Integument Histo

Question 1

Integument

Answer 1

Largest organ in the body
Epidermis and dermis
Protection
Secretion/absorption
Makes vitamin D3
Thermoregulation

Question 2

Epidermis

Answer 2

Keratinized Stratified squamous ET
Stratum corneum
Stratum lucidum (thick skin)
Stratum granulosum
Stratum spinosum
Stratum basale
Keratinocytes
Melanocytes
Langherhan’s cells
Merkel cells

Question 3

Stratum basale

Answer 3

Deepest epidermal layer
1 row of keratinocytes with stem cells interspersed
Contains melanocytes
Contains Merkel cells
Mitotically active
Bound apically via desmosomes
Bound basally via hemidesmosomes

Question 4

Stratum spinosum

Answer 4

Many cell layers thick
Has keratinocytes
Gets thickened to form calluses and corns

Question 5

Stratum granulosum

Answer 5

Thickest nonkeratinized layer
Keratinocytes have keratohyaline granules, the precursor to filaggrin
Filaggrin makes keratin into bundles
Irregularly shaped, variable in size

Question 6

Stratum lucidum

Answer 6

Only in thick skin
No organelles or nuclei
Stains very light (almost transparent)
Right under stratum corneum

Question 7

Stratum corneum

Answer 7

Thickest layer with keratin
No organelles or nuclei
Form water barrier of epidermis via lipids on plasma membrane
Continuously shed
Thicker in thick skin

Question 8

Keratinocytes

Answer 8

Contain keratin
Participate in the epidermal water barrier
Participate in keratinization and desquamation (shedding)

Question 9

Keratinization

Answer 9

Basal cell: contains intermediate keratin filaments held together in tonofibrils
Spinous cell: keratin synthesis still occurring; keratohyaline granules are being produced and lamellar bodies
Granular cells: discharge of lamellar bodies—>water barrier
Filaggrin further promotes aggregation of keratin filaments
Now cornified cells—>keratinized
Process is pH dependent: more superficial, lower pH

Question 10

Melanocytes

Answer 10

Produce melanin, an enzyme that protects cells from UV radiation
Start out in premalanosomes—>melanosomes
Melanosomes extend into the cell processes and melanin is transferred to keratinocytes via phagocytosis “pigment donation”
Tyrosine—>DOPA via tyrosinase
DOPA—>melanin
Epidermal-melanin unit: 1 melanin per 36 keratinocytes

Question 11

Langerhan’s cells

Answer 11

APC’s that are derived from monocytes
Most noticeable in the stratum spinosum layer
Antigen is phagocytized and displayed on the cell surface
Activates lymphocytes

Question 12

Merkel cells

Answer 12

In stratum basale
Acute sensory perception
Associated with nerve endings
Merkel cell carcinoma: uncontrolled proliferation of merkel cells

Question 13

Dermal-Epidermal junction

Answer 13

Dermal papillae
Epidermal ridges
Hemidesmosomes
Focal adhesions

Question 14

Layers of the dermis

Answer 14

Reticular layer

Papillary layer

Question 15

Papillary layer

Answer 15

Right underneath the epidermis
Most superficial is loose areolar CT
Rest is dense irregular CT
Thinner collagen fibers, elastic fibers
Vasculature and nerve endings

Question 16

Reticular layer

Answer 16

Dense irregular CT
Deep to papillary layer
Thicker and less cellular
Langer’s lines-regular lines of tension

Question 17

Hypodermis

Answer 17

Subcutaneous fascia
Deepest layer
Not true Integument
Adipose tissue

Question 18

Meissner’s corpuscles

Answer 18

In dermal papillae

Touch receptors responsive to low frequency stimuli

Question 19

Pacinian corpuscles

Answer 19

In dermis or hypodermis
Round (looks like onion)
Responsive to pressure and vibrations
Fingerprints, joints, internal organs

Question 20

Free nerve endings

Answer 20

Free in that they are not surrounded by CT
Stop in the stratum granulosum
Fine touch, heat, cold, pain
By hair follicles

Question 21

Sebaceous glands

Answer 21

Near hair follicles
Holocrine secretion
Secrete sebum made of triglycerides and cholesterol
Lubricate and soften skin
Water barrier
Pilosebaceous canal-sebum discharged into the hair follicle

Question 22

Sweat (sudoriferous) glands

Answer 22

Eccrine (merocrine) and apocrine

Question 23

Eccrine sweat glands

Answer 23

All around body except for lips and external genitalia
Small lumen
Secrete via merocrine/eccrine secretion
Myoepithelial cells cause secretion
Water, uric acid, ammonia in secretion
Coiled glands
Ducts are stratified cuboidal
Temp regulation via cooling
Cholinergic regulation

Question 24

Apocrine sweat glands

Answer 24

Areola, anus, axilla
Large lumen
Nervous sweat
Contains salt, proteins, carbs in secretion
Myoepithelial cells
Secrete via merocrine secretion
Andrenergic regulation

Question 25

Infundibulum

Answer 25

Hair follicle

From sebaceous gland to opening of surface

Question 26

Follicular bulge

Answer 26

Contains stem cells

Near arrector pili muscle

Question 27

Bulb

Answer 27

Deepest part of hair follicle

Contains invagination where dermal papillae are

Question 28

Hair matrix

Answer 28

Contain matrix cells that divide rapidly

Count for hair growth

Question 29

Medulla of hair shaft

Answer 29

Loose arrangement of keratin fibers

Innermost part

Question 30

Cortex of hair shaft

Answer 30

Surrounds medulla
Hard intermediate keratin filaments
Largest layer

Question 31

Cuticle

Answer 31

Outermost layer of hair shaft

Several layers of overlapping keratinized squamous cells

Question 32

Nail

Answer 32

Highly keratinized cells on a bed of epidermis

Question 33

Nail root

Answer 33

Most proximal region, covers nail matrix

Question 34

Nail matrix

Answer 34

Stem cells divide and form keratinocytes
Nail plate remains attached to nail bed
Pushed forward by continuous growth

Question 35

Lunula

Answer 35

Crescent-shaped white are near nail matrix

Question 36

Cuticle

Answer 36

Extension of skin covering nail root