Integumentary System Flashcards
What are the two principal parts of the skin?
Epidermis
Dermis
Consisting of areolar and adipose tissue is not part of the skin
Hypodermis AKA subcutaneous layer
What are the specific functions of the skin?
Thermoregulation Protection from external environment Cutaneous sensation Excretion Synthesis of vitamin D Reservoir for blood Absorbs substances
What type of tissue is the epidermis and what cells is it made up of?
- Keratinocytes: 90% of the cells; form 4 or 5 layers
- Melanocytes: Pigment-producing cells
- Langerhans Cells: immune cells
- Merkel Cells: For sensation
How are keratinocytes formed?
New cells produced by mitosis become filled w/ keratin, a tough, fibrous protein that waterproofs the skin and underlying tissues from heat, microbes, and chemicals
Produces the pigment melanin
Organelle: melanosome
Melanocytes
The melanosomes synthesize what?
Melanin from tyrosine in the presence of tyrosinase
How does melanocytes transfer melanin granules?
Melanocytes extend between keratinocytes, and transfer melanin granules to them.
Melanin granules then cluster over the nucleus on the side forward the skin surface, shielding nuclear DNA from UV light
Participate in the immune response to microbes that invade the skin
Langerhans cells
How do langerhans cells move through the body?
Originate in the bone marrow
Migrate to the epidermis
When they encounter an antigen they migrate to lymphoid tissue to help initiate the immune response
Where do Merkel cells reside?
The deepest layer of the epidermis where they contact the flattened processes of tactile discs
Sensory Neuron (nerve cell)
Merkel cells
- together the tactile discs function in the sensation of touch
What are the least numerous epidermal cells?
Merkel Cells
Layers of the epidermis (outer to inner)
Stratum corneum Stratum lucidum (only present fingertips, palms, and soles) Stratum granulosum Stratum spinosum Stratum basale
Come Let’s Get Some Beer
Continuously undergo mitosis, thereby forming new skin cells
Keratinocytes
Characteristics of stratum basale
- Deepest layer of epidermis
- Mostly keratinocytes, few melanocytes and Merkel cells
Keratinocytes have what?
Intermediate filaments (tonofilaments) composed of a protein that will later form keratin
Characteristics of stratum spinosum
- 8-10 layers of keratinocytes and few langerhans cells
- Cells are still alive; some divide
- Older cells start to flatten
Characteristics of stratum granulosum
Is the transition between the deeper living cells and the more superficial dead cells
- 3-5 layer of flattened keratinocytes
- Older cells undergo apoptosis (programmed cell death) and die
- Nuclei and organelles degenerate
- Lamellar granules release a waterproofing lipid solution
What is the distinctive feature of stratum granulosum?
Granules of darkly staining keratohyalin granules (a protein that converts tonofilaments into keratin)
Characteristics of stratum lucidum
- Only found on fingertips, palms, and soles
- 3 layers of flattened, dead keratinocytes filled with keratin (tonofilaments and keratohyalin)
Characteristics of stratum corneum
- Most superficial layer
- 25-30 layers of flattened, dead cells
- Interior of cells contains mostly keratin
- Between cells, lipids from lamellar granules provide waterproofing
- Cells are continuously sloughed off and replaced by cells from deeper strata
The dermis is divided into two components based on structure
Papillary region
- more superficial
Reticular region
- the deeper of the two
The dermis is made of what tissue and contains what?
Dense irregular connective tissue; collagen and elastic connective tissue
- Blood vessels
- Nerves
- Glands: sebaceous and sudoriferous (sweat)
- Hair follicles
- Arrectores pilorum muscles (singular is arrector pili)
What receptors are present in the papillary region?
Touch corpuscles (Meissen corpuscles) for touch/ light touch
Free nerve endings with no apparent structural specialization of warmth, coolness, pain, tickle, and itch
Superficial part of the dermis (placing it just deep to the stratum basale)
Papillary region
What greatly increases surface area and what is it good for?
Dermal papillae
- Better adhesion to epidermis
- More surface area for diffusion to and from epidermis
Characteristic of reticular region
Consist of dense, irregular connective tissue containing bundles of collagen and some elastic fibers
Spaces between fibers are occupied by adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands
What provides skin with strength, extensibility, and elasticity?
Collagen and elastic fibers in the reticular region
What is the alternate name, what does it contain and what tissue is the subcutaneous layer made up of?
AKA hypodermis
Areolar and adipose tissues
- Fat
- Fibers that attach the dermis to deeper tissues
- Larger blood vessels
- Sensory receptors pressure sense
Characteristic of epidermal ridges
Ducts of sweat glands open on the tops of the ridges as sweat pores forming a pattern on smooth objects that are touched
What are the three pigments that combine to make the color of the skin?
Melanin (genetically determined)
Carotene (genetically determined)
Hemoglobin (can change)
Exposure to UV light _________ the enzymatic activity of __________, leading to __________ melanin production, which gives the skin a tanned appearance and further protects the body against _________
Increases
Melanosomes
Increase
UV radiation
What is the carotene contribution to skin color and where is it found?
- Yellow- orange pigment that is a precursor to vitamin A, used to synthesize pigments needed for vision
- Found in the stratum corneum and fatty areas of the dermis and subcutaneous layer
What happens when little melanin or carotene are present?
The spider is appears translucent thereby allowing hemoglobin in capillaries of dermis to be expressed; generally pink skin
In the dermis; secrete sebum (oil) into hair follicle
Sebaceous glands
- absent in the palms and soles
In the dermis; duct extends through the epidermis
Sudoriferous glands
Two main types of sudoriferous glands
Eccrine sweat glands (AKA merocrine sweat glands)
Apocrine sweat glands
Eccrine sweat glands (AKA merocrine sweat glands)
- more common, found most places on skin, thermoregulation
- smaller than apocrine
- do not extend deeply
- excrete directly onto the surface of skin
Apocrine sweat glands
- found in association with hair that develops at puberty
- larger secretory portion; larger overall
- found deeper in dermis
- secrete into Pilar’s canal of hair follicle
What happens in psoriasis?
- Keratinocytes divide and move more quickly than normal from stratum basale to stratum corneum, and are shed prematurely
- Immature keratinocytes make abnormal keratin which forms flaky, silvery scales at skin surface (dandruff)
What are the three common forms of skin cancer?
Basal cell carcinomas (most common)
Squamous cell carcinomas
Malignant melanomas (least common, most life-threatening)
What is the least type of skin cancer but most common for children?
Melanoma
What is happening in albinism?
Melanocytes are unable to synthesize tryroinase
What is vitiligo?
Partial or complete loss of melanocytes from patches of skin
Produces irregular white spots
May be an autoimmune disorder
What is cyanosis?
Hemoglobin that is depleted of oxygen
Looks deep, purpleish blue
What is jaundice?
Yellowish appearance to the white of the eyes and skin
Caused by build up of yellow pigment bilirubin in blood
Indicates liver disease
What is erythema?
Redness of the skin
Caused by enforcement of capillaries in dermis with blood due to
- skin injury
- exposure to heat
- infection
- inflammation
- allergic reaction
What is striae?
Scarring of the skin by tearing of dermis (stretch marks; striae gravidarum)
What is alopecia?
Partial or complete lack of hair
May result from again, endocrine disorder, chemotherapy for cancer, or skin disease
What is contact dermatitis?
Inflammation of the skin characterized by redness, itching, and swelling
Caused by exposure of skin to chemicals that bring about an allergic reaction
What happens during epidermal would healing?
- Basal cells at margins of the wound break contact with basement membrane and migrate
- Basal cells contact each other, they stop migrating (contact inhibition)
- Mitosis of basal cells is stimulated
- Keratinocytes move up to form the more superficial layers
What are the stages of deep wound healing?
Inflammatory phase
Migratory phase
Proliferation phase
Maturation phase
What happens in the inflammatory phase?
- Blood clot forms and binds wound edges
- Blood flow increased, blood vessels become more permeable
- WBCs and mesenchymal cells migrate to the area
What happens during the migratory phase?
- Epithelial cells migrate beneath the scab and bridge the wound
- Fibroblasts migrate into the wound and begin to produce collagen fibers
(Fibroblasts derived from mesenchymal cells)
What happens during proliferation phase?
- Growth of epidermal cells beneath scab
- Increase in the amount of collagen
- Regeneration of blood vessels
What happens during the maturation phase?
- Scab is lost
- Collagen fibers become more organized
- Fibroblast numbers decrease
- Blood vessels are restored to normal
If there are any voids in the dermis what are they filled with?
Scar tissue (fibrosis)
- collagen is more dense than in normal dermis
- fewer blood vessels and accessory structures
What are the classifications for first degree burns?
- Involves only the epidermis
- Mild pain and erythema, no blisters
- Skin functions remain intact
- Pain can be reduced by cold water flush
- Heals in 3-6 days, may have have flaking or peeling
- Mild sunburn
What are the classifications for second degree burns?
- Destroys a portion of the epidermis and possibly parts of dermis
- Pain, redness, blister formation, and edema
- Some skin functions are lost
- 3-4 weeks healed if no infection
- Scarring may result
What are the classifications for third degree burns?
- Destroys portion of the epidermis as well as underlying dermis and associated structures
- Skin functions are lost
- Vary in appearance from marble-white to mahogany to charred, dry wounds
- Area is numb due to destruction of sensory nerve endings
- regeneration is slow, grading may be required
What is termed full-thickness burn?
Third degree burns
What is considered partial-thickness burns?
First and second degree burns
Total head and neck
9%
total each upper limb
9 for each, 4.5 for anterior/ posterior
Front and back of torso
18% for each
Lower limbs
18% for each limb, 9% for anterior/ posterior
Perineum
1%
