The epidermis is comprised of what type of tissue?
stratified squamos epithelium
The dermis is comprised of what two types of tissue?
areolar connective tissue
dense irregular connective tissue
List the five major types of cell found in the epidermis.
melanocytes
langerhans cell
lamellar body
Merkel's disc
keratinocyte
What is the function of melanocytes?
to produce the pigment melanin
What is the function of the langerhans cell?
to detect pathogens entering through the skin
What are lamellar bodies full of?
lipids
Merkel's discs function as:
tactile receptors
What type of epidermal cell is most prevalent?
keratinocytes
Squamos cells that are full of keratin make up what percent of the epidermal layer?
90%
List the five layers of the epidermis from bottom to top.
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
The stratum basale is a _______ layer of cells.
single
The cells of the stratum basale are _______ in appearance.
cuboidal
Melanocytes will be located in which layer of the epidermis?
stratum basale
How often will cells undergo mitosis in the stratum basale?
every 19 days
True or False: When an epidermal cell undergoes mitosis, one daughter moves towards the stratum corneum while the other stays in the stratum basale to divide again.
True
What are tonofilaments?
tiny microfilaments that weave together with the fibers of desmosomes and hemidesmosomes to aid in cell attachment
Epidermal cells will contain which types of organelles?
nucleus
mitochondria
ribosomes
rough ER
golgi apparatus
How long does it take for a cell to move from the stratum basale to the stratum corneum?
15-30 days depending on the thickness of the epidermis
Once a cell reaches the stratum corneum, how long until is gets sloughed off?
14 days
In which layer do cells undergo apoptosis, or programmed cell death?
stratum granulosum
How many layers of cells are in the stratum spinosum?
8-10
How many layers of cells are in the stratum granulosum?
3-5
How many layers of cells are found in the stratum lucidum?
4-6
How many layers of cells are found in the stratum corneum?
usually 25-30 but can be as high as 50
What accounts for the "spiny" appearance of the stratum spinosum?
edges of the cells appear spiny where the desmosomes attach
Living langerhans cells and lamellar bodies can be found in which layer of the epidermis?
stratum spinosum
Why do cells undergo apoptosis in the stratum granulosum?
because they have moved to far away from the blood supply
What is the function of keratohyalin?
to convert tonofilaments from lower layers into keratin
When lamellar bodies dump their lipids in order to lubricate and water-proof the cells they become:
lamellar granules
Which layer of the epidermis appears clear upon examination?
stratum lucidum
The stratum lucidum is only present in which two places on the human body?
palms of your hands
soles of your feet
In which layer of epidermis are the cells dead and full of keratin?
stratum corneum
Thickening of the stratum corneum due to repetitive pressure is called a:
callus
What is the last layer of epidermis in which all of the cells are still living?
stratum spinosum
Which epidermal layer is not found all over the body?
stratum lucidum
Which layer of epidermis performs the vast majority of cell divisions?
stratum basale
What are the tw purposes of epidermal ridges discussed in class?
assist in grip and traction
increase surface area
True or False: Epidermal ridges are unique to DNA expression.
True
List the five characterstics of thick skin discussed in class.
presence of stratum lucidum
other layers of epidermis are thicker
no hair/follicles/sebaceous glands
high density of tactile receptors
high density of sweat glands
List the five characteristics of thin skin discussed in class.
absense of stratum lucidum
other layers of epidermis are thinner
contains hair/follicles/sebaceous glands
lower density of tactile receptors
lower density of sweat glands
List the five functions of epidermal growth factor (EGF) discussed in class.
increase cell division in epidermal cells
increase gland secretion
increase cell repair
increase keratin synthesis
increase growth in hair
Name the two layers of the dermis.
papillary layer
reticular layer
What is the papillary layer of the dermis comprised of?
areolar connective tissue
What is the function of the dermal papilla?
to increase the surface area of attachment to the epidermis
The reticular layer dermis is comprised of what type of tissue?
dense irregular collagenous connective tissue
Inflammation of the dermis is known as:
dermatitis
Skin turgor is a measure for assessing what?
hydration
Tattoo ink is deposited in which layer of the cutaneous membrane?
the dermis
Blistering is the result of what physical phenomenon?
the seperation of the dermis and epidermis causing fluid build-up
In some parts of the body, the collagenous fibers of the reticular dermal layer run in a more regular orientation. These are known as:
tension lines, or lines of cleavage
Are the collagenous fibers in the abdomen oriented vertically or horizontally?
horizontally
Why should incisions be made parallel to the tension lines?
wounds are less likely to pull apart
less scar tissue formation
Blood vessel networks in the papillary layer of the dermis are called the:
papillary plexus
The cutaneous plexus can be found in which layer of the cutaneous membrane?
the reticular layer of the dermis
The layer beneath the dermis is named the:
hypodermis
The hypodermis is comprised primarily of:
adipose
Where is a subcutaneous injection deposited?
into the hypodermis
Why would you inject something into the hypodermis?
because you want it to disperse in a slow and controlled manner