All about skin

Skin is the biggest organ in your body.

It makes up around 10-15% of your body weight and it is a flexible, waterproof and airtight barrier from the outside environment.

The skin has 3 layers

• The epidermis – the outermost layer, and your body's first line of defence. Though thin, it forms a waterproof barrier that protects what's underneath. It's also home to melanocytes, the cells responsible for your skin's colour and its natural response to sun exposure.

• The dermis – sitting beneath the epidermis, this layer is significantly thicker and does much of the heavy lifting. It's made up of tough connective tissue and houses blood vessels, nerves, hair follicles and sweat glands.

• The subcutaneous layer – the deepest layer, made up largely of fat and larger blood vessels. It cushions the

  body, helps regulate temperature, and anchors the skin to the muscles and bones beneath it.

  
  

The epidermis is home to a few key players, each with an important job to do.

• Keratinocytes are the main cells in this layer, and they're constantly on the move. They begin life at the base of the epidermis and slowly journey upward over about four weeks, eventually reaching the surface (this layer is called the stratum corneum) where they're shed — making way for the next generation underneath. It's a continuous renewal process happening beneath the surface, whether we notice it or not.

• Langerhans cells act as the skin's immune sentries. They're specialised cells that help the body recognise and respond to foreign invaders and infections, forming a key part of our first-line defence.

• Then there are the melanocytes, the cells responsible for pigment. Interestingly, everyone has roughly the same number of melanocytes — what differs is how much pigment (melanin) they produce. In darker skin, melanocytes produce more melanin, which offers greater natural protection against sun damage. In lighter skin, melanocytes produce less, which is why fair-skinned people tend to be more vulnerable to the effects of UV exposure over time.

  
  

How does sun damage and skin cancer occur?

So what happens when this natural sun protection is pushed to its limit? 

Every time skin is exposed to UV radiation, melanocytes ramp up melanin production in an effort to shield the surrounding cells — it's essentially the body's built-in sunscreen. But this protection has a ceiling, and unlike a suntan might suggest, no amount of melanin can fully undo the damage UV rays cause at a cellular level. Over years of exposure, this damage doesn't disappear — it accumulates, quietly building up in the skin long before any visible signs appear. Damaged cells normally get repaired or die off, but sometimes DNA damage disrupts that process and cells start dividing uncontrollably instead. It's this uncontrolled growth that develops into melanoma, one of the most serious forms of skin cancer.

The sun and aging

The cumulative, often invisible, nature of UV damage also explains why skin ages the way it does. 

Not all skin ageing is the same

•  chronological ageing (the natural, gradual changes that happen with time, regardless of sun exposure) 

• photoageing (damage caused specifically by UV exposure, which tends to show up as wrinkles, pigmentation changes, and loss of skin elasticity). The tricky part is that photoageing doesn't announce itself immediately; the damage is often laid down years, even decades, before it becomes visible. 

This is exactly why regular skin checks matter — by the time changes are noticeable to the naked eye, the groundwork may have been forming for a long time.

If you are ready to come and see one of our very experienced skin cancer practitioners you can either call us on (08) 7557 9611 or head over to our website https://www.gawlerbarossaskincancerclinic.com.au/

You can read more about our Doctors and melanographer, see our pricing structure and book in your skin check. 

We can’t wait to meet you.