Integumentary System

Chapter 5

• Skin & Accessory organs: Hair & hair follicles sebaceous (oil) glandssudoriferous (sweat) glandsnails

Functions of the Integumentary System

1. Protection: from exterior elements2. Sensation: feeling3. Excretion of wastes: sweat4. Synthesis of Vitamin D in sunlight5. Temperature regulation: release/retain heat6. Coloration: pigment of skin7. Water proof: water does not enter inside8. Growth and repair: regenerate

Skin structure 3 main layers1. Epidermis:outer, thinner layer connected to the

basement membrane

2. Dermis:inner, thicker layer

3. Hypodermis / subcutaneous layer (Sub Q): Under the dermis (adipose tissue)

List & Describe the 4 Cells in Epidermis

Found on pg. 152 in textbook 5 Minutes to locate & write…GO!

Cells of the Epidermis

Keratinocytes – produce the strong protein keratin.

Melanocytes – produce the brown pigment melanin

Langerhans’ cells –macrophages that help activate the immune system response

Merkel cells – function as touch receptors in association with sensory nerve endings

General Epidermis Info

Basement membrane= located right underneath the stratum basale and connects epidermis to the dermis

Layers of the Epidermis

Figure 5.2b

Epidermis

outermost layer Made of keratinized stratified squamous

tissue, so it: Lacks blood vessels Is mostly dead

There are 5 distinct layers MITOSIS does occur in bottom layers

5 layers of the Epidermis

Pg 154 in textbook

Stratum basale innermost layer directly above the

basement membrane location

• Merkel Cells• Melanocytes

Simple cuboidal Cells undergo mitosis

here

Stratum spinosum

composed of many layers of rounded cells with large nuclei

Langerhans’ cells are abundant in this layer

Stratum granulosum

composed of 3-5 layers of flattened granular cells

Cells start keratinization process here the process of cells formed in the stratum basale moving up, flattening, dying, and becoming hard and waterproof

Stratum lucidum

translucent layer Not shown in book…

why? Because only

located in thick skin of soles and palms

Stratum corneum

Top layer composed of dead

epithelial cells being flaked off (keratinized)

Functions include: Waterproofing Protection from

abrasion and penetration

SKIN

Dermis inner layer Much thicker than the epidermis Dermis aka. “True Skin” Contains nerve endings, muscle fibers, hair

follicles, sudoriferous glands, sebaceous glands, and blood vessels.

Does not continually shed and regenerate itself

Dermis: 2 Layers 1. Papillary Layer

Arranged in ridges The fingertips and toe tips Ridges allow us to grip things

Dermis: 2 Layers…cont’d2. Reticular Layer

Collagenous fibers: make our skin tough Elastic fibers: make our skin stretchable. Reticular fibers: gives skin its strength & resilience Location of smooth muscle called arrector pili

Stands hair on end when “goose bumps”

Subcutaneous layer or hypodermis

adipose tissue and blood vessels beneath the dermis Function – insulation

Cutaneous Sensation

1. Light touch detection:

Meissner’s Corpuscles located in dermal

papillae of dermis

Cutaneous Sensation

2. Pressure detection =

Pacinian Corpuscles located deep in dermis

and subcutaneous regions

Hair

Shaft: visible part of the hair Medulla: inner core of

the hair Cuticle: layer covering

medulla Cortex: Superficial

portion of hair Root: in dermis

No need to know for test… Just an Interesting FACT:

Straight hair has a rounded follicle Wavy hair has a flattened follicle Kinky or curly hair has a kidney shaped follicle

Are you ready to be grossed out?................

...…

Eye Lash Mites

Skin Color 3 pigments contribute to skin color

Melanin – yellow to reddish-brown to black pigment, responsible for skin colors, related to genetics• Freckles and pigmented moles – result from local

accumulations of melanin

Carotene – yellow to orange pigment

Hemoglobin – reddish pigment responsible for the pinkish hue of the skin

PigmentMore about Melanin: Is produced by melanocytes in stratum

basale layer

People of different races have essentially the same # of melanocytes, but the amount of melanin produced varies

The quantity of Melanin produced depends on 3 factors:

1. Heredity: MOST IMPORTANT• enzyme tyrosinase is absent at birth, then

melanocytes are unable to produce melanin and a condition known as albinism is formed

2. Sunlight Exposure• Causes melanocytes to increase melanin

production and darkening skin color

3. Hormones: ACTH (Adrenocorticotropic Hormone ) and MSH (melanin stimulating hormone)• Hypersecretion of either hormone may darken the

skin

Albinism

Carotene

Hemoglobin

Nails cont’d… Tightly packed hard, keratinized epidermal

cells Functions = manipulation and protection

Ripley’s Believe It or Not Lady

Sudoriferous Glands

Two types1. Eccrine more common, mainly in forehead,

palms, & soles. These function right at birth. -no odor in secretion

Secretion = water plus salts and wastes (urea and uric acid)

2. Apocrine Mainly in armpits, groin, & breasts. Don’t function until puberty. These cause the “cold-sweat” during stress. -odor in secretion

Sebaceous Glands

-Connected to every hair follicle -Secrete sebum (oil) into hair follicle

Function – sebum keeps skin and hair soft

Disorders acne = overproduction of sebum – ducts

clog and inflame

Ceruminous Glands Associated with ears Produces cerumen (earwax)