Transcript Lab 3 The Skin and Synovial Joints 2009

CHAPTER
5
The
Integumentary
System
Copyright © 2010 Pearson Education, Inc.
Skin (Integument)
•
Consists of three major regions
1. Epidermis—superficial region
2. Dermis—middle region
3. Hypodermis (superficial fascia)—deepest
region
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•
Subcutaneous layer deep to skin (not
technically part of skin)
•
Mostly adipose tissue
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Hair shaft
Dermal papillae
Subpapillary
vascular plexus
Pore
Appendages
of skin
• Eccrine sweat
gland
• Arrector pili
muscle
• Sebaceous
(oil) gland
• Hair follicle
• Hair root
Cutaneous vascular
plexus
Adipose tissue
Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Pacinian corpuscle
• Hair follicle receptor
(root hair plexus)
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Figure 5.1
Epidermis
• Keratinized stratified squamous epithelium
• Cells of epidermis
• Keratinocytes—
• Melanocytes--• Epidermal dendritic (Langerhans) cells—
• Tactile (Merkel) cells —
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(a)
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Dermis
Stratum corneum
Most superficial layer; 20–30 layers of dead
cells represented only by flat membranous
sacs filled with keratin. Glycolipids in
extracellular space.
Stratum granulosum
Three to five layers of flattened cells,
organelles deteriorating; cytoplasm full of
lamellated granules (release lipids) and
keratohyaline granules.
Stratum spinosum
Several layers of keratinocytes unified by
desmosomes. Cells contain thick bundles of
intermediate filaments made of pre-keratin.
Stratum basale
Deepest epidermal layer; one row of actively
mitotic stem cells; some newly formed cells
become part of the more superficial layers.
See occasional melanocytes and epidermal
dendritic
cells.
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Figure 5.2a
Layers of the Epidermis: Stratum Basale
(Basal Layer)
• Deepest epidermal layer firmly attached to the
dermis
• Single row of stem cells
• Also called stratum germinativum: cells
undergo rapid division
• Journey from basal layer to surface
• Takes 25–45 days
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Layers of the Epidermis: Stratum Spinosum
(Prickly Layer)
• Cells contain a weblike system of intermediate
prekeratin filaments attached to desmosomes
• Abundant melanin granules and dendritic cells
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Layers of the Epidermis: Stratum
Granulosum (Granular Layer)
• Thin; three to five cell layers in which the cells
flatten
• Keratohyaline and lamellated granules
accumulate
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Layers of the Epidermis: Stratum Lucidum
(Clear Layer)
• In thick skin
• Thin, transparent band superficial to the
stratum granulosum
• A few rows of flat, dead keratinocytes
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Layers of the Epidermis: Stratum Corneum
(Horny Layer)
• 20–30 rows of dead, flat, keratinized
membranous sacs
• Three-quarters of the epidermal thickness
• Functions
• Protects from abrasion and penetration
• Waterproofs
• Barrier against biological, chemical, and
physical assaults
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Stratum corneum
Most superficial layer; 20–30 layers of dead
cells represented only by flat membranous
sacs filled with keratin. Glycolipids in
extracellular space.
Stratum granulosum
Three to five layers of flattened cells,
organelles deteriorating; cytoplasm full of
lamellated granules (release lipids) and
keratohyaline granules.
Stratum spinosum
Several layers of keratinocytes unified by
desmosomes. Cells contain thick bundles of
intermediate filaments made of pre-keratin.
Stratum basale
Deepest epidermal layer; one row of actively
mitotic stem cells; some newly formed cells
become part of the more superficial layers. See
occasional melanocytes and epidermal
dendritic cells.
Desmosomes
Melanin granule
Melanocyte
(b)
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Keratinocytes
Dermis
Sensory
nerve ending Epidermal
Tactile
dendritic cell
(Merkel) cell
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Figure 5.2b
Dermis
• Strong, flexible connective tissue
• Cells include • Two layers:
• Papillary
• Reticular
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Hair shaft
Dermal papillae
Subpapillary
vascular plexus
Pore
Appendages
of skin
• Eccrine sweat
gland
• Arrector pili
muscle
• Sebaceous
(oil) gland
• Hair follicle
• Hair root
Cutaneous vascular
plexus
Adipose tissue
Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Pacinian corpuscle
• Hair follicle receptor
(root hair plexus)
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Figure 5.1
Hypodermis
• Subcutaneous layer deep to the skin
• Composed of adipose and areolar connective
tissue
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Synovial Joints
• Those joints in which the articulating bones
are separated by a fluid-containing joint cavity
• All are freely movable joint _ diarthroses
• Examples – all limb joints, and most joints of
the body
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Synovial Joints: General Structure
• Synovial joints all have the following
• Articular cartilage
• Joint (synovial) cavity
• Articular capsule
• Synovial fluid
• Reinforcing ligaments
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Synovial Joints: General Structure
Figure 8.3a, b
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Synovial Joints: Friction-Reducing Structures
• Bursae – flattened, fibrous sacs lined with
synovial membranes and containing synovial
fluid
• Common where ligaments, muscles, skin,
tendons, or bones rub together
• Tendon sheath – elongated bursa that wraps
completely around a tendon
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Synovial Joints: Friction-Reducing
Structures
Figure 8.4
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Synovial Joints: Stability
• Stability is determined by:
• Articular surfaces – shape determines what
movements are possible
• Ligaments – unite bones and prevent
excessive or undesirable motion
• Muscle tone is accomplished by:
• Muscle tendons across joints acting as
stabilizing factors
• Tendons that are kept tight at all times by
muscle tone
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Synovial Joints: Movement
• The two muscle attachments across a joint
are:
• Origin – attachment to the immovable bone
• Insertion – attachment to the movable bone
• Described as movement along transverse,
frontal, or sagittal planes
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