Skin

Question 1

epidermis

Answer 1

1st layer of epithilia, protective, keratinocytes- most abundant cells.

Question 2

Dermis

Answer 2

source of nutrients for unvascularized epithelium, flexible base, contain hair follicles and sweat glands

Question 3

Hypodermis

Answer 3

superficial facia, insulator- lots of fat, shock absorber

Question 4

functions of skin

Answer 4

1. protection- keratin layer is barrier, protection from water
2. sensation- temp/ touch/ pain
3. thermoregulation- constant core body temp, sweat vasoconstrict to conserve heat
4. metabolism- vitamin D synthesis then goes to kidney and liver

Question 5

Layers of the epidermis

Answer 5

• basal layer
• spinous layer
• granular layer
• lucid layer- only in realy thick skin
• cornified layer

Question 6

basal layer

Answer 6

separated from the dermis by the basement membrane with hemidesmosomes. Mitotic activity all cell division happen here

Question 7

spinous layer

Answer 7

have cells than synthesize cytokeratins that aggregate to form tonofilaments- which associated with desmosomes and hemidesmosomes.

Question 8

granular layer

Answer 8

keratohyalin granules are present, high in protein, filaggrin- dense packing of filaments, lamellar bodies- secrete glycolipids for hydrophobicity

Question 9

cornified layer

Answer 9

layers of fried waxy keratinized cells, cells apoptosis,

Question 10

basal lamina

Answer 10

lamina lucida- clear zone

lamina densa- filamentous type 4 collagen

Question 11

Hemidesmosomes

Answer 11

target for autoimmune diseases causing blisters to form- ex. pemphigus

Question 12

Nonkeratinocytes: langerhans

Answer 12

antigen presenting cells, trap external antigens to send to lymph nodes, found in suprabasal layer

Question 13

nonkeratinocyte: melanocyte

Answer 13

have cytoplasmic extensions, cover nucleus from UV radiation

Question 14

nonkeratinocyte: merkel cells

Answer 14

basal layer, touch receptors

Question 15

Dermis:

Answer 15

1. papilary layer: loose connective tissue
2. reticular layer: dense irregular connective tissue
   contains secretory gands, hair follicles, fibroblasts, collagen, proteoglycans

Question 16

sensory receptors

Answer 16

1. meissner corpuscles: tactile receptors
2. free nerve endings: lack myelin or schwann cells
3. ruffini end organ: responds to stretching
4. pacinian corpuscles: pressure sensitive

Question 17

2 major glands

Answer 17

1. sweat- eccrine and apocrine long coiled ducts that reach to epidermis
2. sebaceous glands- secrete oily products into hair follicles