Skin Anatomy Flashcards
The skin ranges in thickness from __-__ mm
0.5 to 6.0
Where is the thinnest skin located? Where is the thickest skin located?
Eyelids and eardrums
Palms of the hands and soles of the feet
The skin receives about __ of resting cardiac output
one third
What is considered an open wound?
a break in skin integrity (can be as minor as epidermal interruption)
What are the 3 layers of skin?
- epidermis
- dermis
- hypodermis (subcutaneous connective tissue)
What is the basement membrane?
A thin acellular membrane that anchors the dermis to the epidermis and acts as a scaffolding for the epidermis and a selective filter for substances moving between the 2 layers
Describe what happens to the skin as one ages or is exposed to too much sun?
The basement membrane begins to thin and there is disorganization and loss of collagen fibers
The epidermis ranges in thickness from __-__ mm
0.06 to 0.6 mm
Is the epidermis vascular or avascular?
avascular
What are the 5 layers of the epidermis from most superficial to deepest?
- Stratum Corneum
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Germinativum
What are the 4 types of epidermal cell types?
- Keratinocytes
- Melanocytes
- Merkel cells
- Langerhans cells
What 2 epidermal cell types serve as protectors?
keratinocytes and Langerhans cells
What epidermal cell type gives the skin its pigment?
melanocytes
What is the function of the Merkel cells?
mechanoreceptors
Describe the structure of the stratum germinativum and what its function is
It is a single row of keratinocytes that continuously divides to produce the protective protein keratin
Describe the structure of the stratum spinosum
it consists of several layers of more mature keratinocytes and appears “spiny” under microscope
Describe the structure of the stratum granulosum
It contains 3-5 flattened cell rows with increasing concentrations of keratin
Describe the structure of the stratum lucidum
It contains a few layers or flattened, dead keratinocytes which appear clear under microscope
Describe the structure of the stratum corneum
It consists entirely of dead keratinocytes
Which layer of the epidermis is the thickest?
Stratum Corneum
Can be as thick as 20-30 cells thick and accounts for up to 3/4 of the epidermis
How long does it take cells to travel from the stratum germinativum to the stratum corneum?
14-21 days
Occasionally there is a localized buildup of cells of the stratum corneum due to pressure or friction, what is this known as?
a callus
Describe how Langerhans cells help protect the skin
They fight infection by attacking and engulfing foreign material
The epidermis has 3 appendages located within the dermis, what are they?
- hair
- glands (sebaceous and sudoriferous)
- nails
Hair follicles are present everywhere except what 2 places?
palms and soles
What is hair composed of and what is its function?
It is composed of soft keratin and helps to regulate body temperature by trapping air between the hair and the skin’s surface
Each hair follicle contains what type of gland?
sebaceous gland that secretes sebum
What is sebum?
an oily substance tat lubricates the skin and hair
What do sudoriferous glands secrete?
sweat
Sudoriferous glands are present everywhere except where?
the lips and ears
Nails arise from cells within the stratum _______.
germinativum
What are the 7 functions of the epidermis?
- provides a physical and chemical barrier
- regulates fluid
- provides light touch sensation
- assists with thermoregulation
- assists with excretion
- critical to endogenous vitamin D production
- contributes to cosmesis
The dermis is typically - mm thick
2-4 mm
Is the dermis vascular or avascular?
highly vascular
What are the 2 layers of the dermis?
- papillary dermis
- reticular dermis
Describe the structure of the papillary dermis
It consists loosely woven fibers embedded in a gelatinous matrix called ground substance
When and where do blisters tend to form?
Between the papillary dermis and the basement membrane if there is friction between the epidermis and dermis
Describe the structure of the reticular dermis
it consists of dense, irregularly arranged connective tissue
What are the 3 dermal cell types?
- fibroblasts
- macrophages
- mast cells
The fibroblasts are the main cell found within the dermis, what do they produce and based on this what is their function?
Collagen and Elastin
Gives the dermis its characteristic strength and flexibility
What is the function of the mast cells within the dermis?
They are specialized secretory cells that produce chemical mediators of inflammation
What are the 5 functions of the dermis?
- supports and nourishes the epidermis
- houses epidermal appendages
- assists with infection control
- assists with thermoregulation
- provides sensation
What does the hypodermis consists of?
adipose tissue and fascia
What are the 4 functions of adipose tissue?
- provides energy
- cushioning
- insulation
- stores fat-soluble vitamins (A, D, E, K)
What is the function of fascia?
It separates and surrounds structures and facilitates movement between adjacent structures including muscle, tendon, and bone
Is fascia vascular or avascular?
avascular
What are the 3 categories of tissue involvement?
- superficial
- partial thickness
- full thickness
What layers of the skin are affected in superficial wounds?
the epidermis only
Give 2 examples of a superficial wound
- abrasion
- first-degree burn
What layers of the skin are affected in partial thickness wounds?
Epidermis and part of the dermis
How do you know the difference between a superficial and partial thickness?
The patient will feel pain and pressure associated with a partial thickness wound
Give 2 examples of a partial thickness wound
- blister
- second-degree burn (blister and peeling sunburn)
What layers of the skin are affected in full thickness wounds?
Epidermis, dermis, into subcutaneous; possibly to muscle and/or bone
*Always full-thickness if the subcutaneous tissue is involved
