LESSON 18 (Epidermis and Dermis) Flashcards
what does the integumentary system consists of?
skin, hair, nails, sweat glands and sebaceous (oil) glands
what are the 2 regions of the skin? which one is the outermost and the inner? which one is avascular and vascular?
1) epidermis: OUTERMOST and AVASCULAR epithelial tissue
2) dermis: INNER and VASCULAR connective tissue
what is the hypodermis?
- aka SUPERFICIAL FASCIA
- a subcutaneius tissue beneath the skin
- consists of mostly adipose tissue that anchors the skin to underlying muscle
- allows skin to slide over muscle
- acts as a shock absorber and insulator
what are keratinocytes?
- makes up majority of the epidermis cells
- produce a fibrous protective protein called keratin
what are melanocytes?
- epithelial cells that synthesize the pigment melanin and transfer it to kerationocytes to protect the nucleus from UV damage
what are cells?
- tissue-resident macrophages
- a type of white blood cell commonly found in the epidermis
- helps activate the immune system
what are tactile (merkel) cells associated with?
touch and sensory nerve endings
what is Stratum Basale (basal layer)?
- aka Stratum Germinativum due to active mitosis
-the deepest epidermis layer - this layer is firmly attached to the dermis
what does the Stratum Basale consists? and what do they produce?
- a single row of stem cells
- produces 2 daughter cells as it is actively mitotic
what is Stratum Spinosum?
- has 3 to 5 layers of thick cells
- it contains a web-like system of intermediate pre-keratin filaments which is attached to desmosomes
how does keratinocytes appear in the Stratum Spinosum layer?
spikey and prickle cells
what is Stratum Granulosum (granular layer)?
- has 4 to 6 layers
- cells are flattened so the layer is thin
what does Stratum Granulosum accumulate?
- Keratohyaline granules which helps form keratin fibers in upper layers
- and Lamellar granules which slows down the loss of water (as its water-resistant glycolipid)
Why do cells above the Stratum Granulosum die?
because they are too far from the dermal capillaries to survive
where can you find Stratum Lucidum (clear layer)?
- layers that are only found in thick (hairless) skin
ex) palms of hand, soles of feet, surface area of fingers and toes
what does Stratum Lucidum (clear layer) consists of?
- thin, translucent band of 2 to 3 rows of clear, flat, dead keratinocytes
where does the Stratum Lucidum (clear layer) lie?
lies superficial to the Stratum Granulosum
what is Stratum Corneum (horny layer)?
- up to 50 rows of flat, anucleated, keratinized daed cells
- accounts for 3-quarters of epidermal thickness
in what ways does the Stratum Corneum (horny layer) still function even though its dead?
- by protecting deeper cells from the environment
- preventing water loss
- protect from abrasion and penetration
- acts as a barrier against biological, chemical and physical assaults
what is the dermis composed of?
strong, flexible connective tissue
what is the dermis supplied with?
blood vessels, nerves and lymphatic vessels
what is the papillary layer?
- a thin superficial layer of areolar connective tissue
what does the Papillary Layer form?
- dermal papillae which results into fingerprints
what are Dermal Papillae?
- a superficial region of dermis
- sends fingerlike projections up into epidermis
- contains capillary loops, nerve endings and touch receptors
what is the Reticular Layer?
- accounts 80% of dermis thickness
what does the Reticular Layer consists of?
- consists of dense fibrous and connective tissue
- has stretchy elastic fibers and durable collagen
what are Flexure lines
deep dermal folds at or near the joints
what happens to the dermis in the Flexure lines?
it is tightly secured to deeper structures so it cannot slide easily for joint movement
what causes Tension Lines in the reticular layer?
caused due to many collagen fibers running PARALLEL to the skin surface
what are Striae
stretchmarks a more visible version of reticular layer
what are Blisters?
A fluid-filled pockets where the epidermal and dermal layer have been separated
what are melanin?
groups of skin and hair pigments that are brown or black or pinkish red
what are brown or black hair pigments called?
eumelanin
what are pinkish red hair pigments called?
pheomelanin
what are Carotene and where does it accumulate?
- a yellow-orange pigment found in food
- accumulates in the stratum corneum and subcutaneous layer
what causes pinkish hue to be seen in fair skin
due to hemoglobin in the blood
what does Cyanosis (blue skin colour) indicate?
low oxygen of hemoglobin
what does Jaundice (yellowish skin) indicate?
liver disorders can inhibit the processing of yellow bilirubin from damaged red blood cells
what does Erythema (redness) indicate?
fever, hypertension, inflammation, allergy
what does Pallor (pale colour) indicate?
Anemia, low blood pressure, fear, anger
what does Bronzing indicate?
inadequate steroid hormones which causes over-expression of melanin
what does Bruise or Contusion (red, purple, blue, or black marks) indicate?
bleeding or coagulated blood under the skin outside of the blood vessels (hematoma)
