Chapter 6 Flashcards
Cartilage
Not Bone
Skeletal Cartilage
Contains water, lends resiliency
Contains no blood vessels or nerves
Perichondrium surrounds
-Dense connective tissue girdle
–Contains blood vessels for nutrient delivery
All contain chondrocytes in lacunae and extracellular matrix
Skeletal Cartilage (3 Types)
Hyaline Cartilage
Elastic Cartilage
Fibrocartilage
Hyaline Cartilage
- Toughest
- Most abundant type
- Provides support/flexibility
- Collagen fibers only
- Articular and costal
Elastic Cartilage
- External Ear and epiglottis
- Similar to hyaline cartilage, more elastic fibers
Fibrocartilage
- Thick collagen fibers- has great tensile strength
- Intervertebral discs
Growth of Cartilage (3 Types)
Appositional Growth
Interstitial Growth
Calcification of Cartilage
Appositional Growth
External face of existing cartilage
-everything grows out
Interstitial Growth
Expanding cartilage from within
Calcification of Cartilage
- Occurs during normal bone growth
- Calcified cartilage is NOT bone
- Growth Plates close
Classification of Bones (2 Groups)
Location- Axial, Appendicular
Shape- Long, Short, Flat, Irregular
Axial
Head, neck, trunk
Appendicular
Arms, Legs
Long Bones
Longer than they are wide
Shaft and ends
Tibia, Fibula
Short Bones
Cube shaped bones
Sesamoid bones (within tendons, e.g., patella)
Toes
Flat Bones
Thin, flat, slightly curved
Ribs, Skull
Irregular Bones
Complicated shapes
Shoulder Blades, everything else
Functions of Bones (7 Functions)
Support Protection Movement Mineral and Growth Factor Storage Blood Cell Formation Triglyceride (fat) Storage Hormone Production
Support
Upright
Protection
Soft organs
- Skull
- Ribs
Movement
Muscles pull on bones
Mineral and Growth Factor Storage
Calcium and phosphorus, and growth factors reservoir
Blood Cell Formation
Red marrow cavity in certain bones
Triglyceride (fat) Storage
Bone cavities
-Energy source
Hormone Production
Osteocalcin
- Regulates bone formation
- Protection
Bones (3 Levels of Structure)
Organs Contains different types of tissues Three Levels of Structure -Gross Anatomy -Microscopic -Chemical
Common components of all bones
Dense outer layer of compact bone
-Smooth and solid
Spongy inner core
-Trabeculae
Gross Anatomy of Bone
Bone textures
-Compact vs. Spongy
Compact Bone
Dense outer layer
Smooth and solid
Spongy (cancellous or trabecular)
Honeycomb of flat pieces of bone deep to compact called trabeculae
Structure of Short, Irregular, and Flat Bones
Grossly
-Thin plates of spongy bone covered by compact bone
-Plates sandwiched between connective tissue membranes
-Periosteum (outer layer) and endosteum
Shaft
-None and no epiphyses
Bone Marrow
-Throughout spongy bone; no marrow cavity
Articular surfaces
-Cartilage covering
Structure of Typical Long Bone
Diaphysis
-Long tubular shaft
-Compact bone surrounding medullary cavity
Epiphyses
-Bone ends
-External compact bone
-Internal spongy bone
-Articular cartilage covers articular surfaces
-Between is epiphyseal line
–Remnant of childhood bone growth at epiphyseal plate
Articular
Joints where 2 bones come into contact
Medullary Cavity
Holds bone marrow
2 Membranes
Periosteum- peri- outside
Endosteum- endo- inside
Periosteum
White, double-layered membrane
Covers external surfaces except joint surfaces
-Outer fibrous layer of dense irregular
Osteogenic layer adults bone
-Contains primitive stem cells- osteogenic cells
Vascular and nerves
Anchoring points for tendons and ligaments
Endosteum
Covering internal bone surface
Covers trabeculae of spongy bone
Lines canals that pass through compact bone
Contains osteogenic cells that can differentiate into other bone cells
Osteogenic
Osteo-genic
Bone-maker
Ligament
Bone to bone
Tendon
Muscle to bone
Red bone Marrow
Location
-Trabecular cavities of spongy bone
-Scattered throughout flat bones
In medullary cavities and spongy bone of newborns
Location in long bones
-minimal
Yellow marrow can convert to red, if needed
Bone Markings
Sites of muscle, ligament, and tendon attachment on external surfaces
Joint surfaces
Conduits for blood vessels and nerves
Three types of Bone markings
Projections
Depressions
Openings
Projections
Most indicate stresses created by muscle pull or joint modifications
Depressions and Openings
Usually allow nerves and blood vessels to pass
5 Major Types of Cells in Bones
Osteogenic Cells Osteoblasts Osetocytes Bone lining Cells (non-relevant) Osteoclasts
Osteogenic Cells (Osteoprogenitor Cells)
Mitotically active stem cells Location -periosteum and endosteum Function -when stimulated differentiate into osteoblasts or bone lining cells -Some persist as osteogenic cells
Osteoblasts
Function -Bone-Forming -Secrete unmineralized bone matrix -Includes collagen and calcium-binding proteins Actively mitotic
Osteocyte
Mature bone cells in lacunae
Monitor and maintain bone matrix
Act as stress or strain sensors
-Respond to and communicate mechanical stimuli to osteoblasts and osteoclasts so bone remodeling can occur
Osteoclasts
Derived from hematopoietic stem cells that become macrophages
Giant, multinucleate cells for bone resorption
Osteoclasts vs. Osteoblast vs. Osteoctye
- blast- make
- cyte- maintaining
- clast- absorbing
Haversian System
Structural unit of compact bone
Elongated cylinder parallel to long axis of bone
Hollow tubes of bone matrix called lamellae
-collagen fibers in adjacent rings run in different direction
–withstands stress-resist twisting
Microscopic Anatomy of Compact Bone
Central Canal
Perforating Canal
Lacunae
Canaliculi
Central Canal
Runs through core of osteon
Contains blood vessels and nerve fibers
Perforating Canals
Canals lined with endosteum at right angles to central canal
Connect blood vessels and nerves of periosteum, medullary cavity, and central canal
Lacunae
Small cavities that contain osteocytes
Canaliculi
Canals that connect lacunae to each other and central canal
Canaliculi Formation
Osteoblasts secreting bone matrix
When matrix hardens and cells are trapped the canaliculi form
-Allow communication
-Permit nutrients and wastes to be relayed from one osteocyte to another throughout osteon
Central vs. Perforating
Central- middle, whole length, main road
Perforating- back road
Microscopic Anatomy of Bone: Spongy Bone
Appears poorly organized
Trabeculae
-Align along lines of stress to help resist it
-No osteons
-Contain irregularly arranged lamellae and osteocytes interconnected by canaliculi
-Capillaries in endosteum supply nutrients
Chemical Composition of Bone: Organic Components
Includes cells and osteoid
- Osteogenic cells, osteoblasts, osteocytes, bone-lining cells, and osteoclasts
- Osteoid- 1/3 of organic bone matrix secreted by osteoblasts
- -Made of ground substance
- -Collagen fibers
- -Contributes to structure; provides tensile strength and flexibility
Hydroxyapatites (mineral salts)
65% of bone by mass
Mainly of tiny calcium phosphate crystals in and around collagen fibers
Responsible for hardness and resistance to compression
Bone Fun Facts
Half as strong as steel in resisting compression
As strong as steel in resisting tension
Last long after death because of mineral composition
-Reveal information about ancient people
-can display growth arrest lines
–Horizontal lines on bones
–Proof of illness- when bones stop growing so nutrients can help fight disease
Ossification (Osteogenesis)
Process of bone tissue formation Formation of bony skeleton Postnatal bone growth -until early adulthood Bone remodeling and repair -lifelong
Ossification (2 Types)
Endochondral Ossification
Intramembranous Ossification
Endochondral Ossification
Bone forms by replacing hyaline cartilage
Forms most of skeleton
Forms most all bones inferior to base of skull
-Except clavicles
Uses hyaline cartilage models
Requires breakdown of hyaline cartilage prior to ossification
Intramembranous Ossification
Bone develops from fibrous membrane
Forms flat bones, e.g. clavicles and cranial bones
Forms frontal, parietal, occipital, temporal bones, and clavicles
Begins within fibrous connective tissue
Postnatal Bone Growth (2 types)
Interstitial (longitudinal) Growth
Appositional Growth
Interstitial Growth
Increase length of long bones
Requires epiphyseal cartilage
Epiphyseal plate maintains constant thickness
Concurrent remodeling of epiphyseal ends to maintain proportion
Result of 5 zones
5 Zones of Interstitial Growth
Resting (quiescent) zone Proliferation (growth) zone Hypertrophic zone Calcification zone Ossification (osteogenic) zone
Resting Zone
Cartilage on epiphyseal side of epiphyseal plate
Relatively inactive
Proliferation Zone
Cartilage on diaphysis side of epiphyseal plate
Rapidly divide pushing epiphysis away from diaphysis
Hypertrophic Zone
Older cartilage cells enlarge
Calcification zone
Surrounding cartilage matrix calcifies
Ossification zone
Chrondrocyte deterioration
Eroded by osteoclasts
Covered with new bone by osteoblasts
Ultimately replaced with spongy bone
Epiphyseal Plate Growth in Interstitial Growth
Near end of adolescence chondroblasts divide less often
Epiphyseal plate thins then is replaced by bone
Epiphyseal plate course
Epiphyseal Plate Course
Bone lengthening ceases
Bone of epiphysis and diaphysis fuses
Females about 18 years
Males about 21 years
Appositional Growth
Allows bone to widen
Osteoblasts
-Beneath periosteum secrete bone matrix on external bone
Osteoclasts
-Remove bone on endosteal surface
Usually more building up than breaking down
-Thicker stronger bone but not too heavy
Excess of deficits of any cause abnormal skeletal growth
Hormones of Regulating Bone Growth (3 Types)
Growth Hormone
Thyroid Hormone
Testosterone (males) estrogen (females)
Growth Hormone
HGH
most important in stimulating epiphyseal plate activity in infancy and childhood
Thyroid Hormone
Modulates activity of growth hormone
Ensures proper proportions
Testosterone & Estrogen
Promote adolescent growth spurts
End growth by inducing epiphyseal plate closure
