SKIN—THE LARGEST ORGAN

Hypodermis ( subcutaneous layer)

> made up of loose connective tissue and fat >contains larger blood vessels and nerves than those found in the dermis.

Blood vessels in the Dermis

>During exercise, active muscles release heat energy, which is carried away by the blood >Blood vessels in the dermis dilate or expand, allowing more blood to flow through, which draws heat from the body core towards the skin, where it can leave the body.

sweat glands

sweat glands in the dermis to release liquid to the surface of the skin when temperature rises

Dermis

>The dermis helps to maintain body temperature (thermoregulation) >slight shifts in temperature can change the rates of chemical reactions within cells.

Skin

>The skin has three distinct layers, the epidermis and dermis, and the hypodermis

Blood vessels in the Dermis

>They provide nutrients and oxygen to the skin, also play a role in thermoregulation.

Integument system

>considered an organ because it consists of all four tissue types. It also contains accessory organs, such as glands, hair, and nails. > the skin and its accessory organs make up the integumentary system.

Epidermis

>outermost, superficial region of the skin >Structure varies in different areas >act as a physical and biological barrier to the environment.

Function

>primarily used for fat storage > Fat connects skin to underlying tissue and organs, prevent loss of body heat, cushions and protects underlying organs from injury, and serves as a stored energy source that can be used by body cells when needed.

Nerves in the dermis

>take in sensory information on pain, temperature, and itchiness and forward information to the brain to trigger a response

Dermis

>thickest layer of skin >made up of dense irregular connective tissue >Blood vessels, hair follicles, and sweat glands are found in the dermis.

Blood vessels and sweat glands in the Dermis

When your body gets cold Blood vessels will contract, decreasing the flow of heat-carrying blood through the skin to minimize heat loss. Sweat glands will stop producing sweat in order to minimize heat loss through evaporation.

Melanin

influence skin color, provides protection from ultraviolet radiation. The pigment builds up around the nucleus of the skin cells and act as a shield to protect the nuclear DNA from the ultraviolet radiation

Melanocytes

specialized cells that produce a skin-darkening pigment called melanin.

Stratum layer

tightly packed cells of the epidermis provide a protective barrier that prevents foreign and infectious substances from entering the body.

Merkel cells

touch receptors associated with sensory nerve endings. > found in the stratum basal layer of the epidermis >allow us to sense what is happening on the outside of our body