Download Lab 2 Integumentary System, Synovial Joints, Membrane

Integumentary System, Synovial Joints and Build Your Own Membrane
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Skin (Integument)
• Consists of two distinct regions
– Epidermis—superficial region
• Epithelial tissue
– Dermis—underlies epidermis
• Mostly fibrous connective tissue
• Hypodermis (superficial fascia)
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Subcutaneous layer deep to skin
Not part of skin but shares some functions
Mostly adipose tissue that absorbs shock & insulates
Anchors skin to underlying structures – mostly
muscles
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Figure 5.1 Skin structure.
Hair shaft
Dermal papillae
Epidermis
Subpapillary
plexus
Papillary
layer
Sweat pore
Appendages of
skin
Eccrine sweat gland
Arrector pili muscle
Sebaceous (oil)
gland
Hair follicle
Hair root
Dermis Reticular
layer
Hypodermis
(subcutaneous
tissue; not part
of skin)
Nervous structures
Sensory nerve fiber
with free nerve endings
Lamellar corpuscle
Hair follicle receptor
(root hair plexus)
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Cutaneous plexus
Adipose tissue
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Epidermis
• Keratinized stratified squamous epithelium
• Four cell types
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Keratinocytes Melanocytes Dendritic (langerhans) cells Tactile (merkel) cells -
• Four or five distinct layers
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Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum (only in thick skin)
Stratum corneum
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Figure 5.2a The main structural features of the skin epidermis.
Stratum corneum
Most superficial layer; 20–30 layers of dead cells, essentially
flat membranous sacs filled with keratin. Glycolipids in
extracellular space.
Stratum granulosum
Typically five layers of flattened cells, organelles deteriorating;
cytoplasm full of lamellar granules (release lipids) and
keratohyaline granules.
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Dermis
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 dendritic
cells.
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Layers of the Epidermis:
Stratum Basale (Basal Layer)
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Deepest epidermal layer
Also called stratum germinativum
Firmly attached to dermis
Single row of stem cells
– Actively mitotic
– Produces two daughter cells
• One cell journeys from basal layer to surface
– Takes 25–45 days
– Dies as moves toward surface
• One cell remains in stratum basale as stem cell
• Melanocytes compose 10 – 25% of this layer
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Layers of the Epidermis:
Stratum Spinosum (Prickly Layer)
• Several layers thick
• Cells contain web-like system of
intermediate prekeratin filaments attached
to desmosomes
• Abundant melanosomes and dendritic
cells
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Layers of the Epidermis:
Stratum Granulosum (Granular Layer)
• Thin - four to six cell layers
• Cell appearance changes
– Cells flatten
– Nuclei and organelles disintegrate
– Keratinization begins
• Cells accumulate keratohyaline granules
– Help form keratin in upper layers
– Cell accumulate lamellar granules
• Their water-resistant glycolipid slows water loss
• Cells above this layer die
– Too far from dermal capillaries
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Layers of the Epidermis:
Stratum Lucidum (Clear Layer)
• Only in thick skin
• Thin, translucent 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, anucleate
keratinized membranous sacs
• Three-quarters of epidermal thickness
• Though dead, its cells have functions
– Protect deeper cells from environment and
water loss
– Protect from abrasion and penetration
– Barrier against biological, chemical, and
physical assaults
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Figure 5.2b The main structural features of the skin epidermis.
Keratinocytes
Stratum corneum
Most superficial layer; 20–30 layers of dead cells,
essentially flat membranous sacs filled with keratin.
Glycolipids in extracellular space.
Stratum granulosum
Typically five layers of flattened cells, organelles
deteriorating; cytoplasm full of lamellar granules
(release lipids) and keratohyaline granules.
Stratum spinosum
Dendritic
Several layers of keratinocytes unified by desmosomes.
cell
Cells contain thick bundles of intermediate filaments
made of pre-keratin.
Sensory
Stratum basale
nerve
Dermis
Deepest epidermal layer; one row of actively
ending
mitotic stem cells; some newly formed cells
Melanin
Tactile
become part of the more superficial layers.
granule
(Merkel) cell
See occasional melanocytes and dendritic
Melanocyte
Desmosomes
cells.
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Dermis
• Strong, flexible connective tissue
• Cells
– Fibroblasts, macrophages, and occasionally mast
cells and white blood cells
• Fibers in matrix bind body together
– "Hide" used to make leather
• Contains nerve fibers; blood and lymphatic
vessels
• Contains epidermal hair follicles; oil and sweat
glands
• Two layers
– Papillary
– Reticular
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Figure 5.1 Skin structure.
Hair shaft
Dermal papillae
Epidermis
Subpapillary
plexus
Papillary
layer
Sweat pore
Appendages of
skin
Eccrine sweat gland
Arrector pili muscle
Sebaceous (oil)
gland
Hair follicle
Hair root
Dermis Reticular
layer
Hypodermis
(subcutaneous
tissue; not part
of skin)
Cutaneous plexus
Nervous structures
Sensory nerve fiber
with free nerve endings
Lamellar corpuscle
Hair follicle receptor
(root hair plexus)
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Adipose tissue
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Figure 5.4a Dermal modifications result in characteristic skin markings.
Openings of
Friction
sweat gland ducts ridges
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Friction ridges of
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(SEM 12x)
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Figure 5.4b Dermal modifications result in characteristic skin markings.
Cleavage lines in the
reticular dermis
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Chapter 8 – Joints
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Joints (Articulations)
• Articulation
– Site where two or more bones meet
• Functions of joints
– Give skeleton mobility
– Hold skeleton together
• Two classifications
– Functional
– Structural
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Functional Classification of Joints
• Based on
– Amount of movement joint allows
• Three functional classifications:
– Synarthroses—immovable joints
– Amphiarthroses—slightly movable joints
– Diarthroses—freely movable joints
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Structural Classification of Joints
• Based on
– Material binding bones together
– Presence/absence of joint cavity
• Three structural classifications:
– Fibrous joints
– Cartilaginous joints
– Synovial joints
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Synovial Joints: Six Distinguishing Features
1. Articular cartilage: hyaline cartilage
2. Joint (synovial) cavity
3. Articular (joint) capsule
4. Synovial fluid
5. Different types of reinforcing ligaments
6. Nerves and blood vessels
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Figure 8.3 General structure of a synovial joint.
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
layer
Synovial
membrane
(secretes
synovial
fluid)
Articular
capsule
Periosteum
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Other Features of Some Synovial Joints
• Fatty pads
– For cushioning between fibrous layer and
synovial membrane or bone
• Articular discs (menisci)
– Fibrocartilage separates articular surfaces to
improve "fit" of bone ends, stabilize joint, and
reduce wear and tear
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Structures Associated with Synovial Joints
• Bursae
– Sacs lined with synovial membrane
• Contain synovial fluid
– Reduce friction where ligaments, muscles,
skin, tendons, or bones rub together
• Tendon Sheaths
– Elongated bursa wrapped completely around
tendon subjected to friction
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Figure 8.4a Bursae and tendon sheaths.
Acromion
of scapula
Subacromial
bursa
Joint cavity
containing
synovial fluid
Fibrous layer of
articular capsule
Articular
cartilage
Tendon
sheath
Synovial
membrane
Tendon of
long head
of biceps
brachii muscle
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Fibrous
layer
Humerus
Frontal section through the right shoulder joint
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Figure 8.4b Bursae and tendon sheaths.
Bursa rolls
and lessens
friction.
Humerus head
rolls medially as
arm abducts.
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Humerus moving
Enlargement of (a), showing how
a bursa eliminates friction where
a ligament (or other structure) would
rub against a bone
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Three Stabilizing Factors at Synovial Joints
• Shapes of articular surfaces (minor role)
• Ligament number and location (limited
role)
• Muscle tendons that cross joint (most
important)
– Muscle tone keeps tendons taut
• Extremely important in reinforcing shoulder and
knee joints and arches of the foot
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