m2: musculoskeletal system Flashcards
● Framework that helps maintain the body’s shape and enables us to move normally.
● Composed of bones, cartilage, and ligaments
SKELETAL SYSTEM
Functions of the Skeletal System
- Body Support
- Organ Protection
- Body Movement
- Mineral Storage
- Blood Cell Production
Bone Cells
○ Three types:
■ Osteoblast
■ Osteocytes
■ Osteoclasts
○ “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
○ 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
● _
○ _
■ Spaces within the matrix
■ Houses bodies of osteocytes
○ _
■ narrow, long spaces
■ Houses the extensions of osteocytes
● OSTEOCYTES
○ LACUNAE
○ CANALICULI
○ “bone-destroying”
○ Causes bone reabsorption
OSTEOCLASTS
● Porous | less bone matrix |more space
● consists of interconnecting rods or plates of bone (trabeculae)
● Contains : Red Marrow & Yellow Marrow
SPONGY BONE
● Cortical Bone | Solid outer layer of bones
● more matrix and is denser with fewer pores
COMPACT BONE
○ functional unit of compact bone | Central Canal → Bull’s eye
○ AKA: _ System
● OSTEON
Haversian System
STRUCTURES OF A LONG BONE
Diaphysis
Medullary Cavity
Articular Cartilage
Epiphysis
Epiphyseal Plate
Epiphyseal Line
Periosteum
Endosteum
○ Center portion of the long bone
● Diaphysis
○ Hollow center of the long bone
● Medullary Cavity
○ Hyaline cartilage covering ends of bones
● Articular Cartilage
○ Ends of long bones | Mostly spongy bone c outer compact bone
● Epiphysis
○ Growth plate | between the epiphysis and the diaphysis
○ Growth in bone length occurs here
● Epiphyseal Plate
○ When epiphyseal plate ossifies → becomes epiphyseal line
● Epiphyseal Line
○ connective tissue membrane covering the outer surface of a bone
○ Outer - blood vessels and nerves | Inner - single layer of bone cells (Osteoblasts & Osteocytes)
● Periosteum
○ single cell layer of connective tissue
○ lines the internal surfaces of cavities w/in bones
○ Includes osteoblasts & osteoclasts
● 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)
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)
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
Flat Bones
● shapes that do not fit readily into the other three categories
● have specialized functions | providing protection while allowing bending and flexing
Irregular Bones
● shapes that do not fit readily into the other three categories
● have specialized functions | providing protection while allowing bending and flexing
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
