Integument System

Is the Integument system the largest organ system in the body?

True

Layers of the Integument

1st Cornuem, Lucidium, Granulosum, Spinosum, Basale 5th

Epidermis

stratified squamous keratinized epithelium divided into five strata

5th

• Stratum Basale

• single layer of germinal cells resting on the basement membrane which is attached to the dermis

4th

• Stratum Spinosum

• keratinocytes attached to each other by desmosomes on spiny processes

Melanocytes

specialized cells in the body that a produce melanin

Melanosomes

• are specialized parts inside animal cells that make, store, and carry melanin, the pigment responsible for color

• dark cells

Merkel Cells

specialized oval-shaped cells int eh bottom layer of the skins’s epidermis that help help detect light touch and texture

Meissner Corpuscles

• a type of mechanoreceptor (touch sensor) in the skin that detects light touch and low-frequency vibrations

• found close to the surface in locations like fingertips, eyelids, and lips

Pacinian Corpuscle

• a specialized sensory nerve ending the skin and internal organs detects deep pressure and high-frequency vibrations

• found in deep dermis

Sweat Glands : Eccrine

• most numerous types,

• abundant on films soles and foreheads

• ducts connect to pores

• function in thermoregulation

• their secretion is sweat

• stratified cuboidal

Sweat Glands : Apocrine

• activated only during puberty

• specialed skins glands that secrete an oily, protein-rich fluid into hair follicles rather than directly onto the skin surface

Sebaceous Glands

• widely distributed, except for thick skin ofnpalms and soles

• most develop from hair follicles and secrete into hair follciles

• relatively inactive during puberty

• secrete sebum

Sebum

• oily, holocrine secretion

• bactericidal properties

• softest hair and skin

Hair Follicle

3rd

• Stratum Granulosum

• 3-5 layers flattened keratinocytes (cells w/ nuclei)

• keratohyalin granules

• membrane-coated lamellar granules

2nd

• Stratum Lucidium

• only in thick skin

• pale/eosinophilic/refractile

• disrupted nucleus and organelles

• cells filled with keratin

• cells connect together

1st

• Stratum Corneum
  flat and desiccated cells

• layer variably thick

• top layer

• no desmosomes

• desquamation

Keratinocytes

• produced by stems cells in the basale

• release lipids that waterproof the cell

• cells near surface die due to lack of

• primary cell type in the epidermis, making up 90% of the cells in the outermost layer of the human skin

Dendritic (Langerhans) Cells

• star shaped marcophages that patrol deep epidermis

• are key activators of immune system

Merkel (tactile) Cells

• associated with sensory receptors that sense light touch

Papillary Layer

• superficial layer of areolar connective tissue consisting of loose, interlacing collage and elastic fibers and blood vessel (capillary beds)

• loose fibers allow phagocytes to patrol for microorganisms

• Dermal Papillae

Dermal Papillae

• superficial region of dermis that send fingerlike projections up into epidermis

• projections contain capillary loops, free nerve endings and touch receptors (Meissner’s corpuscles)

Reticular Layer

• makes up 80% of dermal thickness

• consists of dense irregular connective tissue

• many elastic fibers provide stretch and recoil properties

• collagen fibers provide strength and resiliency

• Cutaneous Plexus

• ECM contains pockets of adipose cells

Cutaneous Plexus

• network of blood vessels between reticular layer and hypodermis

• sits deep within the skin, marking the transition zone where the dermis meets the fatty tissue of the hypodermis

• made up of medium-to-large arteries and vein that branch out to feed deeper into the skin

External Root Sheath

• the outermost layer of the hair follicles that connects directly to the outer layer of skin

Internal Root Sheath

a cellular layer inside the hair follicle that surrounds, shapes, and protects the growing hair shaft

Glassy Membrane

• thickest basal laminae

• a thick, clear basement membrane that lines the hair follicle

Hair Papilla

• dermal tissue containing a knot of capillaries that supplies nutrients to growing hair

• hair is considered a sensory touch receptor

Arrector Pili

• small band of smooth muscle attached to follicle