Comprehension STOP!
Use your dictionary to find out the meaning of the bold words below.
The Skin
The skin is the largest organ in the body. It is comprised of three layers: the epidermis, the dermis and the subcutaneous fat.
The epidermis Dermis
The epidermis is the outer layer of the skin. It is made up of cells that are produced at the bottom of the epidermis. It takes them about four weeks to reach the surface, where they die and get replaced. The body is constantly shedding dead skin cells and making new ones to replace them.
Subcutaneous fat Oil gland Blood vessels
The epidermis also contains melanin. The more melanin a person has, the darker their skin is. Melanin protects us from the sun. However, it needs to be helped by wearing sun cream.
The dermis
The dermis contains blood vessels and nerve endings. Nerve endings send messages to the brain through the nervous system. The nerve endings in the dermis tell the brain about the things we touch. This is very important, as the brain then tells us how to react to what we’ve touched, such as moving away from something hot.
The dermis also contains oil glands and sweat glands. Oil glands create sebum, an oily substance that moves to the surface of the skin and creates an oily layer to moisten and protect the skin. Sweat glands create sweat, which also moves to the epidermis and is released from tiny holes called pores. Sweat helps us to keep cool.
This layer of the skin also contains hair follicles, where hair begins to grow. Hair follicles are connected to arrector pili. These are tiny muscles that contract when we are cold, making our hair stand up and causing goose bumps.
The blood vessels in the dermis narrow when we are cold to keep the blood away from the cool surface of the skin. In addition to this, they widen when we are hot to bring the blood closer to the surface and help us to cool down.
The subcutaneous fat Subcutaneous fat helps to keep us warm and protects our bones and organs.
The skin is often an overlooked organ. However, the many vital jobs it performs makes it one of the most important organs in the body.
32 Glossary
Brain: A large organ that controls the body and the mind
Cells: The building blocks of living things, which carry out important jobs for the body
Nervous system: Controls all actions in the body
Blood vessel: A small tube that carries blood around the body
Epidermis
Nerve endings Sweat gland Pore Hair follicle Arrector pili
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