The Integumentary System (the skin)

Part 5 of the Epidermis, Stratum Basale

* 1-2 layers of cells made up of dividing keratinocytes * Melanocytes are present that connect to many keratinocytes through finger-like projections * Merkel cells are present and respond to touch

Ruffini Endings

* Receptor that shows very LITTLE adaptation and responds to sustained touch, pressure, and stretch * The most can be found in the fingernail where they can detect pressure while gripping and allows us to hold on to objects we carry

Nails

* Sheets of hardened keratinocytes * Reinforce and protect distal ends of fingers & toes * Nail Matrix produces new growth * Lunula is thick area over matrix Nails are kind of like thin plates. The "plate" looks pink because of the blood vessels below it

Merkel Disks

* Slowly adapts to and responds to changes in positions, pressure, and texture * Allows you to decipher, rough, smooth, soft, or hard (etc.)

Integumentary System:

Protects the internal body from damage. Protection is the most important function and main barrier between the environment and internal organs of the body, shielding them from injury, bacteria, chemical invasion, and UV rays. * Skin, hair, and nails

Meissner corpuscle

* A mechanoreceptor that is rapidly adapting and responds to changes in texture and slow vibrations * They are the most sensitive to light touch in concentrated in areas like the fingers and lips

Pacinian corpuscles

* A mechanoreceptor that is rapidly adapting and responds to deep pressure and slow vibrations

Keratinocytes

* Almost 90% of cells in the epidermis are keratinocytes * Produce and store keratin (green) * Keratin makes cells tough, scaly, and water-resistant

Part 2 of the Epidermis, Stratum Lucidum

* Also composed of dead keratinocytes * Not "Fully Karatinized" * Is only found on the palms of your hands and soles of your feet to provide an extra layer of thickness

Skin Color

* Amount & kind of melanin - ranges from yellow to brown to black; determined by genetics * Amount of carotene * Amount of hemoglobin

Hypodermis

* Attaches skin to muscle/bone * Controls body temperature * Stores fat, protecting muscles / bones * Gives shape to the body and acts as a heat insulator

Blood Vessels

* Blood vessels supply oxygen and nutrients to the epidermis * They carry white blood cells to help fight infection

Part 1 of the Epidermis, Stratum Corneum

* Composed of multiple layers (10-30) of flattened and dead keratinocytes * Dehydrated cells that are "Fully Karatinized" * Provide a protective barrier for the rest of our skin and our internal organs * This layer is thickest in palms of your hands and soles of your feet

Hair Follicle

* Consists of tightly packed kerotinocytes * Melonocytes provide pigment for hair color * The bulbous end is called papilla

Dermis

* Creates sweat * Where the root of each hair is * Brings blood to your skin * Nerves in the dermis tell your brain if something feels nice or if it hurts * Provides strength and elasticity to the skin

Langerhans Cell

* Found in the stratum basale, spinosum, and granulosum * They are antigen-presenting cells which mean they eat foreign microbes and process them to be presented to the lymphocytes to activate the immune system

Part 3 of the Epidermis, Stratum Granulosum

* Keratinocytes are still migrating upward and have lost their nuclei, they still have a cytoplasm * They secrete lipids to form a lipid barrier * It forms a barrier between the active cells of the lower epidermis and the outer dead cells

Part 4 of the Epidermis, Stratum Spinosum

* Keratinocytes retain their nuclei and organelles * Begin the production of Keratin in this layer * Keratinocytes here have spine-like projections which gives rise to this cell layer name

Epidermis

* Layer of skin that you can see * Makes new skin cells at the bottom * Skin cells travel up to the top and flake off after a month * Makes melanin which creates your skin color

Composition of Sweat

* Mostly water * Some salts (electrolytes) * Vitamin C * Metabolic wastes Low pH of sweat inhibits bacterial growth

Free Nerve Endings

* Nerve ending sin the skin are associated with different sense organs to detect touch, temperature, itching, pressure and pain (TTIPP)

Sebaceous Gland

* Produce any oily waxy materials * Helps lubricate and waterproof the skin * Connected to the hair follicles and spread the sebum top the surface of the skin

Melanocyte

* Produces the pigment melanin * Protects the skin from UV radiation

Arrector Pili Muscle

* Small bands of smooth muscle cells connect the hair follicle to the dermis * When the muscles contract, the hair is pulled upright causing a bump in the skin's surface -- we call these " goose bumps"

Fat (adipose) Tissue

* Stores energy * Regulates temperature * Provides protecting cushioning

Sweat Glands

* Sweat is produced by glands deep in the skin * Controls body temperature * Helps keep us cool

Hair

* The average human has over 5 million hairs on their body! * Preserves heat * Hair in nose, ears, and around eyes protect from dust and other small particles * Only a few areas of the body are hairless - the palms of the hands, the soles of the feet, and the lips

Vitamin D

* The skin produces Vitamin D from sunlight * It helps the body absorb important minerals

Krause end Bulbs

* Thermoreceptor that specialized in cold temperatures * They are located in specialized areas (eyes, lips, and tongue)

Apocrine Sweat Gland

* This connects to the hair follicle and secretes a milky type of sweat * Since this type of sweat is nutrient rich, it is the source of bacterial growth and is responsible for most body odor

Eccrine Sweat Gland

* This connects to the surface of the skin and exits through a pore * It is the major type of sweat gland and if found all over the skin to regulate temperature * They are found in high density in the palms, soles, and head * Since this type of sweat is mostly water it does not generate a lot of body odor

UV Rays

* Ultraviolet Rays come from the Sun. * The skin produces "melanin". * The darker your skin, the more melanin you have. * Melanin helps protect against UV rays.

Functions of the Integumentary System

1. Protection of internal organs, tissues, and blood vessels 2. Preventing disease form entering 3. Regulating temperature 4. Protecting form UV rays 5. Producing Vitamin D

Other Components of the Dermis

Collagen - protein that gives toughness and hydration Elastin - fibrous glycoprotien that provides elasticity

Hypodermis (Subcutaneous Fat)

Lies between the dermis and underlying tissues and organs. It consists of mostly adipose (fat) tissue and it is the storage site of most body fat