Lecture 4 (FIRST MIDTERM) Flashcards
Functions of the skeletal system:
- Support and protection
- Mineral (calcium and phosphorus) and lipid storage (yellow marrow - fatty)
- Hematopoiesis (red marrow) - creating blood cells
- Movement
Types of cartilage:
Hyaline
Elastic
Fibrocartilage
Dentin and enamel are derived from what specific germ layer?
Neural crest ectoderm
What are cartilage cells?
chondrocytes
The manner is which cartilage grows:
Interstitial growth (between the cells)
The perichondrium means…
and is made of what?
around the cartilage
dense irregular fibrous connective tissue
Bone cells are called…
Osteocytes
Organic content of bones:
Osteocytes and collagen
Mineral (inorganic) content of bones:
Hydroxyapatite
Types of bones and describe each.
Long bones: longer than they are wide Flat bones: flatter than they are high Short bones: almost cubes (not perfectly) Sesmoid bones: look like sesame seeds Sutural bones: between cranial sutures Irregular bones: unique
If you start “attaching” minerals to the matrix of cartilage, what happens?
It changes into bone
Examples of each type of bone Long bones: Flat bones: Short bones: Sesmoid bones: Sutural bones: Irregular bones:
- Long bones: most limb bones including phalanges
- Flat bones: cranial bones, ribs, sternum, scapula
- Short bones: carpal and tarsal bones
- Sesmoid bones: patella, intratendonous bones
- Sutural bones: between cranial structures
- Irregular bones: vertebrae, pelvic bones, some cranial bones
What is different about sesmoid bones?
They grow inside tendons (like patella bone)
Elevations and projections features
Process:
Ramus:
Process: generic term for a projection
Ramus: a projection that forms a sharp angle
Tendon or ligament features Trochanter/Tuberosity: Tubercle: Crest/Line: Spine:
Trochanter/Tuberosity: rough projections (usually for attachment of ligament/tendon - more surface area)
Tubercle: smooth projection (smaller attachments)
Crest/Line: large and small ridges
Spine: a point
Articulation features Head: Neck: Condyle: Trochlea: Facet:
Head: expanded articular end
Neck: narrow area between head and shaft
Condyle: smooth, rounded articular portion (in pairs)
Trochlea: grooved articular portion
Facet: flat articular area (in between vertebrae)
Depressions and openings features Fossa: Sulcus: Foramen vs. canal: Fissure: Sinus:
Fossa: a depression
Sulcus: a groove (elongated depression)
Foramen vs. canal: single hole vs. 2 connecting holes
Fissure: a cleft
Sinus: a hollow area (usually air-filled)
Parts of a bone
Diaphysis:
Epiphysis:
Metaphysis:
Diaphysis: shaft (single; unpaired)
Epiphysis: expanded end (paired)
Metaphysis: transitional zone between the diaphysis and epiphysis
What is the actual growth plate?
Metaphysis
Structure of bone
Compact bone:
Spongy bone:
Marrow cavity:
Compact bone: dense shell around marrow cavity
Spongy bone: at the ends; lots of holes; meshwork
Marrow cavity: hollow center in the diaphysis
The marrow cavity is also referred to as…
the medullary cavity
The compact bone is also referred to as…
cortical bone (cortex)
The spongy bone is also referred to as…
trabecular bone (“beam”)
What kind of tissue is bone?
connective tissue
What does the matrix of a bone consist of?
- Extracellular fibers (most collagen with inorganic crystals)
- Ground substance (the fluid - minimal)
Most of the mass of bone is…
Inorganic; hydroxyapatite mineral
Hydroxyapatite mineral structure:
Hard, inflexible, brittle; will break
What hold the hydroxyapatite crystals in place?
Collagen fibers
Combination of ______ and _______ makes bone strong and slightly flexible.
Organic content and inorganic content
Osteocytes:
Mature bone cells that occupy lacunae
What are lacunae?
Little spaces in the matrix that hold one osteocyte per lacuna
Osteocytes are connected via what?
Canaliculi (tiny little channels)
Functions of osteocytes:
- Maintain the matrix environment
- Repair damaged bone
Osteochondral progenitor cells:
Located:
- Stem cells that will become osteoblasts
- Located on the interior endosteum (lining the inside of the bone in the marrow cavity)
- And periosteum (outside of marrow cavity)
Osteoblasts:
- Produce new bone
- Secrete the organic matrix (osteoid)
- Promote deposition of hydroxyapatite
Osteiod is…
Organic component of matrix before it becomes mineralized
Osteoclasts:
- Large cells that break down/dissolve bone matrix
- Multi-nucleated
Where are osteoclasts derived from?
macrophages
What is the very middle of bone? And what can you find?
Central canal
Blood vessels
What has layers and surrounds the central canal?
Osteon
Where do you find circumferential lamellae?
The outer and inner surfaces (circumference) of the bone, where they are covered by the periosteum and endosteum
Structure of a periosteum:
Fibrous outer layer
Cellular inner layer
Basic biomechanics Force: Load: Stress: Strain: Elasticity: Stiffness:
Force: mass x acceleration
Load: a force applied to an object
Stress: force/area
Strain: deformation resulting from stress
Elasticity: ability to experience strain and return to original shape
Stiffness: resistance to bending
2 main types of bone and characteristics:
Compact (cortical) bone: dense; stress from limited directions; resists compression & tension; heavy
Spongy (trabecular) bone: resists stress from many directions; stress lines; light
Functional unit of compact bone….
Osteon
Perforating canals allow what?
Blood to come from outside and go from one central canal to another, all the way to the innermost portion of the bone (medullary cavity)
Other names for…
Central canal:
Perforating canal:
Central canal: Haversian canal
Perforating canal: Volkmann’s canal
Where is spongy bone located?
What happens at these locations?
- At the ends of long bones
- Articulation with other bones
Spongy bone helps to do what?
Receives stress and helps to distribute loads from the articular condyles to the cortical (inner) bone where it is the strongest
Compact bones and spongy bones work together to…
Most efficiently handle the load placed on it
