The Integumentary System 5 The Integumentary System

Consists of three major regions Skin (Integument) Consists of three major regions ________________ – outermost superficial region Dermis – __________________ Hypodermis (superficial fascia) – deepest region

Reticular layer of dermis Hair shaft Pore Dermal papillae (papillary layer of dermis) Epidermis Meissner's corpuscle Free nerve ending Reticular layer of dermis Sebaceous (oil) gland Dermis Arrector pili muscle Sensory nerve fiber Eccrine sweat gland Pacinian corpuscle Hypodermis (superficial fascia) Artery Vein Hair root Adipose tissue Hair follicle Eccrine sweat gland Hair follicle receptor (root hair plexus) Figure 5.1

Epidermis Composed of keratinized ____________ ____________ epithelium, consisting of four distinct cell types and four or five layers Cell types include ______________, melanocytes, Merkel cells, and ___________________ cells Outer portion of the skin is exposed to the external environment and functions in protection

Cells of the Epidermis ________________ – produce the fibrous protein keratin ________________ – produce the brown pigment melanin Langerhans’ cells – epidermal macrophages that help activate the immune system Merkel cells – function as touch receptors in association with sensory nerve endings

Layers of the Epidermis Figure 5.2b

Layers of the Epidermis: Stratum Basale (Basal Layer) Deepest epidermal layer firmly attached to the ____________________ Consists of a single row of ___________________ Cells undergo rapid division, hence its alternate name, stratum ________________

Layers of the Epidermis: Stratum Spinosum (Prickly Layer) Cells contain a weblike system of intermediate filaments attached to _________________ _________________granules and _________________ cells are abundant in this layer

Layers of the Epidermis: Stratum Granulosum (Granular Layer) Thin; three to five cell layers in which drastic changes in ______________________ appearance occurs Keratohyaline and ___________________ granules accumulate in the cells of this layer

Layers of the Epidermis: Stratum Lucidum (Clear Layer) Thin, transparent band superficial to the stratum __________________ Consists of a few rows of flat, dead keratinocytes Present only in __________ ___________

Layers of the Epidermis: Stratum Corneum (Horny Layer) Outermost layer of ________________________ cells Accounts for three quarters of the ______________ thickness Functions include: _______________________ Protection from _________________ and penetration Rendering the body relatively __________________ to biological, chemical, and physical assaults

Layers of the Epidermis Figure 5.2b

Dermis Second major skin region containing strong, flexible _____________ tissue Cell types include _______________, macrophages, and occasionally mast cells and ______________________________________ Composed of two layers – ______________ and ___________________

Layers of the Dermis: Papillary Layer Areolar connective tissue with _______________ & _________________________________fibers Its superior surface contains peglike projections called ___________________________________ Dermal papillae contain capillary loops, Meissner’s________________________________ _________________________________________

Layers of the Dermis: Reticular Layer Accounts for approximately _____% of the thickness of the skin Collagen fibers in this layer add _____________ and _________________________ to the skin Elastin fibers provide ______________________ properties

Hypodermis _________________________ layer deep to the skin Composed of _______________ and _________________ connective tissue

Three pigments contribute to skin color: ______________________________– yellow to reddish-brown to black pigment, responsible for dark skin colors ______________________________– result from local accumulations of melanin ______________________________ – yellow to orange pigment, most obvious in the ____________ and __________________________ ______________________________– reddish pigment responsible for the pinkish hue of the skin

Sweat Glands Different types prevent overheating of the body; secrete cerumen and milk ___________________ sweat glands – found in palms, soles of the feet, and forehead _ ___________________ sweat glands – found in axillary and anogenital areas ___________________ glands – modified apocrine glands in external ear canal that secrete cerumen ___________________ glands – specialized sweat glands that secrete milk

Sebaceous Glands Simple ___________________ glands found all over the body Soften skin when stimulated by ___________________ Secrete an oily secretion called ___________________

Hair Filamentous strands of dead ___________________ cells produced by ___________________ __________ Contains hard keratin which is ___________________ ___________________ than soft keratin of the skin Made up of the ___________________ projecting from the skin, and the ___________________ embedded in the skin Consists of a core called the ___________________ ___________________ ___________________ Pigmented by ___________________ at the base of the hair

Hair Function and Distribution Functions of hair include: Helping to maintain ___________________ Alerting the body to ___________________ ___________________ on the skin Guarding the scalp against ___________________ ___________________ ___________________

Hair Function and Distribution Hair is distributed over the entire skin surface except: ___________________ ___________________ ___________________ and portions of the ___________________ ___________________

Hair Follicle Root sheath extending from the ___________________ into the ___________________ Deep end is expanded forming a _______________ A knot of sensory nerve endings (a root hair ___________________) wraps around each hair bulb Bending a hair stimulates these endings, hence our hairs act as ___________________ ___________________ ___________________

Hair Follicle Figure 5.5a

Hair Follicle Figure 5.5c

Types of Hair ___________________ – pale, fine body hair found in children and the adult female ___________________ – coarse, long hair of eyebrows, scalp, axillary, and pubic regions

Hair Thinning and Baldness ___________________– hair thinning in both sexes True, or frank, baldness ___________________ determined and ___________________ condition Male pattern baldness – caused by follicular response to DHT

Structure of a Nail Scale-like ___________________ of the epidermis on the ___________________ , ___________________ surface of fingers and toes Figure 5.6

Functions of the Integumentary System ___________________– chemical, physical, and mechanical barrier ___________________ regulation is accomplished by: ___________________ (cooling) and ___________________ (warming) of dermal vessels Increasing sweat gland secretions to cool the body ___________________ ___________________– exoreceptors sense touch and pain

Functions of the Integumentary System ___________________ functions – synthesis of ___________________ in dermal blood vessels ___________________ reservoir – skin blood vessels store up to 5% of the body’s blood volume ___________________ – limited amounts of ___________________ wastes are eliminated from the body in sweat

Skin Cancer Most skin tumors are ___________________ and do not ___________________ Metastasize means ______________________ A crucial risk factor for nonmelanoma skin cancers is the disabling of the ___________________ Newly developed skin lotions can fix damaged DNA

The three major types of skin cancer are: ___________________ ___________________

Basal Cell Carcinoma Least ___________________ and most common skin cancer Stratum basale cells ___________________ and invade the dermis and hypodermis Slow growing and do not often metastasize Can be cured by ___________________ ___________________ in 99% of the cases

Squamous Cell Carcinoma Arises from ______________________________ of stratum spinosum Arise most often on ___________________ ___________________ ___________________ Grows rapidly and ___________________ if not removed Prognosis is good if treated by ___________________ therapy or ___________________ surgically

Melanoma Cancer of melanocytes is the most dangerous type of skin cancer because it is: Highly __________________________________ Resistant to ______________________________

Skin Cancers Figure 5.7a–c

Melanomas have the following characteristics (ABCD rule) A: Asymmetry; the two sides of the pigmented area do not match B: Border is irregular and exhibits indentations C: Color (pigmented area) is black, brown, tan, and sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil eraser)

Melanoma Treated by wide surgical excision accompanied by immunotherapy Chance of survival is poor if the lesion is over 4 mm thick

Burns First-degree – only the ___________________ ___________________ is damaged Symptoms include localized redness, swelling, and ___________________

Burns Second-degree – ___________________ and upper regions of ___________________ are damaged Symptoms mimic first degree burns, but ___________________ also appear

Third-degree – entire thickness of the skin is damaged Burns Third-degree – entire thickness of the skin is damaged Burned area appears gray-white, cherry red, or black; there is no initial ___________________ or ___________________ (since nerve endings are destroyed)

Estimates the severity of burns Burns considered critical if: Rule of Nines Estimates the severity of burns Burns considered critical if: Over 25% of the body has second-degree burns Over 10% of the body has third-degree burns There are third-degree burns on face, hands, or feet

Rule of Nines Figure 5.8a

Developmental Aspects of the Integument: Fetal Epidermis develops from ___________________ Dermis and hypodermis develop from ___________________ ___________________ – downy coat of delicate hairs covering the fetus ___________________ ___________________– substance produced by sebaceous glands that protects the skin of the fetus in the amnion

Developmental Aspects of the Integument: Adolescent to Adult Skin and hair become ___________________ and acne may appear Skin shows the effects of cumulative environmental assaults around age ___________________ Scaling and ___________________ become more common

Developmental Aspects of the Integument: Old Age Epidermal replacement of cells ___________________ and skin becomes ___________________ Skin becomes _______________________________ Subcutaneous fat layer diminishes, leading to intolerance of ___________________ Decreased ___________________ and loss of subcutaneous tissue leads to ___________________ Decreased numbers of melanocytes and Langerhans’ cells increase the risk of ______________________