A&P Ch. 5
What is the sensory receptor in the Epidermis?
Free nerve endings: dendrites
What are the sensory receptors in the Dermis?
Lamellated Corpuscles: sensitive to pressure
What is the sensory receptor in the Hypodermis?
Name the 5 layers of the Epidermis, from deepest to most superficial.
Protection against disease and prevents loss of water
What are the 2 major functions of the skin?
Due to reduced hemoglobin in blood; the mails and mucous regions turn from blue to dark purple in color.
Yellow color caused from improper liver function
Paleness of skin due to anemia or shock
A genetic lack of skin color due to an inherited inability to produce melanin.
Redness in skin due to engorgement of capillaries due to injury, heat, allergic reaction or inflammation.
Partial or total lack of hair.
Amount and type of melanin in hair.
How is hair color determined?
Due to decreased melanin production
Due to lack of melanin and presence of air bubbles in hair shaft
Bacteria, dehydration, and UV radiation
What 3 things does the skin protect against?
How much of the blood reservoir is in the dermis?
Reticular Region of the Dermis
Deeper part of the dermis which is attached to the subcutaneous layer. Consists of dense irregular connective tissue containing bundles of collagen, some coarse elastic fibers and fibroblasts
Causes the skins color to vary from pale yellow to tan to lack; differences in skin color are to the amount of pigment melanocytes produce and disperse.
-Present in all skin except palmes and soles
Functions: protection, sense of touch
Structure: columns of dead, keratinized cells bonded by extracellular protein
-growth occurs in the matrix deep in the hair follicle
-sebaceous (oil secreting) glands and smooth muscles surround hair
-hair root plexuses (interconnected nerves) surround follicles which respond to touch
Describe the structures and functions of Hair.
-alternate growth and resting stages occur
-hair loss may be attributed to sudden weight loss, radiation, chemotherapy, age, genetics, gender, emotions or stress
Describe hair growth/loss
Simple branched acinar glands connected to hair follicles; secrete oil (sebum), triglycerides, cholesterol, proteins and inorganic salts
-sebum prevents drying of hair, evaporation of water from skin
-keeps skin soft and pliable,inhibits growth of bacteria
-Exocrine and Apocrine sweat glands are the two subcaegories
Seat glands which release sweat into hair follicles and onto the surface of the skin.
Exocrine Sweat Glands
Predominately in forehead, palms and in soles; secrete 600 ml/day, which functions to regulate body temp by evaporation; rids body of wastes
Apocrine Sweat Gland
Found mainly in the axilla, groin, areola, bearded region of face; sweat produced by exocytosis; begin to function at puberty, secretions may be triggered by emotional stress or sexual arousal
Produce ear wax (cerumen), which protects external auditory canal; it can become impacted and need removed
Plates of tightly packed, hard, dead, keratinized epidermal cells which cover the dorsal surface of the distal digits
-normal appear pink due to capillary infusion; abnormal colors may indicate health problems
Epidermal- basal cells surround would with basement membrane; cells enlarge and migrate across would until it's covered; epidermal growth factor stimulates basal stem cell growth to replace cells lost in wound
Deep- occurs when wound extends to dermis
Describe Epidermal wound healing, in contrast to Deep would healing.
1) Inflammatory phase
2) Migratory phase
3) Proliferative phase
4) Maturation phase
List the stages of Deep would healing.
Blood clot forms and unites edges; vasodilation (opening) brings WBCs for phagocytosis of microbes
Describe the Inflammatory phase of deep would healing.
Clot becomes scab; epithelial cells migrate beneath it to bridge would
-fibroblasts migrate beneath it to bridge wound
-granulation tissue fills wound
Describe the Migratory phase of deep would healing.
Excessive growth of epithelial cells beneath scab, deposition of fibroblasts and collagen fibers; continued growth of blood vessels
Describe the Proliferative phase of deep wound healing.
Scab sloughs off and skin returns to normal.
Describe the Maturation phase of deep wound healing.
-when too hot, body produces sweat that evaporates; blood flow increases through skin
-when too cold, the blood flow goes internally; less heat is lost to radiation; swear production decreases and body warms
Describe the regulation of body temp, via the negative feedback system.
Nerve endings receptors-tactile discs and corpuscles of touch
-pressure, vibration, tickling, warmth, and coolness
Describe how the skin assists in cutaneous sensations.
Sweat, ions, organic compounds (such as urea and ammonia), fat-soluble vitamins, anti-inflammatory drugs, gases, and solvents
What does the skin excrete?
Activation of precursor in the skin by UV light; it is modified by the liver and kidneys producing calcitrol, active vitamin D, it aids in the absorption of calcium in the GI tract to the blood
Describe the syntheses of Vitamin D
Superficial, thinner portion of skin, composed of epithelial tissue; keratinized stratified squamous epithelium
Cells: Keratinocytes, melanocytes, langerhans cells, merkel cells
Describe the Epidermis and the cells that make it up.
Make up 90% of the epidermis
-produce the protein keratin (protects underlying skin from heat, microbes and chemicals
-produces lamellar granules which function in waterproofing (loosing water)
8% of the epidermis which produce the pigment melanin ( a brown-black pigment that contributes to skin color and absorbs damaging ultraviolet light)
Epidermis cells that arise from red bone marrow and migrate to the epidermis; participate in immune responses mounted against microbes that invade the skin.
The least numerous of the epidermal cells; located in the deepest layer of the epidermis; contact the flattened processes of a sensory neuron (tactile or merkel disc); function in touch
the Stratum Basale layer of the epidermis
-Deepest layer of the epidermis
-composed of a single row of cuboidal or columnar keratinocytes; has large nuclei, contains ribosomes, contain some rough ER; some are sem cells which undergo mitosis
the Stratum Spinosum layer of the epidermis
-superficial to the stratum basale layer
-many sided keratinocytes fit closely together; may retain their ability to undergo cell division; provide strength and flexibility in skin
the Stratum Granulosum layer of the epidermis
-at the middle of the epidermis
-consists of flattened keratinocytes that produce keratiohyalin, a waterproofing material
-where the cell dies
the Stratum Lucidum layer of the epidermis
-persent only in the thick skin of the fingertips, palms, and soles; consists of flattened clear, dead keratinocytes that contain large amounts of keratin and thickened plasma membrane
the Stratum Corneum layer of the epidermis
-most superficial layer
-consists of layers of flattened dead keratinocytes; the cells are continuously shed and replaced due to friction; functions in waterproofing, protection against microbes and injury
-second, deeper part of the skin ( below epidermis), composed mainly of connective tissue containing collagen and elastic fibers.
-made up of the Superficial papillary region and the Reticular region
Describe the Dermis and the regions that make it up.
the Superficial Papillary Region of the dermis
-the superficial part of the dermis; consists of areolar connective tissue containing fine elastic fibers
a) Dermal Papillae- fingerlike projections into the dermis (look like waves)
b) produces fingerprints
c) Corpuscles of touch (meissner corpuscles): tactile receptors sensitive to touch
d) free nerve endings- warmth, coolness, pain, tickling and itching