Integumentary System Flashcards
Skin facts
What percent of bodyweight
How thick
Body’s largest and heaviest organ
15% of bodyweight
1-2 mm thick
What is the scientific name for skin?
Cutaneous membrane
What lies beneath the dermis?
Subcutaneous membrane
(Hypodermis)
6 skin functions
Resistance to trauma and infection
Other barrier functions
Vitamin D synthesis
Sensation
Thermoregulation
Non-verbal communication
Epidermis
Structure, unique properties
Densely-packed keritanized, stratified squamous epithelium
Dead cells at the surface packed with tough keratin protein
Avascular
Contains sparse nerve endings
Highly mitotic: fastest reproducing cells in the body
Epidermis
4-5 Strata (superficial to deep)
Stratum corneum
Stratum lucidum (only in thick skin)
Stratum granulosum
Stratum spinosum
Stratum basale
Stratum corneum
Dead keratinocytes and keratin
Resistant to abrasion, penetration and water loss
Stratum lucidum
Only found in thick skin
Contains keratinocytes packed with eladin (clear protein)
Stratum granulosum
3-4 layers of keratinocytes
Keratin production!
Keratin combines with lipids to create waterproof barrier for skin
Keratinocytes begin to die here - lack oxygen needed for metabolism
Stratum spinosum
Thickest layer (except in thick skin)
Keratinocytes begin to flatten out
Dendritic cells
Dendritic cells
Type of white blood cell (macrophage) patrols the skin looking for invading organisms and material but more scout than destroyer
Stratum basale
Structure, types of cells, function
Single layer of cells appearing cuboidal at first, become stratified squamous as they move through strata
Mitotic stem cells
Keratinocytes
Melanocytes
Tactile cells
Site for new skin cell production
Mitotic stem cells
Divide to become keratinocytes
Keratinocytes
Basic skin cells layered throughout the strata to form protective thickness of skin
Melanocytes
Produce melanin which absorbs UV light and prevents it from going deeper.
All bodies have same number of melanocytes, they produce diff amounts of melanin
Tactile cells
Attached to neurons in underlying dermis, allow for sensation
Dermal papillae
Form the distinct line between the dermis and epidermis
Under the epidermal ridges like legos locking in place
Dermis
Name the 2 layers
Papillary layer
Reticular layer
Dermis
Papillary layer
Thin layer near dermal papillae
Consists of areolar connective tissue (abundant blood vessels)
Dermis
Reticular layer
dense irregular connective tissue
Hypodermis (subcutaneous membrane)
Functins
Structure
Binds skin to underlying tissue and structures
Has more areolar and adipose tissue than dermis
Highly vascular (provides thermoregulation)
Provides cushion
Hair structure
General, then superficial to deep
Follicle - entire hollow tube around hair
Bulb - base of hair, only part that contains living hair cells
Root - remaining part of follicle under skin’s surface
Shaft - Exposed on skin’s surface
Nail
Extension of what?
Stratum corneum
Nail
Structure
Dead keratinocytes densely packed with parallel, hard keratin fibers
Nail
Structure parts
Nail plate - visible bit
Nail root - embedded under skin
Nail matrix - consists of stratum basale, site for nail growth
Cutaneous glands
2 types and their differences
Exocrine: use ducts to transport their products
Endocrine: use blood supply to transport their products
Exocrine glands
Sweat glands
Found where?
Dermis
Sweat glands
2 types
Merocrine
Apocrine
Merocrine glands
Location - produce what substance
In the dermis all over the body. Most numerous glands!
Produce watery perspiration
Perspiration contents
Water
Sodium Chloride
Potassium
Lactic Acid
Hydrogen Ions (contribute to acid mantle)
Apocrine glands
Found where?
Release what?
Sweat glands that act as scent glands releasing pheromones
Found in:
Groin
Axilla
Areola
Stimulated in response to stress and sexual stimuli
Apocrine gland ducts
Lead to nearby hair follicles rather than an independent sweat pore
Sebaceous glands
Produce what?
Function
Common problem
Sebum
Keeps skin from becoming dry and brittle, makes hair shiny
Ducts usually open into a hair follicle, some directly to the surface.
Acne! Glands producing large amts of sebum that stick to skin cells and plug hair follicle trapping bacteria
Ceruminous glands
Found only in external ear canal
Produce excretions that combine with sebum to form Cerumen (earwax)
Ducts lead directly to surface of skin
Cerumen functions:
Waterproof ear canal
Keeps eardrum pliable
Kills bacteria
Mammary Glands
Located in breasts
Produce milk
