NURS 1750 Lecture Notes - Lecture 4: Erythema, Melanoma, Hair Coloring
28 Jun 2018
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Week Four (Oct. 2-6, 2017)
Anatomy and Physiology I
Chapter Five: The Integumentary System (Pgs. 144-168)
5.1 Structure of the Skin
- The integumentary system contributes to homeostasis by protecting the body and
helping regulate body temperature. It also allows you to sense pleasurable, painful and
other stimuli in your external environment.
-Functions of Entire Integumentary System:
- Regulates body temperature
- Sweat evaporation
- Stores blood
- Vessels
- Protects
- Keratin
- Sebaceous cells
- Lipids
- Intraepidermal macrophages
- Detects cutaneous sensations
- Excretes and absorbs substances
- Salts
- Co2
- Vitamins
- Drugs
- Toxins
- Synthesizes vitamin D- molecule in skin/UV- 10-15 mins biweekly
- The integumentary system is composed of skin, hair, oil, sweat glands , nails and
sensory receptors.
- The skin (cutaneous membrane) covers the external surface of the body's; largest organ.
- The skin consists of two main parts:
- Epidermis: Superficial, thinner portion composed of epithelial tissue.
- Dermis: Deeper, thicker connective tissue portion.
-Subcutaneous (hypodermis) Layer: Located deep into dermis but not
part of skin; consists of areolar and adipose tissue. Fibers from the
dermis anchor skin to this layer.
- Serves as as storage depot for fat and large blood
vessels.
- Contains nerve endings called lamellated corpuscles
(sensitive to pressure).
- Contains large blood vessels that supply skin and
corpuscles that sense pressure.
Topical Medication:
→ Transdermal (transcutaneous)
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●drug with adhesive skin patch
●pass across the epidermis and into the blood vessels of the dermis
●released continuously (controlled rate one to several days)
● used for drugs that are quickly eliminated from the body (would have to take
often)
●absorption rapid in regions where this layer is thin (avoid too fast)
Epidermis
-Composed of keratinized stratified squamous epithelium.
-Mostly consist of keratinocytes (keratin-protection) and lamellar granules
(waterproof sealant)
-Avascular
- Four principle types of cells:
- Keratinocytes (produces keratin).
- Melanocytes (produce the pigment melanin)
-Intraepidermal Macrophages (Langerhans cells) participate in immune
responses mounted against microbes that invade the skin → Helps other
cells of immune system recognize an invading microbe and destroy it.
Form red bone marrow and damage by UV light.
-Tactile Epithelial Cells (Merkel Cells) detect touch sensations,deepest
layer of skin.
Composed of five distinct strata (layers) of cells:
Stratum Basale
- Deepest layer, composes of single row of cuboidal or columnar
keratinocytes that contain scattered keratin intermediate filaments
(tonofilaments);
Stratum Spinosum
- Eight to ten rows of many-sided keratinocytes with bundles of
keratin intermediate filaments; contains projections of
melanocytes intraepidermal macrophages.
Stratum Granulosum
- Three to five rows of flattened keratinocytes, in
which organelles are beginning to degenerate;
cells contain the protein keratohyalin (converts
keratin intermediate filaments into keratin) and
lamellar granules (release lipid-rich, water-
repellent secretion).
Stratum Lucidum
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Week Four (Oct. 2-6, 2017)
- Present only in skin of fingertips, palms, and soles; consists of
four to six rows of clear, flat, dead keratinocytes with large
amounts of keratin.
Stratum Corneum
- Few to fifty or more layers of dead, flat keratinocytes that contain
mostly keratin.
Keratinization and Growth of the Epidermis
- Stem cells divide to produce keratinocytes. → Produces keratin and lamellar
granules that release a waterproof sealant - decrease water entry.loss and
prevents entry of foreign material.
- As keratinocytes are pushed up towards the surface (and thus away from oxygen
and blood supply), they fill with keratin; process known as keratinization.
-Keratinization is the replacement of cell contents with the protein keratin;
occurs as cell moves to the skin surface over 2-4 weeks.
-Epidermal Growth Factor (EGF) and other hormone-like proteins play a role in
epidermal growth.
- When an excessive amount of keratinized cells shed from the skin of the scalp, it
is called dandruff.
- In the chronic skin condition psoriasis, cells shed in 7-10 days as flakey silvery
scales; abnormal keratin is produced; keratinocytes move more quickly than
normal form stratum basale to stratum corneum.
- Callus are caused by frickin which causes increased cell and keratin production.
→ New skin cannot regenerate if stratum basale and its stem cells are destroyed.
Dermis
- Composed of dense irregular connective tissue containing collagen and elastic
fibers.
- Fibroblasts, macrophages and adipocytes are located near subcutaneous layer
while blood vessels,nerve glands, and hair follicles are embedded in dermal
layer.
- There are two major regions of dermis: papillary and reticular region.
- Papillary Region: (below the epidermis)
- Makes up 20% of dermis.
- Contains collagen and elastic fibers.
- Has small nipple-shaped structures that project into the
undersurface of epidermis called dermal papillae.
- All dermal papillae contain capillary loops, some contain
Meissner corpuscles (nerve endings sensitive to touch)
and others contain free nerve endings which give rise to
pain and temperature sensations.
- Reticular Region: (consists of dense irregular connective tissue)
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Document Summary
The integumentary system contributes to homeostasis by protecting the body and helping regulate body temperature. It also allows you to sense pleasurable, painful and other stimuli in your external environment. Synthesizes vitamin d- molecule in skin/uv- 10-15 mins biweekly. The integumentary system is composed of skin, hair, oil, sweat glands , nails and sensory receptors. The skin (cutaneous membrane) covers the external surface of the body"s; largest organ. Epidermis: superficial, thinner portion composed of epithelial tissue. Subcutaneous (hypodermis) layer: located deep into dermis but not part of skin; consists of areolar and adipose tissue. Fibers from the dermis anchor skin to this layer. Serves as as storage depot for fat and large blood vessels. Contains nerve endings called lamellated corpuscles (sensitive to pressure). Contains large blood vessels that supply skin and corpuscles that sense pressure. Pass across the epidermis and into the blood vessels of the dermis. Released continuously (controlled rate one to several days)
