BIOH111 o Cell Module o Tissue Module o Integumentary system o Skeletal system o Muscle system o Nervous system o Endocrine system Endeavour College of Natural Health endeavour.edu.au 1
Textbook and required/recommended readings o Principles of anatomy and physiology. Tortora et al; 14 th edition: Chapter 5 Endeavour College of Natural Health endeavour.edu.au 2
BIOH111 INTEGUMENTARY SYSTEM MODULE o Session 6 (Lectures 9 and 10) Structure and function of the skin and accessory structures Endeavour College of Natural Health endeavour.edu.au 3
BIOH111 Lectures 9 and 10 Structure of the skin and accessory structures Department of Bioscience endeavour.edu.au
Preparation for this session o Complete any missing concepts and linking words from Session 5 o Consider epithelial membrane called cutaneous membrane what is it composed of and where can it be found? Endeavour College of Natural Health endeavour.edu.au 5
Lecture 9: Structure of skin Objectives Define and describe the structure of each skin layer Accessory skin structures Define and describe the structure of each accessory skin structure Lecture 10: Functions of skin Define and describe the function the skin Wound healing Describe process of the epidermal wound healing Describe the process of deep wound healing Compare epidermal and deep wound healing Burns Describe types of burns and damages to the skin layer Describe method for measuring the extent of burns Endeavour College of Natural Health endeavour.edu.au 6
INTEGUMENTARY SYSTEM FUNCTIONS o Thermoregulation o Blood reservoir o Protection o Cutaneous sensations o Synthesis of Vitamin D o Excretion Endeavour College of Natural Health endeavour.edu.au 7
GENERAL ANATOMY o Large organ composed of all 4 tissue types; 2m 2 in area; 1-2 mm thick; weight: 4.5 kg o 3 layers (top 2 layers constitute cutaneous membrane): 1. Epidermis: superficial portion; composed of epithelial tissue 2. Dermis: deeper layer; primarily composed of connective tissue 3. Hypodermis (or subcutaneous layer): deepest layer; consists of areolar and adipose tissue; not part of the skin www.webmd.com Endeavour College of Natural Health endeavour.edu.au 8
EPIDERMIS o Stratified squamous epithelium: avascular (contains no blood vessels) 4 types of cells divided into 5 distinct strata (layers) Endeavour College of Natural Health endeavour.edu.au 9
SPECIALISED CELLS OF EPIDERMIS 1. Keratinocytes: produce keratin and contain lamellar granules function: help protect the skin and underlying tissue from heat, microbes, and chemicals; release lipids (waterproof) 2. Melanocytes: produce pigment melanin function: contribute to skin colour and absorb damaging ultraviolet (UV) light 3. Langerhans cells: derived from bone marrow function: participate in immune response 4. Merkel cells: contact tactile (Merkel) disc function: sensation of touch Endeavour College of Natural Health endeavour.edu.au 10
LAYERS (STRATA) OF THE EPIDERMIS Endeavour College of Natural Health endeavour.edu.au 11
STRATUM BASALE (STRATUM GERMINATIVUM) o Deepest single layer of epidermis o Cells: Merkel cells, melanocytes, keratinocytes and stem cells that divide repeatedly; cells attached to each other and to the basement membrane by desmosomes and hemidesmosomes Endeavour College of Natural Health endeavour.edu.au 12
STRATUM SPINOSUM o Cells: mostly keratinocytes; some melanocytes; 8 to 10 cell layers are held together by desmosomes o Function: provides strength and flexibility to the skin o Melanin is phagocytosed by keratinocytes after nearby melanocytes secrete it in secretory vesicles Endeavour College of Natural Health endeavour.edu.au 13
STRATUM GRANULOSUM o Transition layer between the deeper, metabolically active strata and the dead cells of the more superficial strata o Cells: keratinocytes which contain lamellar granules (release lipid that repels water) and dark-staining keratohyalin granules (keratohyalin converts tonofilaments into keratin); 3-5 layers of flat dying cells that show nuclear degeneration Endeavour College of Natural Health endeavour.edu.au 14
STRATUM LUCIDUM o Present only in the fingers tips, palms of the hands, and soles of the feet. o Three to five layers of clear, flat, dead keratinocytes that contain keratin precursor Endeavour College of Natural Health endeavour.edu.au 15
STRATUM CORNEUM o 25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids from lamellar granules; continuously shed o Function: barrier to light, heat, water, chemicals and bacteria o Callus: an abnormal thickening of the epidermis with constant exposure to friction to this layer Endeavour College of Natural Health endeavour.edu.au 16
Epithelial differentiation KERATINIZATION www.studyblue.com o Keratinization is replacement of cell contents with the protein keratin; occurs as cells move to the skin surface over 2-4 weeks Endeavour College of Natural Health endeavour.edu.au 17
DERMIS o Structure: connective tissue layer composed of collagen and elastic fibers, fibroblasts, macrophages and adipocytes o Contains hair follicles, glands, nerves and blood vessels o Two major regions of dermis 1. Papillary region 2. Reticular region Endeavour College of Natural Health endeavour.edu.au 18
1. PAPILLARY REGION o Top 20% of dermis; finger-like projections are called dermal papillae o Structure: areolar connective tissue containing fine elastic fibers, Meissner s corpuscles, free nerve endings, adipose cells, hair follicles, sebaceous glands, sudoriferous glands o Functions: anchors dermis to epidermis; provides strength, extensibility (ability to stretch), and elasticity (ability to return to original shape after stretching) What is the function of the Meissner s corpuscules and free nerve endings? Endeavour College of Natural Health endeavour.edu.au 19
2. RETICULAR REGION o Bottom 80% of dermis o Structure: dense irregular connective tissue that contains interlacing collagen and elastic fibers; oil glands, sweat gland ducts, adipose and hair follicles o Function: provides strength, extensibility and elasticity to skin Endeavour College of Natural Health endeavour.edu.au 20
SKIN COLOUR PIGMENTS o Melanin: complex polymer derived from tyrosine; produced by melanocytes in epidermis UV in sunlight increases melanin production o Carotene: yellow-orange pigment (precursor of vitamin A); found in stratum corneum and dermis o Haemoglobin: red, oxygen-carrying pigment in blood cells if other pigments are not present, epidermis is translucent so pinkness will be evident Endeavour College of Natural Health endeavour.edu.au 21
ACCESSORY STRUCTURES OF SKIN o Develop from the embryonic epidermis o Cells sink inward during development to form: Hair Oil glands Sweat glands Nails Endeavour College of Natural Health endeavour.edu.au 22
HAIR (PILI) o Present everywhere except palms, palmar surfaces of the digits, soles and plantar surfaces of the digits. o Structure: Shaft: above the skin surface Root: penetrates the dermis and subcutaneous layer Sebaceous apocrine gland attached o Function: prevents heat loss; decreases sunburn; eye protection (eyelashes); senses light touch (hair root plexus) Endeavour College of Natural Health endeavour.edu.au 23
GLANDS OF THE SKIN o Specialized exocrine glands found in dermis 1. Sebaceous (oil) glands 2. Sudoriferous (sweat) glands eccrine and apocrine 3. Ceruminous (wax) glands Endeavour College of Natural Health endeavour.edu.au 24
SEBACEOUS (OIL) GLANDS o Sebaceous (oil) glands are usually connected to hair follicles; they are absent in the palms and soles; secretory portion of gland is located in the dermis o Produce sebum Contains cholesterol, proteins, fats and salts Moistens hairs Waterproofs and softens the skin Inhibits growth of bacteria and fungi (ringworm) o Clinical application: Acne Bacterial inflammation of glands Secretions are stimulated by hormones at puberty gazettereview.com Endeavour College of Natural Health endeavour.edu.au 25
SUDORIFEROUS (SWEAT) GLANDS 1. Eccrine sweat glands: extensive distribution to most areas of skin; secretory portion is in dermis with duct to surface terminate at pores at the surface of the epidermis Regulate body temperature through evaporation (perspiration) Help eliminate wastes such as urea Secretions are more viscous 2. Apocrine sweat glands: limited in distribution to the skin of the axilla, pubis, and areolae; secretory portion in dermis; ducts open into hair follicles health.howstuffworks.com Endeavour College of Natural Health endeavour.edu.au 26
CERUMINOUS GLANDS o Modified sudoriferous glands that produce a waxy substance called cerumen Found in the outer ear Barrier for entrance of foreign bodies o Abnormal amount of cerumen in the outer ear canal can result in blockage and prevent sound waves from reaching the ear drum. Endeavour College of Natural Health endeavour.edu.au 27
NAILS o Structure: Tightly packed keratinized cells; Parts: Nail body Nail root (Lunula is white due to thickened stratum basale) Eponychium (cuticle) (Stratum corneum layer) o Function: Protection Cutaneous sensation Endeavour College of Natural Health endeavour.edu.au 28
Lecture 9: Structure of skin Objectives Define and describe the structure of each skin layer Accessory skin structures Define and describe the structure of each accessory skin structure Lecture 10: Functions of skin Define and describe the function the skin Wound healing Describe process of the epidermal wound healing Describe the process of deep wound healing Compare epidermal and deep wound healing Burns Describe types of burns and damages to the skin layer Describe method for measuring the extent of burns Endeavour College of Natural Health endeavour.edu.au 29
INTEGUMENTARY SYSTEM FUNCTIONS o Thermoregulation o Blood reservoir o Protection o Cutaneous sensations o Synthesis of Vitamin D o Excretion Endeavour College of Natural Health endeavour.edu.au 30
THERMOREGULATION o Too cold: shivering and constriction of surface vessels Hair muscles pull hairs on end so erect hairs can trap air Blood flow to capillaries decreases o Too hot: perspiration and evaporation Hair muscles relax and lie flat heat escapes; sweat secreted by sweat glands Blood flow to capillaries increases Endeavour College of Natural Health endeavour.edu.au 31
Thermoregulation when exercising o In moderate exercise, more blood brought to surface helps lower temperature o With extreme exercise, blood is diverted into muscles and body temperature rises Endeavour College of Natural Health endeavour.edu.au 32
Intrinsic and extrinsic factors influencing thermoregulation Hanna and Teit, 2015 Endeavour College of Natural Health endeavour.edu.au 33
OTHER FUNCTIONS OF SKIN o Blood reservoir extensive network of blood vessels o Protection - physical, chemical and biological barriers tight cell junctions prevent bacterial invasion lipids released decrease evaporation pigment protects somewhat against UV light Langerhans cells alert immune system o Cutaneous sensations Touch, pressure, vibration, tickle, heat, cold, and pain arise in the skin Endeavour College of Natural Health endeavour.edu.au 34
OTHER FUNCTIONS OF SKIN o Synthesis of Vitamin D Necessary vitamin for absorption of calcium from food in the gastrointestinal tract activation of a precursor molecule in the skin by UV light blood enzymes in the liver and kidneys modify the activated molecule to produce calcitriol (the most active form of vitamin D) o Excretion 400 ml of water/day, small amounts salt, CO 2, ammonia and urea Endeavour College of Natural Health endeavour.edu.au 35
EPIDERMAL WOUND HEALING o Abrasion or minor burn o Basal cells migrate across the wound contact with other cells stops migration EGF stimulates basal cells to divide and replace the ones that have moved into the wound full thickness of epidermis results from further cell division Endeavour College of Natural Health endeavour.edu.au 36
DEEP WOUND HEALING o When an injury extends to tissues deep to the epidermis, the repair process is more complex than epidermal healing and scar formation results. o Healing occurs in 4 phases: 1. Inflammatory phase 2. Migratory phase 3. Proliferative phase 4. Maturation phase Endeavour College of Natural Health endeavour.edu.au 37
DEEP WOUND HEALING 1. Inflammatory phase blood clot unites the wound edges, epithelial cells migrate across the wound vasodilatation and increased permeability of blood vessels deliver phagocytes and WBCs 2. Migratory phase regrowth of epithelial cells and the formation of scar tissue by the fibroblasts tissue filling the wound is called granulation tissue Endeavour College of Natural Health endeavour.edu.au 38
DEEP WOUND HEALING 3. Proliferative phase events of the migratory phase intensify 4. Maturation phase the scab sloughs off, the epidermis is restored to normal thickness, collagen fibers become more organized, fibroblasts begin to disappear, and blood vessels are restored to normal Endeavour College of Natural Health endeavour.edu.au 39
EXAMPLE OF PHASES OF DEEP WOUND HEALING Endeavour College of Natural Health endeavour.edu.au 40
Fibrosis o Scar tissue formation (fibrosis) can occur in deep wound healing. Keloid scar extends into previously normal tissue Collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in colour Hypertrophic scar remains within the boundaries of the original wound Endeavour College of Natural Health endeavour.edu.au 41
BURNS o Definition: tissue damage from excessive heat, electricity, radioactivity, or corrosive chemicals. o Effects: Denaturing of proteins in the exposed cells Shock due to water, plasma and plasma protein loss Circulatory kidney problems from loss of plasma Bacterial infection o Types of burns: 1. First-degree 2. Second-degree burn 3. Third-degree or full-thickness Endeavour College of Natural Health endeavour.edu.au 42
Types of burns First-degree - Epidermis only - e.g. sunburn Second-degree burn - Epidermis and part of dermis - Fluid-filled blisters separate epidermis and dermis - Heals without grafting in 3 to 4 weeks; may scar Third-degree - full-thickness - Epidermis, dermis and epidermal derivatives - Damaged area is numb due to loss of sensory nerves Endeavour College of Natural Health endeavour.edu.au 43
BURNS o Determination of how serious is a burn is done by considering: depth, extent, and area involved person s age and general health o E.g. when the burn area exceeds 70%, over half of the victims die o Two methods for measuring burn extent: 1. rule of nines 2. Lund-Bowder method Endeavour College of Natural Health endeavour.edu.au 44
Non assessable Endeavour College of Natural Health endeavour.edu.au 45
o Thermoregulation Recap of Session 6 o Blood reservoir o Protection o Cutaneous sensations o Synthesis of Vitamin D o Excretion Endeavour College of Natural Health endeavour.edu.au 46
Recap of Session 6 Integumentary system is composed of cutaneous membrane (+subcutaneous layer) and accessory structures Epidermis contains specialised cells which allow several functions of the integumentary system (e.g. melanocytes mediate UV protection) Dermis contains several structures which allow specific functions of the integumentary system (e.g. free nerve endings allow for cutaneous sensation of pain) Subcutaneous layer is composed of specific connective tissue specialised for energy storage Accessory structures contribute to the protection and sensation functions of integumentary system Endeavour College of Natural Health endeavour.edu.au 47
Preparation for next session o Complete any missing concepts and linking words from Session 6 o NOTE: your Map 1 missing concepts and linking words should now be complete or near complete. Please submit the answers for feedback to your lecturer via a link you will find in Week 5 tab on LMS. This document is to be submitted in.pdf format. o Review cytoplasm and extracellular matrix structure and functions o Write down any medical terminology you already know Endeavour College of Natural Health endeavour.edu.au 48