The Integumentry System Flashcards
What 4 tissues make up the skin?
- Nerve
- Muscle
- Epithelial
- Connective tissue
What systems exist in the integumentary system?
- Skin aka “cutaneous membrane”: includes epidermis and dermis
- Accessory Structures - hair, oil, sweat glands, and sensory receptors
How thick is the entire system?
1-2 mm thick
Functions of the Integumentary system
- Regulates/maintains body temp.
- “Stores” blood
- Protection - Innate Immune System
- Detects sensations/sensory info
- Excrete/absorbs susbstances
- Sythsizes Vit D
The Cutaneous Membrane consists of:
- Epidermmis - superficial/thin, epithelial tissue, avascular
- Dermis - Deep/thick, connective tissue, vascualar
Vascular portion of Cutaneous Membrane
Dermis
Avascular portion of Cutaneous Membrane
Epidermis - , bottom layer has cells dividing, thus not entirely asvascular
Which layer is NOT a part of the skin?
Subcutaneous or hypodermis
Conatins:
- consists of areolar and adipose tissue
- blood vessel passage
- “pressure sensing” nerve endings
What type of cells make up the Epidermis layer?
Squamous Epithelial cells
What are the 4 principle cell TYPES that make up the epidermis?
- Keratinocytes
- Melanocytes
- Langerhans cells
- Merkel cells
Purpose of Keratinocytes
- produce keratin; protects skin from heat, microbes, and chemicals
- produce lamellar granules; act as waterproofing for skin
In Epidermis
Melanocytes
- produces pigment melanin, colour of skin
- protects skin from UV rays
Langerhans Cells
- Immune response, derived from Red Bone Marrow
- Consists of epidermal Dendritic cells, B cells, Macrophages
Epidermis
Merkel cells
Sensory cells
consist of tactile Merkel discs
Epidermis
5 LAYERS of the Epidrmis:
Deepest 1.Stratum Basale (Germinativum) 2. Stratum Spinosum 3. Stratum Granulosum 4. Stratum Lucidum (only in palms and soles of feet) 5. Stratum Cerneum Superficial
Keratinization
-replacement of cell contents with Keratin (protein)
Stems cells produce keratinocytes; as keratinocytes are pushed upwards through layers, they fill with keratin
The Dermis layer consists of:
- consists of Connective Tissue & Dense Irregular Tissue
Thick layer, thicker than epidermis
Contains:
- Fibres - collagen & elastic
- Cells - fibroblasts, macrophages, fat cells
- Hair follicles, glands, nerve/blood vessels
Collagen Fibers
strength, flexibility
found in parallel bunches
Elastic Fibers
Strong & stretchy
Fibroblasts
Secrete the fibers and ground substance of extracellular matrix
Macrophages
engulf bacteria and cellular debris via Phagocytosis
Fat cells
Store lipids
Majors regions of the Dermis
A. Papillary
B. Reticular
5 Layers from deepest to superficial of the Epidermis
- Stratum Basale (Germinativum)
- Stratum Spinosum
- Stratum Lucidum
- Stratum Corneum
Stratum Basale
(Germanativum)
- Deepest layer, contains Merkel cells, Melanocytes, keratinocutes, and Stem cells. These divided repeatedly to produce Keratinocytes
- Keratinocytes have “Tonofilaments” = produce Keratin in sup. layers
- When this portion of skin is damaged, no new skin can grow
Stratum Spinosum
- Provides strength/flex by cell held together by Desmosomes
- “Spiny appearance
- Melanocytes & Langerhans cells are present
Melanocytes are absorbed by Keratinocytes
Stratum Granulosum
- Middle layer, divides metabolic cells from dead cells
- Apoptosis occurs here
- Kerinocytes here contain protein Keratohyaline = converts tonofilamets into Keratin
- Keratinocytes contain lamellar granules that release lipids that repel H20
Stratum Lucidum
Dead cells
- ONLY present in fingers, soles of feet, palms; places that have extrat friction. Adds tough layer
Stratum Corneum
- Dead skin cells with Keratin & Lamellar Granular lipids to repel H2O
- Protects deeper layers from light, heat, water chems, bacteria
- Callus can form here when there’s extra friction
Keratinization
As Keratinocytes are pushed up through the strata layers, they undergo the process to become keratin. (Tonofilaments + Keratohyaline)
The Dermis
- Dense Irregular C.T., thick
- Made up of Collagen & Elastin
- Has stretch and recoil
- Fibroblasts and Macrophages
- 2 Regions: Papillary and Reticular
Papillary Region
Dermis
- contains Meissners ( touch, sensory) corpuscles and Capillaries
- anchors Epidermis to Dermis
Reticular Region
Dermis
- Collagen fibers (resists stretch)
- Fibroblasts, macrophages,
- B.V. nerves, sebaceous glands, suderiferous glands, ducts/hair follicles
Epidermal Ridges
Finger prints
- in areas of high friction (fingers/hands/feet)
- increases friction for touch sensation (Meissner Corpuscles)
Melanin
- converts Tyrosine to Melanin
- UV increases production
- same # of melanocytes in everyone, but different amount of pigment are produced
Carotene in dermis
- in Stratum Corneum & Dermis
- precursor of Vit A
Hemoglobin
Red, O2 carrying pigments in blood cells
Psoriasis
Rapid division and movement of kertinocytes thorough epidermal strata
Albinism
Inability to produce Melanin or Tyrosinase ( rate limiting enzyme controlling production of Melanin)
Vitiligo
- Complete/partial loss of melanocytes from patches of skin
- could be auto-immune
Skingrafts
- Needed when new skin cannot regenerate if Stratum Basale is damaged
2 types:
Autograft: skin taken from another part of body to replace damaged skin
Isograft: taken from twin
In which Epithelial Layer is Melanin absorbed?
Stratum Spinosum
What Is a Callus?
-Abnorm thickening of Stratum Corneum b/c of increased friction = increase Keratin production
Dandruff
Excessive amount of Keratinized cells shed from Epidermis
Psoriasis
- Chronic skin disorder, knees, elbows, scalp
- skin sheds at rapid rate, (3-5 days) Keratinocytes don’t have time to mature = abnorm Keratin which forms flaky scales
Skin Grafts
Needed when Stratum Basale is destroyed. Usually taken from another region of body
Stretch Marks
Dermal B.V.s and collagen fibres break when skin is overstratched resulting in growth of scar tissue “white streaks”
Tension lines/lines of cleavage
indicate direction of underlying collagen fibres
Albinism
inability to produce pigment - Melanin/melanocytes & tyrosinase, (rate limiting enzyme controlling melanin production).
Age Spots
accumulation of melanin over time due to sun exposure
Vitiligo
Complete or partial loss of melanocytes from patches of skin
Erythema
redness, enlargement of capillaries in dermis during inflam
What parts of the body are the most rapid areas for Transdermal Drug Administration?
Scrotum, face, Scalp - thinnest skin in the body
Pressure Soars aka Decubitus Ulcers
“Bed soars” caused by break in blood flow to an area under pressure, causes necrotization
What is the growth cycle of hair?
- Growth Phase: 2-6 yrs, matrix cells are producing
- Regression Phase: 2-3 wks, matrix stopd, hair follicle stops
- Resting Phase: 3 mths, old hair falls out, new growth begins
85% of scalp hair are in “growth phase”
What type of hair does a fetus have in utero
Lanugo hair - fine, nonpigmented, cover entire fetus
what type of hair does fetal Lanugo hair turn into before birth?
Terminal hair - heavily pigmented hair on eyelids, scalp, eyebrows
Vellus hair - “peach fuzz” replaces hair on rest of body
At puberty, Vellus hair replaced by:
Terminal hair - to face, pubic, limbs, and chest
what hormone stimulates hair grown in males at puberty?
ANDROGENS
The base of a hair follicle is called:
The bulb
List two hair related structures
Arrector Pili: mm in dermis, contract with cold/fear, goosebumps
Hair Root Plexus: Sensory dendrites/neuron that detect hair mvmt
“how you can feel mosquitos”
What is the hair root Plexus?
Dendrites/neurons, detect hair mvmt and sensory touch
The hair follicle consists of:
- External Root Sheath - cont. of epidermis
2. Internal Roots Sheath
What is the function of the site and function of the Hair Matrix
- Exist in the Medula, located in the Bulb
- Site for cell division, Stratum Basale
What are the two types of Melanin that produce hair colour?
- Eumelanin: brown to black
- Pheomelanin: yellow to red
Hormones affect growth/loss of hair
Chemotherapy
rapidly kills dividing cells of hair matrix
15% of hairs in “resting stage” are not affected
Alopecia
partial/complete loss of hair from chemo, genes, age, endocrine disorder
Hirsutism
“wolf boy”
- excessive hair growth all over body
- caused by tumor in adrenal galnds, increases Androgen production
Androgenic Alopecia
male pattern baldness
What are the 4 phases of wound healing?
- Inflam phase: blots clots form, epithelial cells migrate, vasodialation allow increased Phagocytes (neutrophils, macrophages, fibroblasts)
- Migratory Phase: epithelial cells bridge wound, Fibroblasts form scar tissue, revascularaztion, GRANULAR TUSSUE=COLLAGEN +GLYCOPROTIENS
- Proliferation Phase: growth continues
- Maturation Phase: Fibroblast disappear, Collagen fibres organize, B.V.srestored, scab sloughs off
Function of skin (6)
- Thermoregulation
- Blood Reesvoir
- Protection
- Cutaneous Sensation
- Synthesis of Vit D
- Excretion / Absorption
4 types of glands
- Sebaceous - Oil, produces Sebum
- Sudeferous - Sweat, Apocrine (puberty, along hair follicle, B.O.), Eccrine (own gland in epidermis, devel. at birth)
- Ceruminous - Wax, Sebum + Ceruminous = Cerumen
- Mamillary - milk
