Chapter 5 Integumentary System

Front 1

The skin performs a variety of functions:

Back 1

1. Protection

2. Body Temperature regulation

3. Excretion

4. Production of Vitamin D

5. Sensory Reception

Front 2

Epidermis

Back 2

is a keratinized stratified squamous epithelium that contains four distinct types of cells: Keratinocytes, melanocytes, tactile epithelial cells, and dendritic cells

Front 3

Keratinocytes

Back 3

the most abundant epidermal cell, produce keratin, a tough fibrous protein that gives the epidermis its protective properties

Front 4

Stratum Basale

Back 4

- the deepest epidermal layer, is firmly attached to the underlying dermis along a wavy border line

- it consists of a single row of cells, mostly stem cells representing the youngest keratinocytes (divide rapidly, and many mitotic nuclei)

Front 5

Tactile Epithelial cells

Back 5

- Merkel Cells

- Each hemisphere-shaped tactile epithelial cell is intimately associated with a dislike sensory nerve ending and functions as a receptor for touch

Front 6

Melanocytes

Back 6

- Spider-shaped

- make up about 10% to 25% of the cell in the stratum basale

- make the dark skin pigment melanin

Front 7

Stratum Spinosum (Spine)

Back 7

- Several layers thick of keratinocytes unified by desmosomes

- Cells contain thick bundles of intermediate filaments made of pre-keratin (tonofilaments)

- Mitosis occurs here, but less often than in the basal layer

- Dendritic Cells found in this layer

Front 8

Dendritic Cells

Back 8

- Star-shaped cells are part of the immune system

- Police the outer body surface, using receptor-mediated endocytosis to take up foreign proteins (antigens) that have invaded the epidermis

- They leave the skin and travel to a nearby lymph node

Front 9

Stratum Granulosum (Grain)

Back 9

- One to five layers of flattened keratinocytes

- Organelles are deteriorating and cells above are dead

- Cytoplasm full of lamellar granules and keratohyaline granules

Front 10

Stratum Lucidum (Clear)

Back 10

- occurs in thick skin but not in thin skin

- thin translucent band, few rows of flat, dead keratinocytes (light microscope)

- Cells are identical to those at the bottom of the Stratum Corneum

Front 11

Stratum Corneum

Back 11

- Most external part of the epidermis and is many cells thick

- its dead keratinocytes are flat sacs completely filled with keratin because their nuclei and organelles died with the cell

Front 12

How much skin does a person on average shed in a lifetime?

Back 12

40lbs

Front 13

Dermis

Back 13

- the second major region of the skin, is a strong, flexible connective tissue

- binds the entire body together like a body stocking...it is your "hide"

- Has two regions: Papillary dermis and Reticular dermis

Front 14

Papillary dermis (1) and Dermal Papillae (2)

Back 14

(1) the superficial 20% of the dermis, is areolar connective tissue containing very thin collagen and elastic fibers

(2) fingerlike projections that extend into the overlying epidermis

Front 15

What functions do dermal papillae perform?

Back 15

- Increase the surface area for exchange of gases, nutrients, and waste products between the layers

- interlock the dermis and epidermis and prevents blistering

Front 16

What functions do these epidermal ridges provide?

Back 16

- Increase friction and enhances gripping ability and traction of hands/feet

- Fingerprints = "sweat films" because sweat pores open along the crests of the friction ridges

Front 17

Reticular Dermis

Back 17

- account for about 80% of the thickness of the dermis, is dense irregular connective tissue

- its extracellular matrix contains thick bundles of collagen and elastic fibers that run in many different planes

Front 18

Flexure Lines

Back 18

- result from a continual folding of skin, often over joints, where the dermis attaches tightly to underlying structures

- visible in the fingers, wrists, soles, and toes

Front 19

Dermal Plexus

Back 19

- is located between the hypodermis and the dermis

- it nourishes the hypodermis and the deeper portions of the dermis

Front 20

Subpapillary Plexus

Back 20

- located just below the dermal papillae, supplies the more superficial dermal structures, the dermal papillae, and the epidermis

Front 21

Hypodermis

Back 21

- Also called the superficial fascia and subcutaneous layer

- consists of both areolar and adipose connective tissue

- Functions: stores fat, anchors skin, poor conductor of heat

Front 22

Three pigments contribute to skin color

Back 22

1. Melanine

2. Carotene

3. Hemoglobin

Front 23

Melanine

Back 23

- the most important, is made from an amino acid called tyrosine (interacts with tyrosinase to create melanine)

- ranges from yellow to reddish to brown to black

Front 24

Carotene

Back 24

- is a yellow-orange pigment that the body obtains from vegetable sources such as carrots and tomatoes

- tends to accumulate in the stratum corneum of the epidermis and in the fat of the hypodermis

Front 25

Hemoglobin

Back 25

- the pink hue of Caucasian skin reflects the crimson color of oxygenated hemoglobin in the capillaries of the dermis

- Caucasian skin contains little melamine, the epidermis is nearly transparent and allows the color of blood to show through

Front 26

Hematoma

Back 26

the general term for a clotted mass of escaped blood anywhere in the body

Front 27

Nail

Back 27

- made up of dead, keratinized cells

- is a scalelike modification of the epidermis that corresponds to the hoof or claw of other mammals

- are built-in tools that enable us to pick up small objects and scratch the skin when it itches

Front 28

Skin Appendages

Back 28

- nails, hair, hair follicles, sebaceous (oil) glands, and sweat glands

Front 29

Arrector Pilli Muscle

Back 29

- bundle of smooth muscle that runs from the most superficial part of the dermis to a deep-lying hair follicle

- when this muscle contracts in response to cold or fear, the hair stand erected and the skin surfaces dimples, producing goosebumps

Front 30

Sebaceous Glands

Back 30

- are the skin's oil glands

- they are simple alveolar glands with several alveoli opening into a single duct

- occur over the entire body, except the palm and soles

- Secrets Sebum

Front 31

Holocene Secretion of Sebum?

Back 31

- the central cells in the alveoli accumulate oily lipids until they become engorged and burst apart

- Whole cells break up to form the product