Chapter 5 Flashcards
The integumentary system consists of
- Skin
- Hair
- Oil
- Sweat glands
- Nails
- Sensory receptors
Function
- Maintain body temperature
- Converts inactive vitamin D to active form
- Provides sensory info
- Maintains homeostasis
Epidermis
superficial layer ; no blood vessels
Dermis
deeper layer ; contains blood vessels
Hypodermis
deep to dermis; not a layer of skin
• composed of: Areolar tissue + Adipose tissue
Epidermal ridges
more prominent in thick skin ; fingerprint ridges
Free nerve ending
exposed of sensory nerve ending
Dermal Papillae
some have sensory receptors, some have capillary loop; under dermal papillae
Papillary region
superficial part of dermis; few collagen fibres ~ (Loose areolar connective tissue)
Reticular region
deep part of dermis
Arrector pili muscle
attached to hair follicles; causes hair to stand/straighten (goosebumps)
Hair follicle
protects hair root ; each follicle wrapped in nerve
Lamellate corpuscle
Between reticular region + hypodermis, sinks deeper into dermis with age; connective covering around body “bulb-like” ~ detect deep pressure/vibration
Sensory nerves
branch and supply ; ending is wrapped in connective layer
Blood vessels
diameter~ outgoing (vein) , incoming (artery + branches) to skin to provide O2 and nutrition to skin
4 major Cell Types in Epidermis
Keratinocytes
Melanocytes
Intraepidermal macrophages
Tactile epithelial cells
Keratinocytes
• most abundant; spikey
- Makes up 90% of epidermis
• filled with keratin protein ~coated in hydrophobic molecules
• need protection from UV damage
Melanocytes
• fewer than ^ ; tentacle-like
- Makes up 8% — only in stratum basale layer
• melanin granules released by exocytosis ; taken up by keratinocytes
• protects from UV damage
• all bodies have same # of melanocytes
Intraepidermal macrophages (Langerhans cell)
• phagocytosis; eats pathogens; p
• cell of immune system but protects skin from entering pathogens; • main function: immune surveillance
• release chemicals into blood that rush to site of infection.
Tactile epithelial cells (Merkel cell)
• light touch;
• dendrite ending (sensory neuron) + Tactile/Merkel cell = Tactile/Merkel disc
Thin skin layers
• Stratum Basale (stratum germinativum)
• Stratum Spinosum
• Stratum Granulosum
• Stratum Corneum
Thick skin layers
• Stratum Basale (stratum germinativum)
• Stratum Spinosum
• Stratum Granulosum
• Stratum Lucidum
• Stratum Corneum
Stratum basale
- Deepest Layer
- 1 Row Of Cuboidal Or Columnar Keratinocytes
• Has Scattered Keratin Intermediate Filaments (Little To None Filaments); - Stem Cells Undergo Mitosis — Cell Division
• Produce New Keratinocytes; Melanocytes + Tactile Epithelial Cells; Tactile Discs
Stratum spinosum
- 8-10 Rows Of Many-Sided Keratinocytes
- • Has Bundles Of Keratin Intermediate Filaments;
Spikey, Sharp Process - Contains Melanocytes + Intraepidermal Macrophages.
Stratum Granulosum
- 8-10 Rows Of Many-Sided Keratinocytes
- • Has Bundles Of Keratin Intermediate Filaments;
Spikey, Sharp Process - Contains Melanocytes + Intraepidermal Macrophages.
Stratum lucidum
- 4-6 Rows Of Clear, Flat, Dead Keratinocytes
- Large Amounts Of Keratin
- Only In Skin Of Fingertips, Palms, + Soles
Stratum cornuem
- Superficial Layer
- Hard/Rough
- Few To 50+ Rows Of Dead, Flat Keratinocytes - Contain Mostly Keratin.
Melanin
produced by melanocytes in the stratum basale
Pheomelanin
darker pigment
Eumelanin
lighter pigment
Hemoglobin
a red pigment in red blood cells
Carotene
a yellow-orange pigment stored in the stratum corneum + adipose tissue
Albinism
a congenital disorder ; absence of pigment in skin, hair, & eyes
• Lacking enzyme (defective gene) involved in the production of melanin
Vitiligo
a chronic disorder; causes depigmentation patches in skin. • Combo of: genetic factors + autoimmune disease
Hair
on most body surfaces EXCEPT palms + fingers tips + soles of feet • Composed of: Dead, Keratinized epidermal cells
Shaft
above skin surface
Follicle
below level of skin
Root
penetrates into dermis
Hair Growth Stages
• 1. Growth stage
• 2. Regression stage
• 3. Resting stage — 15% of hair is not growing
Types of Hairs
Lanugo
Terminal
Vellus
Lanugo
covers body of fetus
Terminal
Long, coarse, heavily pigmented hairs
Vellus
short, fine, pale hairs
Hair colour
due to amount + type of melanin present in keratinized cells of hair
4 types of skin glands:
4 types of skin glands:
• 1. Sebaceous (oil) glands
• 2. Eccrine sweat glands
• 3. Apocrine sweat glands
• 4. Ceruminous glands
Sebaceous (oil) glands
connected to hair follicles
Eccrine sweat glands
most numerous
Apocrine sweat glands
located in hairy skin areas
Ceruminous glands
modified sweat glands ; located in ear canal
Nails
made of keratinized epidermal cells
Free edge
extends past the finger or toe
Nail body (plate)
visible portion of the nail
Nail Bed
skin below the nail plate
Lunula
thick, white part of the nail
Eponychium (cuticle)
stratum corneum of the epidermis
Nail root
portion that is not visible
Hyponychium
secures nail to the fingertip
Nail matrix
epithelium proximal to the nail root; contains dividing cells, which
produce new nail cells
Thermoregulation
- Sweat
- Blood flow to Dermis
Blood reservoir
- Dermis layer — has many blood vessels
• Can hold 8–10% of total blood flow while adult is at rest!
Keratin
protects tissues from: microbes + abrasion + heat + chemicals
Lipids
released by lamellar granules ; prevent evaporation of water from skin, helping dehydration
Sebum
from sebaceous glands; keeps skin + hairs from drying out
Acidic sweat
slows growth of microbes
Melanin
helps shield against UV light
Macrophages
regulates + phagocytes bacteria
Tactile sensations
touch, pressure, vibration, tickle
Thermal sensations
warm, cool
Excretion
elimination of substances from body
Absorption
passage of materials from external environment into cells
Ultraviolet rays
activate precursor molecule in skin ; allows vitamin D to be made
Vitamin D (Calcitriol)
aids absorption of calcium from foods in GI tract
Epidermal Wound Healing occurs when
superficial wounds affect only the epidermis
Deep Wound Healing Occurs when
an injury extends into dermis + subcutaneous layer
Deep wound healing phases
Inflammatory
Migratory
Proliferative
Maturation
Inflammatory phase
inflammation; blood clot forms in the wound and loosely unites wound edges
Migratory phase
clot becomes a scab; epithelial cells migrate beneath scab to bridge wound
Proliferative phase
growth of epithelial cells beneath scab + continued growth of blood vessels
Maturation phase
scab falls off once epidermis is restored to normal thickness
Fibrosis
formation of scar tissue
Hypertrophic scar
remains in the boundaries of original wound
Keloid scar
extends beyond the boundaries into normal surrounding tissues
Age associated changes
• Wrinkles
• Dehydration + cracking
• Sweat production decreases
• # of functional melanocytes decrease = grey hair + atypical skin pigmentation
• Subcutaneous fat lost —> skin thickness decreases
• Nails = more brittle
Epidermis develops from
Ectoderm
Dermis develops from
Mesoderm
Most common cause of Skin Cancer
Excessive exposure to UV light
1st degree burn
Into epidermis
2nd degree burn
Into dermis
3rd degree burn
Into subcutaneous layer
Pressure Ulcers
shedding of epithelium by a deficiency of blood flow to tissues
Age increases
susceptibility to pressure ulcers (“bed sores”)
