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Foundations Part II > Integumentary System > Flashcards

Flashcards in Integumentary System Deck (34)

What are the types of cells in the skin

1. Keratinocytes (epidermal cells)
2. Merkel cells (tactile cells)
3. Langerhans cells (macrophages that presents antigens)
4. Melanocytes (derived from neural crest cells)


Dermis - what does it contain

Papillary dermis that is loosely packed
Then we have reticular dermis that is densely packed and finally we have hypodermis which has subcutaneous fat


Histology of the skin

On the top we have stratum corneum, the keratin layer.
Below we have papillary dermis and then we have the reticular dermis (that creates the waves)


What are the layers of epidermis

Starting from the top

1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum spinosum (have extensive desmosomes)
5. Stratum basale

In the thickness stratum corneum is much thicker


Excessive skin shedding - what is the condition called and what is the biochemical basis of it


The underlying infiltrating immune cells release cytokines that signals the keratinocytes to proliferate more quickly, reducing the time of the cell cycle.

The blood vessels thicken to provide with the extra nutrients for increased cell activity.
Silver white flaky layer is created which are just a bunch of dead cells on the top of skin


Facts about Psoriasis (there are 4)

Disease of the epidermal-dermal layer:

1. Persistant hyperplasia of keratinocytes due to increased proliferation
2. Neutrophils migrate to the dermis, forming abscess when they die. (or microabscess).
3. Lymphocytes are the ones below the dermis secreting cytokines
4. Also there are nuclei displayed in the now thickened stratum corneum


How are the fingerprints formed

The dermal papillae that come out to the surface of the skin gives us our unique fingerprints


What do we need to know about the keratin that is being expressed in the different layers of the dermis by the keratinocytes

The keratin changes as the cells move along from the basale layer to the spinosum and to granulosum to lucidum and then finally to Stratus corneum


What compound is secreted to aggregate keratin



What layer of cells secrete the keratin aggregate



Where does the fat comes from in the top of the skin

Lamellar bodies


What does the fat do

Envelopes the keratin in structures called cell envelopes


What is the structure of the cell envelope

Lipid is on the outside, cell envelope molecules and then comes the aggregated keratin on the inside surface of the cell envelope


One of the molecules of envelope and how it is cross linked

Loricrin (one of the envelope molecules) is cross linked by transglutaminase K (TGK)


Mutation associated with TGK
(there are 2)

One of them results in scaled fish like skin called Lamellar ichthyosis (there is a mutation is TGK)

The other one is Dermatitis herpetiformis (antibodies directed to TGK, IgA)


Types of cells in the epidermis

1. Melanocytes: derived from neural crest cells, they make melanin and put this melanin in adjacent cells (so not all cells with melanin are melanocytes)

2. Merkel cells: these are also derived from neural crest cells, they are tactile mechanoreceptors

3. Langerhan cells are the macrophages of the skin. They do antigen recognition and phagocytosis


How is melanin made

Made in melanocytes, they make premelanome which then matures into melanosome and is then released and taken in by keratinocytes.


Biochemical details of the production of melanin

Made from oxidation of tyrosine to dihydroxyphenylalanine. This then becomes melanin


What are the spines in the spinosum layer made of? what do they represent?



What are the 2 major types of pemphigus

1. Pemphigus vulgaris (autoantibodies to desmogleins 3)
2. Pemphigus foliaceous (autoantibodies to demoglein 1)

There's another type called the mucocutaneous which have antobodies to 1 and 3 both.


What is the gradient of DG1 and DG3

DG 1 is high on the surface, reduces towards the basal layer and DG3 is high on the basale layer, reduced towards the surface.


What is a factor in mucous membrane

DG1 is not really a factor in mucous membrane, DG3 is present, in the same gradient form


PF and PV, where do they split

PF on the top, PV on the bottom


What is the structure involving hair

1. External root sheath is continuous with the stratum basale.
2. Bunch of stem cells that are keratinocyte in the bugle
3. Internal Root Sheath surround the hair shaft
4. Dermal papillae are a reservoir of stem cells


3 phases of hair growth

1. Anagen - growth phase
2. Catagen - intermediate/regression phase
3. Telogen - rest or shedding phase


What kind of secretion does saebeceous glands have

Holocrine secretions - destroys the cell


What kind of secretion does sweat galnds have

Merocrine secretion


What other important cells are important for sweat secretions

Myoepithelial cells that are repsonsible for moving the sweat up, they are at the base of the sweat glands, they squeeze secretions out


Cystic fibrosis

Defect in the CFTR gene, causes increase chloride ion and Na ion secretion in the sweat


What is the sensory receptor stuff in the skin

There are 5

1. Meissner's corpuscle for two point differentiation in hairy skin
2. Merkel cells - 2 point differentiation in fingers and hands
3. Free nerve endings for temperature
4. Ruffini cells - for stretching
5. Pacinian corpuscle for deep pressure senses and vibration, 2 point differentiation in skin


When is a scar formed and where there is complete recovery

If the wound deep into the dermis, scar will form. If it is only at the epidermis complete regeneration takes place


Know the difference between first and second intention healing

Has to do with the sharpness of the wound. If the wound is not so sharp, the healing is poor resulting in 2nd intention healing


Disease associated with 2nd intention healing

Duputyren's contracture; myofibroblast go out of control
Happens in diabetics often (even almost exclusively)


Explain skin grafting

Skin from another part of the body is removed to be placed over a wound or scar.. The tissue has either been destroyed or damaged. Color and texture of a skin are carefully chosen but sometimes this is not possible.
The thickness of the skin can vary.