Integumentary System

Integumentary System

PP #1

Skin Trivia

• 21 square feet – about the size of a blanket
• 4 kilograms/9 pounds, 7% - 15% of total body weight
• Complex combination of tissues
• Continuous layer
• Humans shed about 600,000 particles of skin every hour

– about 1.5 pounds a year.
– By 70 years of age, an average person will have lost 105

pounds of skin

• Over a million dust mites in your bedding feeding on shed

dead skin cells!

Skin Trivia

• 21 square feet – about the size of a blanket
• 4 kilograms/9 pounds, 7% - 15% of total body weight
• Complex combination of tissues
• Continuous layer
• Humans shed about 600,000 particles of skin every hour

– about 1.5 pounds a year.
– By 70 years of age, an average person will have lost 105

pounds of skin

• Over a million dust mites in your bedding feeding on shed

dead skin cells!

One Square Inch Contains

• 20 blood vessels
• 65 hairs & hair muscles
• 78 nerves
• 78 sensors for heat
• 13 sensors for cold
• 160 sensors for

pressure

• 100 sebaceous/oil

glands

• 1300 nerve endings
• 19,500,000 cells
• 0.5 million cells dying &

being replaced

Integumentary System

Skin:
1.

Membrane – covers body

2.

Organ – contains several kinds of tissues

3.

System - organs and other parts that work
together to perform a specific function

3 main layers/regions of skin

1. Epidermis
2. Dermis
3. Subcutaneous

fascia or
hypodermis

Layers/Regions of the Skin

1. Epidermis:

–

outermost layer of skin

–

Made of 5 smaller layers

–

No blood vessels or nerve
cells

–

2 main layers:
1.

Stratum corneum

2.

Germinativum

FYI: Skin renews itself every 28
days! Replaced about 1000 times
over lifetime!

Layers/Regions of the Skin Epidermis -

2 main layers

1. Stratum corneum

• outermost/top

layer

• shed constantly

– dead cells

2. Stratum
Germinativum

• AKA: stratum

basale – Fx:
makes new skin
cells to replace
old cells

Layers/Regions of the Skin - Dermis

2. Dermis - AKA:

– Corium
– True skin

•Dermis is:

– Tough
– Leathery fibrous

connective tissue

– Vascularized

Dermis

• Papillae:

– specialized cells in

the dermis

– one of the three

main layers of skin

– form the bulb of a

hair follicle

– protrusions of

dermal connective
tissue into the
epidermal layer

– made up of thick

collagen fibers

Contents of Dermis - FYI

• Blood vessels
• Capillaries
• Lymphatic vessels
• Nerves
• Hair shafts & hair

follicles (anagen =
growing follicle,
telogen = resting
follicle)

• Arector pili (hair

muscles)

Contents of Dermis - FYI

• Sudoriferous/sweat

glands (eccrine &
apocrine)

• Sebaceous/oil glands

(sebum = lubricant)

• Ceruminous glands

(cerumen/earwax)

• Sensory receptors

Layers/Regions of the Skin

3. Subcutaneous fascia or

Hypodermis:

• Innermost layer
• Mostly fat (insulate &

absorb shock)

• Soft connective tissue
• Anchors skin to

underlying structures

Skin

Anatomy:

Skin
Structures: