BIOH111 SN06 Integumentary System · oIntegumentary system oSkeletal system ... BIOH111 –INTEGUMENTARY SYSTEM MODULE o Session 6 ... © Endeavour College of Natural Health endeavour.edu.au

© 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


Textbook and required/recommended

readings

o Principles of anatomy and physiology. Tortora et al; 14th

edition: Chapter 5


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


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?


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


INTEGUMENTARY SYSTEM

FUNCTIONS o Thermoregulation

o Blood reservoir

o Protection

o Cutaneous sensations

o Synthesis of Vitamin D

o Excretion


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


EPIDERMIS

o Stratified squamous epithelium:

• avascular (contains no blood vessels)

• 4 types of cells divided into 5 distinct strata (layers)


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


LAYERS (STRATA) OF THE EPIDERMIS


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


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


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


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


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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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


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


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?


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


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


ACCESSORY STRUCTURES

OF SKIN

o Develop from the embryonic

epidermis

o Cells sink inward during

development to form:

• Hair

• Oil glands

• Sweat glands

• Nails


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)


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


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

http://gazettereview.com/2015/07/everything-you-need-to-know-about-acne-and-how-to-cure-it/


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

http://health.howstuffworks.com/wellness/hygiene-tips/body-odor1.htm


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.


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


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


INTEGUMENTARY SYSTEM

FUNCTIONS o Thermoregulation

o Blood reservoir

o Protection



o Excretion


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


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


Intrinsic and extrinsic factors

influencing thermoregulation

Hanna and Teit, 2015


OTHER FUNCTIONS OF SKINo 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


• Touch, pressure, vibration, tickle, heat, cold, and pain arise

in the skin


OTHER FUNCTIONS OF SKIN


• 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, CO2, ammonia

and urea


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


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


DEEP WOUND HEALING1. 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


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


EXAMPLE OF PHASES OF

DEEP WOUND HEALING


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


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


Types of burns

Third-degree

- full-thickness

- Epidermis, dermis

and epidermal

derivatives

- Damaged area is

numb due to loss of

sensory nerves

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


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


Non assessable


Recap of Session 6

o Thermoregulation

o Blood reservoir

o Protection



o Excretion


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

Recap of Session 6


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

Documents

BIOH111 SN06 Integumentary System · oIntegumentary system oSkeletal system ... BIOH111 –INTEGUMENTARY SYSTEM MODULE o Session 6 ... © Endeavour College of Natural Health endeavour.edu.au