MT M3 3.1 into to integu sys Flashcards
skin
The function of the skin is to protect the body, regulate temperature, sense the surrounding environment, and secrete various substances.
skin
protects
The skin protects the deeper tissues from invasion from foreign bodies such as bacteria and viruses. It can prevent mechanical injury and excessive water loss, store both food and water, and guard the body from too much exposure to ultraviolet rays from the sun.
skin
regulates the body’s temperature
When body temperature rises, the blood vessels in the skin can dilate, which enables more blood to be brought to the surface of the body and heat to radiate out from the skin. Additionally, sweat glands will secrete more sweat to evaporate and cool the body. When body temperature drops, the blood vessels in the skin will constrict, which keeps the blood and heat closer to the core of the body.
skin
senses
The skin senses the surrounding environment through millions of nerve endings that sense pain, touch, heat, cold, and pressure. These nerves then travel to the brain and provoke a response to the signal.
skin
secretes
the skin secretes substances through sweat glands and sebaceous glands
Sweat glands
Sweat glands secrete sweat, which is made up of water, salt, and other chemicals. This functions to cool the body.
Sebaceous glands
Sebaceous glands secrete sebum, which is an oily substance that protects the skin from dehydration.
skin
How many layers
The skin is made up of two layers: the epidermis and the dermis
epidermis
The epidermis is the outer layer of the skin, and it is made up of 5 layers. The layers of the epidermis from deep to superficial are
stratum germinativum
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
stratum germinativum
The deepest layer of the epidermis is where new skin cells are generated.
stratum spinosum
Stratum spinosum means “spiny layer.” This layer is above the stratum germinativum, and as the skin cells divide in the lowest layer, the cells are pushed up into the stratum spinosum layer. This layer also contains the Langerhans cells, which function to protect the skin from invading microorganisms
stratum granulosum
The stratum granulosum and stratum lucidum are largely formed from keratin.
Keratin
Keratin is the protein that forms hair, nails, and the thick skin of the palms and soles.
stratum corneum
The stratum corneum is the most superficial layer of the skin that is made up of dead skin cells and functions to protect the deeper layers.
dermis
The dermis is deep to the epidermis and is made up of connective tissue. This layer contains the nerves and nerve endings, blood vessels, sebaceous and sweat glands, elastic fibers, hair follicles, and lymphatics.
macule
Skin signs of disease
A macule is a flat, discolored spot on the skin; a mole is an example of a macule.
wheal
Skin signs of disease
A wheal is a localized, temporary elevation of the skin that is itchy; urticaria or hives are wheals.
papule
Skin signs of disease
A papule is a solid, confined, and elevated area on the skin. A pimple is a papule.
vesicle
Skin signs of disease
A vesicle is a small fluid-filled sac. A blister is a vesicle.
pustule
Skin signs of disease
A pustule is a small, elevated confined lesion that is filled with pus. A pimple can also be a pustule.
ulcer
Skin signs of disease
An ulcer is an erosion, or eating away, of healthy tissue.
fissure
Skin signs of disease
A fissure is a crack-like slit that extends through the epidermis into the dermis.
Hair
Hair is a thin, stringlike structure that develops out of a hair follicle. Each hair has a root embedded in the hair follicle and a shaft, which is the visible portion of the hair. Hair is located throughout the body except for the palms, soles, and penis. Each hair has a small muscle called the arrector pili muscle, which is attached to the follicle. This muscle contracts when the skin is cooled, or the person has an emotional reaction to form “goosebumps”.
Nails
Nails are located on the fingers and the toes. They are made up of hard keratin and cover the end of the fingers and toes. The nail is made up of the nail body and the nail root.
nail body
The nail body is the visible portion of the nail and covers the part of the epidermis called the nail bed.
nail root
The nail root is a fold of epithelial tissue that is not visible.
nail bed
The nail bed is the epithelial tissue located deep to the nail body, and it is a pink color due to the blood vessels that are located in the tissue.
eponychium
nail
The cuticle or eponychium is a small portion of the epithelial fold that extends over the base of the nail body.
lunula
nail
The lunula is a crescent-shaped area at the base of the nail body that is lighter than the rest of the nail. This is caused by compression of the blood vessels that are under the nail body.
Sebaceous glands
Sebaceous glands are the oil-secreting glands that are located within the skin. These glands open into the hair follicle and secrete sebum. Sebum lubricates the hair and the skin. These glands are controlled by the endocrine system, and the amount of sebum that is secreted can vary due to age, disease, puberty, and pregnancy.
free edge
nail
The free edge of the nail is the top of the nail body, and it projects over the tip of the finger or toe. It is the portion of the nail that is trimmed. Nails grow at a rate of 1 mm per week on average.
Sweat glands
Sweat glands are numerous and can be found in every part of the body except for the lips, the tip of the penis, and the area around the clitoris. Sweat functions to cool the body through the evaporation of perspiration and to rid the body of waste.
Merocrine sweat glands
Merocrine sweat glands are located throughout the body and release sweat directly to the skin’s surface. They are most prevalent on the soles of the feet and palms of the hands.
Apocrine sweat glands
Apocrine sweat glands are located in the axillae, around the nipples, and in the groin. They begin to secrete sweat during puberty, and they secrete sweat into the hair follicles located in those areas.
