A&P Flashcards
Stages of Intramembranous Ossification
Ossification center appears in fibrous CT membrane
Bone matrix is secreted within the fibrous membrane
Woven bone & periosteum form
Bone collar of compact bone forms/red marrow appears
Stages of Endochondral Ossification
Formation of bone collar Cavitation of the hyaline cartilage Spongy bone formation Formation of medullary cavity; appearance of secondary ossification centers Ossification of the epiphyses
3 Functional Zones of Postnatal Bone Growth
Growth
Transformation
Osteogenic development
Growth Zone of Long Bone Growth
Cartilage cells undergo mitosis
Pushes epiphysis away from diaphysis
Transformation Zone of Long Bone Growth
Older cells enlarge
Matrix becomes calcified
Cartilage cells die
Matrix begins to deteriorate
Osteogenic Zone of Long Bone Growth
New bone formation occurs
Growth in Length of Long Bones
Cartilage continually grows and is replaced by bone
Remodeling of Long Bones
Bone is resorbed & added by appositional growth
Hormonal Regulation of Bone Growth
Infancy/childhood: GH
Puberty: testosterone & estrogens
Testosterone & Estrogens in Bone Growth
Promote growth spurts
Masculinization & feminization of specific parts of the skeleton
Induce epiphyseal plate closure
Remodeling Units in Bone Remodeling
Osteoblasts & osteoclasts deposit & resorb bone at periosteal & endosteal surfaces
Where does bone deposition occur?
Where bone is injured or added strength is needed
Bone Deposition Requirements
Protein Vitamin C, D, & A Calcium Phosphorus Magnesium Manganese Alkaline phosphatase
How is bone resorption accomplished?
Osteoclasts
What do osteoclasts secrete to resorb bone?
Lysosomal enzymes
Acids
What do lysosomal enzymes do during bone resorption?
Digest organic matrix
What do acids do during bone resorption?
Convert calcium salts into soluble forms
Importance of Ionic Calcium in the Body
Transmission of nerve impulses Muscle contraction Blood coagulation Secretion by glands & nerve cells Cell division
2 Loops that Control Remodeling of Bone
Hormonal mechanism (PTH) Mechanical & gravitational forces
Describe Wolff’s Law
Bone grows or remodels in response to the forces or demands place upon it
Bone’s Response to Mechanical Response
Trabeculae form along lines of stress
Large, bony projections occur where large, active muscles attach
How are bone fractures classified?
Position of bone ends after fracture
Completeness of the break
Orientation of bone to the long axis
+/- bone ends penetrate the skin
Types of Bone Fractures
Non-displaced Displaced Complete Incomplete Linear Transverse Compound Simple Comminuted Spiral Depressed Compression Epiphyseal Greenstick
Describe a Non-displaced Fracture
Bone ends retain their normal position
Describe a Displaced Fracture
Bone ends are out of normal alignment
Describe a Complete Fracture
Bone is broken all the way through
Describe an Incomplete Fracture
Bone is not broken all the way through
Describe a Linear Fracture
Fracture is parallel to the long axis of the bone
Describe a Transverse Fracture
Fracture is perpendicular to the long axis of the bone
Describe a Compound Fracture (Open)
Bone ends penetrate the skin
Describe a Simple Fracture (Closed)
Bone ends do not penetrate the skin
Describe a Comminuted Fracture
Bone fragments into three or more pieces
Describe a Spiral Fracture
Ragged break when bone is excessively twisted (sports injury)
Describe a Depressed Fracture
Broken bone portion pressed inward (skull)
Describe a Compression Fracture
Bone is crushed
Common in porous bones
Describe an Epiphyseal Fracture
Epiphysis separates from diaphysis along the epiphyseal line
Describe a Greenstick Fracture
Incomplete fracture where one side of the bone breaks and the other side bends
Stages in Healing a Bone Fracture
Hematoma Formation
Fibrocartilaginous callous forms
Bony callus forms
Bone remodeling
Fibrocartilaginous Callus Formation
Granulation tissue forms few days after fracture
Capillaries grow into tissue
Phagocytes clean up debris
Bony Callus Formation
Bone trabeculae appear in the fibrocartilaginous callus
Fibrocartilaginous callus converts to bony callus
Bone Remodeling in Bone Fractures
Osteoclasts remove excess material
Osteoblasts lay down compact bone
Define Osteomalacia
Bones are inadequately mineralized
Soft, weak bones
What is osteomalacia caused by?
Lack of calcium or vitamin D deficiency
Common Physical Findings in Rickets
Bowed legs
Deformities of the pelvis, skull, & rib cage
Define Osteoporosis
Bone resorption outpaces bone deposit
Treatment of Osteoporosis
Calcium + Vitamin D Increase weight bearing exercise Hormone replacement therapy Natural progesterone cream Statins
What is Paget’s disease characterized?
Excess bone formation & breakdown
Where is Paget’s disease usually localized?
Spine
Pelvis
Femur
Skull
Treatment of Paget’s Disease
Didronate
Fosfamax
Define Ligament
Connect bone to bone
Provide stability
Define Tendon
Connect bone to muscle
Provide motion
Overuse Injuries to Tendon
Usually respond to rest
Acute Injuries to Tendon
May need surgical repair
Partial Strains, Sprains, & Tears
Will heal if protected
Complete Strains, Sprains, & Tears
Often need surgical repair
Define Bursitis
Inflammation of bursa from overuse
Most Common Deep Bursitis
Greater trochanter
Rotator cuff
Most Common Superficial Bursitis
Olecranon
Pre-patellar
Description of Skeletal Muscle
Striated
Multiple nuclei
Voluntary
Description of Cardiac Muscle
Striated
Single nucleus
Involuntary
Description of Smooth Muscle
No striations
Single nucleus
Involuntary
Function of Skeletal Muscles
Movement of bones or fluids
Maintaining posture & body position
Stabilizing joints
Heat generation
Define Epimysium
Dense regular connective tissue surrounding entire muscle
Define Perimysium
Fibrous connective tissue surrounding fascicles
Define Endomysium
Fine areolar connective tissue surrounding each muscle fiber
What is a sarcomere?
Smallest contractile unit of a muscle fiber
Thick Filaments of a Sarcomere
Entire length of A band
Thin Filaments of a Sarcomere
Run length of I band and part of the A band
Z disc of a Sarcomere
Coin-shaped sheet of proteins that anchors the thin filaments
Connects myofibrils to one another
H Zone of a Sarcomere
Region of only thick filaments
Mid-region where filaments don’t overlap
M Line of Sarcomere
Where thick filaments attach
What are the regulatory proteins that are bound to actin?
Tropomyosin
Troponin
Describe the Sliding Filament Model of Contraction
Myosin heads bind to actin, detach, & bind again
Propel the thin filaments toward the M line
H zones shorten & disappear, sarcomeres shorten, muscle cells shorten, & whole muscle shortens
Requirements for Skeletal Muscle Contraction
Activation
Excitation-contraction coupling
Define Activation Regarding Skeletal Muscle Contraction
Neural stimulation at a neuromuscular junction
Define Excitation-Contracting Coupling
Generation & propagation of an action potential along the sarcolemma
Where are ACh receptors found on the muscles?
Junctional folds of the sarcolemma
What part of neuromuscular transmission does myasthenia gravis and neuromuscular blockers affect?
ACh binding to ACh receptors
What part of neuromuscular transmission does botulinum toxin affect?
Calcium influx into the axon terminals
What part of neuromuscular transmission does MS affect?
Action potential to axon terminals
Define Summation
Rapid sequence of stimuli
Muscle twitches fuse together
Define Tetanus
Very rapid sequence of stimuli
No relaxation
Muscle Fiber Components
Sarcolemma Sarcoplasma Motor end plate T tubule Cisternae Myofibrals
Define Sarcolemma
Muscle cell membrane
Define Sarcoplasma
Muscle cell cytoplasm
Define Motor End Plat
Contact surface with axon terminal
Define T Tubule
Cell membrane extension into the sarcoplasm
Reaches myofibrils
Define Cisternae
Areas of the ER dedicated to Ca storage
On each side of T tubule
What are myofibrils organized into?
Sarcomeres
