Support, Movement, & Responses
Skin is the largest organ of your body. It is made up of three layers: epidermis, dermis, and the fatty layer
1. Epidermis – the outer, thinnest layer. These outermost cells are dead and water repellent. These cells are constantly replaced.
2. Dermis – is located directly below the epidermis. This layer is the thickest and contains blood vessels, nerves, muscles, oil glands, and sweat glands
3. Fatty Layer – is below the dermis and is where most fat is deposited when a person gains weight.
Melanin – epidermis cells produce melanin. It is a pigment that protects your skin and gives it color. The more melanin you have, the darker your skin appears. (Melanin also acts as a natural sunblock. The more you have the more your skin blocks UV rays. The downside is that it also blocks Vitamin D production. *I am in no way telling anyone that they should or should not wear sunblock*)
**The most important function of the skin is protection.** It protects against physical and chemical injury. Other important functions of the skin are: sensory response (touch – nerve cells detect and relay information to the brain), formation of vitamin D, regulation of body temperature (sweat), and ridding the body of waste (sweat).
When skin is injured (scratched, burned, ripped, etc…) it is exposed to harsh conditions and disease causing organisms can enter the body and cause infections. When skin is damaged the epidermis produces new cells and the dermis repairs the tears in the skin.
Different amounts of melanin give humans a variety of skin colors (shades).
Common & Not So Common Problems With Skin
- Acne - caused by a variety of things, causes pimples
- Eczema - a disease that causes dry skin, inflammation, redness, and itchiness
- Skin Cancer (Melanoma) - damage to skin cells from the Sun's harmful UV rays
- Hyperpigmentation - the darkening of an area or areas of skin caused by an increase in melanin production
- Hypopigmentation - the lightening of an area or areas of skin caused by melanin depletion or a decrease in melanin. This causes an increased risk for skin cell damage from UV rays.
- Vitiligo - a condition where the melanin cells are destroyed causing effected areas to be void of color. This causes an increased risk for skin cell damage from UV rays.
Muscles
Muscles help make our daily movements possible. Voluntary muscles are muscles that you are able to control like you hand, arm, and leg muscles. Involuntary muscles are muscles that you can't control consciously like your cardiac (heart) muscles and the muscles that help you breathe and digest food.
** Trivia ** It takes 13 muscles to smile and 43 muscles to frown
Humans have three types of muscle tissue: skeletal, smooth, and cardiac.
- Skeletal - voluntary muscles that move bones. They are the most common muscles and are attached to bones by tendons. Tendons are thick bands of tissue. Skeletal muscle cells are striated; under a microscope, they appear striped.
- Smooth - these muscles is involuntary and non-striated. They are involuntary because you don't consciously control their function. Ex: heart, intestines, bladder, blood vessels, and other internal organs.
- Cardiac - these muscles are found only in the heart. Cardiac muscles are striated. Ex: heart
Common & Not So Common Problems With the Muscular System
- Bruising - blood vessels rupture and leak
- Muscle Sprain or Strain - strains occur when overexerted muscles are stretched or partially torn. Sprains are ligament injuries and require medical attention
- Tendonitis - inflammation to the tendon caused by overuse, age, or injury
- Hernia - when an organ or tissue protrudes through an area of weak muscle
- Muscular Dystrophy - A genetic disorder that in which the fibers of the skeletal muscles are progressively destroyed. There is no cure.
Your skeletal system is made up of 206 bones. Without it, you would be a blob of skin and organs on the floor. It's two most important functions are protection and to assist with locomotion.
Your bones provide protection for your organs and tissue like your heart and ribs. When your muscle is attached to your bones you are able to move. Locomotion is movement.
There are many different types of bones: long bones, short bones, flat bones, and irregular bones but what connects those bones together is a tissue known as cartilage. This flexible yet strong tissue is found in your earlobe, at the end of your nose, and between joints like your knees and elbows. In the early stages of development, your skeletal system is mostly cartilage and then hardens into bone in the early infant stages of life. This is known as ossification.
Common & Not So Common Problems With the Skeletal System
- Bone fractures - when your bone splits or breaks
- Dislocating bones - the ligaments that attach the bones are torn and the bone slips out of its proper place
- Osteoporosis - a progressive loss of bone tissue
- Scoliosis - a curvature of the spine
- Arthritis - the inflammation if joints
- Repetitive Motion Injury - damage to the tissue caused by repeating the same motion over an extended period of time. (computer work or sewing) Carpel Tunnel is an example of repetitive motion injury.