Human Anatomy & Physiology s3

Human Anatomy & Physiology 03B.2 Epi-N-Dermis

Layers of the Epidermis Leave space for the following diagram to be glued.

The following are to be labeled on the above diagram:  Stratum germinativum  Stratum basale  Stratum spinosum  Stratum granulosum  Stratum lucidum  Stratum corneum

Stratum germinativum  “growth layer”  Includes stratum basale & stratum spinosum

Stratum basale  “base layer”  Closest to blood supplyhealthiest  Only layer that can reproduce  Keratinocytes o Keratin (tough, water-resistant protein)

03B.2 Epi-N-Dermis 1 of 6 6/6/2018 Human Anatomy & Physiology  Melanocytes o Melanin (brown protein pigment) . Absorbed by surrounding keratinocytes

 Two categories of melanin: o Eumelanins (dark brown) o Pheomelanins (light brown/red/orange)

 Freckle o clusters of concentrated melanin which are most often visible on people with a fair complexion http://www.medterms.com/script/main/art.asp?articlekey=10102 http://en.wikipedia.org/wiki/Freckle

 Mole o Clusters of concentrated melanin o Often raised http://www.webmd.com/skin-problems-and-treatments/guide/moles

Stratum spinosum  “spiny layer”  as pushed from below become “squished” & look “spiny” on cross section  spot desmosomes can pull out “spines” as cells shrink away from each other, when pulled apart  less healthy  don’t reproduce

Stratum granulosum  “grainy layer”  as cells from stratum germinativum die, they enter stratum granulosum  all cells are dead  look grainy when stained / no nuclei

 basophilic keratohyalin granules (seen on the close-up view). These granules contain lipids, which along with the desmosomal connections, help to form a waterproof barrier that functions to 03B.2 Epi-N-Dermis 2 of 6 6/6/2018 Human Anatomy & Physiology prevent fluid loss from the body.

Stratum lucidum  “light layer” or “clear layer”  Layer looks almost clear  Gets more full of keratin

Stratum corneum  “horny layer” meaning “like an animal’s horm”  Keratin is fully formed, making keratinzed stratified squamous epithelium.

A complete new epidermis forms every 25-45 days.

DERMIS  Your “hide”  Irregular dense fibrous connective tissue

Papillary region  superficial region has bumps called dermal papillae  bumps in the human body are often called papillae (sing. papilla = “nipple”  increase surface area for glue to “hold” more tightly  Arranged in rows to form "prints" of hands/fingers and feet/toes to improve grip  Fingerprints http://www.reachoutmichigan.org/funexperiments/agesubject/lesson s /prints.html

Reticular region  Deeper, irregular swirls of collagen fibers  Nerves, nerve endings, blood vessels, sweat glands, etc.  Reticular = “netlike”

Leave space for the following diagrams to be glued.

03B.2 Epi-N-Dermis 3 of 6 6/6/2018 Human Anatomy & Physiology

The following are to be labeled on the above diagram. Those not italicized need to be placed into your notes.: Epidermis Dermis Subcutaneous tissue (hypodermis) Stratum basale 03B.2 Epi-N-Dermis 4 of 6 6/6/2018 Human Anatomy & Physiology Stratum corneum Hair shaft

Hair follicle  lined by cells derived from the epidermal (outside) layer of the skin  Each follicle normally goes through a five-year cycle of growth and rest, with about 90% of the follicles growing hair at any one time

Papilla of hair bulb  Provides nutrients for growth and development of the hair

Sweat gland

Sebaceous (oil) gland  Lubricates the hair  Keeps hair & skin from drying out

Arrector pili  when contracted, causes hair to “stand up” or goose bumps

Nerve fibers (will need to draw in)

Pacinian corpuscle  receptive to deep pressure

Meissner’s corpuscle  sensitive to light touch

Adipose (fat) tissue

Blood vessels  draw this in red = from heart (arteries);  blue = back to heart (veins)

Other Items: Blisters  epidermis & dermis are tightly connected. 03B.2 Epi-N-Dermis 5 of 6 6/6/2018 Human Anatomy & Physiology  Sometimes when too much friction or burns occur that connection is lost & area fills with interstitial fluid http://en.wikipedia.org/wiki/Blister

Scars  form when a denser-than-usual mass of fibers are produced to replace those damaged in an injury  Keloid Scars o Abnormally large scars

Stretch marks  occur when the skin is overstretched and the dermis tears beneath the epidermis

Remember to: Reduce, Recite, Reflect, & Review! Make your Flashcards & Study 3 x 5!

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