Download Exercise 7

Exercise 7
Integumentary System
Functions
Protection
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Insulates & cushions underlying body
tissues
Protects from mechanical damage,
chemical damage, thermal damage &
bacterial invasion
Prevents water loss
Regulates heat loss
Basic Structure
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2 distinct regions
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Epidermis- superficial, composed of
epithelium
Dermis- underlying connective tissue
Hypodermis (superficial fascia)- not part
of skin; primarily adipose tissue
Epidermis
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Avascular
Keratinized, stratified squamous
epithelium
4 cell types
5 layers
Epidermal Cells
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Keratinocytes
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Most abundant epidermal cells
Produce keratin fibrils
Keratin gives epidermis its durability
Keratinocytes connected by desmosomes
Know figure 7.1
Epidermal Cells (continued)
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Melanocytes
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Black cells that produce melanin
Melanin production increases with
exposure to UV light (sunlight)
Melanin protects cell nuclei by shielding
DNA from UV radiation
Freckles are a concentration of melanin in
1 spot
Epidermal Cells (continued)
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Langerhans’ cells
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Immunity
Merkel cells
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Form touch receptors called Merkel discs at
epidermal-dermal junction
Epidermal Layers
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Skin covering most of the body has 4
layers
Thick skin (palms of hands, soles of feet)
has 5 layers
Know figure 7.2
Epidermal Layers (continued)
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Stratum basale
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Basal layer
Single row of cells adjacent to dermis
Constantly undergoing mitotic division to
produce new cells
Also called stratum germinativum
Epidermal Layers (continued)
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Stratum spinosum
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Spiny layer
Several cell layers immediately superficial
to basal layer
Divide fairly rapidly
Epidermal Layers (continued)
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Stratum granulosum
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Granular layer
Thin layer
2 types of granules
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Lamellated- contain a water-proofing glycolipid
Keratohyaline- combine with intermediate
filaments to form keratin fibrils
Epidermal Layers
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Stratum lucidum
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Clear layer
Very thin & translucent
Not present in regions of thin skin
Epidermal Layers (continued)
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Stratum corneum
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Horny layer
Outermost layer
Accounts for bulk of epidermal thickness
Cells are dead
Fully keratinized
Constantly being rubbed off & being
replaced by division of deeper cells
Dermis
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Dense irregular connective tissue
2 principal regions
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Papillary layer
Reticular layer
Both layers heavily invested with collagenic & elastic
fibers, which give skin its elasticity
Abundant blood supply helps play a part in regulation
of body temperature
Decubitus ulcers can form in bedridden patients who
are not turned regularly; weight of the body exerts
pressure, which restricts blood supply and leads to
tissue death
Dermis (continued)
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Papillary layer
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More superficial region
Areolar connective tissue
Attached to epidermis by dermal papillae (these also
produce finger prints)
Abundant capillary networks
Have pain & touch receptors (Meissner’s corpuscles)
Reticular layer
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Deepest skin layer
Dense irregular connective tissue
Contain arteries & veins, sweat & sebaceous glands, and
pressure receptors (Pacinian corpuscles)
Skin Color
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Result of:
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Relative amount of melanin
Relative amount of carotene
Degree of oxygenation of blood
Can be a diagnostic tool
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Flushed skin may indicate hypertension, fever,
embarassment
Pale skin may indicate anemia
Bluish cast (cyanosis) may indicate inadequate oxygenation
from asphyxiation or respiratory insufficiency
Jaundice (yellowed tissues) usually means liver disease
Bronzing of skin may be from hypoactive adrenal cortex
(Addison’s disease)
Accessory Organs
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Nails, hair, cutaneous glands
Nails
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Derivatives of epidermis
Body- visible attached portion
Free edge- portion that grows out away from body
Root- embedded in skin; adheres to nail bed
Nail folds- overlap borders of the nail
Eponychium- cuticle
Nail bed- extension of stratum basale
Nail matrix- proximal part of nail bed containing germinal cells;
cells become keratinized & die
Lunula- proximal region of matrix, appearing as a white crescent
Know figure 7.4
Hair & Associated Structures
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Hair
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Consists of medulla surrounded by cortex & cuticle
Color is a manifestation of amount & kind of
melanin
Root- portion enclosed within follicle
Shaft- projects from surface of scalp
Hair bulb- collection of germinal epithelial cells; as
cells are pushed from growing region, they
become keratinized & die
Know figure 7.5
Hair (continued)
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Follicle
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Formed from epidermal & dermal cells
Papilla protrudes into hair bulb & provides
nutrients for growing hair
Arrector pili muscle
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Smooth muscle cells connect each follicle
to papillary of dermis
Contraction causes goose bumps
Cutaneous Glands
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2 types
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Sebaceous (oil) glands
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All over the skin, except palms & soles
Ducts usually empty into hair follicle
Product is sebum, a mixture of oil & cells that
keeps skin soft & moist & keeps hair from
becoming brittle
Become very active during puberty
Cutaneous glands (cont.)
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Sudoriferous (sweat) glands
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Widely distributed
Empty through pores
2 types
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Eccrine (merocrine sweat glands)
 Found all over the body
 Produce clear perspiration; mostly water, salts & urea
 Important in heat regulation
Apocrine
 Mostly in axillary & genital areas
 Secrete a milky protein- & fat-rich substance
 May contain pheromones
Know figure 7.7
Exercise 8
Classification of Covering and
Lining Membranes
Epithelial Membranes
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Organ consisting of a epithelial sheet bound to an
underlying layer of connective tissue
3 main types
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Cutaneous membrane (skin)
Mucous membranes (mucosae)- epithelial cells on a layer of
loose connective tissue (lamina propria); line all body
cavities open to exterior (respiratory, digestive, urogenital);
constantly bathed by secretions
Serous membranes (serosae)- layer of simple squamous
epithelium on a small amount of areolar connective tissue;
usually paired; parietal layer lines body cavity, visceral layer
covers outside of organs in that cavity; secretes serous fluid,
which lubricates organs
Know figure 8.1
Synovial Membranes
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Composed entirely of connective tissue
Line cavities surrounding joints
Secrete a lubricating fluid
Also line smaller sacs of connective
tissue (bursae & tendon sheaths)
Know figure 8.2
Histology review
Be able to identify muscle tissue: skeletal, smooth and
cardiac by sight.
Be able to identify the following epithelia by site:
simple squamous (kidney glomeruli)
simple cuboidal (kidney tubules)
simple columnar (digestive tract)
pseudostratified columnar (upper respiratory tract)
stratefied squamous (skin)
stratefied cuboidal (ducts of sweat glands)
stratefied columnar (ducts of large glands, male urethra)
transitional (stretchy bladder)
Connective tissue: Bone, Blood, areolar,
embryonic (mesechymal), adipose, dense, loose, cartilage
Cartilage (connective tissue)
Hyalinetrachia, sternum
Elastic cartilage
Ear, epiglottis
Fibrocartilage
Intervertabral discs