chapter 7

red Bone marrow

(myeloid tissue) fills the marrow cavity of nearly every bone in children. a. Red marrow is often termed hemopoietic tissue because it produces blood cells, but it is actually composed of multiple tissues and acts as an organ unto itself.

calcitriol

A hormone produced from vitamin D that acts in essentially the same manner as parathyroid hormone.

Define mineralization/calcification

Bone, or osseous tissue, is a connective tissue in which the matrix is hardened by mineral deposition

Know the types of bone classifications ?

Flat bones Long bones Short Bones Irregular Bones

Calcitonin

Lowers blood calcium levels, involved in calcium homestasis

Know the basic steps of endochondral ossification as follows starting out with a hyaline cartilage model.

Perichondrium is invaded by blood vessels. Perichondrial cells differentiate into osteogenic cells then into osteoblasts. Osteoblasts build the bone collar on the external surface of the bone. Chondrocytes die In the primary ossification center, osteoblasts replace calcified cartilage with early spongy bone

Know the different types of fractures.

Stress fracture pathologic fracture Fractures are also classified according to the direction of the fracture line, whether the skin is broken, and whether the bone is cracked or broken into pieces.

facts about ostecytes

These cells reside in cavities called lacunae, interconnected by slender channels called canaliculi. i. Osteocytes have slender, fingerlike cytoplasmic processes that reach into the canaliculi to contact neighboring osteocytes; some also contact osteoblasts on the bone surface. ii. Neighboring osteocytes are connected by gap junctions, allowing the passage of nutrients, wastes, and chemical signals. bone dissolving cells

What is hydroxyapatite? Where is it found? Etc.

a crystallized calcium phosphate salt, 10% calcium carbonate, and lesser amounts of magnesium, sodium, potassium, fluoride, sulfate, carbonate, and hydroxide ions. found in inorganic matter

? What is endochondral ossification( figure7.9)?

a process by which bone develops from a preexisting model composed of hyaline cartilage. Most bones of the body develop in this way, and the process includes six stages. (pp. 210-212) (Fig. 7.9)

Know the different phases of healing of a bone fracture (figure 7.18).

a. Formation of a hematoma and granulation tissue.=i. Blood vessels are severed by a fracture; the blood forms a clot called a fracture hematoma Formation of a soft callus.(produ)ce patches of cartilage called the soft callus) Conversion to a hard callus. Recmolding

Be able to identify the general anatomy of a long bone (Figure 7.3)

a. Much of a long bone is composed of an outer shell of dense white osseous tissue called compact (dense) bone. The cylinder of compact bone encloses a space called the medullary cavity, or marrow cavity, which contains bone marrow. c. At the ends of the bone, the central space is occupied by osseous tissue called spongy (cancellous) bone. Spongy bone is always enclosed by compact bone. d. The skeleton is about three-quarters compact bone and one-quarter spongy bone by weight

Facts about osteoblasts

a. Osteoblasts are nonmitotic (do not divide), so differentiation of osteogenic cells is the only way new osteoblasts are generated. b. Osteoblasts synthesize the soft organic matter of the bone matrix, which then hardens by mineral deposition. Stress and fractures stimulate osteogenic cells to multiply rapidly and generate increased numbers of osteoblasts. c. Osteoblasts secrete the hormone osteocalcin, which stimulates insulin secretion by the pancreas, increases insulin sensitivity in adipocytes, and limits growth of adipose tissue.

osteblasts

are bone-forming cells; they are roughly cuboidal or angular and form a single layer on the bone surface under the endosteum and periosteum

Osteocytes

are former osteoblasts that have become trapped in the bone matrix they deposited.

Osteogenic cells

are stem cells that develop from embryonic mesenchyme and then give rise to most other bone cell types.

Long Bones

are the most important bones in body movement. a. Examples are the humerus, radius, and ulna of the arm and forearm; the femur, tibia, and fibula of the thigh and leg; and the metacarpals, metatarsals, and phalanges of the hands and feet. b. Long bones serve as rigid levers that are acted upon by skeletal muscles to produce body movements.

Flat bones

bones enclose and protect soft organs and provide broad surface for muscle attachment. a.Most of the cranial bones are flat bones, thin curved plates. b. Other examples include the ribs, sternum, scapula, and hip bones.

Short bones

carpals and tarsals, are nearly equal in length and width. They produce limited gliding motion.

articular cartilage (hyaline)

covers surfaces that form joints along with lubricating fluid, allow ease of movement

What is compact bone?

dense outer layer of bone

Know calcium homeostasis and the hormones involved.

depends on a balance between dietary intake, excretion and elimination, and exchanges with the osseous tissue. Calcium homeostasis is regulated by three hormones: calcitriol, calcitonin, and parathyroid hormone

What is spongy bone?

found inside bone, spongy and softer consists of a lattice of delicate slivers of bone called spicules and thin plates called trabeculae; the term spongy refers to its appearance, not its hardness. (p. 209) (Fig. 7.4a)

irregular bones

have shapes that do not fit into the preceding categories. Examples include the vertebrae and three tiny middle-ear bones.

uncomplicated fracture

heals in 8 to 12 weeks, but complex fractures and fractures in the elderly take longer; the healing process occurs in four stages.

the two methods of bone development in the human fetus are

intramembranous ossification and endochondral ossification

stress fracture

is a break caused by abnormal trauma to a bone, such as impact from falls, athletics, or combat

pathologic fracture

is a break in a bone weakened due to a disease, such as bone cancer or osteoporosis.

What is bone marrow and where is it located in child? In an adult?

is a general term for soft tissue that occupies the marrow cavity of a long bone, the spaces in spongy bone, and larger central canals; the two kinds are red marrow and yellow marrow. (p. 209) In adults, most red marrow turns to fatty yellow bone marrow.

spongy bone

is covered with endosteum and permeated by spaces filled with bone marrow. 2

Epiphysis

is enlarged to strengthen the joint and provide added surface area for attachment of tendons and ligaments

yellow marrow cavity

no longer produces blood, although in cases of severe or chronic anemia it can transform back into red marrow. b. In adults, red marrow is limited to the skull, vertebrae, ribs, sternum, part of the pelvic girdle, and the proximal heads of the humerus and femur

B able to name the four types of bone cells and their development (figure 7.3)

osteogenic cells, osteoblasts, ostecytes,osteoclasts

What is intramembranous ossification(figure 7.7)

produces the flat bones of the skull and the clavicle; their development includes four stage

parathyroid hormone (PTH)

regulates calcium and phosphorus metabolism involved in calcium homestasis

Diaphysis

shaft of a long bone, provides leverage

Functions of the skeletal system

support, protection, movement, storage, blood cell formation, Electrolyte balance Acid base balance