Tuesday test Skin3

Question 1

Major functions of skin (7)?

Answer 1

Mechanical protection
Moisture barrier
Host defense
Thermoregulation
Excretion of salt
Synthesis of vitamin D & regulation of calcium absorption
Sensory organ

Question 2

How big is skin as an organ?

Answer 2

15-20% of body weight
- 1.5 to 2 square meters of surface area

Question 3

How thick is skin?

Answer 3

Thickness varies from 1 mm (eyelid) to 5 mm (upper back)

Question 4

Cornified barrier is composed of __
What important things does it make?

Answer 4

Keratinocytes
Vitamin D production

Question 5

Cells that protect agains ultraviolet radiation?

Answer 5

Melanin, melanocytes

Question 6

Cells/structures that help with thermoregulation ?

Answer 6

Sweat glands, blood vessels

Question 7

Sensory cells and structures?

Answer 7

Sensory dendrites, mechanoreceptors, thermoreceptors,
nociceptors

Question 8

Leathery barrier is composed of __ and __

Answer 8

Fibroblasts and thick collagen fibers

Question 9

primary barrier against pathogen access to deeper tissues?

Answer 9

Skin

Question 10

Mucous membranes role in pathogenesis?

Answer 10

produce mucus (watery mix of the protein mucin and salts) → trap pathogens and can be expelled from the body

Question 11

The first line of defense in innate immunity are ______, which block pathogen entry into the tissues of the body.

Answer 11

barrier defenses

Question 12

Two main parts of the skin?

Answer 12

Epidermis (keratinocytes and non-keratinocytes) and dermis (Papillary layer, reticular layer).

CT is between them

Hypodermis isnt technically part of the skin

Question 13

2 layers of dermis? major difference

Answer 13

Papillary (loose CT) and reticular (dense CT)

Question 14

Two parts of Hypodermis?

Answer 14

Subcutis

Superficial fascia

I dont know if this is correct!

Question 15

Name the 5 strata of epidermis

Answer 15

from deepest to superficial

Stratum basale

Stratum spinosum

Stratum granulosum

Stratum lucidum

Stratum corneum

Question 16

Stratum basale - special things?

Answer 16

single cell layer between epidermis and dermis

• Germinative layer = high rate of mitosis - only one doing mitosis

• Keratin filaments form fibrils

Question 17

What holds Stratum basale together?

Answer 17

Desmosomes

Question 18

What does stratum spinosum produce?

Answer 18

membrane-coated granules

keratin fibrils

Question 19

how is stratum spinosum hold together?

What does it contain?

Answer 19

desmosomes

Keratohyalin granules, Keratin fibrils, Membrane-coated granules

Question 20

Where are keratohyalin granules formed and what is their role?

Answer 20

Stratum granulosum. Hold keratin fibers together → cell stretches like a pancake

Question 21

Composition of Keratohyalin granules? 3

Answer 21

filaggrin, loricrin, involucrin

Question 22

what is the layer of the cells we only see in thick skin layer?

Answer 22

Stratum lucidum

Question 23

describe stratum lucidum

Answer 23

Extensive crosslinking of keratin fibrils, changes cell shape to squamous

Question 24

What does stratum lucidum do?

Answer 24

Glycolipids (from m-c granules) secreted into extracellular space seal the squamous layers.

Question 25

Cells of the stratum corneum form \_\_\_

Answer 25

Cornified envelope

Question 26

Difference of thick vs thin skin?

Answer 26

- Named for different thicknesses of epidermis, not for thickness of entire skin. Thin skin: almost all has hair; 14 days to turnover/replace. Thick skin: only on palms and soles; hairless; 48 days to turnover.

Question 27

What are the non-keratinocytes cells? What do they originate from?

Answer 27

Melanocytes - originate from Neural crest cells and Merkel cells - originate from ectodermal basal cells

Question 28

Main functions of Melanocytes? How do they originate?

Answer 28

Contain pigment melanin -(Oxidation of tyrosine -\> DOPA -\> melanin), packaged into melanosomes. They are dendritic cells -\> cytoplasmic extensions with over 30 keranocytes. bMelanin granules form a shield protecting stratum basale and nuclei from UV rad Originate from Neural crest cells -\> migrate to epithelium and located between dermis and epidermis

Question 29

How do we visualise melanocytes?

Answer 29

Antibody to a protein, active early in melanin synthesis is used. In the basal layer of epithelium

Question 30

What are Langerhans cells? Where are they located? How does it do its job? How are they attached?

Answer 30

- antigen presenting dendritic cell (derived from a bone marrow macrophages like all monocytes) Located in Stratum spinosum It’s motile and moves within the keratinocytes and bw epithelium and lymph vessels. Migrates regionally to lymph nodes and presents antigens to T cells. Langerhans cells aren’t attached with desmosomes to keratinocytes, but associated with E-cadherins

Question 31

Merkel cells job?

Answer 31

Slowly adapting mechanoreceptor (pressure) touch in thin skin. Sence of touch

Question 32

What do Merkel cells contain? How are they attached?

Answer 32

It’s ectodermal, desmosomal attachments to basal layers of epithelial cells Keratin tonofilaments Small granules presumably containing neurotransmitters

Question 33

What are the sensory innervations of epidermis?

Answer 33

Merkel cells - Tactile -touch to the skin. Unmyelinated nerve ending expands into plate like sensory ending Free nerve endings (Epidermis - Pain, temperature)

Question 34

What does the dermis contain?

Answer 34

Capillary network, AV shunts, Sensory nerve endings

Question 35

How do we prevent loosing heat during a cold day?

Answer 35

Blood supply to superficial capillaries is regulated through Shunts (pericapillary sphincter)

Question 36

What’s the sensory innervation of dermis?

Answer 36

1) Ruffini’s corpuscle (stretching) 2) Meisner’s corpuscle - fine sense of touch (papillary layer, Detects changes in “texture” • Vibrations around 50Hz • Fingertips, lips have increased innervation density (fine touch in thick skin)

Question 37

Sensory Innervation of Reticular layer? What does it sense?

Answer 37

Pacinian corpuscles Rapidly adapting – Type II mechanoreceptor – Deep pressure & vibration

Question 38

At the base of the follicle, the ______ is surrounded by the hair bulb, whose keratinocytes proliferate, take up melanin granules and gain more keratin

Answer 38

dermal papilla (DP)

Question 39

What does Eccrine Sweat Gland secrete? How?

Answer 39

Reabsorbs sodium and chloride ions from the sweat, plus some of the water. its continuous production

Question 40

Eccrine Sweat Gland - what types of cells?

Answer 40

Stratified cuboidal epithelium (two cell layers) Excretory duct

Question 41

Excretory duct locations?

Answer 41

Big glands that lead to body odor; restricted to the arm pits, genital and anal regions

Question 42

What do apocrine sweat glands secrete?

Answer 42

Protein-rich secretion (odorless when secreted but bacteria like it, leading to body odor)

Question 43

Apocrine sweat gland - how does it secrete sweat?

Answer 43

Duct empties into canal of hair follicle, dont produce continuously

Question 44

Apocrine sweat gland structural difference?

Answer 44

Coiled tubular gland: lumen is larger than in eccrine sweat glands

Question 45

Sebaceous glands product? How is it secreted?

Answer 45

Oil (sebum) glands of the skin Secrete into canal of hair shaft -Holocrine secretion: dying sebaceous gland cells…lots of lipids

Question 46

How do Sebaceous glands look like?

Answer 46

Branched acinar glands The acini have no lumens.

Question 47

Describe wound healing process

Answer 47

Blood vessels clot → leukocytes clean the wound → blood vessels regrow and granulatio tissue forms→ stratum basale is restored → producing more keratinocytes