The Integumentary System Structure & Function

Layers of thick skin from superficial to deep

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale.

Stratum Corneum

Superficial layer of the epidermis. 25-30 or more layers of dead, squamus shaped keratinocytes. Tough and water-repellent. Cells are continually sloughed off and replaced with cells from deeper layers.

Stratum Lucidum

Superficial to stratum granulosum. Found in thick skin. Contains dead keratinocytes - they lost their nucleis and organelles. In fresh skin specimen this layer appears translucent.

sudoriferous glands

Sweat glands. Sweat is secreted and functions in excertion and body temperature regulation.

sweat glands

The glands that secrete sweat a. to excrete waste products to the outside. b. way to regulate amounts of heat found inside our body. - located in the dermal layer of the skin.

Hair cross-section appears flat

The hair is curly.

Hair cross-section appears round

The hair is straight.

Hair cross-secioon appears oval

The hair is wavy.

Regions of the dermis

The papillary region and The reticular region.

Cuticle or eponychium

Thickened epithelial tissue along the proximal border of the nail body.

Skin

also know as the integument or cutaneous membrane and is the largest organ of the human body. It contains several types of tissues that work together to perform a specific function.

Dermal Papillae

finger-like projections of the papillary region that extend into the epidermis.

hair shaft

the portion of the hair that projects beyond the skin

Layers of thin skin from superficial to deep

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale.

Reticular Region

- Deep to the papillary region in the dermis and is the larger region. - Composed of dense, irregular connective tissue made of collagen and elastin fibers. - Highly vascular ( veins and arteries) - Contains sebaceous gland, sweat gland, hair follicles, arrector pili smooth muscle - responsible to erecting our hairs- giving us goosebumps, receptors

Integumentary Function

- Protection - protect the body from physical and mechanical forces - Contains sensory receptors -Langerhans cells can interact with T-cells to help protect the body from bacterial agents. - production of vitamin D - regulation of body temp - blood vessels that run in the dermis can expel this heat via radiation, via evaporation, or prevent heat loss by redirecting the blood away from the skin. - excretion - excrete water to the skin's surface via diffusion, waste products can also be excreted via sweating. - growth - the skin can expand due to the elastic fibers.

Papillary Region

- Superficial region of the dermis. - Deep to the stratum basale. - Composed of a thin layer of loose connective tissue that extends into the epidermis. - Blood vessels to help nourish cells and tissues in dermis as well as up to the epidermis. - Nerve endings allow us feel pain/touch and then the signals are relayed all the way to a cell body sit much further away than the skin.

Stratum Spinsosum

- Superficial to the stratum basale. - Keratonytes cells are connected together with desmosomes. - They looks spiny and shriveled because they lost water. - Langerhans cells and projections from melanocytes are seen here.

Stratum Granulosum

- Superficial to the stratum spinosum. - Have tremendous amount of granules that are being produced here called keratohyalin granules - they make keratin-handling proteins. - Stratum granulosum release lamela bodies which contain lipids that form strong lipid layers sitting on top our skin

Hair Follicle

- Surrounds the hair root and is formed by a epidermal layer that project from the reticular dermis. - a beta afferent nerve fiber wrap around the part of the hair that sits in the follicle. - when hair deflected ---> sodium enter the afferent nerve ---> generate action potential ---> send signal to CNS. - perceive light touch on hairy skin. - require constantly changing stimulus

respond to hot temperature

- anterior hypothalamus. - smooth muscles ( arterioles) vasodilate.

Ruffini endings

- collagen connected to the nerve fiber branches. - outside force cause the collagen shifts ---> open up ion channels on never branches ---> sodium sneak in ---> generate action potential ---> send signal to CNS. - sustained deep touch. - reticular dermis

Dermis

- composed of connective tissue. - Attatches to the basement membrane of the epidermis. - Provides nutrients to the epidermis. - divided into layers - the papillary layers and the reticular layers

Epidermis

- contain epithelial tissues - further subdivided into five segments: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum. - Avascular. - outermost layer of the skin - consist four types of cells - Keratinocytes, melanocytes, Langerhans & Merkel cells

merocrine glands

- found on the majority of the body. - Ducts from merocrine glands release water or sweat by exocytosis. - most important glands because it help us cool down via evaporation, eliminate waste products. - release lysozyme and antibodies.

Merkel's disks

- hold a whole bunch of vesicles containing neuropeptides. - sustain light touch - locate from stratum basale to papillary dermis - outer force cause the vesicle to open up and allows the neuropeptide to be liberated. - when neuropeptides lands on neuropeptide reeptor ---> ion channels open ---> sodium enter Merkel's disk ----> make it way to afferent nerve fiber ----> action potential ---> send signal to CNS

Trpv1

- if there is a change in temperature or a pain occur, the heat or pain stimuli will cause a conformation change in structure of the Trpv1. - heat or an injury will cause the cells in the body rupture and release their molecules, these molecules floating around and bind to Trpv1 receptors ---> change the Trpv1 structure ---> activate Trpv1 cells ---> send signals to CNS

Hypodermis

- lowest-most layer of the skin - contain cells such as macrophages and adipose cells. - Adipose cells help absorb shock, insulate the tissues. - also contain a network of protein fibers.

Paccinian corpuscles or Lamellar Corpuscle

- onion-layered mechanoreceptor.. - outer force cause the outer ring to respond by spinning relative t the inside disk. - require a more significant of a stimulus - a push or poke. - require constantly changing stimulus - perceive deep touch in hairy or non-hairy skin - hypodermis - and one disk or ring moved past the other, this allow sodium to enter the ring layer ---> sodium propagate through all cells to the center ---> build up of sodium in the center will initiate action potential at afferent nerve fiber ----> send signal to CNS.

A delta fibers A beta fibers

- pain and temperature ( delta) - perceive every thing else ( beta)

Meissner's corpuscles

- perceive light touch in non-hairy skin/glabrous skin. - require constantly changing stimuli. - Dermis - Meissner's corpuscle's body cell composed of many lamina disks stacking one on top the other. An initial light touch from external environment will cause the epithelial disk to nudge over away, it shift across other epithelial disk was. - when the lamina disk moves away, it allow sodium leak into the disk below it, initiate an action potential and propagate through all of the cells ----> bottom of Meissner's corpuscle, which ends in an Afferent Nerve Fiber ----> central nervous sytem

respond to cold

- posterior hypothalamus - smooth muscle ( arterioles) constrict. - skeletal muscle contract help producing energy by breakdown ATP ---> ADP +Pi -shivering

holocrine glands/ sebaceous gland

- release secretion by disintegrating the whole cell so the entire cell breaks down to release the sebum. - face, chest, back - mostly oily substances - lubricate skin so slow the bacteria growth

A delta fibers

- small diameter, less myelin covered sensory fibers

slow fibers

- small in diameter and un-myelinated.

Aprocrine Glands

-Found in the axilla, genital area, and pigmented area around the nipples. - release secretions from the apex of the cell or the top of the cell breaks off to release a mixture of proteins, lipids, steroids. - they release their contents into the hair follicles. - Not releasing their contents until after puberty. - Involve in emotion sweating

Melanocytes

8% of cells in the epidermis. Produce pigment melanin, which give ski its color.

Keratinocytes

90% of the cells in the epidermis. Produce Keratin - gives the skin strength and make it water proof.

Langerhans

Cells of the immune system. Protect against pathogens that enter the skin. Locate in the stratum spinosum

Dermal Root Sheath

Connective tissue sheath made from the dermis.

Thin skin

Contains 4 strata. Found in the rest of the body.

Thick skin

Contains 5 strata. Found in palms of hands and soles of feet.

Lunula

Cresent-shaped area of the nail body distal to the nail root.

Hyponychium or nail bed

Deep to the free edge and attaches the nail to the fingertip.

Stratum basale

Deepest strata. Composed of simple cuboidal or columnar keratinocytes. One cell layer attatched to the basement membrane. Site of cellular division (germinativum). Melanocytes, Merkel cells are found in this strata.

Hair matrix

Derived from the stratum basale of the epidermis. Site of cellular division, new cells are added to the base of the hair root causing hair to grow.

Nail Matrix

Epithelial tissue deep to the nail root. Site of cellular division; new nails add to the nail body so that the nail grows.

Hair Bulb

Expanded base of the hair follicle.

Free edge

Extends beyond the digit.

Nails

Found at the distal end of the digits. Used for grabbing and manipulating objects and protecting the end of the digits.

Mammary glands

Found in the breasts. Secrete milk after appropriate hormone stimulation.

Papilla

Found in the hair bulb; a projection of connective tissue into the hair follicle. Contains blood vessels to provide nutrients for cells of the matrix.

Nail Root

Found in the skin at the proximal end of the nail body. - Attach directly to the epidermis.

Hair

Found on the majority of the body surface. Composed of dead, keratinized epithelial cells. Has 2 main components: Shaft and Root.

Accessory Structures of the Skin

Include: Hairs, hair follicles, nails, sweat glands, sebacceous glands, ceruminous glands, and mammary glands. Derived from epidermal tissue and extend from the dermis.

Medulla

Inner layer of the hair. Contains pigment that gives hair it's color.

A beta fibers

Large diameter, myelin covered sensory fibers involved in rapidly transmitting sensation.

Merkel

Least abundant cell type in the epidermis. Found in the deepest layer of the epidermis. Serve as touch receptors and associate with neurons.

Cortex

Middle layer of the hair. Contains pigment that gives hair it's color.

Ceruminous glands

Modified sudoriferous glands. Found in the ear canal.

Cuticle

Outer layer; the part of the hair we see. Thin layer of dead, keratinized cells that overlap each other.

Integumentary Components

Skin, Hair Nails, Sweat and sebaceous glands, associated muscle and nervous tissue.

Arrector pili muscle

Smooth muscle attached to a connective tissue sheath around the hair follicle. Contraction of this muscle causes the hair to move a 90 degree angl; causing the skin arund teh hair to raise ("Goose Bumps"). This muscle reacts to a variety of stresses.

Eccrine or merocrine glands and Aprocrine glands

Two types of Sudoriferous Glands.

Nail body

Visible part of the nail. also part of the epidermis. made up of thick keratin

capsaicin

chemical that stimulates receptors that respond to painful heat. bind to Tprv1 receptor in mouth---> change its cell structure ----> activate Tprv1 cells ----> send signals to CNS

Major Divisions of the skin

epidermis - the superficial division; dermis the deep division; hypodermis deep to the dermis (not part of the integumentary system).

Strata

epidermis various layers of cells.

Epidermal ridges

whorls in the palms, fingers, soles and toes made up of dermal papillae. Create more surface area, friction and grip. Also determine a person's finger print.