The Dermis

The Dermis• Strong and stretchy – holds your body

together• Dense fibrous connective tissue– Water– Fibroblasts that produce collagen and elastin– Collagen and elastic fibers• Holds water and keeps skin hydrated• Tough and elastic, but we loose them as we age -

WRINKLES

SmokingDepletes the body of vitamin A and C

which are needed for producing collagen.Limits blood flow to connective tissue.Causes Wrinkles

As we age, the collagen production declines and subcutaneous fat

atrophies causing wrinkles.Sun can cause premature aging

Stretch Marks•If skin is seriously overstretched (weight gain, pregnancy, growth), the deep collagen fibers rupture leaving scars.•Steriods can also cause collagen to atrophy leaving stretch marks with muscle growth

The Dermis Continued…• Varies in thickness throughout the body-

thicker on the palms of hands and soles of feet• 2 layers– Papillary layer – Reticular layer

Papillary layer

• Uneven at the most superficial layer = dermal papillae• Fingerprints• Feeds and nourishes the epidermis• Free nerve endings

– Responsible for feeling pain• Meissner’s corpuscles

– Responsible for light/soft touch– Concentrated in fingertips, palms, lips, tongue

and nipples– # drops by 4 fold between ages 12 and 50

Meissner’s corpuscle

Reticular Layer– The deepest layer– Blood vessels• Help in supplying skin with oxygen and

nutrients• Help regulate body temperature• Also important for healing• If blood flow is restricted to an area for a

period of time, bed sores develop (if a person can’t move- bedridden, in a wheel chair, etc. they are likely to occur)= Decubitis Ulcer

How a bed sore occurs

Decubitis ulcer on a heel

An ulcer on the foot

– Pacinian corpuscles• Responsible for sensing deep pressure • Found deep in the dermis• Sensitive to vibration

– Phagocytes for fighting pathogens

Pacinian Corpuscle

The Glands in the Dermis

• Sebaceous Glands • Sudoriferous Glands– Eccrine

• Produce a clear odorless sweat (water, NaCl, ammonia, urea, uric acid and lactic acid- the part mosquitoes like)

• Released through a pore and help regulate body temp.• If someone stops sweating while they are hot- BAD- can lead to

heat stroke and death.• If it is hot and humid, you are exerting yourself and don’t feel

well, get someplace cool and drink fluids. Exercise and heat can cause you to sweat more than 1 liter of sweat per hour!!! (losing fluids and salts)

• Apocrine Glands- located in the axillary and genital areas- produce a milky or yellowish secretion that is the same as the eccrine secretion plus fatty acids and proteins- It’s odorless until the bacteria on the skin use the proteins and fats and grow in it- Releases “sweat” through hair follicles -May have pheromones?

You can see the difference between Eccrine and Apocrine sweat glands.

Sebaceous Glands• Secret an oily/ waxy matter called SEBUM• Lubricates the skin• Found mostly on face and scalp• Not on the palms or soles• In areas with hair, the sebum is deposited on hair and brought

to surface along hair shaft.• In areas without hair, the sebum comes out of sweat pore• Secrete vernix caseosa- white/waxy/ cheesy looking substance

on newborn babies• Also responsible for Cradle Cap in babies• Steroids can increase sebum production

Vernix caseosa in newborns

Cradle Cap= Seborrhea dermatitis

• Sebum production increases during adolescence and begins to decline around age 20.

• If sebaceous gland is blocked – whitehead• If that sebum dries out - blackhead

Bacteria use sebum as nutrients and cause an immune response, acne.

Hair and Hair Follicles• Functions?

– Eyelashes protect our eyes– Hair on our head may provide a little protection for our head– In early hairier humans- provided a layer of insulation and warmth– Beauty?

• The parts– Hair follicle

• An extension of the epidermis – extending into dermis• Produces hair

– Root• The part of the hair that is IN the follicle

– Shaft• The part of the hair that protrudes from skin• 3 parts

– Medulla = the central core– Cortex = surrounds the medulla– Cuticle = outermost region – what we see

Guinness Record – 18ft 5.45 in

The shape of the hair shaft determines the type of hair you have.

*

• Curly hair tends to be drier- Need a creamier more moisturizing shampoo to coat and protect

• Fine, Oily, limp hair– Panthenol, frequent, gentle daily shampoo. Tea

tree oil

Observe your nails….

A Nail • A scalelike modification of the epidermis• 3 parts of a nail

– Free edge– Body of nail– Root

• Nail bed– stratum basale of the epidermis– Nail matrix is proximal and responsible for growth– Looks pink because of blood supply underneath except for LUNULA

• Nail folds– Skin folds that overlap the edge of the nails– Most proximal one is the cuticle

Longest nails…