Topic 9: Integumentary System Flashcards by gurleene bhathal

What does the system consist of?

 consists of:
o skin
o hair, nails, glands
o sense receptors (nervous)
o muscles

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List the layers of the skin

2 layers

epidermis
dermis

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epidermis

upper layer

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dermis

lower layer

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hypodermis

below skin

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Is the hypodermis part of the skin?

below the skin

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List the characteristics of the Epidermis

stratified squamous epithelium (from ectoderm)
avascular
separated into 4-5 strata (sub-layers) based on cell types:

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List the sub- layers of the epidermis:

o Stratum Basale
o Stratum Spinosum
o Stratum Granulosum
o Stratum Lucidum
o Stratum corneum

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Stratum Basale

single row of cells
2 cell types
i. keratinocytes (90%)
ii. melanocytes (10%)

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keratinocytes

undergo mitosis
make keratin (tough protein)
migrate to surface as new cells produced in basale

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melanocytes

10%)
produce pigment (melanin) for UV light protection

o e.g. sunburns, wrinkles (collagen damage),
cancer (DNA damage)

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skin colour

o we all have the same relative number of
melanocytes, but cells produce different
amounts/shades of melanin

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albinos

no melanin

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blood (hemoglobin

in dermis can give a

pinkish tinge to fair skinned people

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Stratum Spinosum

limited cell division

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Stratum Granulosum

contains dark staining granules

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Stratum Lucidum

flat, dead cells (too far from blood supply)

visible ONLY in thick skin

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Stratum corneum

20 - 30 layers of flat dead cells filled with keratin (tough protein),
surrounded by waterproofing glycolipid (prevents water loss)
shed and replaced from below

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Describe the characteristics of the dermis

contains blood vessels, nerves, glands, hair follicles
2 sub-layers (CT – from mesoderm):
o Papillary Layer
o Reticular Layer

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Papillary Layer

(beneath epidermis)
areolar CT
vascular
has projection into epidermis = dermal papillae
o in thick skin these form epidermal ridges = fingerprints
(improve grip

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Reticular Layer

most of dermis

dense irregular CT

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dermal papillae

has projection into epidermis

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Describe the Hypodermis

(NOT part of skin)

subcutaneous layer; under
superficial fascia; not deep so above

adipose CT below skin
o stores 1⁄2 of body’s adipose tissue (insulation

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Fascia

CT layers that surround and support organs

What does thick vs thin skin refer to?

refers to epidermis (not dermis)

Thin Skin

lucidum not apparent | has hair follicles, sebaceous glands, arrector pili muscles

Thick Skin

found on the palm of the hand and the sole of the foot lucidum visible no hair follicles, sebaceous glands, or arrector pili muscles

Epidermal Derivatives

ALL derived (formed) from the epidermis

List the epidermal derivatives:

1. hair 2. nails 3. skin exocrine glands

Hair

all dead cells

List the parts of hair

a) root b) shaft c) hair follicle

Root

dead cells below the surface of the skin

Shaft

above the skin surface

Hair follicle

surrounds the root - epithelial root sheath - bulb - matrix

epithelial root sheath

several epidermal layers extend into the dermis

bulb

expanded region at base of root

matrix

single layer of cells (derived from basale cells) - site of hair growth and melanin for hair colour

List what is associated with each hair follicle

a) outer CT sheath b) hair papilla c) root hair plexus d) sebaceous (oil) gland e) arrector pili muscle (smooth muscle)

outer CT sheath

holds follicle in place (formed from the dermis)

hair papilla

extends upward beneath matrix o contains blood supply for growing hair o formed from dermi

root hair plexus

- free nerve ending (touch)

sebaceous (oil) gland

- opens into follicle

arrector pili muscle (smooth muscle)

- causes “goosebumps”

Nails

``` very heavily keratinized epidermal cells consists of: o nail root (buried in skin) o body (visible portion) o free edge ```

List the skin exocrine glands

a) sebaceous glands b) sudoriferous glands c) ceruminous glands d) mammary glands

sebaceous glands

connected mainly to hair follicles secretes sebum (oily - mix of fats, salts, proteins) o softens, lubricates hair and skin, prevents drying out, antibioti

sudoriferous glands

``` sweat glands secretory portions in dermis of thick and thin skin ducts open onto skin surface act to: o cool the body body o antibiotic (acidic) o remove wastes (urea, etc.) ```

ceruminous glands

modified sweat glands in ear canal produce ear wax - prevents insects etc from entering

mammary glands

modified sweat glands | produce milk

receptor

sensory neuron (part of NS

Cutaneous Sense Receptors

specialized cell that responds to stimuli (touch, temp., pain)

List the 4 major types of cutaneous sense receptors

1) Touch Receptors 2) Pressure Receptors 3) Thermoreceptors 4) Nociceptors

Touch Receptors

``` a) free nerve endings • in epidermis b) Root Hair Plexuses c) Meissner’s Corpuscles • in dermal papillae • corpuscle ```

corpuscle

= connective tissue capsule surrounding nerve ending

Pressure Receptors

a) free nerve endings • in dermis b) Pacinian corpuscles • deep in dermis or hypodermis

3) Thermoreceptors

• free nerve endings for temperature

Nociceptors

* free nerve endings for pain | * 3rd degree burns = no pain because nociceptors destroyed

Describe which layers get damaged in a first second and third degree burn

``` 1st= epidermis 2= dermis 3= hypodermis ```

When we get a cut which layer of the skin have we reached?

dermis- bc vacular