Unit 1: Integumentary Flashcards
What is the largest organ in the body?
The skin
The skin is also the heaviest organ of the body.
How many centimeters of blood vessels are in one square centimeter of skin?
70 cm
What type of epithelium is the epidermis composed of?
*Stratified squamous epithelium
*Contains 5 layers
What layer of the skin is the dermis?
Connective tissue layer
Skin rests on what?
subcutaneous layer or hypodermis
What are the primary functions of the skin?
- Protection
- Vitamin D synthesis
- Excretion
- Sensation
- Waterproof barrier
- Thermoregulation
- Psychological and social functions
Describe the protective function of the skin.
abrasion, invasion, water loss, UV protection
Describe th benefit of vitamin D synthesis in the skin.
-epidermal keratinocytes when exposed to UV light
–helps maintain health of skeleton by increasing absorption of Ca2+
Describe the excretion function of the skin
Urea and salts (very small amounts)
Describe the sensation function of the skin
receptors for heat, cold, touch, pressure, vibration and pain
Describe the waterproof barrier function of the skin
Sebaceous glands, overlapping of keratinocytes
Describe the thermoregulation function of the skin
-thermoreceptors and sweat glands
-hypothalamus controls cutaneous arteries and sweat glands to retain or dissipate heat
Describe the psychological and social functions of the skin
-appearance and social acceptance
-facial expression and nonverbal communication
What is the role of vitamin D in relation to the skin?
Helps maintain health of skeleton by increasing absorption of Ca2+
Describe the stratified squamous epitheliam.
*These squamous epithelial cells are called keratinocytes, cells filled with keratin (a hard tough protein.)
*Avascular – no blood vessels
What do keratinocytes produce?
Keratin
Describe the Stratum Basale.
*Deepest layer (of epithelium)
*Single layer of cuboidal cells sitting on basement membrane
Name the 5 layers of the epithelium from base to apical layer.
Startum Basale
Startum Spinosum
Stratum Granulosum
Stratum Lucidum
Startum Corneum
What are the main cell types found in the stratum basale?
- Keratinocytes
- Melanocytes
- Tactile cells
Describe the Keratinocytes of the stratum basale.
*undergo mitosis to replace epidermis
*commonest cell of epidermis
*produce keratin (protein)
Describe the Melanocytes of the Stratum basale.
distribute melanin from cell processes
melanin picked up by keratinocytes andused to shade nuclei from UVradiation
Describe the tactile cells of the stratum basale.
What is the function of melanocytes?
Synthesize melanin
What is the stratum spinosum known for?
Several layers thick with desmosomes connecting cells
What are the cell types of the Stratum Spinosum?
*keratinocytes
*Dendric Cells
Describe Keratinocytes of the Stratum Spinosum.
*desmosomes connect cells together
*appear “spiny” due to shrinkageduring histological preparation
Describe the dendric cells of the Stratum Spinosum.
*macrophages that migrate to the epidermis
*help protect body against pathogens
What happens to the nucleus in the stratum granulosum?
Begins to break down
Describe Stratum Granulosum.
*3 to 5 layers
*Cell type
-Flattened keratinocytes
–Contain keratinohyalin granules
—become fibrous keratin
–Produce lipid-filled vesicles thatrelease a glycolipid by exocytosisto waterproof the skin
—forms a barrier between surface cellsand deeper layers of the epidermis
—cuts off surface layers from nutrient supply
–Nucleus begins to break down
What is found in the stratum lucidum?
Thin translucent zone seen only in thick skin
What characterizes the stratum corneum?
Up to 30 layers of dead, scaly, keratinized cells
Describe the Stratum Lucidum.
*Thin translucent zone seen onlyin thick skin (palmar and plantar regions)
*Cells have no nuclei ororganelles
How often is the epidermis replaced?
Every 45 days
What is the thickness range of the dermis?
0.6 mm to 3 mm
Vocab: Stratum Basale
Cells divide by mitosis and some of the newly formed cells become the cells of the more superficial strata.
Vocab: Stratum Spinosum
Keratin fibers and lamellar bodies accumulate.
Vocab: Stratum Granulosum
Keratohyalin and a hard protein envelope form; lamellar bodies release lipids; cells die.
Vocab: Stratum Lucidum
Dead cells containing dispersed keratohyalin.
Vocab: Stratum Corneum
Dead cells with a hard protein envelope; the cells contain keratin and are surrounded by lipids.
What are dermal papillae?
Upward extensions of the dermis into the epidermis forming ridges of the fingerprints
Describe the composition of the Dermis.
Composition:
Collagen and elastic fibers, fibroblasts and accessory structures such as hair follicles and glands
Describe the dermis.
*Dense, fibrous connective tissue deep to the epidermis.
(Leather: dermis from animals.)
*Firmly attached to the epidermis.
*Gives flexible strength to skin.
What layer gives flexible strength to the skin?
Dermis
What are the two layers of the dermis?
- Papillary layer
- Reticular layer
What is the hypodermis also known as?
Subcutaneous tissue or superficial fascia
The hypodermis has more ________ than dermis.
adipose
Describe the reticular layer of the dermis.
Reticular layer: Deep layer of dermis.
*Contains sweat glands, oil glands, and pressure receptors.
*Contains blood vessels for regulation of body temperature.
*Rich in collagen and elastic fibers.
Describe the papillary layer of the dermis.
Papillary layer: upper layer
*Contains fingerlike projections called papillae.
*Papillae contain blood vessels for nourishing the epidermis.
*Papillae contains touch and pain receptors.
What are the functions of the hypodermis?
- Energy reservoir
- Thermal insulation
What pigments contribute to skin color?
- Hemoglobin (red pigment of red blood cells)
- Carotene (yellow pigment of vegetables & egg yolks)
- Melanin
(pigment produced by melanocytes)
–pigment synthesis stimulated by UV radiation from sunlight
–produces yellow, brown, black and reddish hues
What is the primary component of hair?
Keratinized cells
Describe follicle (hair)
Follicle is oblique tube/sack within the skin
Hair and nails are composed of hard ___________
keratin
-toughened by bonds between proteins
Bulb (hair)
bulb is swelling in base where hair originates (mitosis)
Appendages of the skin
-Glands
-Hair
-Nails
___________ in bulb provides nutrients
vascular tissue (dermal papilla) in bulb provides nutrients
Skin derivatives all arise
From the __________
epidermis
How is pulling on the hair resisted?
cells lining the follicle interlock with scales of cuticle to resist pulling on the hair
Hair is a …
Hair is a filament of keratinized cells
-shaft is fully keratinized and is visible above skin
-root is within follicle and not yet fully keratinized
What is the structure of hair?
- Shaft - fully keratinized visible above skin
- Root - within follicle not yet fully keratinized
What are the functions of hair?
- Sensation
- Communication
- Protection
- Thermoregulation
Medulla (hair)
Medulla – central core, large cells and air spaces
What are the 3 parts of a cross section of hair?
Medulla – central core, large cells and air spaces
Cortex – layer of flat cells that surrounds the medulla
Cuticle – single outer layer of heavily keratinized cells arranged overlapping like tiles on a roof
Cortex (hair)
Cortex – layer of flat cells that surrounds the medulla
Cuticle (hair)
Cuticle – single outer layer of heavily keratinized cells arranged overlapping like tiles on a roof
What type of glands are sebaceous glands?
Alveolar glands
Describe sweat glands
Filtrate of blood plasma containing some waste products
-lactic acid forms “acid mantle”
*Eccrine glands
millions of them
cool the body
*Apocrine glands produce sweat containing fatty acids
-found only near hair follicles and respond to stress and sexual arousal
-fatty acids support bacteria → body odor
Name the 4 types of cutaneous glands.
*Sweat glands
–eccrine
–apocrine
*Sebaceous glands
*Ceruminous glands
*Mammary glands
What are the associated structures of hair?
*Hair receptors entwine each follicle
*Arrector pili muscles
smooth muscles that cause goose bumps
*Sebaceous glands are located alongside the hair root
Arrector pili muscles
an associated structure of hair; smooth muscle that causes goose bumps
What is the secretion produced by sebaceous glands?
Sebum
What do eccrine sweat glands primarily do?
Cool the body
What is the difference between eccrine and apocrine sweat glands?
Eccrine glands cool the body; apocrine glands respond to stress and sexual arousal
Describe sebaceous glands.
*Alveolar glands
*Oily secretion called sebum that contains broken-down cells
-Makes hair and skin pliable
-antibacterial properties
-Arrector pili muscles help squeeze sebum up to skin surface
-Assists with waterproof barrier of skin
What do ceruminous glands produce?
Earwax
List two other types of apocrine glands.
*Ceruminous Glands
-Their secretion combines with sebum to produce earwax
-waterproof
-keeps eardrum flexible
bitterness repel mites & other pests
*Mammary Glands
-modified sweat gland
-thicker secretions released by ducts that open at the nipple
What are common types of skin infections?
- Bacterial infections
- Viral infections
- Fungal infections
What is a first-degree burn?
Involves epidermis only; red and swollen
What is unique about third-degree burns?
Entire thickness is destroyed; skin grafting is required
What does the term ‘kerat’ refer to?
Horny/Hard
Describe 2nd degree burns.
Second-degree
– involves epidermis and upper layer of dermis; skin is red and painful with blisters
__________ and __________ are serious problems associated with third-degree burns.
Arthritis and stiffness are serious problems associated with third-degree burns.
What is the term for the layer beneath the epidermis?
Hypodermis
Nails are clear, hard derivative of
*stratum corneum
-(nails) densely packed cells filled with hard keratin
Cut or derm
Epi
Upon or on top of
Sub
Below
Strat
Layer
-Strata (many layers)
Folic
Sack
Thermo
Temperature
Melan
to darken or blacken
