Integumentary System - Skin Flashcards
Integumentary system consists of:
Skin
Hair
Nails
Sweat Glands
Sebaceous (oil) glands
Skin consists of two distinct regions:
Epidermis & Dermis
Epidermis consists of:
Keratinized stratified squamous pithelial tissue and is avascular
Dermis underlies what?
The Epidermis
Dermis consists of:
Mostly fibrous connective tissue and is vascular
Hypodermis is called?
Superficial fascia
Hypodermis characteristics
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
Four cell types found in epidermis:
- Keratinocytes
- Melanocytes
- Dendritic (Langerhans) cells
- Tactile (Merkel) cells
What does kertatinocytes produce?
Fibrous keratin (protein that gives skin its protective properties)
What is the major cell of the epidermis?
Keratinocytes
What is the epidermis tightly connected by?
Desmosomes
How many keratinocytes slough off everyday?
Millions
What are melanocytes and where are they located?
Spider-shaped cells located in deepest epidermis
What do melanocytes produce?
Pigment melanin, which is packaged into melanosomes
Where are melanosomes transferred and what do they do?
To keratinocytes, where they protect nucleus from UV damage
What do dendritic cells look like and what do they do?
Star-shaped macrophages that patrol deep epidermis
What are dendritic cells key activators of?
Immune system
What are tactile cells and what do they do?
Sensory receptors that sense touch
How many layers is the epidermis made up of?
Four or five distinct layers
How many layers does the thick skin have and where are they found?
Five layers (strata) and is found in high-abrasion areas (hands, feet)
How many layers does thin skin have?
Only four strata
Five layers of skin
- Stratum basalt
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum (only in thick skin)
- Stratum corneum
What layer of skin is only found in thick skin?
Stratum lucidum
Stratum basale (basal layer)
- 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
Journey of the Daughter cells:
One daughter cell journeys from basal layer to surface, taking 25-45 days to reach surface
- cell dies as it moves toward the surface
- other daughter cell remains in stratum as stem cell
What is the stratum basale layer also known as and why?
Stratum germinativum because of active mitosis
The stratum basale is also composed of ________.
10-25% melanocytes
Stratum spinosum (prickly layer)
Several cell layers thick
Cell contains weblike system of intermediate prekeratin filaments attached to demosomes
- allows them to resist tension and pulling
Why is the stratum spinosum called the prickly layer?
Keratinocytes in this layer appear spikey (so they call them prickle cells)
What is scattered among the keratinocytes in the stratum spinosum?
Abundant melanosomes and dendritic cells
Stratum granulosum (granular layer)
Four to six cells thick, but cells are flattened, so layer is thin
Cell appearance changes
Cells above this layer die
Description of the cell appearance change in the stratum granulosum layer
Cells flatten, nuclei and organelles disintegrate
Keratinization begins
- cells accumulate keratohyaline granules that help form keratin fibers in upper layers
Cells also accumulate lamellar granules, a water resistant glycolipid that slows water loss
Why do cells above the stratum granulosum layer die?
Too far from dermal capillaries to survive
Stratum lucidum (clear 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 corneum (horny layer)
20-30 rows of flats, anucleated, keratinized dead cells
How much of the epidermal thickness does the stratum corneum account for?
Three-quarters
Even though the stratum corneum has dead cells, the 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
Cells change by going through ______.
Apoptosis (controlled cell death)
What do dead cells slough off as? And how many cells do humans shed every minute?
Dandruff and dander
~ 50,000 cells
What is Dermis?
Strong, flexible, connective tissue
The dermis cells include:
Fibroblasts, macrophages, and occasionally mast cells and white blood cells
Fibers in matrix bind together
- makes up the “hide” that is used to make leather
the dermis contains:
Nerves, blood vessels, and lymphatic vessels
Epidermal hair follicles, oil glands and sweat glands
The two layers of the dermis are . . .
Papillary
Reticular
The papillary layer is . . .
A superficial layer of areolar connective tissue consisting of loose, interlacing collagen and elastic fibers and blood vessels
The loose fibers allow . . .
Phagocytes to patrol for microorganisms
Dermal papillae is . . .
Superficial region of dermis that sends finger like projections up into epidermis
These projections contain:
Capillary loops, free nerve endings, and touch receptors
In thick skin, dermal papillae lie on ____________ which give rise to ____________
top of dermal ridges
Epidermal ridges
Collectively ridges are called
Friction ridges
What do friction ridges do?
Enhance gripping ability
Contribute to sense of touch
Sweat pores in ridges leave unique fingerprint pattern
Reticular layer makes up _______ of dermal thickness
~ 80%
Reticular layer consists of . . .
Coarse, dense fibrous connective tissue
Many elastic fibers provide . . .
Stretch-recoil properties
Collagen fibers provide . . .
Strength and resiliency
- bind water, keep skin hydrated
Cutaneous plexus:
Network of blood vessels between reticular layer and hypodermis
Extracellular matrix contains . . .
Pockets of adipose cells
_________________ in reticular layer are caused by many collagen fibers running parallel to skin surface
Cleavage lines
Cleavage lines are . . .
Externally invisible
Important to surgeons because incisions parallel to cleavage lines heal more readily
Flexors lines of reticular layer are . . .
Dermal folds at or near joints
Dermis is tightly secured to . . .
Deeper structures
Flexors lines are visible on . . .
Hands
Wrists
Fingers
Soles
Toes
Extreme stretching of skin can cause dermal tears, leaving silvery whit scars called __________
Striae aka stretch marks
Acute, short-term trauma to skin can cause ________ which are ___________ that separate _______ and ________ layers
Blisters
Fluid-filled pockets
Epidermal and dermal
Three pigments contribute to skin color:
- Melanin
- Carotene
- Hemoglobin
Melanin is only pigment made in ______ made by _______
Skin
Melanocytes
Excessive sun exposure damages skin causing . . .
Elastic fibers clump, causing skin to become leathery
Excessive sun exposure can . . .
Depress immune system and cause alterations in DNA that may lead to skin cancer
UV light destroys _________ which is necessary for _________
Folic acid
DNA synthesis
______________ is increased reaction to sun
Photosensitivity
Carotene is a _______ to _______ pigment
Yellow to orange
Carotene is most obvious in _______ and ______
Palms and soles
Carotene accumulates in __________ and __________
Stratum corneum and hypodermis
Carotene can be converted to ________ for vision and epidermal health
Vitamin A
Hemoglobin is a _______ of ____ skin due to ______ of _______
Pinkish hue
Fair
Lower levels
Melanin
Cyanosis color and cause
Blue skin color
Low oxygenation of hemoglobin
Pallor color and cause
Blanching or pale color
Anemia, low blood pressure, fear, anger
Erythema color and cause
Redness
Fever, hypertension, inflammation, allergy
Jaundice color and cause
Yellow cast
Liver disorders
Bruises color and cause
Black-and-blue marks
Result of clotted blood beneath skin
Clot is broken down, color of bruise changes
Brown or black “necklace” color and cause
Hyperpigmented dark areas in axillae and around neck may be a sign of insulin resistance and elevated blood glucose levels
The principle of melanin is to ___________.
a) give one that “healthy tan look”
b) keep the body cool
c) provide a waterproof layer
d) shield the nucleus from damage by ultraviolet radiation
D) shield the nucleus from damage by ultraviolet radiation
The touch sensors of the epidermis are the ___________
A. keratinocytes
B. tactile cells
C. epidermal dendritic cells
D. melanocytes
B. Tactile cells
A patient taking a drug that inhibits cell division (such as certain chemotherapy drugs) would expect which layer of the epidermis to be affected first?
a) Stratum corneum
b) Stratum lucidum
c) Stratum spinosum
d) Stratum basale
D. Stratum basale
Fingerprints are copies of __________.
a) dermal papillae
b) epidermal papillae
c) dermal ridges
d) friction ridges
C. Dermal ridges
The principal tissue found in the reticular layer is ___________.
a) dense irregular connective tissue
b) stratified squamous epithelium
c) dense regular connective tissue
d) areolar connective tissue
a) dense irregular connective tissue
Which three pigments contribute to skin color?
A. Carotene, melanin, hemoglobin
B. Keratin, melanin, hemoglobin
C. Melanin, keratin, hemoglobin
D. Hemoglobin, carotene, keratin
A. Carotene, melanin, hemoglobin
Which of the following skin colors may indicate anemia?
A. Erythema
B. Bronzing
C. Black and blue marks
D. Pallor
D. Pallor
