Ch 5, 1 Skin

Question 1

Epidermis

Answer 1

superficial region, epithelial cells
keratinized stratifies squamous 
Cells:
keratinocytes-produce keratin
melanocytes-produce melanin, 10-20% of lower epidermis
epidermal dendritic -(Langerhans)-macrophages, help to activate body defenses
tactile (mekel) - touch receptors
Thickness: 4-5

Question 2

Dermis

Answer 2

middle region
fibrous connective tissue
vascularized

Question 3

hypodermis

Answer 3

deepest region

• -not part of the skin
  1. subcutaneous layer deep to skin
  2. mostly adipose tissue -padding and insulation
  - anchors skin loosely to muscles

Question 4

thin skin

Answer 4

4 layers

Question 5

thick skin

Answer 5

palms, soles of feet, fingertips
5 layers
extra layer called stratum lucidum

Question 6

stratum basale

epidermis

Answer 6

deepest epidermal
single row of stem cells at base
cells undergo rapid mitosis
journey from basal layer to surface take 25-45 days
contains melanocytes and merkel, and dendritic cells

Question 7

stratum spinosum

epidermis

Answer 7

several layers (usually 5)
cells become flattened as they move up
cells contain network of prekeratin filaments attached to desmosomes
abundant in melanin granules and dendritic cells

Question 8

stratum granulosum

epidermis

Answer 8

3-5 layers in which cells flatten from a cube shape
keratin and lamellated granules accumulate
membrane becomes tough and water resistant
cells lose nuclei and other organelles as they die

Question 9

stratum lucidum

epidermis

Answer 9

only in thick skin
thin, transparent band superficial to the stratum granulosum
few rows of flat, dead keratinocytes

Question 10

stratum corneum

epidermis

Answer 10

20-30 layers of dead, fat, keratinized membranous sacs
three quarters of the epidermal thickness
Functions; protection against abrasion, water proofing

Question 11

Dermis

Answer 11

strong, flexible connective tissue
cells include fibroblasts, macrophages, occasionally mast cells amd WBC
2 layers

Question 12

Papillary Layer

dermis

Answer 12

1. areolar connective tissue with collagen and elastin fibers and blood vessels
2. dermal papillae contain..
   capillary loops–aid in diffusion
   meissners corpuscles–touch and light receptors
   free nerve endings–pain sensors
3. Fingerprints-dermal papillary ridges form the epidermal ridges that produces fingerprints

Question 13

reticular layer

dermis

Answer 13

1. 80% of the dermis thickness
2. collagen fibers provide strength and resiliency
3. elastic fibers provide stretch-recoil properties
4. pacinian corpuscle–deep pressure sensors

Question 14

Skin Colour

Answer 14

three pigments contribute

Question 15

melanin

Answer 15

• produced by melanocytes
• yellow to reddish brown to black colour
• migrates to keratinocytes where forms pigment shields for nuclei
• local accumulations of melanin-freckles and moles
• against UF light

Question 16

Carotene

Answer 16

yellow to orange, most obvious in the palms and soles

Question 17

Hemoglobin

Answer 17

pinkish hue of skin

Question 18

cyanosis

Answer 18

abnormal skin colour
lack of oxygen
blue colour

Question 19

jaundice

Answer 19

abnormal skin colour
high bilirubin in blood-liver malfunction
yellow

Question 20

Pallor

Answer 20

abnormal skin colour

anemia-blood loss

Question 21

Blushing

Answer 21

abnormal skin colour
nervous system response to embarrassment
dilation of surface blood vessels