integumentary system Flashcards
largest single organ of the body
skin
- 15% to 20% total body weight
function of the skin
Protection – epidermis
Sensory – dermis
Thermoregulatory – adipocytes
in hypodermis
Metabolic
Sexual signaling
briefly explain the 2 types of skin
The designation “thick” and “thin” refer to the thickness of the epidermal layer.
THICK SKIN
● Palms of the hands and soles of the feet
● 400 to 1400 um
● Areas without hair
THIN SKIN
● Covers the rest of the body
● 75 to 150 um
● Hairy parts of the body
is the epidermis vascular or avascular
Avascular
Peg-and-socket interdigitations in the skin that form unique patterns (loops, arches, whorls) known as dermatoglyphs.
epidermal ridges
(unique in every individual)
Study of the ridge patterns
Dermatoglyphics
- Used in fingerprint identification
- Important for crime investigations
Rare genetic disorder that prevents the develop of fingerprints
Adermatoglyphia
- aka “Immigration Delay Disease”
who discovered Adermatoglyphia
during 2007 by Prof. Peter Itin
- One family from US had a problem when they were about to travel as they did not have fingerprints
Contain many blood vessels that supply the overlying epidermis with nutrients, remove waste products and aid in regulating body temperature.
Dermal Papilla
- irregular projection at the junction of the dermis and epidermis
layers of the skin
- Epidermis
stratified squamous keratinized epithelium - Dermis
CT that supports the epidermis and binds it to the subcutaneous tissue or the hypodermis - Hypodermis
loose CT that attaches skin to the underlying tissues
- Directly attached to the muscles
- Consists of fat for thermal regulation
this forms the major distinction between thick and thin skin
epidermis
○ Thick skin – 5 layers
○ Thin skin – 4 layers (no stratum lucidum)
Parenchyma of the epidermis
keratinocytes
- Parenchyma means major structure or the cells responsible for the main function of certain location
3 Epidermal Cell Types Present
- Melanocytes
● Pigment-producing = produces melanin
● Found in the basal layer - Langerhans Cells
● Antigen-presenting cells found in stratum spinosum layer
○ Located above the stratum basale
● Macrophage in the epidermis
- In the blood, it is called monocytes
- In the tissue, it is called macrophages
● Responsible for helping the body to recognize allergens or foreign bodies - Merkel Cells
● Part of the sensory structure
Antigen-presenting cells found in stratum spinosum layer
Langerhans Cells
- located abv stratum basale
Tactile epithelial cells mostly found in thick skin located in the granular basal epidermal cells
Merkel Cells
- part of the sensory structure
briefly explain the 5 layers of the epidermis
Come Let’s Get Sun Burn
- Stratum corneum
15 - 20 layers of flattened, non-nucleated keratinized cells
cytoplasm is filled with birefringent filamentous keratin
a barrier to light and heat waves, most chemicals and microorganisms
● Squames – horny cornified cells. - Stratum lucidum
seen on thick skin only
thin, translucent layers of extremely flattened eosinophilic cells - Stratum granulosum
3 - 5 layers of flattened polygonal cells undergoing terminal differentiation.
Keratohyaline granules in the cytoplasm - Stratum spinosum
consists of polyhedral or slightly flattened cells having central nuclei with nucleoli and cytoplasm actively synthesizing keratin filaments. - Stratum basale
Aka stratum germinativum
Located @ basal layer
- intense mitotic activity
Capable of mitotic division
- cells below go upwards
- located on the top are dead cells (no nucleus, cytoplasm gets bigger)
*a single layer of basophilic columnar or cuboidal cells on the basement membrane at the dermal-epidermal junction
What is a single layer of basophilic columnar or cuboidal cells on the basement membrane at the dermal-epidermal junction?
Stratum Basale (Basal Layer)
- The deepest layer of the epidermis
- Contains mitotically active keratinocytes
- Houses melanocytes (pigment-producing cells)
- Contains Merkel cells (touch receptors)
the interface between dermis and epidermis in thin skin is held tgt by?
by interlocking epidermal pegs (EP) and dermal papillae (DP)
it synthesize melanin granules and transfer them into neighboring keratinocytes of the basal and spinous layers
melanocyte
- locates in the epidermal basal layer
- produce melanin granules
- transfer melanin to keratinocytes in the basal and spinosus layers
how do melanocytes transfer melanin to keratinocytes?
it sends irregular dendritic processes extend between neighboring keratinocytes → transfer melanin granules → keratinocytes absorb melanin → UV protection
It sends irregular dendritic processes between neighboring keratinocytes for transfer of melanin to those cells
melanocyte
melanin formation
- Melanocytes
- Factory of pigmentation - Inside melanocytes, we have melanosomes
- Workers inside the factory - Inside melanosomes, there will be a conversion of tyrosine
- Amino acid in the tyrosine will be converted into melanin by the enzyme, tyrosinase - Once it becomes melanin, the
invaginations of the melanocytes will bring the melanin to neighboring keratinocytes - In the keratinocytes, once melanin is there, it will form cap-like structure
- Since melanin is the one responsible in absorbing UV radiations coming from the sun
- More melanin, more protection
- Too much exposure from the sun = genetic material can be destructed, causing cancer or other malformations
types of melanin
- Pheomelanin
Responsible for the reddish yellow or orange pigmentation
Western countries
- white skin, blonde hair - Eumelanin
Responsible for the brown-black pigmentation
Asian countries
- brown skin, black hair
type of tissue of dermis
dense irregular CT
a skin treatment where microneedles are pierced into the skin up to the dermal layer
microneedling treatment
- dermis are forced to produce collagen
How is the dermis of thin skin different from thick skin?
More cellular
Well-vascularized
Contains elastin
Less coarse collagen bundles
How many layers are present in the epidermis of thin skin?
Stratum basale (B) – Single-cell thick, mitotically active
Stratum spinosum (S) – Keratin and protein synthesis
Stratum granulosum (G) – Granular layer with keratohyalin
Stratum corneum (C) – Dead keratinized squames
*lacks stratum lucidum
Which layer of thin skin contains most mitotic cells?
Stratum Basale
- Single layer of basophilic columnar/cuboidal cells
- Contains stem cells for regeneration
- Attached to the basement membrane
Which epidermal layer synthesizes keratin and proteins?
Stratum Spinosum
- Produces keratin and other proteins
- Contains desmosomes for cell adhesion
- Appears “spiny” under a microscope
function of the stratum corneum
Protection barrier
- Made of dead squames filled with keratin
- Prevents water loss & microbial invasion
a connective tissue that supports the epidermis and binds it to the subcutaneous tissue.
dermis
- site of such derivatives
hair follicles
glands
rich supply of nerves (sensory receptors or structures)
- a composite structure consisting of the basal lamina and reticular lamina (can usually been w light microscope)
is always found between the stratum basale and the papillary layer of the dermis.
basement membrane
boundary between epidermis and dermis
Dermal papilla
briefly explain the 2 layers of the dermis
- Papillary layer
- Constitute the major part of the dermal papillae (papillary layer)
- Composed of loose CT, with fibroblasts and other connective tissue cells – mast cells and macrophage.
○ Mast cells and macrophage –
response for allergic reactions - Reticular layer
- Composed of irregular dense CT and has more fibers and fewer cells.
- Has network of elastic fibers = elasticity to the skin.
- Older people – reticular layer gets thinner, resulting to their skin turning loose or saggy
why do our skin turn loose or saggy
as we age, our reticular layer gets thinner
Consists of loose connective tissue that binds the skin loosely to the subjacent organs, making it possible for the skin to slide over them.
subcutaneous layer
- aka hypodermis
- contains fat cells (adipocytes) that vary in no. in diff regions of the body and vary in size according to nutritional state
What are the two types of sensory receptors in the skin?
- Uncapsulated Receptors – no capsule
● Tactile disc
associated w epidermal tactile cells
function as receptors for light touch
● Free nerve endings
reasons primiraily to high and low temp, pain and itching
function as tactile receptors
reasons why we can feel pain from capillary puncture
● Root hair plexus or Hair Follicle Receptor
a web of sensory fibers around hair follicles
located in reticular dermis
detects hair movement
- Encapsulated Receptors – covered by CT capsule
● Tactile corpuscles or Meissner’s corpuscles
elliptical structures, perpendicular to the epidermis in the dermal papillae and papillary layer of the fingertips, palms and soles
detect light touch
● Pacinian corpuscles orVater-Pacinian Corpuscles
lamellated corpuscles (due to the onion-like appearance)
for sensing coarse touch, pressure and vibrations
*deep in the reticular dermis
● Krause corpuscles
→ Detect cold (oval/spherical shape)
● Ruffini corpuscles
→ Detect warmth & continuous pressure (oblong shape)
*both ruffini and krause pressure sensing mechanoreceptors in the dermis
Elliptical structures, perpendicular to the epidermis in the dermal papillae and papillary layer of the fingertips, palms and soles.
Tactile Corpuscles or Meissner’s Corpuscles
- detect light touch
Tactile – general term
Meissner’s corpuscles – much more specific
Corpuscles – means capsulated
Respond primarily to high and low temperatures, pain, and itching, but also function as tactile receptors
Free nerve endings
A web of sensory fibers surrounding the bases of hair follicles in the reticular dermis that detects movement of the hairs
root hair plexus or hair follicle receptor
Large, oval structures found deep in the reticular dermis or hypodermis, with an outer capsule and 15 to 50 thin, concentric lamellae and of flat Schwann-type cells and collagen surrounding a highly branched, unmyelinated axon.
Vater-Pacinian Corpuscles or Pacinian Corpuscles
- appearance: onion-like
- for sensing coarse-touch, pressure and vibration’s
What do Krause & Ruffini corpuscles detect?
Krause corpuscles → Detect cold (oval/spherical shape)
Ruffini corpuscles → Detect warmth & continuous pressure in skin (oblong shape)
- deeper tactile receptors
briefly explain the function of each parts
● Krause bulb
● Ruffini
● Root hair plexus
● Pacinian or lamellated
● Meissner or tactile
● Free nerve ending
● Merkel or tactile disc
● Krause bulb
– capsulated, for cold stimulus
● Ruffini
– capsulated, warmth
● Root hair plexus
– uncapsulated, movement of hair
● Pacinian or lamellated
– capsulated, coarse touch, pressure, vibration
● Meissner or tactile
– capsulated, light touch
● Free nerve ending
– uncapsulated, high and low temp, pain, itching
● Merkel or tactile disc
– uncapsulated, light touch
hair shaft -
hair follicle-
○ Hair shaft – seen in epidermis layer
○ Hair follicle – submerged in the dermis and epidermis
Elongated keratinized structures derived from invaginations of the epidermal epithelium
called hair follicles
the color, size, shape and texture of hair is according to
age
genetic background
region of the body
Which areas of the body have minimal hair?
Palms
Soles
Lips
Glans penis
Clitoris
Labia majora
briefly explain the main parts of the hair
- Cuticle
Outermost layer of hair follicle
Protect the shaft from damage
Once damaged, the cortex and medulla are exposed so split ends are seen - Cortex
Middle layer, thickest
Main bulb and figment of hair
Composed of melanin and keratin - Medulla
Innermost
Soft and fragile
Found in thick and coarse hair, absent in thin hair - Hair bulb
Lower part - Matrix
Where the keratinocytes proliferates
Contains melanocytes
Keratin-melanin formation
what happens when the arrector pili is contracted
muscle pulls the follicle nearly perpendicular, increases the
spaces among the hairs; improving its insulation and produces a raised area of skin
- called “goose flesh”
why is it important to bleach before dyeing hair
bleaching kills the cortex and medulla of the hair, pigments of the hair are emptied so the color of the hair without bleaching is not really
showing off
in bleaching, keratin is removed so does the nutrients of the hair, making it brittle and damaged
- needs treatment once in a while
Is a strap of smooth muscle tissue connecting the side of a follicle to the superficial surface of the dermis.
arrector pili muscle
it is a hard, flexible plates of keratin or the dorsal surface of each distal phalanx.
nails
- Formed by a keratinization process similar to hair
Where are nails located?
dorsal surface of each distal phalanx (fingertips & toes)
key protein in nails
Keratin → Makes nails hard & protective
briefly explain the parts of a nail
- Free edge
● Part that is cut when using a nail cutter - Nail body
● The nail itself - Nail groove
● Sides of the nail - Nail fold
● Skin surrounding the sides of the nail - Lunula
● Crescent-like point of nails - Eponychium (cuticle)
● Skin part - Nail bed
● Located at the back of nail body
- layer under the nail plate
- made up of basil & spinosum epidermal layers over dermis - Nail matrix
● Cell division
● Keratin formation, pushed and hardened
✅ Dorsal Nail Matrix (DNM) – Contributes keratinized cells to the nail root
✅ Ventral Nail Matrix (VNM) – Also helps form the nail plate
Nails squeeze up until to the
dermis
ingrown
- excess epidermis are removed to remove ingrown in nail groove
visible part of the nail
nail body
a whitish crescent shaped area at the base of the nail
lunula
it is a stratum corneum that extends into the nail body
eponychium (cuticle)
portion of the nail under the fold
nail root
true or false:
Eponychium and cuticle one structure
false - are often thought of as one structure but is actually not
difference between eponychium and cuticle
Eponychium – thickened layer,
alive
Cuticle – dead, corneum part
function of proximal nail fold (PNF) & eponychium (E)?
PNF – Protects the nail root
Eponychium (cuticle) – Extends from the proximal nail fold, sealing the nail plate
What are the main parts of the nail matrix?
Dorsal Nail Matrix (DNM)
– Contributes keratinized cells to the nail root
Ventral Nail Matrix (VNM)
– Also helps form the nail plate
what does the nail bed made up of
basal & spinous epidermal layers over dermis
what pushes the nail forward as it grows?
continuous keratinocyte proliferation in the nail matrix
Responsible for the formation of sebum
Sebaceous gland
- sebum: complex mixture of lipids called sebum into short ducts which generally open or secreted into hair follicles
- Directly attached to hair follicles
- Embedded in the dermis over most of the body of the surface except thick, hairless skin of the palms and soles. (Palms and soles – sweat glands)
Are branched acinar glands with several acini converging at a short duct which usually empties into the upper portion of
the hair follicle.
Sebaceous gland
type of secretion do sebaceous glands produce?
Holocrine secretion
– Entire sebocyte disintegrates to release sebum
- sebum reaches the skin as the peripheral cells proliferate continuously which pushes mature sebocytes and sebum into ducts and slowly releases onto skin and hair
Main cells of sebaceous glands
sebocytes
- Fill with lipid droplets as they differentiate
- Disintegrate upon secretion (holocrine process)
Responsible for the formation of sweat
Sweat gland
- Epithelial derivatives embedded in the dermis.
- Highly coiled cell, simple stratified
cuboidal in shape
physiological response to increased body temperature during physical exercise or thermal stress and in humans the most effective means of temperature regulation
sweating
briefly explain Apocrine and Merocrine or Eccrine
A. Apocrine
Found in axillary and genitals
Sweat with proteins and other substances
Usually smelly
Largely confined to the skin of the axillary & perianal regions. (depends on sex hormones and is not complete until puberty)
B. Merocrine or Eccrine
Widely distributed in the skin & are most numerous on the soles of the feet (620/cm2).
- 3 million eccrine sweat glands roughly equal the mass of a kidney and can produce as much as 10 L/day.
Found in other parts of the body
Majority of the sweat glands
Clear perspiration (composed of urea, salt, water)
Not that smelly
