A&P Flashcards by Alicia Daum

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

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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

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3 Functional Zones of Postnatal Bone Growth

Growth
Transformation
Osteogenic development

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Growth Zone of Long Bone Growth

Cartilage cells undergo mitosis

Pushes epiphysis away from diaphysis

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Transformation Zone of Long Bone Growth

Older cells enlarge
Matrix becomes calcified
Cartilage cells die
Matrix begins to deteriorate

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Osteogenic Zone of Long Bone Growth

New bone formation occurs

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Growth in Length of Long Bones

Cartilage continually grows and is replaced by bone

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Remodeling of Long Bones

Bone is resorbed & added by appositional growth

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Hormonal Regulation of Bone Growth

Infancy/childhood: GH

Puberty: testosterone & estrogens

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Testosterone & Estrogens in Bone Growth

Promote growth spurts
Masculinization & feminization of specific parts of the skeleton
Induce epiphyseal plate closure

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Remodeling Units in Bone Remodeling

Osteoblasts & osteoclasts deposit & resorb bone at periosteal & endosteal surfaces

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Where does bone deposition occur?

Where bone is injured or added strength is needed

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Bone Deposition Requirements

Protein
Vitamin C, D, &amp; A
Calcium
Phosphorus
Magnesium
Manganese
Alkaline phosphatase

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How is bone resorption accomplished?

Osteoclasts

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What do osteoclasts secrete to resorb bone?

Lysosomal enzymes

Acids

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What do lysosomal enzymes do during bone resorption?

Digest organic matrix

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What do acids do during bone resorption?

Convert calcium salts into soluble forms

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Importance of Ionic Calcium in the Body

Transmission of nerve impulses
Muscle contraction
Blood coagulation
Secretion by glands &amp; nerve cells
Cell division

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2 Loops that Control Remodeling of Bone

Hormonal mechanism (PTH)
Mechanical &amp; gravitational forces

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Describe Wolff’s Law

Bone grows or remodels in response to the forces or demands place upon it

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Bone’s Response to Mechanical Response

Trabeculae form along lines of stress

Large, bony projections occur where large, active muscles attach

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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

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Types of Bone Fractures

Non-displaced
Displaced
Complete
Incomplete
Linear
Transverse
Compound
Simple
Comminuted
Spiral
Depressed
Compression
Epiphyseal
Greenstick

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Describe a Non-displaced Fracture

Bone ends retain their normal position

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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