Chapter 6: Integumentary System Flashcards
What are the cells of the epidermis?
- stem cells–produce keratinocytes (involved in mitosis)
- keratinocytes–produce the fibrous protein kertain (melanin is thrown in here)
- Melanocytes–produce the pigment melanin
- Dendritic cells–(Langerhan’s cells) macrophages that are part of the immune system
- Tacticle cells–(Merkel cells) touch receptors
How is thick skin different from thin skin?
- Thick skin is found only on palms of hands and soles of feet
- thick epidermis with ridges (make fingerprints!) and thick stratum corneum
- Has Stratum lucidum
- No hair follicles or sebaceous glands
- has more sweat glands and sensory receptors
What are the functions of the integumentary system?
- regulation of body temperature
- sweating, vasodilation and constriction of blood cells
- protection
- against bacteria, UV, light, abrasion, dehydration, chemicals
- sensory receptors
- excretion and absorption
- synthesis of Vitamin D
What are the layers /sublayers of the integumentary system and their components?
Cutaneous membrane (skin)
- epidermis
- 5 layers
- dermis
- Papillary
- areolar tissue
- tactile (Meissner corpuscles)
- Reticular
- dense irregular connective tissue
- oil glands, sweat glands, fat, and hair follicles, Lamellar (Pacinian) corpuscles
- Papillary
Subcutaneous membrane
- hypodermis or superficial fascia
- adipose and areolar
- thicker in women, thinner in children and elderly
- on top of muscle
What is the structure of the 5 layers of the epidermis?
Stratum Basale
- combination of tactile cells, melanocytes, keratinocytes, and stem cells
- cells journey from here to the surface
Stratum Spinosum
- 8 to 10 cell layers held together by tight junctions and desmosomes
Stratum Granulosum
- 3-5 layers of flat, dying cells
- contain dark keratohyalin granules
Stratum Lucidum
- 3-5 layers of clear, flat, dead cells
Stratum Corneum
- 20 to 30 layers of flat dead cells filled with Keratin and surrounded by lipids
- continually shed
- resist abrasion, water loss, penetration of bacteria and chemicals
Where are friction ridges formed?
Where dermal papillae are more pronounced in thick skin (palms, soles, finger prints, and footprints)
What are the 3 skin color pigments?
- Melanin
- same number of melanocytes in everyone (some are stronger)
- yellow to tan to black
- Carotene
- yellow-orange pigment
- fat and stratum corneum
- Hemoglobin
- red, oxygen-carrying pigment in blood cells
What are conditions in which skin color may act as a diagnostic clue?
- Cyanosis: blue, lack of oxygen
- Hematoma: bruise
- Alibinism: no melanin
- Pallor: white, shock
- Erythema: red, infection, fever
- Jaundice: yellow, liver problems
CHAPEJ
What are the accessory structures of the integumentary system?
- Hair
- nails
- Sudoriferous glands
- Sebaceous glands
What is the structure of hair?
- Bulb
- contains matrix (which makes hair)
- Root (below skin)
- Shaft (above skin)
- medulla / cortex / cuticle
- center layer/ outer layer / outmost layer
- hair is packed Keratin cells (all dead)
What are the accessory structures and functions of hair?
Structures
- accertor pili (Piloerector)
- smooth muscle contracts in cold or fear, forms goosebumps
- Hair root plexus (nerves, detect hair movement)
Function
- protection
- heat retention
- light touch
- excretion
What is the structure of a nail?
- scalelike modification of epidermis
- nail matrix produces tightly packed keratinized cells
What are the 4 glands and their components?
- Merocrine (Eccrine) glands
- ducts open to surface
- most areas of skin
- sweat glands
- Apocrine
- misnamed (function through exocytosis like eccrine)
- duct opens into hair follicle
- secretes pheromones
- respond to stress and sexual stimulation
- pubic area, armpit, develop after puberty, form BO
- Mammary Glands
- milk
- Ceruminous glands
- ear wax
What are the 3 major types of skin cancer and their components?
- Basal cell carcinoma
- most common
- least malignant
- small, shiny bump with central depression and beaded edges
- form in stratum basale
- Squamos cell carcinoma
- may metastasize if not removed
- early detection and surgical removal
- spread to lymph nodes = lethal
- arises from keratinocytes on stratum spinosum
- raised, reddened, scaly appearance (turn into concave ulcer)
- may metastasize if not removed
- Melanoma
- arises from melanocytes
- least common (>5%) but very malignant
- can be removed if caught early
- higher in men, redheads, bad sunburns as child, genetic risk greatest
What are the warning signs of Melanoma?
Asymmetry
Border
Color
- normal has one color, abnormal has 2 or more or changes color
Diameter
- normal is size of pencil eraser
Elevation / evolution
- normal is flat and doesn’t change
What are burns and their types?
- Burns are caused by heat, electricity, and chemicals
- May result in shock due to dehydration and loss of plasma proteins, circulatory and kidney problems from loss of plasma, and bacterial infection
- First degree
- only epidermis (sunburn)
- Second degree
- destroys epidermis and part of dermis
- fluid filled blisters separater dermis and epidermis
- heals with grafting in 3-4 weeks, may scar
- Third degree
- destroy epidermis, dermis, and possibly muscle
- damaged area numb due to loss of sensory nerves
What in the skin provides resistance to trauma and infection?
- Keratin
- Dermacidin and defensins
- Acid mantle
What are some barrier functions of the skin?
- Water
- UV radiation
- Harmful chemicals
What is vitamin D synthesis?
- Skin carries out first step
- Liver and kidneys complete process
What sense does the skin use?
- Skin is an extensive sense organ
- Receptors for temperature, touch, pain, and more
How does the skin use thermoregulation?
- Thermoreceptors
- Vasoconstriction/vasodilation
- Perspiration
How does the skin use nonverbal communication?
- Facial expression
- Importance in social acceptance and self image
What does the integumentary system consist of?
Consists of the skin and accessory organs; hair, nails, and cutaneous glands
What are the layers of the skin?
- Epidermis: stratified squamous epithelium
- Dermis: deeper connective tissue layer
- Hypodermis—connective tissue layer below dermis (not part of skin, but associated with it)
How large is the skin?
- Skin is the body’s largest and heaviest organ
- Covers 1.5 to ; composes 15% of body weight
What’s the range of the skin’s thickness?
- Skin thickness ranges from 0.5 to 6 mm
- Thick skin covers front of hands, bottoms of feet
- Has sweat glands, but no hair follicles or sebaceous (oil) glands
- Epidermis 0.5 mm thick
- Thin skin covers rest of the body
- Possesses hair follicles, sebaceous glands, and sweat glands
- Epidermis about 0.1 mm thick
What’s so special about the epidermis?
- Keratinized stratified squamous epithelium
- Includes dead cells at skin surface packed with tough keratin protein
- Lacks blood vessels
- Depends on the diffusion of nutrients from underlying connective tissue
- Contains sparse nerve endings for touch and pain
What are the five epidermal cell types?
- Stem cell
- Keratinocytes
- Melanocytes
- Tactile cells
- Dendritic cells
What are stem cells?
Undifferentiated cells that give rise to keratinocytes
In deepest layer of epidermis (stratum basale)
What are keratinocytes?
- Great majority of epidermal cells
- Synthesize keratin
What are melanocytes?
- Synthesize pigment melanin that shields DNA from ultraviolet radiation
- Occur only in stratum basale but have branched processes that spread among keratinocytes and distribute melanin
What are the tactile cells?
- Touch receptor cells associated with dermal nerve fibers
- In basal layer of epidermis
What are dendritic cells?
- Macrophages originating in bone marrow that guard against pathogens
- Found in stratum spinosum and granulosum
How many layers of skin do we have, and what are their names?
Thin skin contains four strata; thick skin contains five strata
- Stratum basale (deepest epidermal layer)
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum (surface layer)
What is Stratum basale (deepest epidermal layer)?
- A single layer of stem cells and keratinocytes resting on the basement membrane
- Stem cells divide and give rise to keratinocytes that migrate toward skin surface to replace lost cells
- Also contains a few melanocytes and tactile cells
What is Stratum spinosum?
- Several layers of keratinocytes joined together
- Named for appearance of cells after histological preparation (spiny)
- Also contains some dendritic cells
What is Stratum granulosum?
- Three to five layers of flat keratinocytes
- Cells contain dark-staining keratohyalin granules
What is Stratum lucidum?
- Thin, pale layer found only in thick skin
- Keratinocytes packed with clear protein eleidin
What is Stratum corneum (surface layer)?
- Several layers (up to 30) of dead, scaly, keratinized cells
- Resists abrasion, penetration, water loss
How are keratinocytes produced?
- Keratinocytes are produced by mitosis of stem cells in stratum basale or mitosis of keratinocytes in deepest part of stratum spinosum
- Mitosis requires abundant oxygen and nutrients, so once cells migrate away from blood vessels of the dermis, mitosis cannot occur
How do we re-create new skin?
- New keratinocytes push older ones toward the surface
- Over time, keratinocytes flatten, produce more keratin and membrane-coating vesicles
- In 30 to 40 days a keratinocyte makes its way to the skin surface and flakes off (exfoliates) as dander
- Slower in old age
- Faster in injured or stressed skin
What are calluses or corns?
- Thick accumulations of dead keratinocytes on hands or feet
What is the dermis?
- connective tissue layer beneath epidermis
- Ranges from 0.2 mm (eyelids) to 4 mm (palms, soles)
- Composed mainly of collagen
- Well supplied with blood vessels, sweat glands, sebaceous glands, and nerve endings
What houses hair follicles and nail roots?
The dermis layer
What tissue uses facial expression of emotion and attaches to the skeletal muscle for smiles?
The dermis layer
what does the dermis layer look like?
- Has a wavy, conspicuous boundary with the superficial epidermis
- Dermal papillae are upward, finger-like extensions of dermis
- Epidermal ridges are downward waves of epidermis
- Prominent waves on fingers produce friction ridges of fingerprints
What is the Papillary layer?
- Superficial zone of dermis
- Thin zone of areolar tissue in and near the dermal papilla
- Allows for mobility of leukocytes and other defense cells
- Rich in small blood vessels
What is the Reticular layer?
- deeper and thicker layer of dermis
- Consists of dense, irregular connective tissue
What is the hypodermis?
- Subcutaneous tissue
- Has more areolar and adipose than dermis has
- Pads body and binds skin to underlying tissues
- Common site of drug injection since it has many blood vessels
What is subcutaneous fat?
- Energy reservoir
- Thermal insulation
- Thicker in women
- Thinner in infants, elderly
What is melanin?
- Most significant factor in skin color
- Produced by melanocytes, accumulates in keratinocytes
- Two forms of the pigment:
- Eumelanin—brownish black
- Pheomelanin—reddish yellow (sulfur-containing)
What’s the difference in people’s melanin?
Darker skinned people
- Produce greater quantities of melanin
- Melanin breaks down more slowly
- Melanin granules more spread out in keratinocytes
- Melanized cells seen throughout the epidermis
Lighter skinned people
- Melanin clumped near keratinocyte nucleus
- Little melanin seen beyond stratum basale
Who has more of melanin?
People of different skin colors have the same number of melanocytes
What causes the skin to get darker?
- Exposure to UV light stimulates melanin secretion and darkens skin
- This color fades as melanin is degraded and old cells are exfoliated
What other pigments can influence your skin color?
-
Hemoglobin—pigment in red blood cells
- Adds reddish to pinkish hue to skin
-
Carotene—yellow pigment acquired from egg yolks and yellow/orange vegetables
- Concentrates in stratum corneum and subcutaneous fat
What is cyanosis?
blueness due to oxygen deficiency
What is erythema?
redness due to increased blood flow to skin
What is albinism?
milky white skin and blue-gray eyes due to genetic lack of melanin synthesizing enzyme
What is jaundice?
yellowing due to bilirubin in blood (can be caused by compromised liver function)
What is hematoma?
bruising (clotted blood under skin)
How long is our hair?
Hair is divisible into three zones along its length.
What are the parts of a hair follicle?
- Bulb
- Root
- Shaft
- Dermal papilla
- Hair matrix
- Follicle
- Epithelial root sheath
- Piloerector muscle(arrector pili)
- Hair receptors
- Connective tissue root sheath
What is the hair’s bulb?
- a swelling at the base where hair originates in dermis or hypodermis
- Only living hair cells are in or near bulb
What is the hair’s root?
the remainder of the hair in the follicle
What is the hair’s shaft?
the portion above the skin surface
What is dermal papilla?
- Bud of vascular connective tissue encased by bulb
- Only source of nutrition for hair
What is the hair matrix?
- Region of mitotically active cells immediately above papilla.
- Hair’s growth center
What is the hair’s follicle?
diagonal tube that extends into dermis and possibly hypodermis
What is the epithelial root sheath?
- Extension of the epidermis lying adjacent to hair root
- Widens at deep end into bulge—source of stem cells for follicle growth
What is the connective tissue root sheath?
Derived from dermis but a bit denser
Surrounds epithelial root sheath
What are hair receptors?
sensory nerve fibers entwining follicles
What is Piloerector muscle (arrector pili)?
- Smooth muscle attaching follicle to dermis
- Contracts to make hair stand on end (goose bumps)
Where do fingernails and toenails come from?
clear, hard derivatives of stratum corneum
What are fingernails and toenails made of?
thin, dead cells packed with hard keratin
What are the functions of our nails?
- Improve grooming, picking apart food, other manipulations
- Provide a counterforce to enhance sensitivity of fleshy fingertips to tiny objects
What is the nail plate?
Hard part of the nail
What is the free edge of the nail?
Overhangs the fingertip
what is the nail body?
Visible attached part of nail
What is the nail root?
extends proximally under overlying skin
What is the nail fold?
Surrounding skin rising above nail
What is the nail groove?
Separates nail fold from nail plate
what is the nail bed?
Skin underlying the nail plate
what is the hyponychium?
Epidermis of the nail bed
what is the nail matrix?
- growth zone (mitotic) of thickened stratum basale at proximal end of nail
- 1 mm per week in fingernails, slightly slower in toenails
What’s the lunule?
- opaque white crescent at proximal end of nail due to thickness of matrix
What’s the eponychium(cuticle)?
Narrow zone of dead skin overhanging proximal end of nail
how many types of sweat(sudoriferous) glands do we have and what are their names?
- Apocrine
- Merocrine
What are apocrine sweat glands?
- Locations: groin, anal region, axilla, areola, beard area in men
- Inactive until puberty
- Ducts lead to nearby hair follicles
- Produce sweat that is milky and contains fatty acids
- Respond to stress and sexual stimulation
- Believed to secrete pheromones—chemicals that can influence behavior of others
