m2: musculoskeletal system Flashcards by aespicy buldak

● Framework that helps maintain the body’s shape and enables us to move normally.
● Composed of bones, cartilage, and ligaments

SKELETAL SYSTEM

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Functions of the Skeletal System

Body Support
Organ Protection
Body Movement
Mineral Storage
Blood Cell Production

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Bone Cells
○ Three types:

■ Osteoblast
■ Osteocytes
■ Osteoclasts

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○ “Bone Building”
○ extensive endoplasmic reticulum and
numerous ribosomes
○ produce collagen and proteoglycans
○ _ - formation of new bones |
occurs multiple times during life
○ produce bone matrix until they
become surrounded by bone matrix →
becomes OSTEOCYTES

OSTEOBLAST

Ossification

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○ Matured Osteoblasts
○ Account for 90–95% of bone cells | life-span of _ yrs.
○ produce the components needed to maintain the bone matrix.

● OSTEOCYTES

25 years

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● _

○ _
■ Spaces within the matrix
■ Houses bodies of osteocytes
○ _
■ narrow, long spaces
■ Houses the extensions of osteocytes

● OSTEOCYTES

○ LACUNAE
○ CANALICULI

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○ “bone-destroying”
○ Causes bone reabsorption

OSTEOCLASTS

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● Porous | less bone matrix |more space
● consists of interconnecting rods or plates of bone (trabeculae)
● Contains : Red Marrow & Yellow Marrow

SPONGY BONE

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● Cortical Bone | Solid outer layer of bones
● more matrix and is denser with fewer pores

COMPACT BONE

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○ functional unit of compact bone | Central Canal → Bull’s eye
○ AKA: _ System

● OSTEON

Haversian System

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STRUCTURES OF A LONG BONE

Diaphysis
Medullary Cavity
Articular Cartilage
Epiphysis
Epiphyseal Plate
Epiphyseal Line
Periosteum
Endosteum

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○ Center portion of the long bone

● Diaphysis

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○ Hollow center of the long bone

● Medullary Cavity

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○ Hyaline cartilage covering ends of bones

● Articular Cartilage

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○ Ends of long bones | Mostly spongy bone c outer compact bone

● Epiphysis

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○ Growth plate | between the epiphysis and the diaphysis
○ Growth in bone length occurs here

● Epiphyseal Plate

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○ When epiphyseal plate ossifies → becomes epiphyseal line

● Epiphyseal Line

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○ connective tissue membrane covering the outer surface of a bone
○ Outer - blood vessels and nerves | Inner - single layer of bone cells (Osteoblasts & Osteocytes)

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● Periosteum

○ single cell layer of connective tissue
○ lines the internal surfaces of cavities w/in bones
○ Includes osteoblasts & osteoclasts

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● Endosteum

● Length is greater than their breadth
● shape enhances their function in movement of appendages
● Found in the limbs (humerus, femur, metacarpals, metatarsals and phalanges)

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Long Bones

● approximately as wide as they are long
● help transfer force between long bones
● Found in the hand and foot (scaphoid, lunate, talus and calcaneum)

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Short Bones

● relatively thin | flattened shape
● well-suited to providing a strong barrier around soft organs
● Skull bones, the ribs, the scapulae , and the sternum

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Flat Bones

● shapes that do not fit readily into the other three categories
● have specialized functions | providing protection while allowing bending and flexing

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Irregular Bones

● shapes that do not fit readily into the other three categories
● have specialized functions | providing protection while allowing bending and flexing

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Sesamoid Bones

● Movement of the body ● Maintenance of posture ● Respiration ● Communication ● Constriction of organs and vessels ● Contraction of the heart

FUNCTIONS OF MUSCLE

FUNCTIONAL PROPERTIES ● _ ○ ability of muscle to shorten forcefully, or contract ● ○ capacity of muscle to respond to a stimulus ● _ ○ muscle can be stretched beyond its normal resting length and still be able to contract. ● _ ○ ability of muscle to recoil to its original resting length after it has been stretched.

● Contractility ● Excitability ● Extensibility ● Elasticity

Connective Tissue Coverings ○ _ ■ connective tissue sheath | surrounds each skeletal muscle ○ _ ■ Subdivides each muscle into FASCICLES ■ loose connective tissue | passageways for blood vessels and nerves ○ _ ■ delicate layer of connective tissue ■ separates the individual muscle fibers within each fascicle

○ Epimysium ○ Perimysium ○ Endomysium

● _ ○ muscle cell plasma membrane ● _ ○ multiple per cell at the periphery ● _ ○ Mm cell cytoplasm ● _ ○ contains actin and myosin filament ○ composed of about 1500 adjacent MYOSIN FILAMENTS and 3000 ACTIN FILAMENT ● _ ○ myofilaments in the sarcomere provide the mechanical aspect of muscle contraction. ○ _ ■ thin filaments ○ _ ■ thick filaments

● SARCOLEMMA ● NUCLEUS ● SARCOPLASMA ● MYOFIBRIL ● MYOFILAMENTS ○ ACTIN ○ MYOSIN

● SARCOMERE ○ join end to end, forming the myofibrils ○ smallest portion of a muscle that can contract ○ arrangement of the actin and myosin myofilaments within sarcomeres that gives skeletal muscle its striated appearance ○ _ _ ■ Z stands for ZWISCHENSCHEIBE (between) ■ stationary anchor for actin myofilaments ○ 3 REGIONS: ■ two lighter-staining regions (_ BAND) ■ central darker-staining region (_ BAND)

● SARCOMERE ○ Z DISKS I BAND A BAND

● _ BAND ○ contain only _ myofilaments (thin filaments) ○ Light bands ● _ BAND ○ Dark band ○ Contains _ and _ filaments ● _ _ ○ contains only _ myofilaments (thick filaments) ● _ _ ○ Center of the H zone ○ consists of delicate protein filaments that hold the myosin myofilaments in place

● I BAND - actin ● A BAND- myosin and actin ● H ZONE- myosin ● M LINE

_ MYOFILAMENTS ● composed of three separate proteins: ○ (1) _ ○ (2) _ ○ (3) _ ● Attachment sites on Actin → Receptor sites for Myosin Head

ACTIN ○ (1) actin ○ (2) tropomyosin ○ (3) troponin

● _ ○ long, fibrous protein that lies in the groove along the fibrous actin strand ○ Relaxed mm → covers the attachment sites on actin (uncovering these are required for mm contraction)

● Tropomyosin

● _ ○ 3 subunits: ■ a subunit that anchors the troponin to the actin ■ subunit that prevents the tropomyosin from uncovering the actin attachment sites in a relaxed muscle ■ subunit that binds Ca 2+

● Troponin

_ MYOFILAMENTS ● many elongated myosin molecules shaped like golf clubs ● Myosin Molecules are composed of: ○ _ _ ○ _ _ portions (2) ■ heads bind to active sites → form cross-bridges (mm contraction) ■ heads are attached to the rod portion by a hinge region that bends and straightens during contraction ■ heads break down adenosine triphosphate (ATP), releasing energy ● Part of the energy is used to bend the hinge region of the myosin molecule during contraction

MYOSIN ○ Rod portion ○ Myosin head portions (2)

NEUROMUSCULAR JUNCTION STRUCTURE ● _ _/ _ ○ consists of a group of enlarged axon terminals that rests on a portion of the sarcolemma ○ Composed of: ■ axon terminals ■ area of the muscle fiber sarcolemma they innervate ● _ _ ○ Found on the axon ○ Synaptic vesicles contain Acetylcholine ● _ _ ○ Space between the presynaptic terminal and the muscle fiber ● _ _ _ / _ Membrane ○ muscle cell membrane in the area of the junction

● Neuromuscular Junction / Synapse ● Presynaptic Terminal ● Synaptic Cleft ● Motor End Plate / Postsynaptic Membrane

● parallel arrangement of myofilaments in a sarcomere causes muscle contraction ● During _ _ → actin and myosin myofilaments in the sarcomere slide past one another and shorten the sarcomere ○ myofilaments remain the same length (even at rest) ○ myofibrils, muscle fibers, muscle fascicles, and muscles shorten during contraction

SLIDING FILAMENT THEORY mm contraction

● _ ○ muscle that accomplishes a certain movement, such as _ brachii in elbow flexion ● _ ○ muscle acting in opposition to an agonist, such as _ brachii in elbow flexion

● Agonist - BICEPS ● Antagonist- TRICEPS

● _ ○ group of muscles working together to produce a movement (ex. _ brachii and _ are synergists in elbow flexion) ● _ _ ○ among a group of synergists, if one muscle plays the major role in accomplishing the movement. The _ is the prime mover in flexing the elbow.

● Synergists - Biceps & brachialis ● Prime mover - brachialis

● _ ○ length of the muscle does not change, but the amount of tension increases during the contraction process. ● _ ○ amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. ● _ ○ muscle shortening ● _ ○ muscle lengthening ● _ ○ same rate of movement

● Isometric ● Isotonic ● Concentric ● Eccentric ● Isokinetic

○ fasciculi arranged in a circle - orbicularis oris

● Circular

○ fascicles that arrive at one common tendon from a wide area, creating muscles that are triangular in shape - pectoralis

● Convergent

○ fasciculi are organized parallel to the long axis of the muscle, but they terminate on a flat tendon that spans the width of the entire muscle. - abdominal muscles

● Parallel

○ barbs on a feather from a common tendon that runs the length of the entire muscle Unipennate - Bipennate - Multipennate

● Pennate Unipennate - digital extensor Bipennate - rectus femoris Multipennate - deltoideus

○ fibers run the length of the entire muscle and taper at each end to terminate at tendons, creating a wider belly than the ends - biceps brachii

● Fusiform

m2: musculoskeletal system Flashcards

(44 cards)