Integumentary SystemIntegumentary System

Chapter 5Chapter 5

Learner ObjectivesLearner Objectives

To analyze the structural and functional To analyze the structural and functional relationships of the tissues within the relationships of the tissues within the integument.integument.

To identify characteristics of the aging To identify characteristics of the aging process on the integumentary system.process on the integumentary system.

To investigate the role of radiation in To investigate the role of radiation in cancer and mutations. cancer and mutations.

To analyze the effects of force on the skin.To analyze the effects of force on the skin.

FunctionsFunctions

Protects internal structures, prevents the Protects internal structures, prevents the entry of infectious agents, regulates body entry of infectious agents, regulates body temperature, produces vitamin D, and temperature, produces vitamin D, and detects stimuli such as touch, pain, and detects stimuli such as touch, pain, and temperature.temperature.

HypodermisHypodermis Not really a layer of the skin (subcutaneous Not really a layer of the skin (subcutaneous

tissue or superficial facia) – the “basement” of tissue or superficial facia) – the “basement” of the skin. the skin.

Attaches the skin to underlying bone and Attaches the skin to underlying bone and muscle.muscle.

Loose connective tissue with collagen and Loose connective tissue with collagen and elastin fibers.elastin fibers.

Cells are predominately fibroblasts, adipose Cells are predominately fibroblasts, adipose cells, and macrophages.cells, and macrophages.

It is full of blood vessels and nerves.It is full of blood vessels and nerves. ½ of the bodies stored fat.½ of the bodies stored fat.

EpidermisEpidermis Stratified squamous epithelium separated from the Stratified squamous epithelium separated from the

dermis by its basement membrane.dermis by its basement membrane. Thin, not blood vessels, nourished by diffusion from the Thin, not blood vessels, nourished by diffusion from the

capillaries in the papillary layer of the dermis.capillaries in the papillary layer of the dermis. Most of the cells are keratinocytes which produce keratin Most of the cells are keratinocytes which produce keratin

(protein mixture).(protein mixture). Keratinocytes are responsible for the structural strength Keratinocytes are responsible for the structural strength

and permeability.and permeability. Melanocytes are also present – skin color.Melanocytes are also present – skin color. The stages of keratinization form the strata of the The stages of keratinization form the strata of the

epidermis.epidermis.

EpidermisEpidermis

Stratum Basale: most deep strata. Single Stratum Basale: most deep strata. Single layer of cuboidal shaped cells. Epidermis layer of cuboidal shaped cells. Epidermis anchored to the basement membrane by anchored to the basement membrane by cell junctions. Cells are called cell junctions. Cells are called keratinocytes. Mitosis occurs every 19 keratinocytes. Mitosis occurs every 19 days and it takes 40-56 days for the days and it takes 40-56 days for the stratum basale to reach the surface.stratum basale to reach the surface.

EpidermisEpidermis

Stratum Spinosum: 8 to 10 layers of many-Stratum Spinosum: 8 to 10 layers of many-sided cells which flatten as they move sided cells which flatten as they move toward the surface. Additional keratin toward the surface. Additional keratin fibers and lipid filled organelles (called fibers and lipid filled organelles (called lamillar bodies) within the kertinocytes. No lamillar bodies) within the kertinocytes. No mitosis occurs. Cell connection begin to mitosis occurs. Cell connection begin to degenerate.degenerate.

EpidermisEpidermis

Stratum Granulosum: 2-5 layers of Stratum Granulosum: 2-5 layers of flattened diamond-shaped cells with long flattened diamond-shaped cells with long axes which are parallel to the surface. axes which are parallel to the surface. Protein granules called keratohyelin Protein granules called keratohyelin accumulates in the cytoplasm.accumulates in the cytoplasm.

EpidermisEpidermis

Stratum Lucidum: Thin clear zone – Stratum Lucidum: Thin clear zone – several layers of dead cells without several layers of dead cells without boundaries. Keratin fibers present but not boundaries. Keratin fibers present but not granules.granules.

Only see this layer in thick skin.Only see this layer in thick skin.

EpidermisEpidermis

Stratum Corneum: most superficial Stratum Corneum: most superficial stratum. 25 or more layers of dead stratum. 25 or more layers of dead stratified squamous cells. Cornified cells stratified squamous cells. Cornified cells – dead cells surrounded by a hard protein.– dead cells surrounded by a hard protein.

Exocrine gland ducts come to the surface Exocrine gland ducts come to the surface of this layer to secrete sebaceous oils and of this layer to secrete sebaceous oils and sweat.sweat.

DermisDermis Dense irregular connective tissue with Dense irregular connective tissue with

fibroblasts, few adipose cells and fibroblasts, few adipose cells and macrophage.macrophage.

Structural strength of the skin.Structural strength of the skin. Nerve endings, hair follicles, smooth Nerve endings, hair follicles, smooth

muscles, glands and lymphatics extend muscles, glands and lymphatics extend into the dermis.into the dermis.

Made of 2 indistinct layers: Reticular and Made of 2 indistinct layers: Reticular and Papillary.Papillary.

Dermis – Reticular LayerDermis – Reticular Layer DeepDeep Continuous with hypodermis.Continuous with hypodermis. Main fibrous layer with mats of fibers resist Main fibrous layer with mats of fibers resist

stretching.stretching. Elastin and collagen are heavier in some Elastin and collagen are heavier in some

areas – results in cleavage or tension areas – results in cleavage or tension lines. If the skin is overstretched the lines. If the skin is overstretched the dermis may rupture leaving striae or dermis may rupture leaving striae or stretchmarks.stretchmarks.

Dermis – Papillary LayerDermis – Papillary Layer

SuperficialSuperficial Extensions (papillae) that go into the Extensions (papillae) that go into the

epidermis.epidermis. Layer has more cells and fewer fibers.Layer has more cells and fewer fibers. There are a large number of blood vessels There are a large number of blood vessels

which supply the epidermis with blood, which supply the epidermis with blood, nutrients, remove wastes, and aid in nutrients, remove wastes, and aid in regulating the body temperature.regulating the body temperature.