HLT31507 CERTIFICATE III IN NUTRITION & DIETETIC ASSISTANCE

Week 03SKIN & BODY MEMBRANES

delivered by:Mary-Louise Dieckmann

Body MembranesFunctions:• Lining cavities• Protects organs• Covers body surfaces• Lubricates body surfaces

Classifications of Body Membranes

Two Classifications:

• Epithelial Membranes– Cutaneous membrane– Mucous membrane– Serous membrane

• Connective Membranes

Cutaneous Membrane• Cutaneous membrane = the skin– Dry membrane– Outermost protective boundary

• Superficial Epidermis– Keratinized stratified squamous epithelium

• Dermis (underneath)– Dense connective tissue

Mucous Membranes• Lines all body cavities open to exterior body surface• Adapted for absorption or secretion

Serous Membranes

Lines body cavities that are closed to the exterior of the body

Always occurs in pairsSerous layers separated by

serous fluid

Connective Membranes

• Synovial membranes that cushion or protect their structures

• Contain no epithelial cells

• Line fibrous capsules – synovial joints, bursae and tendon sheaths

The Integumentary System• Skin (cutaneous membrane)• Skin derivatives:– Sweat glands– Oil glands– Hair– Nails

Functions of the Skin• Protects deeper tissue from:– Mechanical, chemical, bacterial and thermal damage– Ultraviolet radiation– Desiccation

• Aids in heat regulation• Aides in excretion of urea and uric acid• Synthesizes Vitamin D

Structure of the Skin

• Epidermis – outer layer– Stratified squamous epithelium. Avascular and

most cells are keratinocytes– Four or five layers (four mostly, five on palms of

hands and soles of feed) • Dermis – underlying layer– Dense connective Tissue

• Hypodermis – not part of the skin– Anchors skin to underlying organs, mostly

comprised of adipose tissue

Epidermis

• Stratum basale• Stratum spinosum• Stratum granulosum• Stratum lucidum (only

in thick skin)• Stratum corneum

Melanin• Pigment produced by melanocytes• Yellow, to brown to black• Mostly found in stratum basale• Amount of melanin produced depends on genetics and exposure to sunlight

Dermis

Two layers:Papillary layer– Projections known as dermal papillae– Pain receptors– Capillary loops

Reticular layer– Blood vessels– Nerve receptors– Glands

Skin Structure

Colour Determinants• Melanin– Yellow, brown or black pigments

• Carotene– Orange-yellow pigment (from vegetables)

• Haemoglobin– Red colouring from blood cells in dermis– Oxygen content determines extent of red colouring

Skin DerivativesSebaceous glands:– Produce oil – lubricates the skin and kills bacteria– Most glands have ducts that empty into hair follicles– Glands activated at puberty

Skin DerivativesSweat Glands– Widely distributed across the body– Two types:• Eccrine – open via duct to pore on skin surface• Apocrine – duct empties into hair follicles

Sweat

• Composition:– Mostly water and some metabolic waste– Fatty acids and proteins in apocrine glands

• Function:– Helps dissipate excess heat and excrete waste

products– Acidic nature inhibits the growth of bacteria

• Odour is from bacteria on skin

Homeostatic Imbalances of the Skin

• Infections:– Athletes foot (fungal infection)– Boils and carbuncles (bacterial infection)– Cold Sores (virus)– Contact dermatitis (allergic reaction)– Impetigo (bacterial infection)– Psoriasis (cause unknown, can be triggered by trauma, infection or stress)

Homeostatic Imbalances of the Skin

• Burns– Tissue damage and cell death caused by heat, electricity, chemicals or UV radiation– Associated dangers include:• Dehydration• Electrolyte imbalance• Circulatory shock

Homeostatic Imbalances of the Skin

Skin Cancer• Two types – benign (encapsulated) and malignant (metastasized)

• Most common type of cancer

Homeostatic Imbalances of the Skin

Basal cell carcinoma (BCC)– Least malignant and most common type– Arises from stratus basale

Squamous cell carcinoma (SCC)– Arises from stratum spinosum and metastasizes to lymph nodes – early removal allows good chance of a cure

Melanoma– Most deadly of skin cancer – cancer of melanocytes– Metastasizes rapidly to lymph and blood vessels– Detected using ABCD rule

Homeostatic Imbalances of the Skin

ABCD Rule:A – Asymmetry (two sides of pigmented mole do not match)B – Border irregularity (borders of mole are not smooth)C – Colour (different colours in pigmented area)D – Diameter (sport is larger than 6mm in diameter)