Chapter 11- Musculoskeletal System Flashcards
Skeletal muscle
Involved in support and movement. Propulsion of blood in the Venus system.
Thermal regulation.
Striated.
Under voluntary or somatic control. Polynucleated.
What are the two types of fibers in skeletal muscle?
Slow twitch fibers that carry out oxidative phosphorylation. White fast twitch fibers that rely on anaerobic metabolism.
Myoglobin
An oxygen carrier that uses iron in a heme group to bind oxygen. Present in slow and fast twitch fibers. More numerous in slow twitch fibers.
Smooth muscle
Present in the respiratory reproductive cardiovascular and digestive systems. Non-striated.
Under involuntary or autonomic control.
Uninucleated.
Can display myogenic activity (contraction without neural input)
Cardiac muscle
The contractile tissue of the heart. Striated.
Under involuntary or autonomic control.
Uninucleated,sometimes binucleated. Can display myogenic activity (contraction without neural input). Cells are connected with intercalated discs that contain a gap junctions. (Allows for full of ions directly between cells it allows for rapid uncoordinated depolarization of muscle cells)
Sarcomere
The basic contractile units of striated muscle. Contains thick myosin and thin actin filaments.
What are the bodyguards of actin filaments?
Troponins and tropomyosin that both are found on the thin filament of actin
M line of the sarcomere
Located in the middle of the sarcomere
I – band of the sarcomere
Contains only thin filaments
H zone of the sarcomere
Consists of only thick filaments
A band of the sarcomere
Contains thick filaments in their entirety. The only part of the sarcomere that does not change size during contraction.
Myocyte
Muscle cell/muscle fiber
Sarcomeres attach end to end to become what?
Myofibril. Each muscle cell or muscle fiber contains many myofibrils.
What surrounds myofibrils?
Sarcoplasmic reticulum And sarcolemma
Sarcoplasmic reticulum
A calcium containing modified endoplasmic reticulum.
A network of specialized smooth endoplasmic reticulum and transmits the electrical impulse as well as the storage of calcium ions.
Sarcolemma
Cell membrane of a myocytes or muscle cells/muscle fiber
T tubules transverse tubules
Allows for distribution of the action potential to all sarcomeres in a muscle. Oriented perpendicularly to myofibrils
Where does muscle contraction begin?
The neuromuscular junction.
Neuromuscular junction
Where the motor neuron releases acetylcholine that binds to receptors on the sarcolemma causing depolarization.
What causes depolarization in the musculoskeletal system?
Release of acetylcholine that binds to receptors on the sarcolemma 
Depolarization and muscle cells leads to what action?
Depolarization spreads down the sarcolemma to the T tubules and triggers release of calcium ions.
Calcium binds to what to expose the myosin binding sites on the actin thin filament?
Binds to troponin which causes tropomyosin to expose the myosin binding site.
Myosin binding to what molecule allows for the binding and release of myosin to the actin filament?
ATP
What causes the relaxation of muscles?
Muscle relaxes when acetylcholine is degraded by acetylcholinesterase. The signals and allows calcium to be brought back into the Sarco plasmic reticulum. ATP binds to the myosin head and it releases from actin.
Frequency summation
Addition of multiple simple twitches before the muscle has an opportunity to fully relax
Tetanus
A more prolonged and stronger contraction caused when simple twitches occur so frequently and do not allow the muscle to relax at all.
How do cells reduce oxygen debt?
Muscle cells have additional energy reserves to avoid being in a situation where the amount of oxygen needed is more than the amount of oxygen present.
Creatinine phosphate
Can you transfer a phosphate group to ADP to form ATP
Myoglobin
A human containing proteins that is a muscular oxygen reserve
What are the two divisions of the human skeletal system?
The axial and appendicular skeleton
Axial skeleton
Consists of structures in the midline such as the skull vertebral column rib cage and hyoid bone
Appendicular skeleton
Consist of the bones of the limbs the pectoral girdle and the pelvis.
Where is bone derived from?
From embryonic mesoderm includes both compact and spongy types
Compact bone
Provide strength and his dense
Spongy or cancellous bone
Has the loudest like structure consisting of bony spy tools known as trabeculae. Cavities are filled with bone marrow.
Long bones
Contain shafts called diaphysis that flare to form metaphyses and terminate in the epiphyses
What part of the bone allows for linear growth of the bone?
The epiphyseal or growth plate within the epiphyses
What is the layer of connective tissue that surrounds the bone
Periosteum
Tendons versus ligaments
Tendons connect bones to muscles. Ligaments connect muscle to muscle
Bone matrix
Where the strength of compact bone comes from. Contains both organic and inorganic components.
Organic components include collagen glycoproteins and other peptides. Inorganic components include calcium phosphate and hydroxide ions which harden together to form hydroxyapatite crystals
Lamellae
Bone organized into concentric rings. Organize around a central Haversian or Volksmann canal. Structural unit known as an osteom.
Where do osteocytes reside?
Between lamellar rings.
Canaliculi
Connected with lacunae and allow for nutrient and waste transfer
Osteoblasts
Build bone
Osteoclasts
Reabsorb bone
What hormone is involved in the reabsorption of bone/promotes osteoclasts activation.
Parathyroid hormone. Increases reabsorption of bone increases calcium and phosphate concentrations in the blood. Essentially breaks down bone
Vitamin D’s role in the musculoskeletal system
Increases reabsorption of bone, increases turnover and subsequently the production of stronger bone
Calcitonins role in the musculoskeletal system
Increases bone formation decreasing calcium concentrations in the blood
Cartilage
A firm elastic material secreted by chondrocytes.
Matrix is called chondrin.
Avascular and not innervated
Endochondral ossification
Development of fetal bones from cartilage.
Intramembranous ossification
Formation of bone, example: the skull form directly from undifferentiated tissue (mesenchyme)
Immovable joints
Joints that are fused together to form sutures or similar fibrous joints. Found primarily in the head where the anchor bones of the skull together. 
Movable joints
Strengthen by ligaments and contain a synovial capsule. A layer of soft tissue secretes synovial fluid (into the synovium) which lubricates the movement of structures in the joint space.
Antagonistic pairs of muscles
Muscles that serve opposite functions when one muscle contracts the other lengthens
