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Layers of the dermis
Papillary is superior to reticular layer
Tissue found in papillary
Areolar CT
Tissue found in reticular
Dense irregular CT
Features found in papillary layer
Dermal papillae
Features found in reticular layer
Lines of cleavage
Function of dermal papillae
Increase the area of contact with epidermis, supply nutrients to epidermis through capillaries, sensory nerve endings for touch
Significance of cleavage lines
Resist stress
Composition of subcutaneous layer
Areolar CT and adipose CT
Functions of subcutaneous layer
Cushion & protect, energy storage, thermal insulation
Functions of nails
Protection, manipulation/grasping, scratching
Functions of hair
Protection, facial expression, heat retention, visual identificaiton, chemical signal dispersal, sensation
Function of arrector pili muscle
Cause hair to stand on end
Merocrine sweat glands
Most numerous sweat gland, discharge onto skin surface as sweat. Help with thermoregulation and protection.
Apocrine sweat glands
Discharge into hair follicles, discharge is viscous and turbid.
Function of sebaceous glands
Lubricate hair and protection
Secretion from sebaceous glands
Discharge into hair follicles, discharge is sebum
What is acne?
Plugged sebaceous gland
What is an articulation?
A place of contact between bones, bones and cartilage, and bones and teeth
Structural classification of joints
Fibrous, cartilage, synovial
Functional classification of joints
Synarthroses, amphiarthroses, diarthroses
What happens when mobility increases?
Stability decreases
What happens when mobility decreases?
Stability increases
Location of gomphoses
Between root of teeth & alveolar processes of mandible & maxilla
Structural & functional class of gomphoses
Fibrous, synarthrosis
Location of sutures
Between certain bones of skull
Structural & functional class of sutures
Fibrous, synarthrosis
Location of syndesmoses
Between radius & ulna and between tibia & fibula (interosseous membrane)
Structural and functional class of sutures
Fibrous, amphiarthrosis
Location of synchondroses
Epiphyseal plate, costochondral joints. Joined by hyaline cartilage
Structural and functional class of synchondroses
Cartilage, synarthrosis
Location of symphyses
Pubic symphyses, intervertebral joint
Strucutral and functional class of symphyses
Cartilage, amphiarthroses
What do all synovial joints have in common?
Diarthroses, seperated by a fluid-filled joint cavity
What features are present in synovial joints?
Articular cartilage, articular capsule (fibrous layer and synovial membrane), and joint cavity (contains synovial fluid)
Function of synovial fluid
Lubricate articular cartilage, nourish chondrocytes of articular cartilage, and absorb shock
Function of articular cartilage
Covers articulating bone surfaces, reduces friction between movement, absorbs compression, prevents damage to ends of bones. Avascular!
Function of joint cavity
Space that separates articulating bones, holds synovial fluid
Uniaxial
Bones move in one plane
Biaxial
Bones move in two planes
Multiaxial
Bones move in multiple planes
Plane (gliding) synovial joint
Uniaxial, two flat surfaces meet. Found in intertarsal and vertebrocostal joints
Hinge synovial joint
Uniaxial, convex surface of one meets concave depression of another. Found in humeroulnar (elbow) joint
Pivot synovial joint
Uniaxial, rounded surface of one fits ring formed by ligament in another. Found in atlantoaxial and proximal radioulnar joints
Condylar (ellipsoidal) synovial joint
Biaxial, oval condyle of one fits elliptical cavity of another. Found in metacarpophalangeal (knuckle) joint
Saddle synovial joint
Biaxial, complementary convex and concave surfaces. Found in first carpometacarpal (thumb) joint
Ball & socket synovial joint
Multiaxial, spherical head of one fits into cuplike depression of another. Found in glenohumeral (shoulder) joint
Major components of skeletal system
Bone, cartilage, ligaments, tendons, articulation structures
Compact bone v. spongy bone
Compact is much more dense and rigid, withstands mechanical stress (80% of bone mass). Spongy is deep to compact, store bone marrow and distribute stress (20% of bone mass)
Hyaline cartilage in human skeleton
Fetal skeleton, costal cartilage, articular cartilage, epiphyseal plate
Fibrocartilage in human skeleton
Intervertebral discs, pubic symphysis, menisci of knee
General functions of bone
Support & protection, levers for movement, hemopoiesis (blood cells production), storage of minerals/energy reserve (calcium and phosphate)
Functions of the integument
Protection, immune function, prevent water loss/gain, sensation, metabolic regulation (vitamin D production), secretions/absorption, temperature regulation
How does the integument protect the body?
Helps protect against injury, toxins, pathogens, temperature extremes, solar radiation
How does the integument prevent water gain/loss?
Water-resistant epidermis (not water-proof!)
How does the epidermis participate in calcium & phosphorus utilization?
Keratinocytes synthesize cholecalciferol (Vitamin D3) which is converted to other substances in liver and kidney, results in increased phosphorus & calcium absorption in small intestine
How does integument participate in secretions?
Discharges substances from the body such as sweat (cools body and excretes waste products) and sebum (lubricates epidermis & hair & improves water resistance)
How does integument participate in absorption?
Allows hydrophobic substances to cross barrier, absorbs certain chemicals and drugs (transdermal administration)
Vasoconstriction
Blood vessel diameter narrows, blood further from surfaces, helps conserve heat when the body is cold
Vasodilation
Blood vessel diameter expands, blood closer to surface, releases excess heat when the body is hot
Layers of epidermal strata shortcut
Superficial to deep —> Come, Let’s Get Sun Burned
Layers of epidermal strata
Superficial to deep —> Stratum corneum, Stratum lucidum (only in thick skin), Stratum granulosum, Stratum spinosum, Stratum basale
Keratinocytes
Synthesize keratin, found in all layers of epidermis
Melanocytes
Produce and store melanin (protection against cancer, protect keratinocytes), found in stratum basale
Tactile cells
Detects light touch and pressure, found in stratum basale
Epidermal dendritic cells
Immune cells, found in stratum spinosum and stratum granulosum
Stratum basale
Deepest epidermal layer, single layer of cuboidal/columnar cells attached to basement membrane, contains keratinocytes, melanocytes, and tactile cells
Stratum spinosum
Non-dividing keratinocytes connected through membrane junctions (adhesion proteins) & epidermal dendritic cells (phagocytize pathogens and cancer cells)
Stratum granulosum
3-5 layers of flattened cells, process of keratinization begins here, named for keratin & lipid-based substance cytoplasmic granules
Stratum lucidum
2-3 layers of flattened, dead keratinocytes (featureless w/ indistinct boundaries), only found in thick skin
Stratum corneum
Most superficial layer, 20-30 layers of dead keratinocytes, dry & thickened surface
Features of thick skin
Found in palms of hands and soles of feet, contains all 5 epidermal strata, contains only sweat glands, range of thickness is 0.4mm - 0.6mm
Features of thin skin
Covers most of body, lacks stratum lucidum, contains sweat glands, hair follicles, and sebaceous glands, range of thickness is 0.075mm - 0.150mm
What causes difference in skin color?
Hemoglobin, carotene, melanin
Hemoglobin
Oxygen-binding protein in red blood cells, blood vessels in dermis take on a reddish blue
Carotene
Yellow-orange pigment acquired from diet
Melanin
Pigment with black, brown, tan, yellow-brown shades
How does melanin help with protection?
Shields keratinocyte DNA from UV radiation
How does melanin color skin?
Melanocyte activity (environment) and color of melanin (genetics)
Long bones
Longer than they are wide (femur, metacarpals)
Short bones
Length equals width (sesamoid bones, carpals)
Flat bones
Thin/curved bones (frontal bone of skull, rib bones)
Irregular bones
Elaborate/complex shape (vertebra, ethmoid bone)
Anatomy of long bones
Diaphysis (shaft), medullary cavity (hollow space within diaphysis), epiphysis (ends, proximal & distal), metaphysis (junction between diaphysis and epiphysis), epiphysial plate (layer of cartilage in metaphysis that allows growth)
Periosteum
Protective sheath surrounding all areas of long bone except areas covered by articular cartilage (fibrous layer, cellular layer, perforating fibers)
Endosteum
Where spongy bone dissolves into medullary cavity, incomplete layer of cells
Nutrient foramen
Opening in long bone where blood vessels and nerves enter and exit
Gross anatomy of non-long bones
External surface is compact bone, interior is spongy bone, no medullary cavity
Red bone marrow
Reticular CT, immature blood cells, and fat. Homopoiesis (formation of blood cells and platelets). Most common in children, found in medullary cavity of long bones. In adults, only remains in portions of axial skeleton and epiphyses of humerus and femur
Yellow bone marrow
Adipose CT. Energy reserve. Most common in adults
Osteoprogenitor cells
Stem cells, divide into 1 stem cell and 1 osteoblast
Osteoblasts
Perform bone deposition (build bones), secrete osteoid and regulate mineralization. Cuboidal shape with abundant rough ER & golgi, become trapped in bone matrix & differentiate into osteocytes
Osteocytes
Mature bone cells, performs mechanosensation (perceives mechanical stimuli) and orchestrates bone remodeling
Osteoclasts
Large, multinucleated phagocytic cells located in resorption lacuna, perform bone resportion (break down)
Organic component of extracellular matrix of bone
Osteoid (collagen fibers, ground substance of glycosaminoglycans, proteoglycans, & glycoproteins). Resists torsion (twist) and tensile (stretch)
Inorganic compounds of extracellular matrix of bone
Hydroxyapatite crystals (calcium phosphate, calcium hydroxide, other salts and ions). Resists compressional forces
Calcification
Osteoid & hydroxyapatite work together, osteoblasts secrete semisolid osteoid, hydroxyapatite crystals form around collagen fibers (think rock candy on a stick). Requires vitamin D and A.
Bone resorption (breakdown of bone tissue)
Osteoclasts secrete proteolytic enzymes that digest organic compounds, hydrochloric acid to dissolve inorganic compounds
Intramembranous ossification bones
Flat bones of facial skull, some facial bones, mandible, and central bone of clavicle.
Steps of intramembranous ossification
Ossification center forms in thickened mesenchyme
Osteoid undergoes calcification
Immature woven bone (primary bone) and periosteum form
Lamellar bone (secondary bone) replaces woven bone, forming compact & spongy bone
Bones of endochondral ossification
Upper & lower limbs, pelvis, vertebrae, ends of clavicle