Chapter 6 Bones & Skeletal Tissue Flashcards
(25 cards)
Name the different types of skeletal cartilage
Hyaline cartilage, Elastic Cartilage, Fibrocartilage
Name the fibers that the Hyaline, Elastic & Fibrocartilage are made up of & locations in the body where you will find them
–Hyaline cartilage
- Fine Collagen fibers
- •Provides support, flexibility, and resilience
- •Articular, costal, respiratory, nasal cartilage
–Elastic cartilage
- •Similar to hyaline cartilage, but contains more stretchy elastic fibers.
- •External ear and epiglottis
–Fibrocartilage
- •Thick collagen fibers—has great tensile strength
- •Menisci of knee; vertebral discs
List and describe the important functions of bones
•Support
- Provides a framework that supports and anchors all soft organs (ex. Ribs support the thorax wall)
•Protection
- (ex. Skull and vertebrae surround soft tissue of the nervous system)
•Movement
- Levers for muscle action
•Storage
- Calcium and phosphorus, and growth factors reservoir
- Triglyceride (fat) storage in bone cavities
•Blood cell formation
- hematopoiesis in red marrow cavities of bones
•Hormone production
- Osteocalcin
- Regulates bone formation
- Protects against obesity, glucose intolerance, diabetes mellitus
- Created by the cells in our bones
How many named bones are in the skeleton?
206
What are the two groups that a skeleton are divided into?
Axial skeleton
- Long axis of body (Skull, vertebral column, rib cage)
Appendicular skeleton
- Bones of upper and lower limbs (Girdles attaching limbs to axial skeleton)
Describe the gross anatomy of a typical flat bone and a long bone
Long Bones
- Longer than they are wide
- Shaft + two ends that are often expanded
- Named for their shape and not necessarily their size!!!
Flat bones
- Thin, flat, slightly curved
- Sternum, scapulae, ribs, most skull bones
Indicate the locations and functions of red and yellow marrow
Red marrow
- Found within trabecular cavities of spongy bone and flat bones (e.g., Sternum)
- Consists mainly of hematopoietic tissue (population of stem cells, every cell type w/in our blood)
- Adult long bones have little red marrow
- Heads of femur and humerus only
Yellow marrow
- Consists mainly of fat
- Found in hollow interior of long bones
- Yellow marrow can convert to red, if necessary
Indicate the locations and functions articular cartilage
Articular (hyaline) cartilage
- covers articular surfaces (light blue)
- Covers Epiphysis of long bones (joints)
Indicate the locations and functions of periosteum and endosteum.
Periosteum
- White, double-layered membrane that covers most external surfaces
- Many nerve fibers and blood vessels
- Anchoring points for tendons and ligaments
Endosteum
- Delicate connective tissue membrane covering internal bone surface
- Covers trabeculae of spongy bone(light yellow)
- Lines canals that pass through compact bone
- Contains osteogenic cells that can differentiate into other bone cells
Describe the histology of compact bone
•Osteon or haversian system
- –Structural unit of compact bone
- –Elongated cylinder parallel to long axis of bone
- –Hollow tubes of bone matrix called lamellae
•Canals
- –Central (haversian) canal
- •runs through core of osteon
- •Contains blood vessels and nerve fibers
•Lacunae
- –small cavities that contain osteocytes
•Canaliculi
- –hairlike canals that connect lacunae to each other and central canal
Describe the histology of 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
Discuss the chemical composition of bone and identify organic
•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 (proteoglycans and glycoproteins)
- Collagen fibers
- Contributes to structure; provides tensile strength and flexibility
- Resilience of bone due to sacrificial bonds in or between collagen molecules
–Stretch and break easily on impact to dissipate energy and prevent fracture
–If no addition trauma, bonds re-form
Discuss the chemical composition of bone and identify inorganic components
•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
Expalin endochondral ossification
•Endochondral ossification
–Bone forms by replacing hyaline cartilage
–Bones called cartilage (endochondral) bones
–Forms most of skeleton
Describe the process of long bone growth that occurs at the epiphyseal plate (Intersitital Growth)
Resting (quiescent) zone
- Cartilage on epiphyseal side of epiphyseal plate
Proliferation (growth) zone
- Rapidly divide pushing epiphysis away from diaphysis = lengthening
Hypertrophic zone
- Older chondrocytes closer to diaphysis and their lacunae enlarge and erode à interconnecting spaces
Calcification zone
- Surrounding cartilage matrix calcifies, chondrocytes die and deteriorate
Ossification (osteogenic) zone
- Chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction
- Spicules eroded by osteoclasts
- Covered with new bone by osteoblasts
- Replaced with spongy bone
Compare the locations and remodeling functions of the osteoblasts, osteocytes and osteoclasts
Osteoblasts
- Bone-forming cells that are actively mitotic
- Secrete unmineralized bone matrix called osteoid
- Includes collagen and calcium-binding proteins
- Collagen = 90% of bone protein
- Responsible for bone growth
Osteocytes
- Mature bone cells in lacunae
- Monitor and maintain mineralized bone matrix
- Act as stress or strain sensors
- Respond to and communicate mechanical stimuli to osteoblasts and osteoclasts (cells that destroy bone) so bone remodeling can occur
Osteoclasts
- Derived from hematopoietic stem cells that become macrophages
- Giant, multinucleate cells for bone resorption
–Ruffled border increases surface area for enzyme degradation of bone and seals off area from surrounding matrix
Name the five major cell types
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Bone lining cells
- Osteoclasts
Explain how hormones regulate bone remodeling
•Growth hormone
- Most important in stimulating epiphyseal plate activity in infancy and childhood
•Thyroid hormone
- Modulates activity of growth hormone
- Ensures proper proportions
•Testosterone (males) and estrogens (females) at puberty
- Promote adolescent growth spurts
- End growth by inducing epiphyseal plate closure
- Excesses or deficits of any cause abnormal skeletal growth
Explain the Calcium (Ca+) negative feedback system
- Stymulus; falllling blood Ca+ levels
- Parathyroid gland release parathyroid hormone (PH)
- PTH must increase
- Osteoclasts break down bone matrix & release Ca+ into blood
Describe the different types of bone fractures
–Position of bone ends after fracture
- •Nondisplaced—ends retain normal position
- •Displaced—ends out of normal alignment
–Completeness of break
- •Complete—broken all the way through
- •Incomplete—not broken all the way through
–Whether skin is penetrated
- •Open (compound) - skin is penetrated
- •Closed (simple) – skin is not penetrated
Describe the steps to fracture repair.
- A hematoma forms
- Fibrocaritaginous callus forms
- bony callus forms
- bone remodeling occurs
Explain the disorder of bone remodeling seen in osteoporosis
- Group of diseases
- Bone resorption outpaces deposit
- Spongy bone of spine and neck of femur most susceptible
- Vertebral and hip fractures common
Name the Mechanisms of Postnatal Bone Growth
•Interstitial (longitudinal) growth
- Increase in length of long bones
•Appositional growth
- Increase in bone thickness
Describe the process of Appositional Growth: Growth in Width
- •Osteoblasts beneath periosteum secrete bone matrix on external bone
- •Osteoclasts remove bone on endosteal surface
- •Usually more building up than breaking down
- A Thicker, stronger bone but not too heavy
