514-1 Flashcards
Name four appendages or “derivatives” of skin.
Hair, nails, sweat glands (eccrine), and sebaceous glands.
T/F
All four main classes of tissue are found in the integumentary system.
True
T/F
Dermatology is the study and treatment of the epidermis.
False.
It is the study and treatment of the entire integumentary system.
What are the two main functions of skin as a barrier?
Prevent things coming in.
Prevent things going out (especially water).
How does skin use UV light in Vitamin D3 production?
UV changed a cholesterol-type molecule into cholecalciferol, which is converted to calcitrol (a hormone) in the liver and kidney.
What does calcitrol do?
A hormone that absorbs phosphorus and calcium from the digestive tract.
What waste product is exuded through the skin?
Urea
What neural structure is responsible for the regulation of sweat secretions?
The hypothalamus.
What are the 3 main divisions of skin?
Epidermis, Dermis, Hypodermis
How thick (in mm) is thin and and thick skin? Where is it found?
Thin: 1-2mm and found over most of the body
Thick: up to 6mm. Found on the palms and soles.
What are the 2 main protective components to the epidermis?
Keratin and lipids.
The dermis has connective tissue that can be described as _______ and ______?
Loose. Dense-irregular.
T/F
The dermis is avascular and innervated.
False.
Dermis is highly vascular and innervated.
What is a good sign you’ve hit hypodermis with an incision?
You see adipose tissue.
The basement membrane defines the border between what two layers of the integument?
Epidermis and Dermis
the membrane is on the basal side of the basal cells
Name four main components in the epidermal epithelium.
Keratinocytes (most numerous)
Melanocytes
dendritic Langerhan’s cells (immune patrol)
Merkel cells (sensory)
What is the function of rete ridges?
Resist shearing forces.
What is the term for the dermal interdigitations with rete rigdes?
Dermal Papillae
Name the 5 layers of the epidermis.
Stratum Corneum Stratum Lucida Stratum Granulosum Stratum Spinosum Stratum Basale Cute Little Girls Sing Badly
What are 2 other names for the Stratum Basale?
Germinatavum or Basal Cell Layer
What is the most mitotically active layer in the epidermis?
Stratum Basale
What type of collagen is the basement membrane made out of?
Type IV
What are the three main types of cells in the Stratum Basale?
Keratinocytes
Melanocytes
Merkel Cells (sensory)
What cell dominates the landscape of Stratum Spinosum?
Keratinocytes (slowly maturing)
Why does the Stratum Spinosum appear “spiny”
An artifact of histologic preparation (fixing, etc.)
Do Dendritic cells in the Stratum Spinosum have desmosomes?
No. They need to be mobile to seek out pathogens.
From where are dendritic cells derived?
Bone Marrow
What junction binds keratinocytes in the stratum spinosum?
Desmosomes
What is the general class of proteins making up a cell junction in a Desmosome?
Cadherins
What is the function of cell processes in dendritic cells?
Antigen seeking.
What’s a good indication you’re looking at a dentritic cell?
Characteristic indented nucleus.
There are small granules on the exterior of dendritic cells of unknown function. What are they called?
Birbeck cells
Does keratin waterproof the skin?
No. Lipids do.
Why does the stratum granulosum stain darkly?
Increasing protein content (of keratin/keratin precursors including keratohyalin)
What do keratinocytes secrete through exocytosis in the granular layer?
glycolipids.
What are the dark staining granules in the stratum granulosum?
Condensing keratin.
What are the lipid-containing bodies called that discharge into the intercellular space in the granular layer?
Lamellar bodies.
Where is stratum lucidum best seen?
Thick skin
this makes the layers of maturation/degradation more visible
Do cells in the stratum lucidum contain nuclei?
Typically no
How many layers of cells can be in the stratum corneum?
Up to 30 layers.
How long does it take for a keratinocyte to go from the base layer to exfoliation in the stratum corneum?
15-30 days
What is psoriasis?
a type of hyperplasia in which the basal cells produce keratinocytes too rapidly.
this is caused by an invasion of neutrophils into the epidermis
With psoriasis, how many days does it take for a keratinocyte to travel from the bottom to the top of the epidermis?
7 days
In the cell, what to keratin granules condense on to?
The cytoskeleton.
In what layer of the epidermis do the lamillar bodies first appear?
Stratum Spinosum
In what layer of epidermis does the keratinocyte produce many intermediate filaments onto which keratohyalin condenses?
Stratum granulosum
What type of response is pruning?
Autonomic blood vessel restriction
What is pemphigus, and what two epidermal layers does it affect?
autoimmune disease
causes blistering of the skin in the stratum spinosum
detaches degrades the desmosomes attaching the basal cells to the basement membrane.
What are the three “immigrant” cells of the epidermis?
Merkel’s cells
Melanocytes
dendritic Langerhan’s cells
Where are the melanocytes derived from embryologically?
Neural crest cells
What do melanocytes inject into surrounding cells?
Melanosomes.
How many cells can one melanocyte inject?
Up to 36 (maybe more)
- in normal tissue the melanocyte stays put and injects the cells moving up around it.
What is the reverse-exocytosis process of melanocyte injection called?
cytocrine injection
Does the number of melanocytes differ greatly between people with light and dark skin pigmentation?
No. Melanocyte number is about the same. Melanin production and chemistry varies.
What color is eumelanin and what is it made of?
Black.
Pure tyrosine polymer.
What is the mixed polymer of tyrosine and cysteine called?
phaeomelanin
What is the key enzyme in the production of melanin?
Tyrosinase.
Relate the following skin conditions to color:
Cyanosis, Erythema, Jaundice, Addison’s Disease
Blue, Red, Yellow, Bronzing (too much Acth)
What skin condition is associated with a very low incidence of skin cancer?
Vitiligo
What are some signs of vitiligo?
Bilaterally expressed patterned albinism
thought to be auto-immune
What are the 3 kinds of hemangiomas?
Normal (caused by benign capillary tumors) - can be lasered
Strawberry - disappear with age
Port Wine - last for life
What do you call an aggregation of melanocytes on the skin?
A freckle.
When are friction ridges (fingerprints) formed?
In utero
When are flexion creases formed?
After birth.
Where is the Meissner’s corpuscle found and what does it sense?
Dermal papillae
Tactile receptor
What are Meissner’s copuscles composed of and where are they commonly found?
Nerve ending wrapped with connective tissue (fibrous capsule)
Abundant in vermillion zone of lip
What is the high resolution tactile receptor in the epidermis?
Merkel Cell
Where are Merkel cells found and where are they derived from?
Found in Basal layer (attach to keratinocyes via desmosomes)
Derived from neural crest cells
Describe Merkel cell innervation
Cells secrete neurotransmitters to a disk connected to free nerve endings.
What do free nerve endings respond to?
Pain and temperature.
What is the function of pacinian corpuscle membranes?
Increases the sensory field.
What is the sensory difference between Pacinian and Ruffini’s corpuscles?
Pacinian - pressure, stretch, tickle, vibration
Ruffini’s - displacement of collagen fibers
Which nerve ending is attached to a hair follicle?
Peritrichal
Re-Cap: Name 5 sensory receptors in the skin.
Meissner’s corpuscle, Merkel Cell, Free nerve endings, Pacinian/Ruffini’s, and Peritrichal
Name 2 layers of the Dermis
Papillary layer (dermal papillae) Reticular layer (dense irregular connective tissue)
What is adipose in the hypodermis called?
subcutaneous fat
What makes hair and nails tougher than regular keratin?
Disulfide bridges.
What is the fine fetal hair called?
Lanugo
What is unpigmented hair of children (and adults) called?
Vellus
T/F
The hair follicle is a dermal structure.
False.
This is an epidermal structure and the stratum basale can be traced all the way around it.
What is the autonomic muscle on a hair follicle called?
Arrector pilli (piloerector muscle)
What does the hair follicle refer to?
The infolding of skin surrounding the hair
From bottom to top, name four hair structures
Dermal papillae, bulb, root, shaft
What are the 3 layers of the hair shaft?
Cuticle
Cortex
medulla
What stains dark in the hair bulb?
Melanocytes
The epithelial root sheath (of a hair root) is composed of what?
Inner and outer root sheath
Where is the neurovascular supply for the hair located?
Dermal Papillae
What separates the epithelial root sheath from the hair?
Basement membrane.
What are the 3 stages of the hair growth cycle?
Growth Stage (6-8 years) Shrinking Stage (2-3 weeks -catagen) Resting Stage (1-3 months - telogen)
Describe Alopecia
Immune response attacking follicles causing hair loss
What is the term for excessive hair growth usually caused by a hormone imbalance?
Hirsutism
What’s another name for the nail cuticle?
Eponychium
What is the epithelium of the nail bed called?
hyponychium
What is the mitotic area of the nail and where is it?
Nail Matrix
Proximal end of the nail
What’s the difference between and apocrine and eccrine gland?
Eccrine is sweat gland on the surface
Apocrine is sweat gland in the hair follicle
When do apocrine glands appear in the body and what to they respond to?
puberty
stress or excitement
What’s another name for body odor?
Bromhidrosis
What are the glands found in the external auditory meatus called?
Ceruminous glands
From what cell does the most serious skin cancer originate?
Melanocyte (melanoma)
Cancer originating from keratinocytes in the stratum spinosum is called?
Squamous cell carcinoma
Cancer arising from the stratum basale is called?
Basal cell carcinoma
Relate burn degree to depth.
1st degree - epidermis
2nd degree - dermis
3rd degree - hypodermis
Why is melanin found in the inner ear?
Anti- free radical activity
What are some components to wound healing?
Fibrin clot, macrophages, neutrophils, platelet plug
This is followed by epidermal enclosure under the scab
When are skin grafts necessary?
When there are insufficient keratinocytes to repopulate skin.
Human skin is known as the
Integument
