Integumentary & Lymphatic System Flashcards
integumentary system
Skin System
The skin consists of 3 main layers
Epidermis
Dermis
Subcutaneous / adipose layer
Epidermis
The superficial layer of skin, formed of epithelial tissue
Formed of ‘keratinised epithelium’
Dermis
The middle layer of skin, formed of connective tissue
The dermis contains a matrix of collagen and elastic fibres
contains accessory structures such as sweat glands, hairs and sebaceous glands
Subcutaneous / adipose layer
An insulating and protective layer of fatty tissue
Epidermis Cells
90% of epidermal cells are Keratinocytes
8% of epidermal cells are Melanocytes
2% of epidermal cells are Langerhans cells (immune)
Keratinocytes
Keratinised cells in epithelial epidermis - Keratin is a tough fibrous protein that
protects from heat, microbes & chemicals
Melanocytes
create Melanin and give skin its pigment - colour
Types of melanin in skin
Eumelanin (brown/black) &;
Pheomelanin (reddish/yellow)
Layers of The Epidermis
Stratum corneum - 25-30 layers of flattened dead keratinocytes.
Stratum lucidum - Clear layer of cells - only in Thick areas of skin (heels)
Stratum granulosum - ‘Grainy’ cells that are becoming keratinised and slowly cut off from blood supply- dying
Stratum spinosum - new keratinocytes
Stratum basale - Single row dividing to form new keratinocytes.
How long does it take for the epidermis to be replaced
40 days
jaundice
yellow skin Colour from pathology due to bilirubin
The Dermis
The thickest layer in the skin, formed of connective tissue. The dermis contains a matrix of collagen and elastic fibres.
Collagen & Elastic fibres
Collagen - strength
Elastic - recoil
Dermis accessory structures
- Arterioles & capillaries (thermoregulation).
- Lymph vessels & ; sensory nerve endings.
- Sweat glands (and ducts), hairs & arrector pili muscles, sebaceous glands.
- Fibroblasts and immune cells – macrophages & mast cells.
What do sweat glands excrete
water, urea, sodium, ammonia
purpose pf sweat glands
Body heat used to evaporate sweat – help regulate body temperature.
Names of sensory nerve endings in Dermis
Meissner’s corpuscle
Pacinian corpuscle
Free nerve ending
Meissner’s corpuscle
Light pressure nerve ending
Pacinian corpuscle
sensitive to deep pressure
Small muscles attached to each hair follicle
arrector pili
Sebaceous Glands
secrete sebum which keeps hair soft, provides water-proofing for the skin and is anti-microbial
Skin Functions
protection thermoregulation Vit D production Sensation Absorption Excretion
How does skin Protect
- Physical Barrier
- Sebum - contains fatty acids which inhibit microbial growth
- Sweat - contains lysozymes
- Desquamation
- Nerve sensors - induce protective reflexes
Desquamation ?
shedding of skin cells
Normal Body Temp
36.5 – 37.5°C
Temperature control centres
hypothalamus & medulla oblongata
brain stem
How does skin control body temp
- Sweat - water evaporates
2. (vasodilatation/vasoconstriction) - blood moves towards skin surface
Hypothermia
core temperature drops below 35 C
Hyperthermia
core temperature elevates above 38.5oC
How does the skin help Vit D production
UV light activates a vitamin D precursor in the skin.
The kidneys convert the precursor to calcitriol.
Where is Vit D stored
Liver
Calcitriol use
increase uptake of calcium
and phosphorus from food into blood, thus, ultimately supporting bone density.
What is the Active form of Vit D
Calcitriol
Skin Absorption
Vit A, D, E, K Some medications, Essential Oil 02 & CO2 Toxins
Superficial Wound healing
- Basel cells move across the gap until CONTACT INHIBITION occurs.
- Epidermal growth factor causes multiplication of the basal cells until space is filled.
Deep wound healing
Inflammatory phase
Proliferative phase
Remodelling phase
Deep wound healing - Inflammatory phase
leukocytes to clean up
Blood clot forms
repair the basement membrane
Deep wound healing - Proliferative phase
Laying of collagen & blood vessels.
Growth & repair of epithelial cells.
Keloid Scar
Normally raise - takes up larger space than the wound
Hypertrophic scar
more common. Stays within the boundary of wound.
Stratum corneum
Most superficial layer of the epidermis.
Flattened dead Keratinised cells.
Stratum basale
The innermost layer of the epidermis.
Single row dividing to form new keratinocytes.
Types of Nerve Ending in Demis
Meissner’s corpuscle
Pacinian corpuscle
Free Nerve Endings
