Integumentary System Flashcards
Integumentary System
► Consists of:
- Skin
- Hair
- Nails
- Sweat Glands
- Sebaceous (oil) Glands
Superficial layer
-Consists of stratified squamous epithelial tissue and is avascular
Epidermis
Underlies epidermis
-Mostly fibrous connective tissue, vascular
Dermis
(Subcutaneous tissue)
-Subcutaneous layer deep to skin
-Not part of skin but shares some functions
-Mostly adipose tissue that absorbs shock and insulates
-anchors skin to underlying structures: mostly muscles
Hypodermis
_______ - consists mostly of keratinized stratified squamous epithelium
Epidermis
Produce fibrous keratin (protein that gives skin its protective properties) Major cells of epidermis, Tightly connected by desmosomes Millions slough off every day
Keratinocytes
▸ Four cell types found in epidermis:
▸ Keratinocytes
▸ Melanocytes
▸ Dendritic (langerhans) cells
▸ Tactile (Merkel) cells
▸ Five Layers of Epidermis Skin
(Only in thick skin)
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum lucidum
- Stratum Corneum
Spider-shaped cells located in deepest epidermis Produce pigment melanin, which is packaged into melanosomes
Melanosomes are transferred to keratinocytes, where they protect nucleus from UV damage
Melanocytes
Star-shaped macrophages that patrol deep epidermis
Are key activators of immune system
Dendritic (langerhans) cells
Sensory receptors that sense touch?
Tactile (Merkel) cells
Deepest of all epidermal layers (base layer)
• Layer that is firmly attached to dermis
• Consists of a single row of stem cells that actively divide (mitotic), producing two daughter cells each time
One daughter cell journeys from basal layer to surface, taking 25-45 days to reach surface
Other daughter cell remains in stratum basale as stem cell
Layer also known as STRATUM GERMINATIVUM bec. of active mitosis
10 25% of layer also composed of melanocytes
Stratum Basale (basal layer)
• Several Cell layers thick
• Cells contain weblike system of intermediate prekeratin filaments attached to desmosomes
• Allows them to resist tension and pulling
• Keratinocytes in this layer appear spikey, so they are called prickle cells
• Scattered among keratinocytes are abundant melanosomes and dendritic cells
Stratum Spinosum (prickly layer)
• Four to six cells thick, but cells are flattened, so layer is thin
• Cell appearance changes; transitional stratum
Cells flatten, nuclei and organelles disintegrate
• Keratinization begins
Cells accumulate keratohyalin granules that help form keratin fibers in upper layers
Cells also accumulate lamellar granules, a water- resistant glycolipid that slows water loss Cells above this layer die
Too far from dermal capillaries to survive
Stratum Granulosum (granular layer)
• Found only in thick skin
• Consists of thin, translucent band of two to three rows of clear, flat, dead keratinocytes
• Lies superficial to the stratum granulosum
Stratum lucidum (clear layer)
• 20-30 rows of flat, anucleated, keratinized dead cells
• Accounts for three-quarters of epidermal thickness
• Though dead, cells still function to:
• Protect deeper cells from the environment
• Prevent water loss
• Protect from abrasion and penetration Act as a barrier against biological, chemical, and physical assaults
Stratum Corneum (horny layer)
Strong, flexible connective tissue
▸ Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells
▸ Fibers in matrix bind body together
• Makes up the “hide” that is used to make leather
► Contains nerves, blood vessels, and lymphatic vessels
► Contains epidermal hair follicles, oil glands, and sweat glands
► Two layers
• Papillary
• Reticular
Dermis
► Superficial layer of areolar connective tissue consisting of loose, interlacing collagen and elastic fibers and blood vessels
► Loose fibers allow phagocytes to patrol for microorganisms
Papillary Layer
_________ : Superficial region of dermis that sends finger like projections up into epidermis
• Projections contains capillary loops, free nerve endings, and touch receptors (tactile corpuscles, also called Meissner’s corpuscles)
Dermal Papillae
________ are small projections that provide blood supply to the epidermis.
Dermal papillae
Papillary Layer
► In thick skin, dermal papillae lie on top of dermal ridges, which give rise to epidermal ridges
Collectively ridges are called _________.
•Enhance gripping ability
•Contribute to sense of touch
•Sweat pores in ridges leave unique fingerprint pattern
friction ridges
_________ in reticular layer are caused by many collagen fibers running parallel to skin surface
• Externally invisible
• Important to surgeons because incisions parallel to cleavage lines heal more readily
Cleavage (tension) lines
Reticular Layer (cont.)
► _______ of reticular layers are dermal folds at or near joints
• Dermis is tightly secured to deeper structures
• Skin’s inability to slide easily for joint movement causes deep creases
• Visible on hands, wrists, fingers, soles, toes
Flexure lines
Clinical - Homeostatic Imbalance
▸ Extreme stretching of skin can cause dermal tears, leaving silvery white scars called ______.
• Also known as “stretch marks”
Striae
▸ Acute, short-term traumas to skin can cause ______, fluid-filled pockets that separate epidermal and dermal layers
blisters
Give the 3 pigments contributes the skin color
- Melanin
- Carotene
- Hemoglobin
• Only pigment made in skin; made by melanocytes Packaged into melanosomes that are sent to keratinocytes to shield DNA from sunlight
Sun exposure stimulates melanin production
• Two forms; reddish yellow to brownish black
• All humans have same number of keratinocytes, so color differences are due to amount and form of melanin
Freckles and pigmented moles are local accumulations of melanin
MELANIN
• Yellow to orange pigment
Most obvious in palms and soles
• Accumulates in stratum corneum and hypodermis
• Can be converted to vitamin A for vision and epidermal health
Carotene
Pinkish hue of fair skin is due to lower levels of melanin
• Skin of Caucasians is more transparent, so color of hemoglobin shows through
Hemoglobin
Just Notes - no need to answer
▸ Excessive sun exposure damages skin
• Elastic fibers clump, causing skin to become leathery
• Can depress immune system and cause alterations in DNA that may lead to skin cancer
• UV light destroys folic acid
Necessary for DNA synthesis, so insufficient folic acid is especially dangerous for developing embryos
• Photosensitivity is increased reaction to sun Some drugs (e.g., antibiotics, antihistamines) and perfumes cause photosensitivity, leading to skin rashes
Clinical - Homeostatic Imbalance
Just Notes - no need to answer
▸ Excessive sun exposure damages skin
• Elastic fibers clump, causing skin to become leathery
• Can depress immune system and cause alterations in DNA that may lead to skin cancer
• UV light destroys folic acid
Necessary for DNA synthesis, so insufficient folic acid is especially dangerous for developing embryos
• Photosensitivity is increased reaction to sun Some drugs (e.g., antibiotics, antihistamines) and perfumes cause photosensitivity, leading to skin rashes
Clinical - Homeostatic Imbalance
Alterations in skin color can indicate disease
Blue skin color: low oxygenation of hemoglobin
Cyanosis
Alterations in skin color can indicate disease
• (redness) Fever, hypertension, inflammation, allergy
Erythema
• (blanching or pale color) Anemia, low blood pressure, fear, anger
Pallor
• (yellow cast) Liver disorders
Jaundice
Alterations in skin color can indicate disease (cont.)
• Inadequate steroid hormones (example:Addison’s disease)
Bronzing
• (black-and-blue marks) Clotted blood beneath skinAlterations in skin color can indicate disease (cont.)
Bruises
▸ Consists of dead keratinized cells
► None located on palms, soles, lips, nipples, and portions of external genitalia
Hair