Integumentary System

What is the main function of the integumentary system?

Protection

What is keratin?

A dry, tough protein that protects the skin from friction.

What is melanin?

A brown pigment that gives skin its color and protects the skin from UV radiation.

How does the integumentary system regulate temperature?

Sweat helps cool the body.

What are exteroceptors?

Receptors that detect sensations from outside the body.

How does the integumentary system provide sensation?

Exteroceptors and hair receptors detect stimuli from the outside environment.

How does the integumentary system help with metabolism?

It uses cholesterol molecules to help produce vitamin D.

What are the 4 main functions of the integumentary system?

Protection, temperature regulation, sensation, and metabolism.

Keratinocytes

Produce fibrous protein keratin (most common cells)

Melanocytes

Produce brown pigment, melanin

What are Merkel cells?

Sensory cells in the epidermis that help detect light touch.

What are Langerhans cells aka Dendritic cells?

They perform phagocytosis and help defend the skin against pathogens.

Stratum Basele (Germinativum)

Deepest epidermal layer firmly attached to the basal lamina.

What cells does the Stratum Basele have?

Melanocytes, Merkel cells, and active mitotic cells.

Stratum Spinosum

Has 8-10 layers, Keratinocytes are attached to each other by desmosomes.

What cells does the Stratum Spinosum have?

Melanin granules and Langerhans cells are abundant in this layer.

Stratum Granulosum

The layer where keratinocytes flatten, nuclei and organelles disintegrate, and the cell membrane thickens. Keratinocytes produce lamellated granules (lipids) that prevent water from passing between keratinocytes, and they produce keratin.

Stratum Lucidum

Thin translucent band, few rows of flat, dead keratinocytes. Present ONLY in the thick skin where no hair is produced.

Stratum Cornemum

Accounts for three quarters of the epidermal thickness. Takes 15-20 days from basale to corneum then cells shed after 2 weeks.

Dermis

Second major skin region.

What cells does the Dermis have?

Fibroblasts, macrophages, mast cells and white blood cells.

Papillary layer

Made of areolar connective tissue. It forms projections called dermal papillae and contains the papillary plexus, Meissner’s corpuscles, and free nerve endings. Dermal papillae create the ridges that form fingerprints and footprints.

Reticular layer

Approximately 80% of the skin's thickness. It is made of dense irregular connective tissue and contains the cutaneous plexus, hair follicles, sweat glands, and sebaceous glands. Deterioration of elastic fibers with aging can lead to wrinkles.

Hypodermis

Lies superficial to fascia of skeletal muscles. Composed of adipose and areolar CT. Fat storage. Shock absorber. Insulator.

What is the 3 pigments contribute to skin color?

Melanin, freckles and pigmented moles result from local accumulations of melanin.

Carotene

A yellow-orange pigment found in the stratum corneum that can be converted into vitamin A.

What is hemoglobin's role in skin color?

Hemoglobin in the blood contributes to the color of the skin.

Sebaceous glands (holocrine glands)

Secretes sebum into the hair follicle to keep hair moist and inhibits bacterial growth.

Acne

Inflammation caused by bacteria.

Eccrine (menocrine) sweat glands

All over body, more in palms and soles of feet. Regulates body temperature by evaporation.

Apocrine sweat glands

Axilla, groin, face and nipples function at puberty. Release by exocytosis and odorless secretion.

Hair

Millions of hair found all over the body. Nonliving structure made by hair follicles. Hard keratinized cells that do not flake off.

What are the hair main functions?

Sensory and protection.

Nails

Modified epidermis containing hard keratin. It appears pink due to capillaries in dermis. Change in appearances provides useful diagnosis information.

What is the arrector pili?

A small smooth muscle attached to a hair follicle that contracts and causes the hair to stand up (goosebumps).

What is the hair bulb?

The enlarged base of the hair follicle where hair growth begins.

What is the hair follicle?

A tube-like structure in the skin that surrounds and holds the hair root.

What is the hair root?

The portion of the hair located below the skin, inside the hair follicle.

What is the hair shaft?

The portion of the hair that extends above the surface of the skin.

What is a Meissner's (tactile) corpuscle?

A sensory receptor that detects light touch.

What is a Pacinian (lamellated) corpuscle?

A sensory receptor that detects deep pressure and vibration.