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Endeavour College of Natural Health endeavour.edu.au 1
BIOH111
oCell Module
oTissue Module
o Integumentary system
oSkeletal system
oMuscle system
oNervous system
oEndocrine system
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Textbook and required/recommended
readings
o Principles of anatomy and physiology. Tortora et al; 14th
edition: Chapter 5
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BIOH111 INTEGUMENTARY
SYSTEM MODULE
o Session 6 (Lectures 9 and 10) Structure and
function of the skin and accessory structures
BIOH111Lectures 9 and 10
Structure of the skin and accessory
structures
Department of Bioscience
endeavour.edu.au
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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?
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ObjectivesLecture 9:
Structure of skin
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
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INTEGUMENTARY SYSTEM
FUNCTIONS o Thermoregulation
o Blood reservoir
o Protection
o Cutaneous sensations
o Synthesis of Vitamin D
o Excretion
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GENERAL ANATOMY
www.webmd.com
o Large organ composed of all 4 tissue
types; 2m2 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
http://www.webmd.com/beauty/wrinkles/cosmetic-procedures-overview-skin
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EPIDERMIS
o Stratified squamous epithelium:
avascular (contains no blood vessels)
4 types of cells divided into 5 distinct strata (layers)
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SPECIALISED CELLS OF EPIDERMIS1. 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
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LAYERS (STRATA) OF THE EPIDERMIS
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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 hemi-
desmosomes
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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
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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
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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
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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
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Ep
ith
elia
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iffe
ren
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o Keratinization is replacement of cell contents with the protein
keratin; occurs as cells move to the skin surface over 2-4 weeks
KERATINIZATION
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https://www.studyblue.com/notes/note/n/integument-/deck/4421919
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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
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1. PAPILLARY REGION
o Top 20% of dermis; finger-like projections
are called dermal papillae
o Structure: areolar connective tissue
containing fine elastic fibers, Meissners
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 Meissners
corpuscules and free
nerve endings?
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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
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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
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ACCESSORY STRUCTURES
OF SKIN
o Develop from the embryonic
epidermis
o Cells sink inward during
development to form:
Hair
Oil glands
Sweat glands
Nails
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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)
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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
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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 i
