Ch. 5 The Integumentary System

Front 1

4 Major Functions of the Skin

Back 1

1. Protects the underlying body tissues.

2. Helps regulate the body temperature.

3. Receives stimuli from the external environment.

4. Synthesizes vitamin D.

Front 2

Epidermis

Back 2

The outer, thinner layer of skin composed of stratified squamous epithelium.

There are no blood vessels in the tissue, and the cells are packed closely together.

In thin skin found along most body surfaces, there are four different layers, or strata.

In thick skin such as on the palms of the hands and soles of the feet, the epidermis has five strata.

Front 3

Stratum Basale/ Germinativum
(Epidermis)

Back 3

The innermost layer of epidermis lying on the basement membrane next to the dermis.

Is a single cell layer where cell division occurs frequently and new cells push up into the next higher layer as they mature.

Most cells found in this layer are melanocytes, keratinocytes, Merkel cells, and epidermal dendritic cells.

Front 4

Melanocytes

Back 4

Cells that synthesize melanin.

Front 5

Keratinocytes

Back 5

The predominant epidermal cells producing keratin to waterproof the epidermis.

Front 6

Merkel Cells

Back 6

A type of sensory receptor that are sensitive to touch when compressed or disturbed.

Front 7

Epidermal Dendritic Cells

Back 7

Are part of the immune system and are located in the stratum basale.

Front 8

Stratum Spinosum
(Epidermis)

Back 8

The layer above the stratum basale, it consists of keratinocytes with desmosomes intercellular junctions.

The protein keratin is synthesized here.

Less frequent cell division occurs in this layer.

Front 9

Stratum Granulosum
(Epidermis)

Back 9

The layer above the stratum spinosum, this layer is composed of flattened cells with granules of keratohyalin.

This layer is rich in both keratin and keratohyalin.

It contains three to five cell layers, and as the cells die, they are replaced by keratin and keratohyalin.

Front 10

Stratum Lucidum
(Epidermis)

Back 10

The layer above the stratum granulosum, it is found only in thick skin.

The cells are closely packed and clear, and its keratinocytes are usually dead and without nuclei.

The cells are filled with eleidin which is eventually transformed to keratin.

Front 11

Eleidin

Back 11

A transparent substance which is formed from the keratohyalin.

Front 12

Stratum Corneum
(Epidermis)

Back 12

The uppermost layer at the body surface made up of about 25 layers of dead and dry squamous cells.

The cytoplasm of most cells has been replaced by keratin.

Keratin waterproofs the cell surface, while the cells provide a barrier against infection and mechanical injury.

Front 13

The 5 Layers of the Epidermis

Back 13

From deep to superficial:
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum

Front 14

Dermis

Back 14

The second major layer of the skin composed of two layers, the papillary layer and the reticular layer.

Specialized fibrous elements and unique polysaccharide gels help bind the dermis to the epidermis.

This binding prevents large molecules and microorganisms from entering the dermis.

Front 15

Dermis Cont.

Back 15

Communicates closely with the epidermis by the basement membrane.

It is highly vascularized and innervated.

Front 16

Dermal Papillae
(Dermis)

Back 16

Bumps of the dermis that project into the epidermis and form ridges to help anchor the epidermis and dermis together.

Hair follicles are found in the dermal papillae.

Front 17

Papillary Layer
(Dermis)

Back 17

Contains loose, areolar connective tissue having macrophages, blood vessels, fibroblasts, sensory receptors, and other cells.

This layer contains many blood vessels providing nourishment to cells of the epidermis above.

Has sensory receptors for pain, pressure, temperature, and touch.

Front 18

Reticular Layer
(Dermis)

Back 18

Contains sebaceous (oil) glands as well as fat cells, sweat glands, and larger blood vessels.

Contains connective tissues, with fibers running in multiple directions.

Has sensory receptors for pain, pressure, temperature, and touch.

Front 19

Hairs (Pili)

Back 19

A skin derivative found on the entire body except the eyelids, palms of the hands, soles of the feet, and lips.

Are organs of sensation and skin protection.

A hair fiber consists of a shaft extending above the skin surface and a root lying within a hair follicle.

Front 20

Hair Follicle

Back 20

A mass of epidermis, extending down into the dermis and forming a small tube.

It swells at its base to form a hair bulb, which is infiltrated by connective tissues, blood vessels, and nerves to form the dermal papillae.

Front 21

Nails

Back 21

A curved plate of keratin resting on a nail bed supplied with blood vessels.

Formed from the growth of epidermal tissue into the dermis.

Front 22

Sweat (Sudoriferous) Glands

Back 22

The most numerous skin glands.

Subdivided into Eccrine Sweat Glands and Apocrine Sweat Glands.

Front 23

Eccrine Sweat Glands

Back 23

Are widely distributed over the body and produce sweat, which is liberated into ducts.

Front 24

Apocrine Sweat Glands

Back 24

Liberate their secretions to a duct and a portion of the cell is cast off as a vesicle in the process.

Are larger sweat glands found primarily in the tissues of the groin and armpits.

They secrete a scented white, cloudy substance in which bacteria grow and produce end products having odors.

Are active during sexual and emotional stimuli.

Front 25

Ceruminous Glands

Back 25

Located in the ear canal where they secrete cerumin.

Are a form of apocrine skin gland.

Front 26

Mammary Glands

Back 26

Specialized apocrine glands modified for the production and secretion of milk.

Front 27

Sebaceous Glands

Back 27

Secretes the substance sebum, usually into hair follicles.

Are simple, branched, alveolar glands.

Are classified as holocrine glands.

Front 28

Sebum

Back 28

Consists primarily of lipids and oils to keep the hair supple and the skin soft and pliant.

Prevent excess water loss from the epidermis.

Has antibacterial properties.