Integumentary System
Chapter 5
Learner Objectives
 To
analyze the structural and functional
relationships of the tissues within the
integument.
 To identify characteristics of the aging
process on the integumentary system.
 To investigate the role of radiation in
cancer and mutations.
 To analyze the effects of force on the skin.
Functions
 Protects
internal structures, prevents the
entry of infectious agents, regulates body
temperature, produces vitamin D, and
detects stimuli such as touch, pain, and
temperature.
Hypodermis
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Not really a layer of the skin (subcutaneous
tissue or superficial facia) – the “basement” of
the skin.
Attaches the skin to underlying bone and
muscle.
Loose connective tissue with collagen and
elastin fibers.
Cells are predominately fibroblasts, adipose
cells, and macrophages.
It is full of blood vessels and nerves.
½ of the bodies stored fat.
Epidermis

Stratified squamous epithelium separated from the
dermis by its basement membrane.
 Thin, not blood vessels, nourished by diffusion from the
capillaries in the papillary layer of the dermis.
 Most of the cells are keratinocytes which produce keratin
(protein mixture).
 Keratinocytes are responsible for the structural strength
and permeability.
 Melanocytes are also present – skin color.
 The stages of keratinization form the strata of the
epidermis.
Epidermis
 Stratum
Basale: most deep strata. Single
layer of cuboidal shaped cells. Epidermis
anchored to the basement membrane by
cell junctions. Cells are called
keratinocytes. Mitosis occurs every 19
days and it takes 40-56 days for the
stratum basale to reach the surface.
Epidermis
 Stratum
Spinosum: 8 to 10 layers of manysided cells which flatten as they move
toward the surface. Additional keratin
fibers and lipid filled organelles (called
lamillar bodies) within the kertinocytes. No
mitosis occurs. Cell connection begin to
degenerate.
Epidermis
 Stratum
Granulosum: 2-5 layers of
flattened diamond-shaped cells with long
axes which are parallel to the surface.
Protein granules called keratohyelin
accumulates in the cytoplasm.
Epidermis
Lucidum: Thin clear zone –
several layers of dead cells without
boundaries. Keratin fibers present but not
granules.
 Stratum
 Only
see this layer in thick skin.
Epidermis
 Stratum
Corneum: most superficial
stratum. 25 or more layers of dead
stratified squamous cells. Cornified cells
– dead cells surrounded by a hard protein.
 Exocrine gland ducts come to the surface
of this layer to secrete sebaceous oils and
sweat.
Dermis
 Dense
irregular connective tissue with
fibroblasts, few adipose cells and
macrophage.
 Structural strength of the skin.
 Nerve endings, hair follicles, smooth
muscles, glands and lymphatics extend
into the dermis.
 Made of 2 indistinct layers: Reticular and
Papillary.
Dermis – Reticular Layer
 Deep
 Continuous
with hypodermis.
 Main fibrous layer with mats of fibers resist
stretching.
 Elastin and collagen are heavier in some
areas – results in cleavage or tension
lines. If the skin is overstretched the
dermis may rupture leaving striae or
stretchmarks.
Dermis – Papillary Layer
 Superficial
 Extensions
(papillae) that go into the
epidermis.
 Layer has more cells and fewer fibers.
 There are a large number of blood vessels
which supply the epidermis with blood,
nutrients, remove wastes, and aid in
regulating the body temperature.