A&P 210: Chapter 7

Flat bones

- "flat" name is misleading as bones are often curved - sternum, scapula, ribs, hip bones

Treatment of fractures

- Closed reduction involves manipulating bone fragments into their normal positions w/o surgery - Open reduction involves the surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments. - Traction is used to treat femurs in children. It aligns bone fragments by overriding the force of thigh muscles. It's rarely used for elderly patients. -Hip fractures are usually pinned and early ambulation (walking) is encouraged because it promotes blood circulation and healing.

Spongy bones consists of

- Slivers of bone called spicules​ - Thin plates of bone called trabeculae​ (lines of stress) - Spaces filled with red bone marrow

Order of vitamin D synthesis and its effect (calcitriol)

- Sunlight converts 7-dehydrocholesterolto vitamin D₃, cholecalciferol. - Liver adds a hydroxyl group converting it to calcidiol​ - Kidneys add another hydroxyl group, converting that to calcitriol - in the most active form, calcitriol increase blood calcium by acting on three target organs: 1) small intestine (inc. calcium absorption) 2) skeleton (inc. calcium resorption), and 3) kidneys.

Short bones

- allow small degrees of motion in 2 degrees of freedom - length and width are similar in proportion - scaphoid, wrist, ankle

Bone cells: Osteoblasts

- bone building/forming cells - abundant in mitochondria - overactivity results in increased bone density - make organic matter of matrix that hardens by mineral deposition

Bone cells: Osteoclasts

- bone resorbing/dissolving cells - have ruffled borders - resorption bays: pits where osteoclasts reside - remodeling: bone-dissolving osteoclasts and the bone-depositing osteoblasts - massive, multinucleate cells - develop from same bone marrow stem cells that give rise to blood

secretion of calcitonin

- calcitonin is released from the C cells of the thyroid gland when too high. lower blood calcium concentration: Osteoclast inhibition:​ Reduces osteoclast activity Less calcium liberated from bones​ Osteoblast stimulation​: Increases number and activity of osteoblasts​ Deposits calcium into the skeleton - The effects on osteoclasts cause a decrease in bone resorption and a concurrent increase in bone deposition due to the activity of osteoblasts. -The decline in bone breakdown and increased mineralization causes blood calcium to decrease back to normal levels.

what will happen in response to an excess blood calcium level?

- calcitonin secretion - increased osteoblast activity - less bone resorption

Bone matrix: inorganic

- calcium carbonate - hydroxyapatite - provides hardness - resists compressive (pushing) forces

Calcium homeostasis + 3 hormones

- depends on balance b/w dietary intake, urinary and fecal losses, and exchanges b/w osseous tissue - calcitriol, calcitonin, parathyroid hormone

Bone cells: Osteocytes

- former osteoblasts - bone cells encased in matrix - trapped in lacunae - lacunae - canaliculi - cytoplasmic processes

Healing of fractures

- hematoma formation: convert to tissue; invade capillaries - soft callus formation: collage and fibrocartilage convert tissue to soft callus - hard callus: osteoblasts deposit bony collar to unite pieces - Bone remodeling: bone fragments are removed by osteoclasts, while osteoblasts deposit spongy bone and convert to compact bone

What are the components of the skeletal system?

- ligaments - cartilage - bones not: tendons

red bone marrow (myeloid tissue) + yellow marrow

- nearly in every bone in a child - adults, found in skull, vertebrae, ribs, sternum, pelvic girdles - found in adults - no longer produce blood

Irregular bones

- oddly shaped bones usually found in axial skeleton - sacrum, vertebrae, skull boned

endochondral ossification

- ossification of hyaline cartilage - primary and secondary bone marrow cavities - limited to articular cartilage - femur - bone collar - epiphyseal plates - metaphyses

Parathyroid hormone

- parathyroid hormone raise calcium blood level - Parathyroid hormone causes an increase in the number of osteoclasts and greater rates of bone resorption. - promotes calcium reabsorption by the kidneys, less lost in urine - calcidiol to calcitriol in kidneys - Inhibits collagen synthesis by osteoblasts, inhibiting bone deposition - As a result of direct actions on the target cells of the bone and kidneys along with an indirect action on the small intestine (calcitriol), parathyroid hormone works to increase blood calcium levels.

intramembranous ossification

- parietal bones - maxilla

long bones

- serve as levers for body movements - length and width differ - femur, humerus, radius, ulna, tibia, fibula, metacarpals, metatarsals, phalanges

rickets + osteogenesis imperfecta

- soft bones due to deficiency of calcium salts - brittle bones due to lack of protein, collagen

Bone cells: Osteogenic cells

- stem cells - differentiate to (produce new) osteoblasts

Bone matrix: organic

- synthesize by osteoblasts - collagen - glycosaminoglycans, proteoglycans, glycoproteins - provides flexibility - resist tensile (pulling) forces

Physiology of osseous tissue

A mature bone remains a metabolically active organ​ Involved in own maintenance of growth and remodeling​ Exerts influence over the rest of the body by exchanging minerals with tissue fluid​ Disturbance of calcium homeostasis in skeleton disrupts function of other organ systems​ Especially nervous and muscular

Interstitial growth + Appositional growth

Interstitial growth: bones increase in length Appositional growth: increase in width

The skeletal system helps maintain acid-base balance by BLANK

absorbing or releasing alkaline phosphate and carbonate salts

The storage or release of buffering compounds works to aid the body in BLANK balance.

acid-base

Within compact bone, a central canal is found at the center of which structure?

an osteon

displaced fracture

at least one piece is shifted out of alignment with the other

Contained within the spongy sections of bones, red bone marrow is responsible for BLANK.

blood formation

nondisplaced fracture

bone pieces remain in proper anatomical alignment

BLANK is found in compact bone, but not spongy bone

central canals

If the BLANK component of bone is not in adequate amounts, the flexibility of bone will be compromised.

collagen

A BLANK fracture is one in which the bone is broken into three or more pieces

comminuted

Which type of bone tissue is found more commonly in the diaphysis of a long bone?

compact

Mineral deposition

crystallization process in which calcium phosphate and other ions are taken from blood plasma and deposited in bone tissue Osteoblasts produce collagen fibers that spiral length of res osteon

Minerals can be stored in the skeleton, which acts as a reservoir, storing or releasing minerals as needed to maintain BLANK throughout the body.

electrolyte balance

The spurt of growth in puberty results from cell proliferation and hypertrophy in BLANK

epiphyseal plate

The BLANK of the entire skeleton or skeletal elements utilizes the anchoring of muscles to attachment sites on the bones, which then serve as levers.

movement

During the healing of a bone fracture, a hard callus is formed by BLANK

osteoblasts

The BLANK contains hydrogen pumps that lead to the formation of hydrochloric acid, which is used to dissolve bone minerals in a process called BLANK.

osteoclasts;mineral resorption (dissolve bone and release minerals in blood)

The skull, pelvis, ribs, vertebral column, and sternum provide BLANK to many delicate organs of the body by encasing them in hardened, shell-like or caged structures.

protection

Which type of bone tissue arranges itself along the lines of forces that are encountered by a bone?

spongy

The bones of the skeleton provide structure to the body and serve as a BLANK to hold up the body and maintain proper positioning of some organs.

support

greenstick fracture

the bone is incompletely broken on one side but merely bent on the opposite

Osteoporosis

the most common bone disease​ Severe loss of bone density​ Bones lose mass and become brittle due to loss of organic matrix and minerals

Greenstick fractures most commonly occur in children because BLANK.

their bones contain larger quantities of collagen

In an adult, a compound fracture of the BLANK could lead to a "fat" embolism entering the blood stream.

tibia