Ch. 5 Flashcards
Integumentary system
Consists of skin and accessory structures, such as hair, glands and nails.
FUNCTIONS:
- Protection
- Sensation
- Temperature regulation
- Vitamin D production
- Excretion
What are the 2 major tissue layers of the skin?
Epidermis & Dermis
Epidermis
Superficial layer of the skin
consisting of stratified squamous epithelial tissue / seperated from dermis by basement membrane / no blood vessels
Cells are keratinocytes which produce keratin
Melonscytesproduce pigment / color
Langerhans cells part of immune system
Merkel cells specialized cells associated with nerve endings responsible for detecting light touch
-Protects against damage from abrasion and reduces water loss
Dermis
A layer of connective tissue
Epidermis rests on the dermis
Responsible for strenght of the skin
Subcutaneous tissue
A layer of loose connective tissue
Skin rests on top of - not part of skin or integumentary system
Connects skin to underlying muscle or bone
What are the cells of the epidermis?
- *Keratinocytes** which produce keratin
- *Melonscytes** produce pigment / color
- *Langerhans** cells part of immune system
- *Merkel cells** specialized cells associated with nerve endings responsible for detecting light touch
Keratinization
Process in which Keratinocytes change shape and chemical composition, where cells accumulate keratin
Cells eventually die and produce an outer layer of dead, hard cells which resist abrasion and forms a barrier
Psoriasis
Skin disease
Large scales of epidermal tissue are sloughed off
Strata
Region
The 5 strata are: Stratum basale, Stratum spinosum, Stratumgranulosum, Stratuml lucidum, Stratum corneum
Stratum Basale
Deepest portion of epidermis
Single layer of cuboidal or columnar cells
Epidermis is anchored to basement membranes by hemidesmosomes
Keratinocytes are strengthened internally by keratin fibers
*Keratinocyte stem cells undergo mitosis every 19 days
Stratum Spinosum
On top of stratum basale
8 - 10 layers of many sided cells
as cells are pushed to the surface they flatten, desmosomes break apart and new ones build
*As karatinocytes progess through the stratum, additional keratin fibers and lamellar bodies form inside the cells
Lamellar bodies
Lipid filled membrane bound organelles
Stratum granulosum
3rd layer up
2-5 layers of somewhat flat diamond shaped cells
Presences of protein granules called Keratohyalin, which accumulate in the cytoplasm of the keratinocyte. Lamellar bodies release their lipids, the keratinocyte dies, keratin fibers and granules within the cytoplasm do not degenerate
Stratum Lucidum
4th layer up / only found in thick skin
several layers of dead keratinocytes, kertain fibers are present, cells appear transparent
Stratum Corneum
Top layer / superficial layer
25 or more dead layers of overlapping squamous cells joined by desmosomes
When the desmosomes break apart the cells shed from the surface of skin
Cornified cells
Dead keratinocytes with a hard protein envelope
Thick skin
Has all 5 epithelial strata
Found: palms of hands, soles of feet and finger tips
Thin skin
Has 4 layers of epithelial strata - missing stratum lucidum
Found: on rest of the body, (minus soles of feet, finger tips and palms of hands)
Callus
Stratum corneum increases in thickness
Usually on an area subject to friction or pressure
Corn
Skin over boney areas develop a cone shaped structure
Melanin
group of pigments responsible for skin, hair and eye color
Melanocytes
Produced melanin
Irregularrly shaped cells with many long processes that extend between the keratinocytes of the stratum basale and stratum spinosum
Melansomes
Vesicles in which melanocytes package melanin
Albinism
Genetically agressive trait that results from inability to produce tyrosinase. Result is the deficiency or absence of pigment of skin, hair and iris of eyes
Erythema
Condition in which the skin turns a reddish hue when the amount of blood flowing increases
Cyanosis
A bluish skin color from a decrease in blood flow
Carotene
A yellow pigment found in plants such as carrots and corn.
What 2 layers is the dermis composed of?
Papillary layer
Reticular layer
Papillary layer
Superficial dermis layer
loose connective tissue with thin fibers that are somewhat loosely arranged, also contains blood vessels
Reticular layer
composed of dense irregular connective tissue
Resistant to stretching
Dermal papille
Projections that extend toward the epidermis
Friction ridges
The dermal papille under thick skin lie in parallel curved ridges creating patterns called friction ridges
Cleavage lines / tension lines
When elastic and collagen fibers are oriented more in one direction than others
Stretch marks
When skin is overstretched and dermis ruptures and leaves lines visable through epidermis
Intradermal injection
Goes into the dermis
Subsutaneous injection
extends into the subcutaneous tissue
Aka insulin
Intramuscular injection
reaches deep muscle tissue
Aka vaccines
lanugo
delicate and unpigmented hairs on fetus
Terminal hairs
By birth the hairs that replace the lanugo of the scalp, eyelids and eyebrows
Vellus hairs
Short fine and usually unpigmented replace the lanugo on rest of the body
Hair shaft
Protrudes above the surface of the skin
Hair root
located below the surface of the skin
What are the 3 columns of dead keratinized epithelial cells on the root and shaft of hair?
Medulla
cortex
Cuticle
Medulla
Central axis of hair
consists of 2-3 layers of cells containing keratin
Cortex
Surrounded medulla and forms the bulk of the hair
cells contain hard keratin
Cuticle
covers the cortex
single layer of cells containing hard keratin
Hair follicle
tubelike invagination fo the epidermis that extends into the dermis.
Hair develops and grows within each follicle
Matrix
inside the hair bulb
mass of undifferentiated epithelial cells
growth zone / produces both the hair and internal epithelial root sheath
Hair papilla
Dermis of skin projects into the hair bulb
Within hair papilla are blood vessels that provide nourshment
Alopecia areata
spot baldness
extensive hair loss
Arrector pili
Smooth muscle cells
Causes hair to stand up
