The surface of the _______ is about ___m2 in an adult. It weighs about ______, more than twice as much as any other ______ and about ____of body weight.
skin, 2, 5kg, organ, 1/6
The skin is also called _______ and _________.
dermis and epidermis
What is dermatology ?
The branch of medicine that treats diseases of the skin.
Why is the dermatological disease pemphigus so troubling?
In this disease the patiant mounts an immune defense (autoimmunity) against proteins of his own desmosomes and hemidesmosomes.
Which cell junctions are are critical for skin structure and function?
desmosomes and hemidesmosomes
Epidermis
Outside layer of the skin
mostly comprised of dead cells, which have expelled their nucleus and all organelles
become simply bags of a protien called keratin.
Dermis
A living layer of tissue undrneath the epidermis.
contains that blood vessels, nervers , glands, and living skin cells
Hair roots are found in the dermis , and there is a small bit of muscle (the arrector pili) wich controls the angle of each hair.
Subcutaneous layer
beneath the dermis
Also called the hypodermis
Not technichally part of the skin, but is a layer of areolar and/or adipose connective tissue.
What are the 3 layers of the Integument (Skin) structure?
Superficial to deep
1. Epidermis
2. Dermis
3. Subcutaneous (hypodermis) layer
The skin is...
keratinized statified squamous epithelium
What are the layeres of the Epidermis from deepest to most superficial?
stratum basale: lay rom which all others regenerate
stratum spinosum: "spiney"
stratum granulosum: "grainy"
stratum lucidum: "clear"
stratum corneum: "horn-like"
A mnemonic for these layers is - Before Singing, Get Legal Counsel
Another mnemonic from supericaial to deep is- Cher Likes Getting Skin Botoxed
Keratinocytes
all layers of the dermis contain Keratinocytes
generated by cell division in the statum basale (deepest layer of epidermis).
the more superficial the layer the more dead keratinocytes predominate
The ______ _______ consist entirely of two dozen rows of deat, flat ___________ with no other cell types present.
stratum corneum, keratinocytes
True or false: The other cell types (other than keratinocytes) are found only in the deeper layers of the epidermis : basale and spinosum.
True.
The stratum lucidum is found...
...only in thick (hairless) skin.
Keratinocytes are constanly made in the _______ _______ and as cells are pushed more _________, they lose their ______ and _______ and become dead bags of ________.
these cells are also called corneocytes, and they are constanly shed from the surface of the stratum corneum. The shed fakes are called squames.
Humans shed about ________ dead keratinocytes per hour. These dead ____ ____ amount to about _______ per day or _______ per year.
600,000, skin cells, 2grams, 0.7 kg
True ore false: And estimated 1/3 orm more of "housedust" is shed skin flakes. (Only about half is soil from the outdoors. The remainer is carpet and upholstery fibers.)
True.
When someone is allergic to "house dust" they are actually allergic to ...
...dust mite dung
Tiny mites, Dermatophagoides pteronyssinus, eats skin flakes as its primary source of food. Its feces are a strong allergen for many humans.
What are the two types of skin?
Thin and thick
Thin skin
covers everthing except th palms, fingertips, and soles of the feet
hariry skin
is about 0.1mm thick
Lacks a stratum lucidum
the spinosum and corneum are very thin
Thick Skin
also called glabrous (latin glaber, "bald") skin
found on the ventral (palmer) surface of the hand (i.e. palms and fingertips) and on the soles (plantar surface) of the feet.
from 6 to 45 times as thick as thin skin
most of the increased thickness is because of the spinosum, lucidum, and corneum.
What are the four cell types found in the epidermins?
Dead keratinocytes
Melanocytes
Langerhans cells
Merkel discs
Dead Keratinocytes
a cell membrane surrounding the protein keratin.
Makes up about 90% of the cells of the epidermis
These also secrete lipids that give skin waterproof and flexible properties.
Melanocytes
About 8% of the cells in the epidermis
Carry melanin, pigment granuels that give the skin its color
Langerhans cells
More rare
the skins version of a type of immune cell calleda dendritic cell
Donot confuse these with the beta cells of the islets of langerhans in the pancreas: same name, completely different function
Merkel disc
The rarest epidermal cell
A type of nervous system cell that detects light touch.
The ____ is specialized to protect the _____ and to ______ against microbial ________.
skin, body, defend, invaders
The skin serves to _____ the blood, when necessay, and to _____ the sensory modalties of _____: pressure, _______, pain, ________.
cool, detect, touch, vibration, temperature
Keratin and lipids of the skin...
...help make a waterproof seal between the moist tissues below and the dry outside world.
There is a small amount of ________ from the skin. The skin also is critical in the _________ of precursors which form ___________.
