The skin is the largest organ of the human body, with a total area of about 20 square feet. It protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold.
Structure of the Skin
The skin is made up of three layers: the epidermis, dermis, and subcutaneous tissue.
Epidermis: The outermost layer of the skin. It is made up of several layers of cells and is responsible for the waterproof barrier of the skin.
Dermis: The middle layer of the skin. It contains blood vessels, nerve endings, sweat glands, and hair follicles.
Subcutaneous tissue: The innermost layer of the skin. It is made up of fat and connective tissue that insulates the body and cushions the internal organs.
Functions of the Skin
Protection: The skin acts as a barrier that protects the body from harmful microbes, UV radiation, and physical injuries.
Regulation: The skin helps regulate body temperature through sweating and the dilation or constriction of blood vessels.
Sensation: Nerve endings in the skin allow us to sense touch, pressure, temperature, and pain.
Excretion: The skin helps eliminate waste products through sweat.
Construct an argument from evidence to explain the likelihood of an organism’s ability to survive when compared to the resources in a certain habitat (e.g., freshwater organisms survive well, less well, or not at all in saltwater; desert organisms survive well, less well, or not at all in woodlands).
Create models that illustrate how organisms and their habitats make up a system in which the parts depend on each other.