Skin Anatomy

Question 1

Skin Functions

Answer 1

1. Homeostasis
2. Provides boundaries for fluid retention
3. Protects underlying tissues
4. Modulates body temperature
5. Excretes urea, salts, water
6. Vitamin D synthesis
7. Sensory receptor

Question 2

Types of tissues and functions

Answer 2

1. epithelial
   
   • covers surfaces, forms glands
2. connective
   
   • supports body and organs
   • store fat/energy
   • immune cells
3. muscular
   
   • 4. nervous
   • cutaneous innervation
   • visceral innervation

Question 3

Epithelia Classification

Answer 3

Number of layers:

1. Simple
2. Stratified

Shape of cells:

• squamous
• cuboidal
• columnar
• pseudostratified

*Shape is important in determining function

Question 4

simple squamous

Answer 4

• diffusion, transport
• ex. filtration in the kidneys, air sacs in lungs, blood vessels

Question 5

stratified squamous

Answer 5

• protects againts abrasion
• lines estophagus, mouth, and vagina

Question 6

simple cuboidal

Answer 6

• involved in active transport
• secretion and absorption
• found in kidney tubules, small glands

Question 7

stratified cuboidal

Answer 7

• protective tissue
• found in sweat glands, salivary glands, mammary glands

Question 8

simple columnar

Answer 8

• absorption
• mucus, enzyme secretions
• found in bronchi, uterus, digestive tract, parts of the bladder

Question 9

stratified columnar

Answer 9

• secretion
• protection
• found in male urethra and some glandular ducts

Question 10

pseudostratified columnar

Answer 10

• secretion and movement of mucus
• found in trachea and most of upper respiratory tract

Question 11

transitional epithelium

Answer 11

• allows the urinary organs to expand and stretch
• lines the bladder, urethra, and ureters

Question 12

Primary Layers of Skin

Answer 12

1.Epidermis

• Epithelium
• Basement Membrane

2.Dermis

• Dense Connective Tissue
• Vasculature and Nerves

3.Hypodermis

• Loose Connective Tissue
• Adipose Tissue

Question 13

Epidermis

Answer 13

• most superficial layer
• avascular, supplied by diffusion from dermis

Question 14

Layers of Epidermis

Answer 14

1. “Horny Layer”
   
   • stratum corneum
   • stratum lucidum
2. Cellular Layer
   
   • stratum granulosum
   • stratum spinosum
   • stratum basale

Question 15

stratum corneum

Answer 15

• “Cornified layer”
• DEAD cells with hard protein envelope
• Contain keratin
• Protects skin against abrasion and penetration

Question 16

stratum lucidum

Answer 16

• “shiny layer”
• DEAD cells contain keratohyalin
• only on THICK skin (palms and soles)

Question 17

stratum granulosum

Answer 17

• “granular layer”
• cells undergoing apoptosis
• keratinocytes and tonofilaments
• cells contain:
  
  • keratohyalin granules- help form keratin
  • lamellated granules- waterproofing glycolipid

Question 18

stratum spinosum

Answer 18

• “Prickle cell layer”
• cells rich in intermediate filament and desmosomes
• Langerhans cells
  
  • ​star-shaped macrophages

Question 19

stratum basale

Answer 19

• “basal layer”
• place for regeneration
• basal keratinocytes
• Merkel cells
  
  • sense changes in temperature
  • attached to sensory nerve endings
• Melanocytes
  
  • produce melanin
  • originate in neural crest cells
    
    • in basal layer projections into spinosum layer
  • melanin granules cluster on apical side of keratinocyte nucleus
    
    • more melanon stored in keratinocytes

Question 20

basement membrane

Answer 20

• single cuboidal layer held together by desmosomes and hemidesmosomes
• anchors epithelia to the dermis

Question 21

Dermis

Answer 21

• deep to epidermis
• strong, flexible dense connective tissue
• rich in collagen and elastic fibers
• richly supplied with blood vessels, immune cells, and nerves
• 2 Layers:
  
  • Papillary
  • Reticular

Question 22

Papillary layer of dermis

Answer 22

• LOOSE AREOLAR CT
• rich in elastic fibers
• dermal papillae
  
  • finger-like projections that carry vasculature and nerve fibers to epidermis
  • dilate and contrict to influence body temperature

Question 23

Reticular layer of dermis

Answer 23

• DENSE, IRREGULAR CT
• collagen fibers –> strength
• elastic fibers –> elasticity
• flexure lines
  
  • creases over joints where the dermis is anchored to skeletal structures
• other structures:
  
  • adipocytes
  • hair follicles
  • nerves
  • sebaceous glands
  • sweat glands