Exam 3 - integument

Question 1

What are the layers of thick skin?

Answer 1

• Deepest
  
  • Reticular
  • Papillary
  • Stratum Basale (germinativum)
  • Stratum spinosum
  • stratum granulosum
  • Stratum lucidum
    
    • absent in thin skin
  • Stratum corneum
• Superfical

Question 2

What are characteristics of basale (germinativum)

Answer 2

• Deepest
• columnar to high cubodial keratinocytes
• keratins 5 and 14 ( low-molecular weight keratins)
• single layer
  
  • held together by desmosomes
  • hemidesmosomes hold layer to basal lamina
• high mitotic activity
  
  • produces tems cells defferentiating keratinocytes
  • afffect by chemotherapeutic ad radiation treatments
  • keratinocytes arise from here

Question 3

What are characteristics of the stratum spinosum

Answer 3

• polyhedral shaped cells (prickle cells)
• keratins 1 and 10
• keratohyalin granules develop
• membrane coating granules first appear
  
  • lamellar bodies
    
    • contain lipid carbohydrates and hydrolytic enzymes
• tonofibrils
  
  • form intercellular bridges

Question 5

What is the stratum granulosum

Answer 5

• Multilayered
• keratins 2e and 9
• flattened nucleated keratinocytes
• keratohyalin aggregates
  
  • fillagrin induces cross linkage of keratin filaments by disulfide bonds
  • no limiting membrane
• Membrane coating granules (lamellar bodies
  
  • acylglucosylceramide to intercellular spaces
• tonofilaments

Question 6

What is the stratum lucidum?

Answer 6

• Flat keratinocytes lacking uclei and organelles
• only found in thick skin
• contains eleiden (a precursor to keratin)

Question 7

What are the characteristics of stratum corneum?

Answer 7

• Multilayered (5-50 layers)
• Thicker in thick skin
• Enucleated, flattened, dead keratinocytes
• cytoplasm replaced by keratin
• cytoplasm contains
  
  • keratin cross linked with filaggrin to the cornified cell envelope

Question 8

What are the different parts of the cornified cell envelope ?

Answer 8

• Extracellular
  
  • multi-lamellar lipid layer covalently linked to involucrine
• cornified enevolpe
  
  • involucirne
  • small proline rich proteins
  • loricrin
• Intracelular
  
  • fillagrin and keratin complexes

Question 9

Answer 9

TIssue Slide

e

Question 10

Tissue slide

Answer 10

Question 11

Tissue Slide

Answer 11

Question 12

What are two layers of the dermis?

Answer 12

• Papillary layer (closest to epidermis)
  
  • Loose Ct
  • Separated from epidermis by basal lamina
  • network of fine elastic fibers and abundant capillaries
• Reticular layer
  
  • dense irregular CT
    
    • includes dibrocytes, macrophages, and adipocytes

Question 13

HOw the dermis adn hypodermis compare and contrast?

Answer 13

• Dermis
  
  • dense fivrous irregular connective tissue layer benaeth epidermis
  • dervived from embryonic mesoderm
  • induces development of epidermis and epudermal dervatives
  • supports epidermis
• Hypodermis
  
  • loose connective tissue that underlies dermis
  • corresponds to superfical fascia of gross anatomy
  • technically no part of skin
  • may contain fat cells that can form a thick layer called
    
    • oanniculus adiposus

Question 14

How do thick and think skin compare?

Answer 14

• Thick skin
  
  • occurs only on palms and soles and is hairless
  • epidermis varies from .4 to .6 mm thick
  • displays all five epudermal layers
• Thin skin
  
  • occurs over rest of body
  • epidermis varies from 75 to 150 um thick
  • thinnest thin skin is on eyelids
  • thickest think skin is on back
  • thicker on extensor surfaces than flexor surfaces
  • epidermal layers less distinct and lacking stratum lucidum

Question 15

What is part of the integument is responsible for finger prints

Answer 15

• Primary dermal ridge
  
  • formed during 3rd and 4th months of fetal life
  • subdivided into secondary dermal ridge by interpapillary peg
• Interpapillary peg
  
  • downward growth of epidermis along crest
• Secondary dermal ridges
  
  • occur in double rows branched
  • thin collagenous, reticularm ad elastic fibers
• Dermal Papillae
  
  • Upward prjoects from each secondary dermal ridge

Question 16

Tissue Slide

Answer 16

Question 17

What is keratinization?

Answer 17

Question 18

What are langerhans cells?

Answer 18

• dendritic cells
• from monocytes
• antigen presenting cells
• primarily in stratum spinosum
• migrate from epudermis to lymph nodes
• birbeck granules

Question 19

What are merkel cells?

Answer 19

• Mechanoreceptors
• may also act as diffuse neuroendocrine cells
• usually in stratum germinativum
• contain catecholamine-like granules

Question 20

What are melanocytes?

Answer 20

• Derived from melanoblasts
• does not form dermosome attachments in epidermis
• inject melanin granules into keratinocytes
• pathway for melanin
  
  • tyrosine -> 3,4 dihyrdroxyphenylalanine (DOPA) -> dopaquinone -> melanin
    
    • REQUIRES tyosinase

Question 21

What is the embryonic orgins of the epidermis ?

Answer 21

• Epidermis
  
  • starts as a single layer of ectodermal cells
  • divide during sizth week to form
  • periderm
    
    • sloughs off to form vernix xaseosa
  • inner cubodial germinal layer
    
    • continues to proliferate to form adult layers of the epidermis adn derivatives
      
      • 10 week fingernails
      • 12 week hairbuds and toenails
        *

Question 22

What is the embryonic origins of the dermis

Answer 22

derived form the mesoderm

Question 23

What are the characteristics of the sebaceous glands?

Answer 23

• Holocrine glands
• branched acinar glands with short ducts
• found everywhere except palms and soles
• continuously produce sebum
  
  • released into follicle
• growth is stimulated at puberty by sex hormones

Question 24

What are the two sweat (sudoriferous ) glands?

Answer 24

• Both merocrine and apocrine glands
  *

Question 25

What are merocrine flands?

Answer 25

• coiled, simple tubular secretory portions
  
  • lined by simple epithelium
  • apical dark secretory cells that secrete glycoproteins
  • basal clear cells secrete water ad eletrolytes
  • Myoepithelial cells
• Duct system consists of stratified cubodial epithelium except in epidermis
• cholinergic endings

Question 26

What are apocrine galdns?

Answer 26

• Found in labia majora, areola, and axillary and anal regions
• secreations are thicker and more viscous than mercrine types
• excretory duct opens into hair follicle
• adrenergic innvervation
• inactive unitl puberty
• special types
  
  • cerminous glands
  • glands of moll

Question 27

Wha tis the structure of the hair follicle

Answer 27

• Develope from epidermis as elastic and keratinized threads
  
  • root sheaths (external adn internal)
  • hair shaft
  • hairbulb
• Savaceous galnds and arrector pilu musces are associated with ahir follicles

Question 28

What is the structure of the hair bulb?

Answer 28

• exapnded lower part of hair follicle
• matrix (allows hair to grow long)
• vascularized dermal papilla

Question 29

What is the structure of both external and internal root sheaths?

Answer 29

• external
  
  • down growth of epidermis
• internal
  
  • generated by bulb matrix
  • layers
    
    • henles layer (outemost)
    • huxleys layer
    • cuticle
      
      • interlocks with cuticle of hair shaft

Question 30

What is structure of the hair shaft?

Answer 30

• medulla (inner most)
• cortex
• curticle

Question 31

tissue slide

Answer 31

Question 32

tissue slide

Answer 32

Question 33

tissue slide

Answer 33

Question 34

tissue slide

Answer 34

Question 35

tissue slide

Answer 35

Question 36

tissue slide

Answer 36

Question 37

What are keratinocyte stem cells

Answer 37

• Reeastablish epiderm in sverly burned patients
• MIgration pathways
  
  • bulb-epidermis stem cell pathway
  • bulb sebaceous gland stem cell pathway
  • Bulb hair stem cell pathway
• Singaling pathways
  
  • wnt signaling pathway
  • notch signaling pathway