BIO 50 LEC - INTEGUMENTARY SYSTEM

• Protection

• Temperature maintenance

• Sensory reception

• Synthesis and storage of nutrients

• Excretion and secretion

Functions of Integumentary System

Protection

guards the body’s physical and biochemical integrity

Temperature maintenance

helps maintain a constant body temperature by regulating heat exchange with the environment (thermoregulation)

Sensory reception

provides sensory information about the surrounding environment

synthesis and storage of nutrieents

synthesis of vitamin D

excretion and secretion

Glands secrete salt, water and organic wastes

• Epidermis

• Dermis

• Hypodermis

Principal parts of the Integumentary System

Epidermis

• superficial, thinner portion

• stratified squamous epithelium

Dermis

• deeper, thicker, connective tissue

• mainly dense connective tissue

Subcutaneous layer (Hypodermis)

• consists of areolar and adipose tissue

• mainly adipoe tissue and loose connective tissue

Epidermis

-(keratinized) stratified squamous epithelia/epithelium

-avascular

dermis

mainly dense connective tissue

hypodermis

mainly adipose tisssue and loose connective tissue

• hair

• duct of sweat gland

What can be found in the epidermis?

• blood vessel

• pressure-sensitive sensory receptor

• smooth muscle

What can be found in the dermis?

• sweat gland

• hair follicle

• oil gland

What can be found in the hypodermis?

• Keratinocytes

• Melanocytes

• Langerhans cells

• Merkel cells

Principal cells of the Epidermis (4)

Keratinocytes

• 90% of epidermal cells

• produce the protein keratin

• produce lamellar granules, which release a water proofing sealant

Melanocytes

- 8% of epidermal cells

- produce melanin (brown-black pigment)

- contributes to skin color

- protects cells/body from damaging UV light

Langerhans cells

- arise from the bone marrow and migrate to the epidermis

- participate in immune response against microbes

- easily damaged by UV light

Merkel cell

- least numerous

- found in the deepest layer of the epidermis

- merkel cells and tactile disc (sensory neuron) function in the sensation of touch

• stratum corneum

• stratum lucidum

• stratum granulosum

• stratum spinosum

• stratum basale

5 layers of the epidermis

stratum corneum

• outermost layer of dead, fully keratinized cells

• where dead keratinocytes can be found

stratum lucidum

found in thick skin, adds extra protection

stratum granulosum

• where lamellar granules can be found

• where cell begin to die & flatten, more keratin added

stratum spinosum

• where cells start to produce keratin

• this is where langerhans cells can be found

stratum basale

• this is where merkel cell and tactile disc can be found

• where cell division occurs

• Thin

• Thick

Types of Skin

Thin

- type of skin that covers all parts of the body except for the palms, palmar surface of the digits and the soles

- few dermal papillae; lacks epidermal layers

- sparser distribution of sensory receptors

Thick

- (type of skin) palms, palmar surfaces of the digits and soles

- lacks hair follicles, arrector pili muscles, and sebaceous glands

- more sweat glands and densely clustered sensory receptors

• Papillary layer

• Reticular layer

layers of the dermis (2)

Papillary layer

• Dermal papillae

• Tactile receptors, meissner's corpuscle

Reticular layer

• Dense, irregular connective tissue

• Elastic fibers, collagen fibers

Subcutaneous layer

• Stabilize the position of the skin relative to the underlying tissues.

• Energy reserve, shock absorber

• hemoglobin

• carotene

• melanin

Pigments (Skin)

epidermal pigmentation and dermal blood supply

structural basis of skin color… interaction between _____ and ____________

hemoglobin

red pigment in red blood cells

carotene

yellowish (yellow-orange) pigment precursor of vit. A

melanin

brown black pigment (melanocytes)

Cyanosis

sustained reduction in circulatory supply

Albinism

inherited inability of an individual to produce melanin

Vitiligo

partial or complete loss of melanocytes from patches of skin; produce irregular white spots

Jaundice

yellow cast; usually signifies a liver disorder

Bruises (Hematoma)

unusual tendency to bruising; deficiency of Vit C or hemophilia

hair and nails

protect the body (accessory structures)

gland

help regulate body temperature (accessory structures)

hair, nails, glands

accessory structures

• Medulla

• Cortex

• Cuticle

Hair (layers)

Medulla

(hair layer) 2-3 rows of polyhedralshaped cells containing pigment granules and air spaces

Cortex

(hair layer) elongated cells

Cuticle

(hair layer) single layer of thin, flat cells

Sebaceous glands (Oil)

- sebum, mixture of oily substance and fragmented cells

- keeps the skin moist and soft. Also contains chemicals that kill bacteria

White head

duct is blocked by sebum

Blackhead

oxidation of accumulated material

Acne

active infection of gland

• Eccrine

• Apocrine

Sudoriferous gland (sweat) types

Eccrine

- more numerous and found all over the body

- produce a clear secretion (water, salts, metabolic wastes and lactic acid

- help regulate body temperature

Apocrine

- axillary and genital areas

- empty into hair follicles

- begins to function during puberty (androgens)

- precise function is not known, but they are activated by nerve fibers during pain and stress and during sexual foreplay

Ceruminous glands

- modified sweat in the external ear

- combined secretion of ceruminous and sebaceuos glands : cerumen or earwax

eccrine

apocrine

sudoriferous glands (sweat) types

cerumen or earwax

combined secretion of ceruminous and sebaceous glands

Epidermal Wound Healing

contact inhibition

Deep Wound Healing

- dermis, subQ layer

inflammatory phase

- blod clot forms (Mast cells) during this phase

inflammation

vascular response that helps eliminate microbes, foreign matl and dying tissue

• migratory phase

• proliferative phase

• maturation phase

Deep Wound Healing (Phases)

Fibrosis

scar tissue formation

Burns

tissue damage inflicted by intense heat or electricity

first-degree (1º), second-degree (2º), third-degree (3º)

Classification of Burns (degrees)

first-degree burn (1º)

• classification of burns

• affects the epidermis only

second-degree burns (2º)

epidermis and the outer portion of the dermis

third-degree burn (3º)

destroys the epidermis, dermis, and accessory structures

Rule of nines

-Divide the body into 11 areas

-9% of the total body area

-Head/neck -9%-Trunk 36%

-Upper limbs 18%

-Lower limbs 36%

-Perineum 1%

second-degree burns

Over 25% of the body has ___________ (classification of burns)

3rd degree burns

There are ______ of the face, hand, or feet (considered critical)

rule of nines

it divides the body into 11 areas

9% of the total body area

9%

head/neck (percentage)

36%

trunk (percentage)

18%

upper limbs

36%

lower limbs

1%

perinium