Introduction to skin L2

Introduction to Skin Integumentary System

First session

What does skin do?

• Prevents dehydration

• Helps maintain body temperature

• Helps excrete excess water & waste

• Helps protect the body

The Skin

• The skin is the largest organ in the body, (almost 20sq feet) and is subjected to continuous wear & tear
• The study of the skin is called dermatology
• The skin hair and nails are collectively called the integumentary system

Key latin terms (Roots)

• Epi - Outer or outermost
• Hypo - low
• Hyper -high
• Stratum - stripe, layer

The Skin

Outer part of the body and is divided into 3 parts

The Epidermis

Stratum Corneum/Horny Layer

• Outer most layer of the skin

• Approx. as thick as a sheet of paper

• Made up of 5 layers.

Stratum Lucidium/Clear Layer

Stratum Granulosum / Grainy Layer

Stratum Spinosum / Spikey or Spiney Layer

Stratum Germinativum / Base or Basal Layer

You will need to know these and the order of growth

Stratum Germivatum/ Basal layer

• The deepest layer of the epidermis containing cells (keratinocyte stem cells) that are constantly dividing by the process of MITOSIS and pushing cells into the next layer of the epidermis
• Contains brown pigment producing cells called MELANOCYTES
• New cells are made in the deepest layer (stratum Germinativum/Basal cell layer) and rise to the surface as they mature. This process is called DESQUAMATION

It takes approx 2 weeks for cells to rise from the Basel cell layer to the horny layer and then a further 2 weeks to die and fall off.

Stratum Spinosum / Spikey Layer

• Made up of about 10 rows of prickly shaped cells which can no longer divide.
• Largest layer of the epidermis

Stratum Granulosum/ Grainy Layer

• In this layer the prickly cells gradually flatten out and are filled with granules which are the precursors to Keratin (A tough, fibrous, insoluble protein).
• Also aids in waterproofing the skin.

Stratum Lucidium/ Clear Layer

• A wavy thin line of see through cells, not present all over the body, mainly in the palms of hand and soles of feet.
• It is thought to play a part in the formation of fingerprints

Stratum Coreum / Horny Layer

• Outer most layer made up of dead & dying cells
• As new cells are pushed up from below the horny top layer is pushed off
• We shed skin cells every day
• This layer is not present under the nails as the thnail itself protects the delicate structures beneath.

The Dermis

• Thicker layer under the Epidermis
• Known as the true skin
• Roughly 1-2mm thick, 3mm on soles & palms. Thinner in females
• Contains specialised structures of glands & hairs

Subcutaneous Layer / Hypodermis

• Deepest layer of the epidermis

• Made up primarily of fat cells and adipose tissue

We will look at these in detail next week

Wordwall Epidermis Quiz

https://wordwall.net/resource/88081916

Home Work

1. Learn the names of the 5 layers of the Epidermis
2. Learn the order that the Epidermis layers grow

There will be a quiz at the start of next lesson