A/P Ch 5

Flash cards

What are the major regions of the skin?

What are the major regions of the skin?

1. Epidermis – outermost superficial region

2. Dermis – middle region

3. Hypodermis (superficial fascia) – deepest region

Figure 5.1

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Figure 5.1

Epidermis

Dermis

Hypodermis(superficialfascia)

Hair root

Hair shaft

Pore

Dermal papillae (papillary layer of dermis)

Meissner's corpuscle

Free nerve endingReticular layer of dermis

Sebaceous (oil) gland

Arrector pili muscle

Sensory nerve fiberEccrine sweat gland

Pacinian corpuscle

Artery

Vein

Adipose tissue

Hair follicle receptor(root hair plexus)

Hair follicle

Eccrine sweatgland

Describe the Epidermis

• Composed:

• Cell Types:

• Cell Layers:

• Main Function:

Describe the Epidermis

• Composed: keratinized stratified squamous epithelium

• Cell Layers: Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale

• Cell Types:keratinocytes, melanocytes, Merkel cells, and Langerhans’ cells

• Main Function: protection

Layers of epidermis

What is Keratinocytes?

What is Keratinocytes?

produce the fibrous protein keratin

What is Melanocytes?

What is Melanocytes?

produce the brown pigment melanin

What is Langerhans’ cells?

What is Langerhans’ cells?

epidermal macrophages that help activate the immune system

What are Merkel cells?

What are Merkel cells?

function as touch receptors in association with sensory nerve endings

Describe the Stratum Basale

Describe the Stratum Basale

• Deepest epidermal layer firmly attached to the dermis

• Consists of a single row of the youngest keratinocytes

• Cells undergo rapid division

Describe Stratum Spinosum

Describe Stratum Spinosum

• Cells contain a weblike system of intermediate filaments attached to desmosomes

• Melanin granules and Langerhans’ cells are abundant

• “Prickly Layer”

Describe Stratum Granulosum

Describe Stratum Granulosum

• Thin; three to five cell layers in which drastic changes in keratinocyte appearance occurs

• Keratohyaline and lamellated granules accumulate in the cells of this layer

Describe the Stratum Lucidum

Describe the Stratum Lucidum

• Thin, transparent band superficial to the stratum granulosum

• Consists of a few rows of flat, dead keratinocytes

• Present only in thick skin

• “Clear Layer”

Describe the Stratum Corneum

Describe the Stratum Corneum

• Horny Layer

• Outermost layer of keratinized cells

• Accounts for three quarters of the epidermal thickness

• Functions include:– Waterproofing– Protection from abrasion and penetration– Rendering the body relatively insensitive to biological,

chemical, and physical assaults

Describe the Dermis

Describe the Dermis• Second major skin region containing

strong, flexible connective tissue

• Cell types include: fibroblasts, macrophages, and occasionally mast cells and white blood cells

• Composed of two layers 1. Papillary

2. reticular

Describe the Papillary Layer

Describe the Papillary Layer

– Areolar connective tissue with collagen and elastic fibers

– Its superior surface contains peglike projections called dermal papillae

– Dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings

Describe the Reticular Layer

Describe the Reticular Layer

– 80% of the thickness of the skin

– Collagen fibers in this layer add strength and resiliency to the skin

– Elastin fibers provide stretch-recoil properties

What is the Hypodermis?

What is the Hypodermis?

• Subcutaneous layer deep to the skin

• Composed of adipose and areolar connective tissue

• Fatty Layer

What three pigments contribute to skin color

What three pigments contribute to skin color?

– Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colors

• Freckles and pigmented moles – result from local accumulations of melanin

– Carotene – yellow to orange pigment, most obvious in the palms and soles of the feet

– Hemoglobin – reddish pigment responsible for the pinkish hue of the skin

What’s the function of sweat glands?

What’s the function of sweat glands?

Different types prevent overheating of the body; secrete cerumen and milk

Describe Eccrine Sweat Glands?

Describe Eccrine Sweat Glands?

found in palms, soles of the feet, and forehead

Describe Apocrine sweat glands

Describe Apocrine sweat glands

found in axillary and anogenital areas

(arm pits, areola of nipples, and genitals)

Describe Ceruminous glands

Describe Ceruminous glands

modified apocrine glands in external ear canal that secrete cerumen

Describe Mammary glands

specialized sweat glands that secrete milk

Glands

Describe Sebaceous Glands

Describe Sebaceous Glands

• Simple alveolar glands found all over the body

• Soften skin when stimulated by hormones

• Secrete an oily secretion called sebum

Describe Hair

Describe Hair

• Filamentous strands of dead keratinized cells produced by hair follicles

• Contains hard keratin

• Pigmented by melanocytes at the base of the hair

Functions of hair include

Functions of hair include

– Helping to maintain warmth

– Alerting the body to presence of insects on the skin

– Guarding the scalp against physical trauma, heat loss, and sunlight

Hair is distributed over the entire skin surface except:

Hair is distributed over the entire skin surface except:

– Palms, soles, and lips

– Nipples and portions of the external genitalia

What is Vellus Hair?

What is Vellus Hair?

pale, fine body hair found in children and the adult female

What is Terminal hair?

What is Terminal hair?

coarse, long hair of eyebrows, scalp, axillary, and pubic regions

Describe Hair thinning and balding

Describe Hair thinning and balding

• Alopecia – hair thinning in both sexes

• True, or frank, baldness – Genetically determined and sex-influenced

condition – Male pattern baldness – caused by follicular

response to DHT

Structure of a Nail

Functions of the Integumentary System

Functions of the Integumentary System

• Protection

• Body temperature regulation • Cutaneous sensation

• Metabolic functions

• Blood reservoir

• Excretion

What does the skin protect from?

What does the skin protect from?

chemical, physical, and mechanical barrier

How is Body Temperature is accomplished?

How is Body Temperature is accomplished?

– Dilation (cooling) and constriction (warming) of dermal vessels

– Increasing sweat gland secretions to cool the body

Explain Cutaneous Sensation

Explain Cutaneous Sensation

exoreceptors sense touch and pain

Describe Metabolic Functions

Describe Metabolic Functions

Synthesis of vitamin D in dermal blood vessels

Describe the Blood Reservoir function of the skin

Describe the Blood Reservoir function of the skin

skin blood vessels store up to 5% of the body’s blood volume

What does the skin Excrete?

What does the skin Excrete?

limited amounts of nitrogenous wastes are eliminated from the body in sweat

Briefly describe Skin Canser

Briefly describe Skin Canser

• Most skin tumors are benign and do not metastasize

• A crucial risk factor for non-melanoma skin cancers is the disabling of the p53 gene

• Newly developed skin lotions can fix damaged DNA

What are the 3 major types of skin cancer?

What are the 3 major types of skin cancer?

– Basal cell carcinoma

– Squamous cell carcinoma

– Melanoma

Describe Basal Cell Carcinoma

Describe Basal Cell Carcinoma

• Least malignant and most common skin cancer

• Stratum basale cells proliferate and invade the dermis and hypodermis

• Slow growing and do not often metastasize

• Can be cured by surgical excision in 99% of the cases

Describe Squamous Cell Carcinoma

Describe Squamous Cell Carcinoma

• Arises from keratinocytes of stratum spinosum

• Arise most often on scalp, ears, and lower lip

• Grows rapidly and metastasizes if not removed

• Prognosis is good if treated by radiation therapy or removed surgically

Describe Melanoma

Describe Melanoma

Cancer of melanocytes is the most dangerous type of skin cancer because it is:

– Highly metastatic

– Resistant to chemotherapy

• Chance of survival is poor if the lesion is over 4 mm thick

Skin cancers

What characteristics does Melanoma Have?

What characteristics does Melanoma Have?

(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)

Describe a First Degree Burn

Describe a First Degree Burn

only the epidermis is damaged

– Symptoms include localized redness, swelling, and pain

Describe a Second Degree Burn

Describe a Second Degree Burn

Epidermis and upper regions of dermis are damaged

– Symptoms mimic first degree burns, but blisters also appear

Describe a Third Degree Burn

Entire thickness of the skin is damaged

– Symptoms: Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed)

What does the Rule of Nines estimate?

What does the Rule of Nines estimate?

• 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

Explain Fetal Skin Development

Explain Fetal Skin Development

• Epidermis develops from ectoderm

• Dermis and hypodermis develop from mesoderm

• Lanugo – downy coat of delicate hairs covering the fetus

• Vernix caseosa – substance produced by sebaceous glands that protects the skin of the fetus in the amnion

Describe skin development (Adolescent – Adult)

Describe skin development (Adolescent – Adult)

• Skin and hair become oilier and acne may appear

• Skin shows the effects of cumulative environmental assaults around age 30

• Scaling and dermatitis become more common

Describe skin development (old-age)

Describe skin development (old-age)

• Epidermal replacement of cells slows and skin becomes thinner

• Skin becomes dry and itchy

• Subcutaneous fat layer diminishes, leading to intolerance of cold

• Decreased elasticity and loss of subcutaneous tissue leads to wrinkles

• Decreased numbers of melanocytes and Langerhans’ cells increase the risk of skin cancer

Questions from the Textbook and

Lab Homework

What type of granules are extruded from the kerationocytes prevent

water loss by diffusion through the epidermis?

What type of granules are extruded from the kerationocytes

prevent water loss by diffusion through the epidermis?

Lamellated

What produces the fibers in the dermis?

What produces the fibers in the dermis?

Fibroblast

What type of glands respond to rising androgen levels?

What type of glands respond to rising androgen levels?

Apocrine glands

Phagocytic cells that occupy the epidermis are called?

Phagocytic cells that occupy the epidermis are called?

Langerhan’s Cells

A unique touch receptor formed from a stratum basale cell and

nerve fiber is a …..

A unique touch receptor formed from a stratum basale cell and

nerve fiber is a …..

Merkel disc

What layer is present in thick skin but not in thin skin?

What layer is present in thick skin but not in thin skin?

Stratum Lucidum

What cell-to-cell structures hold the cells of the stratum spinosum

tightly together?

What cell-to-cell structures hold the cells of the stratum spinosum

tightly together?

Desmosomes

What substance is manufactured in the skin that plays a role in

calcium absorption in the body?

What substance is manufactured in the skin that plays a role in

calcium absorption in the body?

Vitamin D

Which epidermal cell type is most numerous?

Which epidermal cell type is most numerous?

Keratinocyte

which cell functions as part of the immune system

which cell functions as part of the immune system

An epidermal dendritic cell

the epidermis provides a physical barrier due largely to the

presence of

the epidermis provides a physical barrier due largely to the

presence of

Collagen

skin color is determined by

skin color is determined by

-the amount of blood

-pigments

-oxygenation level

the sensations of touch and pressure are picked up by

receptors located in

the sensations of touch and pressure are picked up by

receptors located in

The stratum spinosum

Skin surface markings that reflect points of tight dermal attachment to underlining tissues are called?

Skin surface markings that reflect points of tight dermal attachment to underlining tissues are called?

Flexure Lines