Skin Part of me is floating in the air around you. I weigh 16% of your body weight I have been called a shield, a temperature control, and an automatic sensor I am waterproof. I belong to the integumentary system I am your body’s largest organ. What am I? Can you imagine the absolute mess you would make if you walked around without your skin on? Flesh would be dangling from your bones, various innards would be trailing along behind you, everyone would be able to see your muscle sinew and so on… you’d look an absolute fright! Now your skin might look like a very tight, one coloured onesie but it is actually a very sophisticated organ. You never think of your skin weighing anything, do you? But in the unfortunate event that is was separated from the rest of your body and you chucked it on your bathroom scales, your skin would come to somewhere between 4 and 8 kilograms (depending on how tall you are!) that’s heavier than a bowling ball. In fact it’s more like a month old baby or a vacuum cleaner. Like everything else in your body, your skin is made up of cells. Remember them? In fact, its made up of 35billion cells. That’s quite a lot by the way. If you stood 35billion hamsters in a line they would stretch all the way around the sun – not that hamsters are exactly the same as cells but you get the idea – 35billion is a big number! Your skin totally sheds and replaces itself every weeks. It’s a bit like getting a brand new outfit once a month except you don’t get to choose what it looks like. It doesn’t shed in one go like a snake or a lizard sheds but rather it flakes constantly A lot of that dust you see around your house and especially in your bedroom when you’ve forgotten to clean it in a while – is actually you – your skin. The amount of skin you shed in your lifetime could fill up an entire wheelbarrow. If you could actually see them as they were coming off it would look like a cloud of very disgusting snow! On the very surface of your skin & hair are microscopic bacteria, viruses, fungi and insects all working together to keep you and your largest organ healthy. It sounds disgusting, and you might just pass out from the grossness if you walked around looking at everyone with microscopic lenses in your glasses but in actual fact the bacteria, viruses and fungi are mostly harmless and nothing to worry about – unless something goes horribly wrong but we will get to that later. Your skin is famous for housing one of your 5 senses – one you rely on a great deal to keep you functioning and safe – your sense of touch – the nerve endings in your skin or receptors can feel 4 things - temperature, pain, pressure or texture? In order for our skin to be able to sense these things it contains many many nerve endings and receptors and I am going to show you where they can be found in the skin along with a few other interesting things in there. If I were to take a punch of skin in the shape of a cube or rectangle from say your leg, this is what it might look like. First there would be a layer of fat at the bottom protecting your whole body and covering your muscle & bone. This layer is called the hypodermis. Hypodermis – or the subcutaneous tissue is where your fat lives. Fat keeps us warm and protects us from bumps and falls. It’s like a massive shin pad that covers your whole body. (the only part of your skin which doesn’t have this layer is the EYELIDS) Dermis – the thick middle layer – there is A LOT going on here. There are a load of blood vessels, nerve endings as well as your sweat and oil glands which stop your skin getting too dry. And sweat comes out your pores and cools your body down when your too hot – like after exercises. Another funny thing about sweat is that is doesn’t actually stink when its fresh out of your sweat glands. It’s only when the bacteria living on your skin decide to take a refreshing sweaty drink that you start stinking. This is the strongest layer of your skin and its what prevents your top layer from ripping like glad wrap. The dermis is the layer which contains your fingerprints and it’s also where tattoo ink goes. Hair follicles are found here along with the arector muscle which is what kicks into gear when your body gets too cold and you start making goodbumps and shivering. The muscle causes your hair to stand on end and creates a blanket of trapped air around you to warm you up – like an invisible blanket. Epidermis – the top layer, the bit you can see or touch. It’s the layer that keeps you waterproof otherwise you’d swell up and go mushy like a sheet of lasagne. Your skin colour also depends on your epidermis because it contains melanin. The more melanin you have the darker your skin colour – the less melanin you have the lighter your skin colour. Also the epidermis has freckles – little patches of melanin. Now lets build an edible skin model together so we can remember the layers & also the main functions of our skin which are temperature control, your sense of touch and protection Lumps and Bumps Now unless you walk around in a robot suit your skin is going to get some sort of damage to your epidermis (the top layer of skin) at some stage. On this poster I have some pictures of real damage to the epidermis. I’m going to choose people to come out and lift one of the flaps – tell me what damage has been done to the skin and how you might treat the damage using what’s here in my home first aid kit – blisters, bruises, burns, school sores, warts, splinters, bites Blisters: this is where rubbing or friction cause the epidermis layer to separate from the dermis layer – causing a fluid filled bubble – the fluid is actually plasma (fun fact). There’s not a whole lot we can do for blisters except apply some sort of healing gel like aloe vera and then cover the blister to prevent it from popping (we want to keep harmful bacteria out of the skin). You can use a special blister bandaid with a raised centre or some petroleum jelly or paw paw ointment and a padded dressing. Bruises: This is where impact has caused blood vessels under your epidermis to burst and pool – they are trapped there. Bruises go from red, to black (oxygen gets used up), to purples, green then yellow. Ice pack wrapped in a thin towel, cream to speed up the healing Sunburn: aloe vera or calamine lotion & cool showers – avoid at all costs (you will see why when we visit the skin dr’s office shortly) Burn from hot water or flame – this is called a first degree burn which means it has only damaged the epidermis - cool running water for 20mins or a cold pack (no ice!) petroleum jelly. 2nd degree = dermis, this may require a trip to the GP and some stronger cream & painkillers as the burn has affected the 2nd layer of the skin called the dermis. 3rd degree burn = the bottom layer - hypodermis, subcutaneous tissue – severe – needs hospital attention – you will likely get wrapped in glad wrap to prevent infection and the damage will leave scars on your other layers. Warts: Salycilic Acid (wart off and a blade) Splinters: Drawing ointment and tweazers Bites: Stingoes – if you have none then toothpaste Often there are skin problems and injuries that just need more than our home kit… or even our regular GP. They require a skin doctor – skin doctors are called Dermatologists. - Eczema (Henry) Melanoma + sun protection (Claire) Activities 1) Sutches using pork skin 2) Polymer clay bake in oven 3D skin models 3) Splinters in oranges (little kids) using tweezers 4) Fingerprints using charcoal/2B pencils 1 small patch of skin 3 metres of blood vessels 600 pain sensors 30 hairs 300 sweat glands 4 oil glands 13 metres of nerves 9000 nerve endings 6 cold sensors 36 heat sensors 75 pressure sensors
