Upload
jeffrey-arnold
View
217
Download
1
Tags:
Embed Size (px)
Citation preview
The Integumentary System
The skin and its accessories
General Features
Body’s largest organSurface area of 1.2 to 2.2 square
meters4-5 Kilograms (7% of body weight)1.5-4.0 millimeters thick (paper towel)Damage impairs nearly every other
system
Functions
Protection-Provides a chemical, physical(mechanical) and biological barrier
Thermoregulation-Body temperature regulation
Sensory Organ-temperature, pressure, touch, and pain
Metabolic-Synthesis Vitamin D
Excretion-Small amounts of Nitrogenous wastes, water and salt
Blood reservoir
General Structure
EpidermisDermis Hypodermis /Subcutaneous (not
offically considered a part of the skin, but important none the less)
Epidermal Layers
Stratum corneum-outer most layer; 20-30 cell layers thick; 3/4 of epidermal layer
Stratum Granulosum-3-5 cell layers; last layer of the epidermis to receive nourishment
Stratum Basale/Germinativum-rapidly dividing cells; melanocytes lie directly above these cells
Epidermis Cell Types Keratinocytes Melanocytes
Keratin producing cells
Constantly rubbing off
Upper cells are dead
Forms an outer protective barrier
Melanin producing cells
Deepest layerProtect dividing
cells beneath them
Keratin
Protein found in the epidermis, hair and nails that makes those structures hard and water-repellent.
Melanin
Dark pigment formed by melanocytes; imparts color to hair and skin
EpidermisThick Skin Thin Skin
Dust Mite & Epidermal Cell
Features of the Dermis
Cell types: fibroblasts, macrophages, WBC’s
Fibers: collagen; reticular, elastic
Other Structures: nerve fibers;blood vessels; hair follicles; glands
Dermis
Dermis
“True Skin”Acts like a “body stocking” to hold
the body togetherConnective tissue; highly
vascularized
Layers of the DermisPapillary Reticular
Loosely wovenDermal papilla
form ridges to make finger-prints
Lots of blood vessels
80% of the dermisVery dense and
collagen rich
Hypodermis or Subcutaneous Layer
Although not officially considered a part of the skin, it must be examined in order to fully comprehend integumentary structure.
Features of the Hypodermis
Storage site for adipose tissue
Loosely anchors the skin to underlying muscle. Sliding allows blows to slide off and allows movement.
Factors Determining Skin Color
Melanin: Ranges from yellow to reddish-brown to black. Absorbs radiation from UV light to protect dividing cells beneath it.
Hemoglobin: Imparts a pinkish tint; lack of O2 gives a bluish cast (Cyanosis)
Carotene: Orange to yellow pigment found in many vegetables; accumulates in the stratum corneum
Effects of Aging
Fewer melanocytesFewer active hair folliclesDecreases sebaceous gland activityThin epidermisReduced sweat gland activityReduced blood supplyThinner dermis
FYI: One Square Inch of Skin Contains
65 Hairs 95-100 sebaceous glands 650 sweat glands 78 sensory apparatuses (for heat) 1,300 nerve
ending to record pain 13 sensory apparatuses (for cold) 9, 500, 000
cells 19 yards ( 17 mtrs) of blood vessels 78 yards (70
mtrs) of nerves 19,500 sensory cells at the ends of nerve fibres 160-165 pressure apparatuses for the perception
of tactile stimuli.