Lifestyle Chemistry Part 3: Skin

Identify the role of skin as: An organ to separate the body from the external environment An organ assisting in body temperature control An organ to protect against entry by disease- causing organisms

Skin Vocabulary

Skin Vocabulary

define the term ‘microflora’ and discuss the role of the microflora on skin in different parts of the body

What is microflora? microflora is defined as microorganisms surviving as microscopic communities. Most microflora on and in the body are bacteria.

More Vocabulary!! Bacteria: single-celled procaryotic organisms belonging to the protist kingdom. Staphylococci: cocci bacteria appearing in grape-like formations. Cocci: sphere-shaped bacteria. Microbes: micro-organisms. Micro-organisms: microscopic, often single-celled, organisms. Sebum: oil produced by sebaceous glands in the dermis. Epidermis: outermost layer of the skin which protects the underlying tissue, forms a barrier from heat loss, water loss and micro-organisms. Keratin: tough protein present in the epidermis of vertebrate organisms.

Microflora and Skin Micro-organisms prefer moist environments. Nutrients available for microflora: Sweat from sweat glands contains sodium chloride and lactate. Sebum, an oily substance from sebaceous glands next to hair follicles.

Microflora and Skin Why does microflora not colonise? The skin surface is constantly losing clumps of dead skin. Any microbes on the skin surface are lost. The pH of skin is slightly acidic – at 5.5 pH. Most microbes prefer a pH neutral environment of 7. For these reasons, only specific microbes are able to survive on the skin surface.

Microflora and Skin The action of microflora on the skin causes the oil on the skin to become acidic. Microbial action on sebum releases smelly gases, commonly referred to as body odour.

Bacteria

Moulds Explain the difference between moulds and bacteria when viewed under a microscope.

1 Types of Microflora Resident microflora Found on the skin surface and are thought to reside in the sebaceous glands under the skin. Bacterial counts are higher where more oil is being produced by sebaceous gland activity. Thought to play an important role in protecting the individual from more pathogenic or disease-causing bacteria. The body is protected from skin diseases and disorders by the microbes living on the skin surface.

2 Types of Microflora Transient microflora The first source is the external environment eg. soil, water and air. Contact with soil, water and air transfers any microbes present to the skin surface. The second source is the natural microflora that comes out of body orifices such as the nasal passages, ear canals and anus. Micro-organisms are transferred to various parts of the body by the hands. Transient microbes can cause diseases such as diarrhoea and meningitis.

discuss the term pH in terms of its ability to describe the acidity of a substance

pH Scale

Explain the relationship between the natural pH of the skin and the action of Microflora Natural oil produced by glands in the skin Perspiration

pH and the Skin The natural pH of the skin is slightly acidic, with a pH range of 4.5 to 6.

pH and the Skin Factors that make our skin slightly acidic: Sebum has a slightly acidic pH Perspiration: Sweat produced by heat is more acidic than sweat in response to exercise.

Identify and explain the use of common components of body soaps, cleaners and shampoos and the reason for their use.

Skin Soaps Soap coats the skin in grease-removing chemicals. They consist of a hydrocarbon chain which is repelled by water but attracted to oil, grease and dirt. Surfactant

Cleansers Common components include mineral oil, water and a stearate. Contain a moisture absorber Dissolve Sebum and loosen particles of grime and dirt.

Shampoos Extra chemicals in shampoo make the lather stay in the hair and remove grease. The detergent in shampoo emulsifies the sebum into the water to be washed away.