Integumentary System Flashcards
What is the integumentary system?
A complex set of organs consisting of the skin and its appendages (sweat and oil glands, hairs, and nails) that serves several functions, mostly protective.
What are the two layers of the skin?
The epidermis and dermis.
What is subcutaneous tissue?
The layer of tissue beneath the dermis that is mostly made up of fat and connective tissue.
What are some functions of the skin and its derivatives?
Mostly protective functions, such as regulating body temperature, protecting against physical and chemical damage, and preventing water loss.
What causes skin color?
The amount and type of melanin produced by melanocytes in the epidermis.
What are sweat and sebaceous glands?
Sweat glands produce sweat to regulate body temperature, while sebaceous glands produce oil to lubricate and waterproof the skin and hair.
What are some developmental aspects of the integumentary system?
Changes in skin thickness, elasticity, and pigmentation occur with aging, and skin cancer risk increases with prolonged sun exposure.
What are some things that can go wrong with the integumentary system?
Skin conditions such as acne, eczema, and psoriasis, as well as skin cancer and infections.
What are some functions of the skin?
Regulating body temperature, protecting against physical and chemical damage, and preventing water loss.
What is the subcutaneous tissue?
The layer of tissue just deep to the skin, consisting mostly of adipose tissue with some areolar connective tissue, that anchors the skin to underlying structures and acts as a shock absorber and insulator.
What are the functions of the subcutaneous tissue?
To anchor the skin to underlying structures, act as a shock absorber and insulator, and protect the body by allowing the skin to slide relatively freely over those structures.
What is the skin’s total surface area and how much does it weigh in the average adult?
The skin’s total surface area is 2.2 square meters, and it accounts for about 7% of total body weight in the average adult.
What are the two distinct layers of the skin?
The epidermis, composed of epithelial cells and the outermost protective shield of the body, and the underlying dermis, making up the bulk of the skin and composed mostly of dense connective tissue.
Which layer of the skin is vascularized?
Only the dermis is vascularized. Nutrients reach the epidermis by diffusing through the tissue fluid from blood vessels in the dermis.
What are some of the appendages of the skin?
Eccrine sweat gland, arrector pili muscle, sebaceous (oil) gland, hair follicle, hair root.
What are some of the nervous structures in the skin?
Sensory nerve fiber with free nerve endings, lamellar corpuscle, hair follicle receptor (root hair plexus).
What is the function of the dermal vascular plexus?
To supply blood to the skin and help regulate body temperature.
What is the purpose of the Check Your Understanding section?
To test the reader’s comprehension of the material presented in the chapter.
Name the four types of cells found in the epidermis.
Keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells.
What is the chief role of keratinocytes?
To produce keratin, the fibrous protein that helps give the epidermis its protective properties.
What is the most common type of cell found in the epidermis?
Keratinocytes.
What is the function of melanocytes?
To produce melanin, the pigment that gives color to the skin and protects it from UV radiation.
What are the major layers of the epidermis?
Stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.
What is the deepest layer of the epidermis?
Stratum basale.
What is the most superficial layer of the epidermis?
Stratum corneum.
What is the function of dendritic cells in the epidermis?
To help the immune system recognize and respond to pathogens.
What is the function of tactile epithelial cells in the epidermis?
To detect touch sensations.
What is the fibrous protein produced by keratinocytes?
Keratin.
What are keratinocytes and how are they tied together?
Keratinocytes are epithelial cells that produce keratin and are tied together by desmosomes for strength and, in some layers, by tight junctions to hinder movement of water between cells.
Where do keratinocytes arise from and what stimulates their growth?
Keratinocytes arise in the deepest part of the epidermis from a cell layer called the stratum basale. They undergo almost continuous mitosis in response to epidermal growth factor, a peptide produced by various cells throughout the body.
What happens to keratinocytes as they move towards the skin surface?
As keratinocytes move towards the skin surface, they make keratin that eventually fills them. By the time they approach the skin surface, they are dead, scale-like flat sacs completely filled with keratin.
What are melanocytes and what is their function?
Melanocytes are epithelial cells that synthesize the pigment melanin. They are found in the deepest layer of the epidermis and transfer melanin to nearby keratinocytes, forming a pigment shield that protects the nucleus from the damaging effects of ultraviolet (UV) radiation in sunlight.
What are dendritic cells and what is their function?
Dendritic cells are star-shaped cells that ingest foreign substances and are key activators of our immune system. They arise from bone marrow and migrate to the epidermis, extending their processes among the surrounding keratinocytes to form a more or less continuous network.
What are tactile epithelial cells and what is their function?
Tactile epithelial cells, also called Merkel cells, are present at the epidermal-dermal junction and are intimately associated with a disclike sensory nerve ending. The combination functions as a sensory receptor for touch.
What are the layers of the epidermis in thick skin and what are their functions?
In thick skin, the layers of the epidermis from deep to superficial are stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. These layers contain stem cells, keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells, and are responsible for producing and protecting the skin.
What are the layers of the epidermis in thin skin and how do they differ from thick skin?
In thin skin, the stratum lucidum appears to be absent and the other strata are thinner than in thick skin. Thin skin covers the rest of the body and is less subject to abrasion than thick skin.
What is the stratum basale and what is its function?
The stratum basale is the deepest epidermal layer, also called the stratum germinativum. It consists of a single row of stem cells representing the youngest keratinocytes, which undergo almost continuous mitosis. Each time one of these basal cells divides, one daughter cell is pushed into the cell layer just above to begin its specialization into a mature keratinocyte, while the other daughter cell remains in the basal layer to continue the process of producing new keratinocytes.
What is the stratum granulosum and what is its function?
The thin stratum granulosum consists of one to five cell layers in which keratinocyte appearance changes drastically, and the process of keratinization begins. These cells flatten, their nuclei and organelles begin to disintegrate, and they accumulate two types of granules: keratohyaline granules that help to form keratin in the upper layers, and lamellar granules that contain a water-resistant glycolipid that is secreted into the extracellular space. Together with tight junctions, the glycolipid plays a major part in slowing water loss across the epidermis.
Name the layers of the epidermis from superficial to deep that a rusty nail would pierce when stepping on it barefoot.
The layers of the epidermis that a rusty nail would pierce from superficial to deep are the stratum corneum, stratum lucidum (if present), stratum granulosum, stratum spinosum, and stratum basale.
What is the major function of the stratum basale?
The major function of the stratum basale is to produce new keratinocytes to replace the ones shed from the surface of the skin.
Why are the desmosomes and tight junctions connecting the keratinocytes so important?
The desmosomes and tight junctions connecting the keratinocytes are important because they help to hold the cells together and provide strength and stability to the epidermis.
What problems might be caused if the dead cells of the stratum corneum did not shed from the body and continued to accumulate?
If the dead cells of the stratum corneum did not shed from the body and continued to accumulate, it could cause dry, flaky skin, clogged pores, and potentially lead to skin infections.
What are cleavage lines in the skin?
Separations between underlying collagen fiber bundles in the reticular dermis that tend to run longitudinally in the skin of the limbs and in circular patterns around the neck and trunk.
Why are cleavage lines important to surgeons?
When an incision is made parallel to these lines, the skin gapes less and heals more readily.
What is the function of collagen fibers in the dermis?
They give skin strength and resiliency that prevent minor jabs and scrapes from penetrating the dermis.
What is the function of elastic fibers in the dermis?
They provide the stretch-recoil properties of skin.
What are flexure lines in the skin?
Dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures.
Where are flexure lines visible in the body?
On the wrists, fingers, soles, and toes.
What are friction ridges in the skin?
Skin ridges that may enhance our ability to grip certain kinds of surfaces and contribute to our sense of touch by enhancing vibrations detected by the large lamellar corpuscles (receptors) in the dermis.
What is the function of sweat pores along the crests of friction ridges?
They leave identifying films of sweat called fingerprints on almost anything we touch.
What is the reticular dermis?
The deeper layer of the dermis that accounts for about 80% of the thickness of the dermis and is coarse, dense irregular connective tissue.
What is the extracellular matrix of the reticular dermis composed of?
Thick bundles of interlacing collagen fibers.
What is the dermal vascular plexus?
The network of blood vessels that nourishes the reticular dermis and lies between this layer and the subcutaneous tissue.
What are striae?
Silvery white scars that result from extreme stretching of the skin, such as during pregnancy, that can tear the dermis.
What is melanin?
A polymer made of an amino acid called tyrosine that determines skin color.
What is the enzyme responsible for melanin synthesis?
Tyrosinase.
How does prolonged sun exposure affect skin color?
It causes a substantial melanin buildup, which helps protect the DNA of skin cells from UV radiation by absorbing the rays and dissipating the energy as heat. In all but the darkest-skinned people, this defensive response causes skin to darken visibly (tanning occurs).
What is carotene and where is it found in the body?
A yellow to orange pigment found in certain plant products such as carrots. It tends to accumulate in the stratum corneum and in the fat of the subcutaneous tissue.
What is the role of hemoglobin in determining skin color?
The pinkish hue of fair skin reflects the crimson color of the oxygenated pigment hemoglobin (he9mo-glo0bin) in the red blood cells circulating through the dermal capillaries. Because light-skinned people have only small amounts of melanin in their skin, the epidermis is nearly transparent and allows hemoglobin’s color to show through.
What are freckles and pigmented nevi?
Local accumulations of melanin.
What is cyanosis and what does it indicate?
Blueness of the skin due to poorly oxygenated hemoglobin, which can be a sign of respiratory or cardiovascular problems.
Name three alterations in skin color and their possible causes.
Pallor (emotional stress, low blood pressure, anemia), erythema (blushing, fever, inflammation, allergy), jaundice (liver disorder)
What are bruises and how do their color, size, and shape help in forensic medicine?
Bruises are areas of skin discoloration caused by blood leaking from damaged blood vessels. The color, size, and shape of bruises can help determine the timing and severity of an injury in forensic medicine.
What are the skin appendages and their functions?
Hair and hair follicles (sense insects, guard against physical trauma, heat loss, and sunlight), nails (protect fingertips and toes), sweat glands (regulate body temperature), sebaceous glands (secrete oil to lubricate and waterproof skin).
What is the structure of a hair and what is it made of?
Hairs are flexible strands produced by hair follicles and consist largely of dead, keratinized cells. They are made of hard keratin which is tougher and more durable than the soft keratin found in typical epidermal cells.
What is the main function of hair in humans?
To sense insects on the skin before they bite or sting us. Hair on the scalp guards the head against physical trauma, heat loss, and sunlight. Eyelashes shield the eyes, and nose hairs filter large particles like lint and insects from the air we inhale.
What are the three concentric layers of a hair?
The medulla, cortex, and cuticle.
What is the medulla of a hair?
The central core of a hair consisting of large cells and air spaces. It is the only part of the hair that contains soft keratin and is absent in fine hairs.
What are the chief regions of a hair?
The root, which is embedded in the skin, and the shaft, which projects above the skin’s surface.
What determines the shape of a hair?
The shape of the hair shaft. If it is flat and ribbonlike, the hair is kinky. If it is oval, the hair is silky and wavy. If it is perfectly round, the hair is straight and tends to be coarse.
What is the arrector pili?
A small band of smooth muscle attached to the follicle that causes the hair to stand upright when contracted, producing goosebumps.
What is the sebaceous gland?
A gland that secretes an oily substance called sebum, which lubricates the hair and skin.
What is the hair bulb?
The expanded base of the hair follicle that contains the hair matrix, which produces new hair cells.
What is the hair matrix?
The actively dividing area of the hair bulb that produces new hair cells.
What is the glassy membrane?
A thickened, clear layer of the follicle wall that surrounds the hair bulb.
What is the melanocyte?
A cell in the hair bulb that produces pigment, giving hair its color.
What is the follicle wall?
The connective tissue sheath that surrounds the hair follicle.
What is the peripheral connective tissue sheath?
The fibrous sheath that surrounds the follicle wall.
What is the external root sheath?
The downward continuation of the epidermis that surrounds the follicle.
What is the internal root sheath?
The layer of epithelial tissue that surrounds the hair root and the lower part of the shaft.
What is the subcutaneous adipose tissue?
The layer of fat cells beneath the skin that provides insulation and padding.
What are the muscle cells called that raise hair on the skin?
Arrector pili.
What is the function of arrector pili muscle cells?
To raise hair on the skin.
What is the location of arrector pili muscle cells?
In the skin.
What is the other name for arrector pili muscle cells?
Raiser of hair.
What is the pronunciation of arrector pili?
ah-rek-tor pi-lye.
What is the arrector pili?
A tiny muscle attached to the base of a hair follicle in mammals.
What is the function of the arrector pili?
To contract and make the hair stand up, causing ‘goosebumps’ on the skin.
At what angle does the arrector pili approach the skin surface?
At a slight angle.
What are goose bumps?
Small bumps that appear on the skin in response to cold temperatures or fear.
What causes goose bumps?
The contraction of small muscles at the base of each hair on the skin, which causes the hair to stand up and create a bump.
What is the purpose of goose bumps?
In animals, it can be a response to fear or aggression, making the animal appear larger and more intimidating. In humans, it is a vestigial response that has lost its original purpose.
What is the scientific term for goose bumps?
Piloerection.
What other factors can cause goose bumps?
Strong emotions, such as nostalgia or awe, can also cause goose bumps.
What is the evolutionary purpose of goose bumps?
In animals, it can be a response to fear or aggression, making the animal appear larger and more intimidating. In humans, it is a vestigial response that has lost its original purpose.
What is the advantage of retaining heat for animals?
It helps them stay warm in cold environments.
How do animals protect themselves from cold environments?
By retaining heat.
What kind of animals stay warmer due to their fur?
Furry animals.
What is the function of fur in furry animals?
To help them stay warm.
What is the benefit of staying warm for animals?
It helps them survive in cold environments.
What is the name of the phenomenon where an animal’s hair stands on end?
Piloerection.
What is the purpose of piloerection in animals?
To make the animal look larger and more formidable.
Which part of the body is affected by piloerection in animals?
Hair or fur.
Which animals exhibit piloerection?
Many mammals, including cats, dogs, and humans.
What is another name for piloerection in humans?
Goosebumps or goose flesh.
What is sebum?
Sebum is an oily substance secreted by the sebaceous glands in the skin.
What is the function of sebum?
The function of sebum is to moisturize and protect the skin and hair.
Where is sebum produced?
Sebum is produced by the sebaceous glands in the skin.
What is the role of sebum in the skin?
Sebum helps to lubricate the skin surface.
How does sebum act as a skin lubricant?
Sebum is secreted onto the skin surface where it acts as a lubricant.
What is terminal hair?
Terminal hair is a type of hair that is thick, long, and pigmented. It is the hair that grows on the scalp, lashes, and eyebrows.
What is vellus hair?
Vellus hair is a type of hair that is short, fine, and unpigmented. It is the hair that covers most of the body.
What is the difference between terminal hair and vellus hair?
Terminal hair is thicker, longer, and pigmented, while vellus hair is shorter, finer, and unpigmented.
Where is terminal hair found?
Terminal hair is found on the scalp, lashes, and eyebrows.
What is the color of terminal hair?
Terminal hair may be darker in color.
What is the difference between scalp hair and body hair?
Scalp hair is terminal hair, while body hair is mostly vellus hair.
What is the texture of terminal hair?
Terminal hair is thick in texture.
What are terminal hairs?
Thick, long, and pigmented hairs that grow in certain areas of the body.
When do terminal hairs appear in the body?
At puberty.
Where do terminal hairs appear at puberty?
In the axillary and pubic regions.
What is the difference between terminal and vellus hairs?
Terminal hairs are thicker, longer, and more pigmented than vellus hairs, which are shorter, finer, and less pigmented.
What is the role of androgens in the growth of terminal hairs?
Androgens stimulate the growth of terminal hairs in certain areas of the body, such as the axillary and pubic regions.
What are the other areas of the body where terminal hairs may grow?
Terminal hairs may also grow on the face, chest, and legs in males, and on the face and lower abdomen in females.
What is the function of terminal hairs in the axillary and pubic regions?
Terminal hairs in these regions may help to reduce friction and chafing, and may also play a role in pheromone signaling.
What are androgens?
Male sex hormones.
What are the effects of androgens?
Stimulating effects.
Which gender has higher levels of androgens?
Males.
What is the role of androgens in male development?
They play a crucial role in male development.
What is the primary androgen in males?
Testosterone.
What are the secondary sexual characteristics that androgens help develop in males?
Facial hair, deep voice, and muscle mass.
What is the medical condition caused by low levels of androgens in males?
Hypogonadism.
What is the medical condition caused by high levels of androgens in females?
Polycystic ovary syndrome (PCOS).
What is the cortex?
A bulky layer surrounding the medulla.
What is the location of the cortex?
Around the medulla.
What is the function of the cortex?
The cortex is responsible for processing and integrating sensory information, as well as for initiating voluntary motor movements.
What is the relationship between the cortex and the medulla?
The cortex surrounds the medulla.
What is the outermost cuticle made of?
A single layer of cells.
What is the purpose of hair conditioners?
To smooth out the rough surface of hair.
What is the benefit of using hair conditioners?
It makes hair easier to comb and manage.
What is the main ingredient in most hair conditioners?
Emollients, such as silicone or oils.
What is the difference between a regular conditioner and a leave-in conditioner?
A regular conditioner is rinsed out after a few minutes, while a leave-in conditioner is not rinsed out and is left on the hair.
How often should you use hair conditioner?
It depends on your hair type and condition, but generally 2-3 times a week is recommended.