dermis
It is the second layer. We found here a more complex structure, “blood supply.” The growth of hair takes place. The dermis is a tough and elastic layer, which contains white fibrous tissue interlaced with yellow elastic fibers.
Subcutaneous Hypodermis
This inner layer is where we found adipose tissue; it acts like a cushion for delicate organs. It also functions to insulate the body to maintain body temperature. It is the deepest layer of skin. This layer is loose fibrous connective tissue and fat (adipose) cells interlaced with blood vessels. In females, the hypodermis is generally about 8% thicker than in males.
Follicles
Hair follicles are covered by cells that create the proteins that form hair.
Glands
There are two types of glands: Eccrine glands and Apocrine glands.
- Eccrine glands: These glands are linked to the sympathetic nervous system, and they occur all over the body.
- Apocrine glands: These glands are bigger than Eccrine glands; they occur in the armpits and groin areas and produce the “body odor.”
Hypothalamus
The importance of the hypothalamus in the homeostasis process is: It sends a nervous signal to the sweat-producing skin glands to help the body keep the stable conditions. If the body is hot, the sweat glands produce sweat to get the body cold. If the body is cold, the sweat glands constrict, and sweat production decreases.
Hairs
Hairs are structures made of keratinized cells; they grow up in the dermis layer. The principal function of hair is to protect the body and sensory reception, for example, the “goosebumps.”
Nails
Nails are plates of epidermal cells, keratinized, dead, and hard.
Sebaceous Glands
The sebaceous glands are connected to hair follicles; it is found in the dermis layer. They secrete an oily substance named fat.
Sweat Glands
The sweat glands are divided into two:
- Eccrine glands: They are all over the world.
- Apocrine glands: They are localized in some zones: armpits, groin areas, and chin.
Ceruminous Glands
They are located in the auditory external conduct. The ear-wax constitutes a sticky barrier against foreign bodies.
The Integumentary System
It is composed by:
- Skin: Epidermis, Dermis, Subcutaneous layer
- Hair
- Nails
- Glands: Eccrine, Apocrine
Stratum Corneum or Horny Layer
It is the outermost layer of the cell. The surface layer is composed of twenty-five to thirty sub-layers of flattened scale-like cells. This surface layer is considered the real protective layer of the skin. These cells are keratinized because the cells called protoplasm change to a protein (keratin), and it helps the skin to give its protective property.
Stratum Germinativum
It is the deepest layer of the cell. Here new cells are formed and gradually change in form as they move upward to the outer layers, becoming keratinized in the process. (They move upward “stratum corneum”).