1.1 Describe the anatomy and physiology of the skin in relation to skin breakdown and the development of pressure sores

This guide will help you answer 1.1 Describe the anatomy and physiology of the skin in relation to skin breakdown and the development of pressure sores.

Understanding the structure and function of the skin is essential in recognising how skin breakdown and pressure sores (also known as pressure ulcers) develop. The skin is the largest organ of the body and provides a critical protective barrier. Its anatomy and physiology play an essential role in keeping the body’s internal environment stable, but when compromised, this increases vulnerability to damage like pressure sores.

The Anatomy of the Skin

The skin has three main layers: the epidermis, the dermis, and the subcutaneous (fat) layer. Each layer contributes to the integrity and functionality of the skin.

Epidermis

The epidermis is the thin, outermost layer of the skin. It serves as a protective shield against environmental factors like bacteria, dirt, and harmful ultraviolet (UV) rays.

Key features of the epidermis include:

• Keratinocytes: These cells produce keratin, a protein that strengthens and waterproofs the skin.
• Melanocytes: These produce melanin, giving skin its pigment and protecting it from UV damage.
• Langerhans Cells: These are part of the immune system and help detect harmful bacteria or viruses.
• Stratum Corneum: This is the outermost part of the epidermis, consisting of dead skin cells that are continually shed and replaced.

The epidermis does not contain blood vessels. Nourishment for this layer comes from the blood supply in the dermis beneath it.

While the epidermis renews itself constantly, if it is damaged or exposed to excessive moisture or friction, the protective barrier can weaken. This increases the risk of skin breakdown and contributes to the initial development of pressure sores.

Dermis

The dermis lies below the epidermis and is thicker. This layer provides elasticity, strength, and support to the skin. It contains a variety of components:

• Collagen and Elastin Fibres: These give the skin its structure and the ability to stretch and recoil.
• Blood Vessels: These ensure a steady supply of oxygen and nutrients to the skin.
• Sweat Glands: These help regulate body temperature.
• Sebaceous (oil) Glands: These moisturise the skin and protect it from dryness.
• Nerve Endings: These allow the skin to sense touch, pressure, pain, and temperature.

Damage to the dermis, such as through prolonged pressure or shear forces, can impair its ability to provide the necessary nutrients to the epidermis. This leads to tissue breakdown.

Subcutaneous Layer

Below the dermis lies the subcutaneous layer, made up primarily of fat and connective tissues. This layer acts as an insulator, conserving body heat, and as a cushion to absorb shocks or pressure.

Key attributes of this layer include:

• Storage of energy in the form of fat.
• Protection of underlying organs and muscles.
• Support for blood vessels and nerves passing into the dermis.

When pressure persists long enough to compress the blood flow in this layer, cells begin to die, significantly increasing the risk of a deep, more severe pressure sore.

Physiology of the Skin and Its Role

The primary functions of the skin include protection, sensation, temperature regulation, and excretion. These physiological roles make the skin essential for overall health.

Protective Function

The skin acts as the first line of defence against physical, chemical, and microbial harm. Its tough cells and waterproof surface prevent bacteria, toxins, and harmful substances from accessing deeper tissues. Breaks in this defence, such as skin tears or ulcers, leave underlying tissues more vulnerable to infection.

Sensation

Nerve endings embedded in the dermis allow the skin to detect changes in temperature and pressure. These sensory signals alert the body to conditions that might cause harm, such as excessive heat or the discomfort of prolonged pressure in one area. If these signals are ignored or diminished, the likelihood of pressure damage increases.

Temperature Regulation

Sweat glands within the dermis release sweat to cool the body, while blood vessels dilate or constrict to retain or release heat. Impaired circulation due to pressure can interrupt this function, leading to overheating or tissue damage.

Excretion and Absorption

Skin allows waste products such as urea and salts to be excreted through sweat. It can also absorb certain substances, such as creams and medications. However, excessive absorption of moisture from prolonged incontinence or sweating can make skin more fragile and prone to breakdown.

Factors Leading to Skin Breakdown

Skin breakdown occurs when the structure or function of the skin is compromised. This can happen due to physical, internal, or environmental factors. Common causes that lead to skin breakdown in the context of pressure sores include:

• Pressure: Prolonged pressure on an area reduces blood flow, depleting oxygen and nutrients needed to keep skin tissue alive.
• Shearing Forces: This occurs when skin is dragged or pulled, such as when repositioning a person in bed. Shearing damages deep tissues beneath the skin.
• Friction: Repeated rubbing weakens the top layer of the epidermis and exposes it to further damage.
• Moisture: Excessive moisture, whether from sweating, wound exudate, or incontinence, softens the skin and makes it more prone to tears and infections.
• Poor Nutrition and Hydration: Lack of proper nutrients and water makes the skin less supple and resilient, increasing vulnerability.
• Medical Conditions: Conditions such as diabetes, arteriosclerosis, or reduced mobility compromise circulation, making the skin more prone to breakdown.

Development of Pressure Sores

Pressure sores develop when sustained pressure or friction damages the skin and underlying tissue. The process begins subtly but can worsen without intervention. Understanding how they form helps care workers provide effective prevention and support.

Stage 1: Non-Blanching Redness

In the initial stage, the skin appears red or discoloured, and it does not turn white when pressed (non-blanching). The area may feel warmer or cooler than the surrounding skin and may be tender or itchy. At this stage, damage is reversible if pressure is relieved.

Stage 2: Partial Thickness Loss

This stage involves damage to the epidermis and possibly the dermis, creating an open wound or blister. The wound may be shallow and appear as a clear fluid-filled blister or a pink, painful sore.

Stage 3: Full Thickness Skin Loss

At this stage, the damage reaches the subcutaneous layer. The sore appears as a deep crater, and fat tissue may be visible. Dead (necrotic) tissue and signs of infection, such as redness and fever, are common.

Stage 4: Full Thickness Tissue Loss

This is the most severe stage. The ulcer extends deeper into muscles, tendons, or even bones. Large amounts of necrotic tissue are likely present, increasing the risk of serious infections such as sepsis.

Preventative Measures

Preventing pressure sores starts with understanding the factors that lead to their development.

Strategies include:

• Regular Repositioning: Changing a person’s position often reduces prolonged pressure on one area.
• Skin Inspection: Frequent checks identify early signs of redness or skin breakdown.
• Use of Pressure-Relief Devices: Special mattresses, cushions, and overlays help distribute pressure evenly.
• Good Nutrition and Hydration: Providing sufficient calories, protein, vitamins, and fluids strengthens skin integrity.
• Ensuring Clean and Dry Skin: Rapidly cleaning and drying areas exposed to sweat or incontinence prevents excessive moisture.

Final Thoughts

The anatomy and physiology of the skin highlight its role as a protective yet vulnerable organ. Damage to its layers or interruption of its functions leaves the body susceptible to problems such as pressure sores. By understanding the structure and the factors that weaken the skin, care workers can take steps to prevent and manage skin breakdown effectively. Early intervention and consistent care make a significant difference in maintaining healthy skin and improving the well-being of those at risk.