The Integumentary System Human Anatomy & Physiology

6 Functions of the Skin

Protection, excretion, sensation, regulation, storage, synthesis

3 Layers of the Skin

1. Epidermis

2. Dermis

3. Hypodermis or Subcutaneous

Layers of the Epidermis

Stratum Corneum

Stratum Lucidum

Stratum Granulosum

Stratum Spinosum

Stratum Basale

Stratum Corneum

Protective outermost layer (25-30 layers of dead skin cells)

What is a callus

Constant exposure to friction in the stratum corneum

Stratum Lucidum

The clear layer (translucent), 3-5 layers of dead cells, produces a precursor to keratin

Stratum Granulosum

Helps waterproof skin, 3-5 layers of flattened keratinocytes, keratin production cells to help keep the skin waterproof, some living cells (not much)

Stratum Spinosum

Spiny layer, 8-10 layers of keratinocytes, some mitosis, strong cells to cell connections, some layers of living cells

Stratum Basale

The birthplace of new cells, single row of cubiodal or columnar cells that are constantly dividing (mitosis), melanocytes present here, if damaged skin cannot regenerate, new cells push older ones outward

Four types of skin cells (found in the epidermis)

Keratinocytes

Melanocytes

Langerhans cells

Merkel cells

Keratinocytes

Keratin producing cells. Keratin is a protein that keeps the skin, 90 of skin cells (keratin producing cells)

Melanocytes

Melanin producing cells. Melanin is brown-black pigment which absorbs UV light, damaged by excessive UV light

Langerhans cells

Part of immune response against microbes, easily damaged by UV light

Merkel cells

work with sensory neurons to detect touch sensations

Dermis

Made of strong and flexible connective tissue (mostly collagen and connective fibers, which is what accounts for elasticity)

Cell types of dermis

Fibroblasts, macrophages, a few mast cells and white blood cells

What are stretch marks

A tear in the dermis

What are wrinkles

As we age collages fibers of the matrix begin to stiffen and break. Excessive sun exposure speeds up the stiffening of the fibers

What are blisters

Separation of the dermis from the epidermis by a fluid-filled pocket

Subcutaneous (Hypodermis)

Consists of loose connective and adipose tissue. Excellent insulator and shock absorber, anchors the skin to the organs below

3 factors responsible for our skin color

1. Melanin

2. Carotene

3. Hemoglobin

Melanin

Produced in stratum basale, brown color. UV light stimulates melanin production (a tan).

Carotene

Yellow/orange pigment/ Comes from many fruits/veggies. The skin the absorbs this pigment.

Hemoglobin

Blood pigment having a reddish color. The more oxygenated the blood, the redder the color

1st Degree Burn

Damage limited to the epidermis

2nd Degree Burn

Damage extends to dermis (has raised blister in addition to the reddening)

3rd Degree Burn

Damage extends even farther to the hypodermis and destruction of tissues. May require skin graft

Grey Hair

A decline in melanin production in our hair = grey hair

Glands

Epithelial cells that secrete

3 types of glands

1. Oil glands (sebaceous glands)

2. Sweat Glands (sudoriferous glands)

3. Ceraminous gland

Oil gland/ Sebaceous glands

Secrete an oily substance called sebum, which prevents epidermal water loss

Pimples

Too much sebum

Sweat glands/sudorigerous glands

Two Types:

1. Eccrine: release the watery sweat through pores in the epidermis to regulate body temp

2. Apocrine: produce a thicker more viscous and pungent sweat

Ceraminous gland

Found in the ear (ear wax)