Musclular & Skeletal System

What are the three types of muscle tissue?

Skeletal muscle, smooth muscle, and cardiac muscle.

What are the key characteristics of skeletal muscle?

Striated appearance, voluntary movement, and multinucleated cells.

What are the connective tissue wrappings of skeletal muscle from outside to inside?

Epimysium, Perimysium, and Endomysium.

What is a sarcomere?

The functional unit of a muscle fiber spanning from Z-line to Z-line, consisting of thick (myosin) and thin (actin) filaments.

What are the structural zones of a sarcomere?

Z-line, M-line, I-band, H-zone, and A-band.

What occurs during skeletal muscle hypertrophy?

Increase in cell size, muscle fiber diameter, number of nuclei, sarcomeres, and mitochondria.

What are the three types of skeletal muscle contractions?

Concentric, eccentric, and isometric.

What are the characteristics of Type I skeletal muscle fibers?

Slow-twitch, high endurance, lots of myoglobin and mitochondria, aerobic metabolism, red appearance, small diameter.

What are the characteristics of Type IIB skeletal muscle fibers?

Fast-twitch, high power, low myoglobin and mitochondria, anaerobic glycolysis metabolism, white appearance, large diameter.

What is a motor unit?

One motor neuron and all the muscle fibers it innervates.

What are the stages of a simple muscle twitch?

Latent period, contraction, and relaxation.

What is temporal summation?

Increasing the frequency of action potentials before a muscle fiber fully relaxes to generate more force.

What is tetanus?

A rapid frequency of action potentials generating maximum tension and a constant state of contraction without relaxation.

What is tonus?

A constant partial contraction maintaining body posture, balance, and coordination.

What characterizes single-unit smooth muscle?

Cells connected by gap junctions that contract as a single unit, found in visceral organs.

What characterizes multi-unit smooth muscle?

Fibers individually innervated and contracting independently with more precise control, found in the iris and bronchioles.

What are intercalated disks in cardiac muscle?

Cell junctions containing gap junctions for electrical transmission and desmosomes for mechanical strength.

What are the four components of the vertebrate endoskeleton?

Cartilage, bone, ligaments, and tendons.

What are the functions of bones?

Support soft tissue, protect organs, aid movement, store calcium, produce blood cells, and store energy.

What is the difference between woven and lamellar bone?

Woven bone is immature, weak, and unorganized; lamellar bone is mature and compact.

What are the two main divisions of the skeletal skeleton?

Axial skeleton and Appendicular skeleton.

What are sutures?

Immobile joints of dense connective tissue binding skull bones together.

What are the three joint types based on movement?

Fibrous joints, cartilaginous joints, and synovial joints.

What are the four types of bone cells?

Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts.

What is spongy (cancellous) bone?

Interior bone with a porous trabeculae lattice containing red and yellow bone marrow; highly vascular.

What is compact (cortical) bone?

Dense outer layer of bone organized into osteons.

What is an osteon?

The fundamental structural unit of compact bone including a Haversian canal and surrounding lamellae.

What are Volkmann's canals?

Horizontal passageways connecting Haversian canals and the periosteum.

What is the periosteum?

The thin outer membrane surrounding the bone containing blood vessels and nerves.

What is the epiphyseal plate (growth plate)?

The location of bone growth in the metaphysis containing dividing cartilage cells.

What is bone composed of?

Collagen fibers and hydroxyapatite crystals.

What is endochondral ossification?

Bone formation where a cartilage model is replaced with bone over time.

What is intramembranous ossification?

Undifferentiated mesenchyme cells directly developing into bone with no cartilage intermediate.