Unit 4: Integumentary system Flashcards
Three layers on the skin
Epidermis, Dermis, Hypodermis.
outer most:
middle:
(superficial fascia-outside of muscle)- Deepest region
Epidermis,
Dermis,
Hypodermis.
Functions of the skin
protection, body temperature regulation, Cutaneous sensation, metabolic function, blood reservoir, excretion
protection
chemical, physical, and mechanical barrier
Dilation
cooling via blood vessels
Constriction
warming via blood vessels
metabolic function
synthesis of vitamin D in dermal blood vessels
Cutaneous sensation
exo-receptors sense touch and pain
blood reservoir
Blood vessels store up to 25%of the body’s blood volume.
Characterization of epidermis
composed of keratinized (hardened keratin protein) stratified squamous epithelium.
consists of 4 to 5 layers
Cell types for protection
(epidermis layer)
Keratinocytes (structure), Melanocytes (coloring), Merkel (sense of touch), and Langerhans’ cells (immune)
keratinocytes
produce fibrous protein keratin.
product from stressors
extremely insoluble in water and organic solvents
most abundant in picture.
Melanocytes
produce (brown) melanin pigment
UV protection
(Attached to basement membrane)
Merkel cells
touch receptors in association with nerve endings.
(basal layer/right above dermal layer)
Langerhans cells
epidermal macrophages that help activate the immune system
Two types of skin:
Thick: 5 layers
Thin: 4 layers
Stratum basale baby layer (bottom)
Deepest layer, attached to the dermis
Skin grows out of this layer
Single row of keratinocytes
Rapid cell division (mitosis)
Stratum Spinosum
Keratinocytes appear “spiny” almost dehydrated
5-7 layers
Had filaments
Cells start to stick together
Contain melanin and langerhans cells
What are filaments
Stick out of the cells as they shrivel and this is what makes this layer appear spiny.
Stratum granulosum
Forms ridged membrane too keep cells form collapsing
Thin layer 3-5 layers
Rectangle like keratinocytes
Cells start to die
Keratohyalin granules
Lamellated granules
Keratohyalin granules
Give keratin hardening
Lemellated granules
Water proofing glycolipid (repels water)
Stratum Lucidum (clear layer)
Extra layer of protection
Kinda dead cells
Thin transparent bad superficial to stratum granulosum
A few rows of flat dead keratinocytes
ONLY PRESENT IN THICK SKIN
Thick skin
Heal, plantar, palm surface
Stratum corneum
Outer layer of keratinized cells (cornified)
Accounts for 3/4 of the epidermal thickness
DEAD DEAD
20-30 layers thick
Functions of stratum corneum
Water proofing protection from abrasion and penetration
Rendering the body relatively insensitive to biological, chemical and physical assaults
Dermis
Second major skin region contain gin string flexible connective tissue (areolar etc)
Semi fluid matrix heavily embedded with collagen
Highly vascular and lots of nerve endings
Fibroblasts macrophages, mast cells/white blood cells
Composed of toe layers
Stratum granulosum
Thin layer 3-5 cells
Drastic changes In keratinocytes
Cells start to die
Keratohyalin and lamellated granuales accumulate
Keratohyalin granules
Give rise to ketamine (hardening )
Lamellated granules
Give rise to a water proofing glycolipids
Stratum Lucidum
clear layer/extra layer of protection
kinda dead, few rows of flat dead keratinocytes,
only in thick skin
Stratum Corneum
outermost layer of keratinized (cornified) cells
accounts for 3/4 of the epidermal thickness
20-30 layers
functions of Stratum Corneum
water proofing
protection from abrasion and penetration
rendering the body relatively insensitive to biological, chemical and physical
Dermis
middle layer; contains connective tissue Loose connective (areolar).
semi-fluid matrix heavily embedded with collagen (very strong). HIGHLY Vascular and nerve endings
Cells in the Dermis
Fibroblasts
macrophages
occasionally mast/white blood cells
2 layers of dermis
Papillary and Reticular
Papillary layer
Areolar/loose connective tissue with collagen and elastic fibers
Papillae in the superior surface
What are dermal papillae
Contain capillary loops, meissner’s corpuscles and free never endings
dermal papillae make up epidermal ridges = fingerprints
Meissner’s corpuscles
type of nerve ending responsible for light touch
ex: fingertips and palms
Reticular layer
80% of the thickness of skin
collagen fibers in this layer add strength and resiliency to skin.
Elastin fibers provide stretch-recoil properties.
hypodermis
- subcutaneous layer/superficial facia
-Adipose (fat tissue) and areolar connective
connects dermis to underlying muscle
-adipose absorbs shock and insulates against heat loss.
3 pigments that make up skin color
- melanin
-carotene
-hemoglobin
melanin
yellowish to reddish-brown to black pigment responsible for dark skin colors
freckles and pigmented moles
carotene
yellow to orange: most obvious in the palms and soles of feet
hemoglobin
reddish pigment: pinkish hue of light skin
skin appendages
from dermis and epidermis
includes: Nails, hair, sweat/oil glands and hair follicles
sweat glands
simple cuboidal: sudoriferous
basically everywhere
jobs: regulate temperature, release water, salt and nitrogenous bases.
Sebaceous glands
Protect and lubricate, keep off microbes
Hemostasis
Body’s response to losing blood and that the “wall” has been compromised.
