What chiefly increases muscle mass after repeated bouts of high-exertion exercise?

Hypertrophy of existing fast glycolytic (FG) muscle fibers.

Which receptor does NOT bind and hydrolyze ATP to perform its function?

Nicotinic acetylcholine receptor.

Which skeletal muscle fiber type has the highest concentration of mitochondria and myoglobin?

Slow oxidative (SO) fibers.

Compared with fast glycolytic fibers, do fast oxidative-glycolytic (FOG) fibers have less myoglobin and fewer mitochondria?

No. FOG fibers have more myoglobin and mitochondria than fast glycolytic fibers.

Does anaerobic glycolysis produce enough ATP to support strong muscle contraction?

Yes. It can rapidly supply ATP, though it is less efficient and cannot sustain activity as long as aerobic metabolism.

Which skeletal muscle fiber type is most susceptible to fatigue?

Fast glycolytic (FG) fibers.

Why are slow-twitch fibers called slow?

Their contraction lasts relatively long after an action potential.

Which muscle fiber type would be abundant in the spine-stabilizing erector spinae?

Slow oxidative (SO) fibers.

What is a motor pool?

All alpha motor neurons that innervate one skeletal muscle.

What is a motor unit?

One alpha motor neuron and all the skeletal muscle fibers it innervates.

Are motor pools completely silent when muscles are not being consciously used?

No. Motor neuron activity can continue to help maintain muscle tone and posture.

Is skeletal muscle tension regulated directly by synapses from motor neurons located in the brain and brainstem?

No. Lower motor neurons in the spinal cord or cranial nerve motor nuclei directly innervate skeletal muscle fibers.

Which neurotransmitter directly stimulates skeletal muscle fiber contraction at the neuromuscular junction?

Acetylcholine.

Where does the calcium that triggers skeletal muscle contraction come from?

The sarcoplasmic reticulum.

Which transporter removes Ca2+ from the cytosol to allow skeletal muscle relaxation?

SERCA (sarcoplasmic/endoplasmic reticulum Ca2+ ATPase).

What type of drug can help treat myasthenia gravis by increasing acetylcholine availability?

An acetylcholinesterase inhibitor.

What is a synergist muscle?

A muscle that assists a movement primarily produced by another muscle.

Which lever class makes up most levers in the human body?

Third-class levers.

Which lever class tends to provide the greatest force multiplication?

Second-class levers.

What is the minimum contractile unit of skeletal muscle?

The sarcomere.

What defines one sarcomere?

The region of a myofibril between two consecutive Z discs (Z lines).

Where are thick myosin filaments joined within a sarcomere?

At the M line.

Which protein filament is particularly important for driving muscle contraction?

Actin, which interacts with myosin.

Which is NOT a major function of muscle tissue: movement, thermogenesis, circulatory blood flow, or plasma calcium homeostasis?

Plasma calcium homeostasis is not a major general function of muscle tissue.

Which muscle type is not striated?

Smooth muscle.

What is the smallest unit in the structural hierarchy of skeletal muscle?

The myofilament is the smallest component; among the common listed structures (fiber, fascicle, muscle belly, myofibril), the myofibril is smallest.

What does the perimysium surround?

Muscle fascicles.

What does the epimysium surround?

The whole muscle belly.

What does the endomysium surround?

Individual muscle fibers (myofibers).

Which fascicle arrangement is associated with greater muscle force?

Pennate arrangements, such as bipennate, because they allow more fibers to fit into a given muscle volume.

In most cases, what happens when a muscle contracts?

Its insertion moves toward its more stable origin.

Through which junctions does depolarization spread between cardiac muscle cells?

Gap junctions in intercalated discs.

Is nerve input necessary to initiate cardiac muscle contraction?

No. Cardiac muscle is autorhythmic, although nerves can modify its rate and force.

Does cardiac muscle contraction rely on Ca2+ entering across the sarcolemma?

Yes. Extracellular Ca2+ entry helps trigger further calcium release inside the cell.

Which listed structure is made of smooth muscle?

The arrector pili muscle.

Which muscle type can withstand the greatest degree of stretch while still contracting?

Smooth muscle.

Which protein binds Ca2+ to regulate skeletal muscle contraction?

Troponin.

What structure supplies the Ca2+ that drives skeletal muscle contraction?

The sarcoplasmic reticulum.

The dystrophin-dystroglycan-laminin complex is functionally similar to which cell attachment structure?

A hemidesmosome, in that it helps connect the cell's internal cytoskeleton to the extracellular matrix.

What do SERCA and Na+/K+ ATPase have in common?

Both are primary active transporters that use ATP to move ions against their electrochemical gradients.

Does stretching a muscle more always increase the force it can produce?

No. Force depends on the starting length; it is greatest near an optimal sarcomere length.

Which sarcomere region contains only thin filaments?

The I band.

Which sarcomere region contains only thick filaments?

The H zone.

Which protein binds and hydrolyzes ATP to drive muscle contraction?

Myosin.

Which sarcomere proteins are anchored to the Z disc?

Thin actin filaments are anchored to the Z disc; titin also attaches there and helps center/elasticize thick filaments.

Which sarcomere distance remains constant during contraction?

The length of the thick filaments (A band); the distance between Z discs decreases.

Which protein chiefly contributes to the elasticity and extensibility of striated muscle?

Titin.

What type of joint is commonly enclosed by a fluid-filled capsule?

A synovial joint, functionally classified as a diarthrosis.

Which joint types contain cartilage?

Symphyses contain fibrocartilage; synovial joints have articular cartilage at the bone ends.

What type of synovial joint is the knee?

A hinge-type modified hinge joint.

Which synovial joint allows you to turn your head from side to side?

The pivot joint between the atlas and axis.

What structure connects the tibia and fibula along much of their shafts?

The interosseous membrane, a fibrous connection.

Which joint/structure contributes to forearm pronation and supination alongside the radioulnar pivot joints?

The interosseous membrane between the radius and ulna transmits forces and helps stabilize the bones; pronation/supination occurs at the proximal and distal radioulnar pivot joints.

What do cartilage and epithelial tissue have in common?

Both are avascular (lack blood vessels).

Is cartilage found only in joints classified as cartilaginous joints?

No. Cartilage also occurs in synovial joints as articular cartilage and in other structures.

Which cells produce and maintain fibrocartilage extracellular matrix?

Chondroblasts produce matrix and mature into chondrocytes, which maintain it.

What type of joint is a gomphosis?

A fibrous joint, such as a tooth anchored in its socket.

Which joints are particularly prone to synostosis?

Epiphyseal plates, which ossify as bones mature.

What type of joint is an intervertebral disc connection between vertebral bodies?

A symphysis (secondary cartilaginous joint).

How is the pubic symphysis classified functionally by movement?

An amphiarthrosis: a slightly movable joint.

Is elongation of long bones mediated only by appositional growth?

No. Lengthwise growth occurs through endochondral ossification at the epiphyseal plates; appositional growth increases width.

Where is the secondary ossification center typically located?

In the epiphysis.

Which bone cells sense and initiate responses to mechanical stress?

Osteocytes.

What does increased parathyroid hormone (PTH) generally do to bone resorption?

It increases bone resorption and helps raise blood calcium.

What effect does estrogen have on osteoclast activity?

It suppresses osteoclast activity, reducing bone resorption.

What chiefly forms the soft callus during bone repair?

Fibrocartilage.

Where is active 1,25-dihydroxyvitamin D ultimately produced?

In the kidneys.

Can compact bone grow interstitially?

No. Bone grows appositionally; it does not expand interstitially like cartilage.

Which bones are classic examples of intramembranous ossification?

Flat bones of the cranium.

Osteoprogenitor cells are derived from what cell type?

Mesenchymal cells.

Which growth mechanism forms the length of long bones?

Endochondral ossification.

Which bone-related cells produce and secrete collagen?

Osteoblasts; chondroblasts also secrete collagen in cartilage.

How do long bones increase in width as a person grows?

Appositional growth.

Which is NOT a major function of bone: calcium homeostasis, blood pressure regulation, fat storage, or blood cell production?

Blood pressure regulation.

Which bone is part of the appendicular skeleton rather than the axial skeleton?

The femur. The axial skeleton includes the skull, vertebral column, and thoracic cage.

Which is NOT part of the appendicular skeleton: mandible, pelvic girdle, scapula, or ulna?

The mandible; it is part of the axial skeleton.

Which is an example of an irregular bone?

The atlas (first cervical vertebra).

Where is red marrow mainly found in adult long bones?

Primarily in the proximal epiphyses of certain long bones; the diaphysis mainly contains yellow marrow in adults.

What are the two major components of bone matrix?

Collagen fibers and hydroxyapatite crystals.

Which cells break down bone matrix?

Osteoclasts.

What is the principal structural unit of compact bone?

The osteon (Haversian system).

What travels through central (Haversian) and perforating (Volkmann) canals?

Blood vessels and nerves.

What cells are found in lacunae within an osteon?

Osteocytes.

Are trabeculae soft and squishy?

No. Trabeculae are bony struts that form the framework of spongy bone.

Where are osteoprogenitor cells found in high numbers?

In the periosteum (and also in the endosteum).

Which cells secrete type II collagen in cartilage?

Chondroblasts; mature chondrocytes maintain the cartilage matrix.

What structural component do cartilage and bone both contain?

Collagen fibers.

What is the primary role of osteocytes in bone?

They sense mechanical stress and help coordinate the bone's response to loading.

What is the effect of elevated parathyroid hormone (PTH) on bone resorption?

It increases bone resorption, helping raise blood calcium levels.

Which bone growth process increases the length of long bones?

Endochondral ossification at the epiphyseal plate.

Which bone growth process increases the width of long bones?

Appositional growth.

Which process forms the flat bones of the cranium?

Intramembranous ossification.

What type of ossification forms the secondary ossification center?

Endochondral ossification; the secondary center is typically in the epiphysis.

What is the difference between osteoblasts and osteoclasts?

Osteoblasts build bone matrix; osteoclasts resorb (break down) bone matrix.

What is an osteon?

The principal structural unit of compact bone, organized around a central (Haversian) canal.

What is found in the lacunae of an osteon?

Osteocytes.

What is the function of Haversian and Volkmann canals?

They provide passageways for blood vessels and nerves within compact bone.

What are trabeculae?

Bony struts that form the lattice-like framework of spongy bone.

Where are osteoprogenitor cells especially abundant?

In the periosteum; they are also found in the endosteum.

What type of collagen is secreted by chondroblasts in cartilage?

Type II collagen.

What forms the soft callus during bone healing?

Fibrocartilage.

What is the effect of estrogen on osteoclasts?

Estrogen suppresses osteoclast activity and reduces bone resorption.

Where is 1,25-dihydroxyvitamin D (active vitamin D) produced?

The kidneys carry out the final activation step.

What type of joint connects a tooth to its socket?

A gomphosis, which is a fibrous joint.

What is synostosis?

Fusion of bones that were previously separated by a joint or connective tissue.

What kind of joint is the intervertebral disc between vertebral bodies?

A symphysis, a secondary cartilaginous joint.

Which structures contribute to forearm pronation and supination?

The proximal and distal radioulnar pivot joints; the interosseous membrane also connects and stabilizes the radius and ulna.

What two types of joint/connection does the fibula form with the tibia?

The proximal tibiofibular plane synovial joint and the distal tibiofibular syndesmosis; the interosseous membrane also connects the shafts.

What is the functional classification of a pubic symphysis?

Amphiarthrosis: a joint that permits limited movement.

What is a synovial joint generally enclosed by?

A joint capsule surrounding the joint cavity, which contains synovial fluid.

What is the difference between a motor pool and a motor unit?

A motor pool is all alpha motor neurons innervating one muscle; a motor unit is one alpha motor neuron and all the muscle fibers it controls.

Why are slow oxidative (SO) muscle fibers resistant to fatigue?

They contain abundant mitochondria and myoglobin and rely heavily on aerobic metabolism.

Which skeletal muscle fibers fatigue most readily?

Fast glycolytic (FG) fibers.

Which skeletal muscle fiber type has the greatest mitochondrial and myoglobin concentration?

Slow oxidative (SO) fibers.

What is a muscle synergist?

A muscle that assists the muscle primarily responsible for a movement.

Which lever class provides the greatest force multiplication?

Second-class levers.

Which lever class is most common in the human body?

Third-class levers.

What is the smallest contractile unit of skeletal muscle?

The sarcomere.

What are the boundaries of a sarcomere?

Two adjacent Z discs.

What sarcomere region stays the same length during contraction?

The A band, which corresponds to the length of the thick filaments.

Which protein hydrolyzes ATP to power cross-bridge cycling?

Myosin.

Which protein binds calcium to regulate skeletal muscle contraction?

Troponin.

What does SERCA do in a skeletal muscle fiber?

Uses ATP to pump Ca2+ from the cytosol back into the sarcoplasmic reticulum, promoting relaxation.

Which neurotransmitter stimulates skeletal muscle at the neuromuscular junction?

Acetylcholine.

Why can acetylcholinesterase inhibitors help in myasthenia gravis?

They slow acetylcholine breakdown, increasing its availability at the neuromuscular junction.

How are cardiac muscle cells electrically connected?

Gap junctions in intercalated discs allow depolarization to spread between cells.

Is cardiac muscle contraction dependent on nerve input to start each beat?

No. Cardiac muscle is autorhythmic, though autonomic nerves can modify heart rate and force.

Which muscle type can contract despite a large degree of stretch?

Smooth muscle.

Which connective tissue sheath surrounds a muscle fascicle?

Perimysium.

Which connective tissue sheath surrounds an individual muscle fiber?

Endomysium.

Which connective tissue sheath surrounds the whole muscle?

Epimysium.

What is the role of the dystrophin–dystroglycan–laminin complex?

It helps link the muscle fiber's internal cytoskeleton to the extracellular matrix, functionally resembling a hemidesmosome.

Does greater muscle stretch always result in greater contraction force?

No. Force depends on starting length and is greatest near the muscle's optimal length.

What happens to the distance between Z discs during contraction?

It decreases as the sarcomere shortens.

What protein contributes strongly to the elasticity and extensibility of striated muscle?

Titin.

Which muscle tissue type is not striated?

Smooth muscle.

What is the main source of calcium that initiates skeletal muscle contraction?

The sarcoplasmic reticulum.

Which transporter moves calcium back into the sarcoplasmic reticulum?

SERCA, a primary active Ca2+ ATPase.

What is one major function of bone that is NOT listed as a primary function in the lecture quiz?

Blood pressure regulation.

Which skeleton division includes the skull, vertebral column, and thoracic cage?

The axial skeleton.

Which skeleton division includes the limbs and the pectoral and pelvic girdles?

The appendicular skeleton.

Is the femur part of the axial or appendicular skeleton?

The appendicular skeleton.

Is the mandible part of the axial or appendicular skeleton?

The axial skeleton.

What type of bone is the atlas (first cervical vertebra)?

An irregular bone.

What are the main mineral and protein components of bone matrix?

Hydroxyapatite crystals and collagen fibers.

Which marrow is mostly found in the diaphysis of adult long bones?

Yellow marrow; the statement that red marrow is mostly in the diaphysis is false.

Can compact bone grow by interstitial growth?

No. Bone grows in thickness by appositional growth; it does not grow interstitially.

Which type of joint is the knee commonly classified as in the lecture quiz?

A hinge joint (more precisely, a modified hinge synovial joint).

Which joint type permits head rotation from side to side?

A pivot joint, especially the atlanto-axial joint.

Are both cartilage and epithelial tissue avascular?

Yes. Neither tissue normally contains blood vessels within the tissue itself.

Which cells produce and maintain fibrocartilage matrix?

Chondroblasts produce matrix; chondrocytes maintain it.

Which type of joint contains cartilage but is not a synovial joint?

A cartilaginous joint, such as a symphysis.