Lecture 9(unit 2)-integumentary System

Question 1

Functions of the integumentary system

Answer 1

• Protection
• Body temperature regulation
• Excretion
• Vitamin D3 synthesis
• Sensory input
• Lipid storage
• Immune Function

Question 2

Epidermis overview

Answer 2

• Multiple (5)layers of cells (stratified squamous Epithelium)
• Deeper layers of epidermis form epidermal ridges

Question 3

Primary cell type in epidermis?

Answer 3

-Keratinocytes
•Body’s most abundant epithelial cell.
•Continuously produced by stem cell divisional deepest layers.
•Shed at exposed surfaces

Question 4

Epidermis layers from top to bottom

Answer 4

1. Stratum Corneum
2. Stratum Lucidum (only in thick skin)
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Basale (Stratum germinativum)

Question 5

Thin skin vs. Thick skin

Answer 5

-Thin skin
   • Covers most of body surface 
   • Contains 4 strata (layers)
   • About as thick as a plastic sandwich bag
-Thick skin
   • Found on palms of hands and soles of feet
   • Contains 5 strata (layers)
   • About as thick as paper towel

Question 6

Stratum Basale

Answer 6

• Basal (bottom) layer of the epidermis
• Attached to basement membrane by hemidesmosomes
• Most cells here are basal cells, stem cells that divide to replace more superficial keratinocytes
• Merkel cells that respond to touch are also found here

Question 7

Fingerprints

Answer 7

• Pattern of epidermal ridges on surface of fingertips
• Determined by genes and intrauterine environment during fetal development
• Unique pattern that does not change during lifetime
• Used to identify individuals

Question 8

Stratum Spinosum (“spiny layer”)

Answer 8

• Composed If 8-10 layers of keratinocytes bound together by desmosomes
• Only looks spiny when on a prepared slide

-Contains dendritic (Langerhans) cells
• Part of immune response defending against microorganisms and superficial skin cancers

Question 9

Stratum granulosum (“grainy layer”)

Answer 9

• Composed of 3-5 layers of keratinocytes
• Most cells have stopped dividing and started producing keratin and keratohyalin
• Cells grow thinner and flatter
• Cell membranes thicken and become less permeable

Question 10

Stratum lucidum (“clear layer”)

Answer 10

• Found only in thick skin
• Separates stratum corneum from underlying layers
• Flattened, densely packed dead cells filled with keratin and keratohylin

Question 11

Stratum corneum (cornum, horn)

Answer 11

• Outermost, protective region with 15-30 layers of keratinized cells (filled with keratin)
• Dead Cells still tightly connected by desmosomes

-Water resistant, not waterproof
• Lose water through INSENSIBLE PERSPIRATION ( unable to see or feel) and SENSIBLE PERSPIRATION(sweat)

Question 12

Hypodermis

Answer 12

• Skin rests on it, but it’s not part of skin
• Aka “Subcutaneous Tissue”, “Superficial fascia”
• Consists of loose connective tissue

-Types of Cells:
•Fibroblasts
•Adipocytes
•Macrophages

Question 13

Factors affecting skin color

Answer 13

-Hereditary factors:
•Amount of melanin

-Environmental factors:
•Sunlight UV

-Physilogical Factors:
•Vassodialation/Vasoconstriction of dermal blood vessels
•Excercise, blushing
•Accumalation of dietary carotene (orange/yellow color)

Question 14

Sensory receptors in the integument

Answer 14

• 400cm of nerve fibers per cm2 of skin

Question 15

Receptors in the epidermis

Answer 15

-Free nerve endings
• Sensitive to touch and pressure
• Between epidermal Cells

-Tactile discs
• Detect texture and steady pressure
• Found in deepest layer of epidermis

Question 16

Receptors in the dermis

Answer 16

• Meissner’s corpuscles
  • Detect light touch, pressure, and vibration
  • Found in the papillary layer
• Ruffini Corpuscles
  • Sensitive to pressure and stretching of skin
  • Found in the reticular layer
• Lamellated (pacinian) corpuscles
  • Detect deep pressure and vibration
  •Found in both dermal layers and in hypodermis

Question 17

What are dermis’s two major layers?

Answer 17

• Papillary layer

- Reticular layer

Question 18

Papillary layer

Answer 18

• Immediately adjacent to stratum basale’s basal lamina

- Compromised of Areolar (loose) connective tissue, capillaries (thermoregulation), nerves, muscle (arrector pili)

Question 19

Reticular layer

Answer 19

• Deep to the papillary layer
• Meshwork of Dense irregular CT . Containing both collagen and elastin. Collagen fibers extend into the hypodermis, anchoring the skin
• Surrounds blood vessels and accessory structures (such as hair follicles, sweat/sebaceous glands)

Question 20

what can u find in Subcutaneous layer/ hypodermis ?

Answer 20

• Adipose

- Blood vessels

Question 21

Found on nails of fingers and toes (for Protection)

Answer 21

• Nail (keratin)
• Lateral nail folds/grooves
• Eponychium (thickened epidermis bear root)
• Lanula (Pale region distal to eponychium)
• Nail bed (pink due to blood vessels underneath)
• Nail toot (extends deep into dermis, active cell division)

Question 22

What happens as you grow older?

Answer 22

• Epidermis thins (germinative cell activity slows)
• Fewer Langerhans Cells (poorer immune system)
• Reduced Vitamin D production
• Reduced meloncyte activity (susceptible to UV damage)
• Loss of secondary sexual characteristics (changes in hair/ body fat distribution)
• Hair follicle activity slows or ceases
• Dermis becomes thin, less elastic wrinkles
• Reduction in skin blood supply and activity of sweat glands less able to lose body heat

Question 23

What are the Four cell types in Epidermis

Answer 23

• Keratinocytes (abundant epithelial Cells in 4-5 layers)
• Melanocytes (produce brown pigment)
• Merkel Cells (sensation touch, surround cell dendrite)
• Langerhans/dendritic Cells (wandering phagocytes [eats bacteria])

Question 24

Hair growth cycle

Answer 24

• Anagen (growth phase)
• Catagen (transition phase)
• Telogen (resting phase)

Question 25

Functions of hair

Answer 25

• Thermoregulation
• Protect against UV light
• Guard nostrils/ears/ eyes from foreign particles/ insects
• Social Function (mate attraction, aggression, etc)