Entire Exam 2 Study Set

FRQ: What triggers PTH, and what are its four actions?

Low blood calcium triggers PTH from the parathyroid glands: it increases osteoclast activity, decreases osteoblast activity, increases urinary phosphate loss, and decreases urinary calcium loss, raising blood calcium.

FRQ: What triggers calcitonin, and what are its two actions?

High blood calcium triggers calcitonin from the thyroid, which decreases osteoclast activity and increases osteoblast activity to lower blood calcium.

FRQ: How is calcitriol activated, and what are its three actions?

UV converts skin's 7-dehydrocholesterol to vitamin D3; the liver converts this to calcidiol and the kidneys to calcitriol. Calcitriol raises blood calcium through bone resorption, reduced kidney calcium loss, and increased intestinal calcium/phosphate absorption.

FRQ: What are the four steps of intramembranous ossification?

1) Osteoblasts deposit osteoid in embryonic mesenchyme; 2) osteoid calcifies, trapping osteocytes; 3) spongy bone and periosteum develop; 4) compact bone forms at the surfaces, leaving spongy bone inside.

FRQ: What are the steps of endochondral ossification?

1) A hyaline cartilage model forms; 2) shaft cartilage calcifies and periosteum develops; 3) blood vessels, a primary ossification center, and compact bone develop in the shaft; 4) a medullary cavity and secondary centers in the epiphyses develop; 5) epiphyseal plates allow growth; 6) plates become lines, leaving articular cartilage at joint surfaces.

FRQ: Explain Wolff's law with examples.

Bone remodels in response to demands: exercise strengthens it, trabeculae align with compression, and large projections form where strong, active muscles attach.

FRQ: What are the four stages of fracture repair?

1) Bleeding forms a hematoma; 2) a soft callus develops, with spongy bone near new vessels and fibrocartilage farther away; 3) a hard bony callus replaces fibrocartilage; 4) osteoclasts remove excess bone during remodeling.

What are the five functions of bone?

Bones provide support, protection, movement, blood cell formation, and storage of inorganic salts.

How do compact and spongy bone differ?

Compact bone has dense, continuous matrix; spongy bone has branching trabeculae and spaces that reduce weight.

What is one example of each bone shape listed in the slides?

Long: femur; short: carpals; flat: sternum; irregular: vertebrae.

What is an osteon?

An osteon is a central canal containing nerves and blood vessels surrounded by layers of compact bone matrix.

What are lacunae and canaliculi?

Lacunae house osteocytes, and canaliculi are tiny channels connecting these spaces.

How do central and perforating canals differ?

Central canals run along osteons; perforating canals cross between them.

Where are the periosteum and endosteum?

Periosteum covers the outer bone surface; endosteum lines internal bone surfaces.

What are the diaphysis, epiphyses, and metaphyses?

The diaphysis is the shaft, epiphyses are the ends, and metaphyses lie between the shaft and ends.

How do red and yellow marrow differ?

Red marrow produces blood cells; yellow marrow is fatty marrow in adult long bones.

What do the four bone cell types do?

Osteogenic cells produce osteoblasts; osteoblasts build bone; osteocytes maintain bone; osteoclasts resorb bone.

How do interstitial and appositional growth differ?

Interstitial growth lengthens bone, while appositional growth thickens it.

Which bones form by intramembranous versus endochondral ossification?

Intramembranous ossification forms skull flat bones and the clavicle; endochondral ossification forms most bones from hyaline cartilage models.

How do an epiphyseal plate and line differ?

The epiphyseal plate is the growth region in a growing bone; the epiphyseal line remains after growth ends.

How do mineral deposition and resorption differ?

Deposition moves calcium and phosphate from blood into bone; resorption returns bone minerals to blood.

What are calcium's three functions in the slides?

Calcium supports communication between neurons, muscle contraction, and blood clotting.

How do hypocalcemia and hypercalcemia affect the body?

Low blood calcium causes nervous excitability and spasms; high blood calcium causes nervous depression, weakness, and potentially cardiac arrest.

How do stress and pathological fractures differ in the lecture?

Stress fractures follow abnormal trauma; pathological fractures occur in bones weakened by disease.

How do closed and open fractures differ?

Closed fractures leave skin intact; open fractures have bone protruding through skin.

How do complete and incomplete fractures differ?

Complete fractures divide bone into separate pieces; incomplete fractures extend only partway through it.

What are greenstick, hairline, and comminuted fractures?

Greenstick: one side bends while the other breaks incompletely; hairline: fine crack; comminuted: three or more pieces.

What are linear, transverse, and oblique fractures?

Linear fractures run parallel to the bone's long axis, transverse fractures run perpendicular, and oblique fractures run diagonally.

What causes a spiral fracture?

A spiral fracture results from twisting stress.

How do displaced and nondisplaced fractures differ?

Displaced fragments are out of alignment; nondisplaced fragments remain aligned.

How are joints classified structurally and functionally?

Structural classification uses binding material (fibrous, cartilaginous, synovial); functional classification uses the movement allowed.

What do synarthrosis, amphiarthrosis, and diarthrosis mean?

Synarthrosis means immovable, amphiarthrosis means slightly movable, and diarthrosis means freely movable.

What binds fibrous joints, and where are sutures found?

Fibrous connective tissue binds fibrous joints; sutures join skull bones.

What is a syndesmosis, and what are examples?

A syndesmosis binds bones by ligaments, as between radius and ulna or tibia and fibula, allowing the most fibrous-joint movement.

What is a gomphosis?

A gomphosis is a peg-in-socket fibrous joint attaching a tooth to its socket.

What is a synchondrosis, and what is an example?

A synchondrosis is an immovable cartilaginous joint joined by hyaline cartilage, such as an epiphyseal plate.

What is a symphysis, and what are examples?

A symphysis is a slightly movable cartilaginous joint joined by fibrocartilage, such as intervertebral discs or the pubic symphysis.

What defines a synovial joint?

A synovial joint has a cavity containing synovial fluid and is freely movable, or diarthrotic.

What movement and examples identify ball-and-socket joints?

Ball-and-socket joints allow multiaxial movement, as at the hip and shoulder.

What movement and example identify condylar joints?

Condylar joints allow biaxial movement, as at the knuckles between metacarpals and phalanges.

What movement and example identify plane joints?

Plane joints allow nonaxial gliding, as between carpal bones.

What movement and example identify hinge joints?

Hinge joints allow uniaxial flexion and extension, as at the elbow.

What movement and example identify pivot joints?

Pivot joints allow uniaxial rotation, as between the atlas and axis around the dens.

What movement and example identify saddle joints?

Saddle joints allow biaxial movement, as between the first metacarpal and trapezium at the thumb base.

How do flexion and extension differ?

Flexion decreases a joint angle by bending; extension increases it by straightening.

How do abduction and adduction differ?

Abduction moves away from the body's midline; adduction moves toward it.

What is rotation?

Rotation turns a bone around its long axis, medially toward or laterally away from the midline.

What is circumduction?

Circumduction moves a limb's far end in a circle while the near end stays relatively fixed.

How do forearm supination and pronation differ?

With the elbow bent, supination turns the palm up; pronation turns it down.

How do dorsiflexion and plantar flexion differ?

Dorsiflexion lifts the foot toward the shin; plantar flexion points the foot and toes downward.

How do inversion and eversion differ?

Inversion turns the sole inward; eversion turns it outward.

How do protraction and retraction differ?

Protraction moves the head forward; retraction moves it backward.

How do elevation and depression differ?

Elevation raises the shoulders; depression lowers them.

What is lateral flexion?

Lateral flexion bends the trunk to the side.

What are fulcrum, effort, and resistance in the body?

The joint is the fulcrum, muscle provides effort, and the load is resistance.

What lies in the middle of each lever class, with examples?

First class: fulcrum (seesaw); second class: resistance (wheelbarrow); third class: effort (elbow flexion).

How do you calculate mechanical advantage (MA)?

MA equals effort-arm length divided by resistance-arm length, with both measured from the fulcrum.

What does mechanical advantage above or below 1 mean?

MA above 1 favors force; MA below 1 favors speed and distance of movement.

What structures cover and enclose a synovial joint?

Articular cartilage covers bone ends, a fibrous capsule encloses the joint, and a synovial membrane lines the capsule.