Integumentary System (Chapter 5) Flashcards
What does the integumentary system consist of
Skin, Accessory organs such as hair, nails, sweat glands, sebaceous (oil glands)
Structure of the skin
Epidermis, Dermis, Hypodermis or Subcutaneous Layer
Function of the Epidermis
Protects skin and underlying tissues from heat, microbes, and chemicals; prevents water loss and gain
Structure of the Epidermis
Primarily keratinized stratified squamous epithelium; avascular (no blood vessels)
Keratinocytes Function
Produce keratin; protects from heat, microbes, and chemicals; contributes to water proofing; produces lamellar granules
Structure/Function of Lamellar Granules
Contains glycolipids; upon secretion it provides a water repellant seal
Melanocytes Function
Produce melanin granules in response to UV light; transferred to keratinocytes via cytoplasmic processes; forms protective “umbrella” over nucleus of keratinocytes
Langerhans’ Cells (Dendritic Cells) Function
Originate in red bone marrow which then migrate to dermal capillaries in epidermis which phagocytize microbes, toxins, and debris; functions as an active immune response as needed
Merkel Cells Function
Makes contact with the Merkel disc of a sensory neuron; gives perception of light touch
Layers of Epidermis (highest to lowest)
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Structure of Stratum Basale
Single row of stem cells that actively divide using mitosis which result in two daughter cells
Function of the daughter cells in stratum basale
One daughter cell journeys from basal layer to surface, process takes 25-45 days; other daughter cell remains in stratum basale as a stem cell which continues to divide
Structure of Stratum Spinosum
8-10 cell layers thick; keratinocytes in dried out tissue appear spiny due to the presence of fibers attached to desmosomes in adjacent cells; scattered among keratinocytes are abundant melanin granules and dendritic cells
Structure of Stratum Granulosum
4-6 cell layers thick; functions as a transition layer; cells flatten and begin undergoing apoptosis; keratinization begins and cells accumulate keratinohyaline granules
Structure of Stratum Lucidum
Only appears in thick skin, consists of 2-3 thin rows of translucent bands of dead keratinocytes; increased amounts of keratin with thickened plasma membrane
Structure of Stratum Corneum
20-30 rows of anucleated, keratinized dead cells; glycolipids are found between cells; accounts for 75% of epidermal thickness
Function of Stratum Corneum
Protects deeper cells from external environments; prevents water loss; protects from abrasion; acts as a barrier against microbial, chemical, and physical assaults
Structure of Dermis
strong, flexible CTs; cells consist of macrophages and other WBCs; collagen fibers bind water to keep skin hydrated; contains nerves, blood vessels, and lymphatic vessels; contains hair follicles, oil glands, and sweat glands
Structure of Papillary Layer
Consists of areolar CT and blood vessels; loosely arranged fibers allow phagocytes to patrol dermis; dermal papillae are fingerlike projections that go up into epidermis; it contains capillary loops, free nerve endings, and Meissner’s Corpuscles (light touch receptors)
Function of friction ridges
Enhance gripping ability, contribute to sense of touch, sweat pores in ridges leave unique fingerprint patterns
Structure of Reticular Layer
Consists of dense irregular CT with many elastic fibers, elastic fibers allow stretch-recoil properties, collagen fibers allow for strength and resiliency; cutaneous plexus is a network of blood vessels between reticular layer and hypodermis; find bulk of glands, hair follicles, and Pacinian Corpuscles (deep pressure receptors)
Function of Hypodermis
Fat storage for energy source, insulation against heat loss, and protection from physical trauma; Pacinian Corpuscles that allow for deep pressure sensations
Structure of Hypodermis
Areolar and adipose CTs; protein fibers from dermis which anchor skin proper to hypodermis; hypodermis attaches underlying tissues to organs; contains large blood vessels that supply the skin
Three types of skin pigments
Melanin, Carotene, and Hemoglobin
Function of Hair
Protects scalp from injury and sun, decreases heat loss, and perception of light touch
Structure of Hair
Hair root: lies within hair follicle; Hair shaft; projects above skin surface; Medulla: large, irregularly shaped cells with pigment granules; Cortex: flattened cells with pigment granules; Cuticle: single layer of cells overlapping cells with lots of keratin
Structure/Function of Hair Root Plexus
Sensory neuron dendrites surrounding hair follicle; sensitive to light touch; nerve impulses generated when hair shafts bend
Hair Pigment Source
Produced by melanocytes associated with matrix of hair follicle which then pigment granules pass into epithelial cells of cortex/medulla
Function of Nails
Protects ends of digits against trauma, grasp and manipulate small objects, scratch skin
Structure of Nail
Nail body/plate: visible portion of nail; Free edge: extends past distal end of digit; Nail root: buried within fold of skin; Nail matrix: epithelium deep to nail root which is the site of mitosis, affected by age, health, nutrition; Eponychium (cuticle): skin fold over nail root; Hyponychium: skin beneath free edge of nail that protects nail bed; Nail bed: attaches nail to fingertip; Lunula
Eccrine Gland Structure/Function/Secretion
Simple, coiled tubular gland; regulate body temp via evaporation and eliminate small amounts of metabolic wastes; true sweat
Apocrine Gland Structure/Function/Secretion
Primarily secrete into hair follicles; true sweat which is odorless when secreted but becomes odorous after mixing with bacteria on skin surface
Ceruminous Gland Structure
simple, coiled, tubular glands or pores that open onto surface of skin; lined with simple cuboidal epithelium
Ceruminous Gland Location
Skin found in external auditory canal, lies deep to sebaceous glands
Ceruminous Gland Function
Acts as a sticky barrier to keep foreign bodies out of the auditory canal
Ceruminous Gland Secretion
Earwax
Sebaceous Gland Structure
branched, acinar, simple, coiled, tubular glands or pores that open onto surface of skin; lined with simple cuboidal epithelium
Sebaceous Gland Location
Hair Follicles
Sebaceous Gland Function
Coats skin/hair to prevent drying and brittleness; Waterproofs hair and skin; Secretion inhibits growth of bacteria
Sebaceous Gland Secretion
Sebum (oil); can result in black or white heads
Mammary Gland Structure/Function/Secretion
Modified apocrine glands; found within breasts to nourish infants; milk
Structure/Function of Chemical Skin Barrier
Sweat (acidic pH), sebum (antimicrobial), melanin (UV light damage)
Structure/Function of Physical Skin Barrier
Water loss/gain, limits penetration of some chemicals
Structure/Function of Biological Skin Barrier
DCs/epidermis, macrophages in dermis, phagocytosis of microbes, toxins, debris
Process of Vitamin D Synthesis
UV rays activate inactive vitamin D precursors in skin, enzymes in liver produce calcidiol which enter blood stream and travel to kidneys which convert calcidiol to calcitriol, calcitriol increases absorption of Ca+2 from small intestines
Cutaneous Sensations
Free nerve endings: pain, warm/cold, vibration, itching, tickling; Hair root plexuses: hairs bending; Merkel discs: light touch; Meissner’s Corpuscles: light touch; Pacinian Corpuscles: deep pressure
Increase in Body Temp Mechanism
Blood vessels dilate, sweat glands become active, hair lies next to skin to promote heat loss -> body temp decreases
Decrease in Body Temp Mechanism
Blood vessels constrict, sweat glands become inactive, hairs become erect (arrector pili contract), shivering due to skeletal muscle contractions to produce heat -> body temp increases
Define Hyperthermia
Body temp rises above normal temperature
Mechanism for Heat Stroke
Hypothalamus becomes depressed which suspends all cooling mechanisms; Initiates positive feedback mechanism: increased body temp increases metabolic rate which then increases heat production; Skin becomes dry, organs may be damaged, brain may be damaged
Mechanism for Heat Exhaustion
Headache, nausea, vomiting associated with dehydration; Heat loss mechanisms still in play which can lead to heat stroke
Mechanism for Fever
Controlled hyperthermia initiated by hypothalamus due to bacterial pyrogens
Define Hypothermia
Body temp decreases below normal temperature
First Degree Burns
Affects only epidermis and skin functions are intact; Characterized by redness and pain with no blisters; Heals in 3-6 days
Second Degree Burns
Destroys epidermis and parts of the dermis with some skin functions lost; Characterized by redness, pain, and blisters; Can heal in 10-15 days
Third Degree Burns
Entire thickness of skin and subcutaneous layer destroyed; Skin turns gray/white, red or black; Most skin functions lost: no blood vessels, sweat glands, sebaceous glands, or hair follicles; No pain due to lack of sensory nerve endings; Most likely require skin grafting to prevent extensive fluid loss and infection
Fourth Degree Burns
All skin layers, tendons, muscles, and sometimes bone are destroyed; Very low survival rate; Autografting or Lab Grown Skin
Epidermal Wound Healing Mechanisms
Basal stem cells break away from basement membrane, enlarge, and migrate across wound; Migrate as a sheet until advancing cells from opposite sides of the wound meet and stop migrating due to contact inhibition; As basal stem cells migrate EGF stimulate basal stem cells to divide and replace those migrated into wound; Stimulates those newly migrated cells in the wound to divide and form new strata; Epidermis thickens
Decubitus Ulcer
Localized breakdown and ulceration of skin due to an interference with its blood supply
Eczema
Inflammation of skin and is characterized by patches of red, blistering, itchy skin
Impetigo
Signs and symptoms include red sores that quickly rupture, ooze and then form a yellow-brown crust
Psoriasis
Chronic autoimmune condition distinguished by epidermal patches that are raised and reddened and covered with silvery scales that itch, burn, and sometimes bleed
Vitiligo
Pigment loss produces milk-white patches (depigmentation) on skin and is more prominent in people with dark skin
Contact Dermatitis
Red rash or bumps and severe itching. Dry, cracked, red patches that drain fluid and crusting of skin
Alopecia
Hair falls out in patches due to immune system attacking their follicles; baldness
Albinism
Defect of melanin production that results in little to no color in skin, hair, and eyes
Acne Vulgaris
Blackheads, blemishes, whiteheads, pimples, or zits that occur on the face, neck, shoulders, back, or chest
Cold Sores
Small fluid filled blisters usually occurring around lips
Seborrhea
Excessive discharge of sebum from sebaceous glands
Onychomycosis
Nail becomes thickened or discolored and sometimes pieces break off
Tinea Infection
Dermatophytosis fungi that affect certain areas. Red, itchy, scaly or raised patches; Tinea Pedis: foot, Tinea Captis: scalp, Tinea Cruris: groin and pelvic region
Melanoma
Change in existing moles or unusual growth on skin. Changes in mole include itching, scaliness, spreading of pigment from mole to surrounding skin
Basal Cell Carcinoma
Pearly white or waxy bump. Flat scaly brown or flesh colored patches in dorsal, or thoracic regions of body
Squamous Cell Carcinoma
Firm red nodule, flat sore with a scaly crust
