Chapter 7: Osseous Tissue Flashcards
Functions of the Skeleton
- Support
- Protection
- Movement
- Electrolyte Balance
- Acid-Base Balance
- Blood Formation
The hardening process of matrix in osseous tissue is called what?
mineralization or calcification
Most of the cranial bones are in the form of thin curved plates called____ _______, such as the paired parietal bones that form the dome of the top of the head. The sternum, scapula, ribs, and hip bones are also_______ ______.
flat bones
The most important bones in body movement are the ______ _______ of the limbs—the humerus, radius, ulna, femur, tibia, fibula, metacarpals, metatarsals, and phalanges. ________ _______ also serve as rigid levers that are acted upon by skeletal muscles to produce the major body movements.
long bones
Bones of the wrists and ankles that are approximately equal in length and width which produce relatively limited gliding movements. The patella is also an example.
short bones
Other bones that do not fit in the categories of other bones such as the vertebrae and three tiny ear bones.
irregular bones
Shaft of a bone
diaphysis
Head at each end of bone
epiphysis
The joint surface where one bone meets another is covered with a layer of hyaline cartilage called the______ _______.
articular cartilage
Blood vessels penetrate into the bone through minute holes called ________ _________.
nutrient foramina
Bone is covered with a sheath called _________.
periosteum
Collagen fibers of the outer layer that penetrate into the bone matrix are called ___________ _______.
perforating fibers
A thin layer of connective tissue that lines the internal marrow cavity, covers all honeycomb surfaces of spongy bone, and lines the canal system in compact bone is called ___________.
endosteum
Composed of hyaline cartilage that separates the marrow spaces of the epiphysis and diaphysis and is a zone where bone elongation takes place is called the _____________ ________.
epiphyseal plate
The spongy layer in the cranium is called ______.
diploe
Stem cells that develop from embryonic mesenchymal cells and then give rise to most other bone cell types that are found in the endosteum and inner layer of the periosteum and multiply continually, and some go on to become osteoblasts are called _________ ______.
osteogenic cells
Bone forming cells are called _________.
osteoblasts
Former osteoblasts that have become trapped in the matrix they have deposited that reside in lacunae that are connected canaliculi are called __________.
osteocytes
Functions of osteocytes
- Resorb bone matrix
- Deposit bone matrix
- Contribute to the homeostatic maintenance of both bone density & blood concentrations of calcium and phosphate ions
- Strain sensors
Bone-dissolving cells on the bone surfaces that develop from the same bone marrow stem cells that give rise to the blood cells are called __________.
osteoclasts
Deep infoldings of the plasma membrane located on the side of the osteoclast facing the bone surface whose function is to increase cell surface area and thus enhances the efficiency of bone resorption is called the __________ _________.
ruffled border
The pits that osteoclasts often reside in that they have etched into the bone surface are called _________ _____.
resorption bays or Howship lacunae
Crystallized calcium phosphate
hydroxyapatite
A combination of two basic structural materials that can combine the optimal mechanical properties of each component is called a _________.
composite
Onionlike layers of matrix concentrically arranged around a central canal (haversian canal) and connected with each other by canaliculi are called ___________ __________.
concentric lamellae
The basic structural unit of compact bone composed of a central canal and its lamellae is called an ________. Also known as a cylinder of tissue surrounding a central canal.
osteon
Along their length, central canals are joined by transverse or diagonal passages called __________ ______.
perforating canals or Volkmann canals
The inner and outer boundaries of dense bone are arranged in _______________ __________ that run parallel to the bone surface.
circumferential lamellae
Between osteons there are irregular regions that contain the remains of old osteons that broke down as the bone grew and remodeled itself. These regions are called _________ ________.
interstitial lamellae
Type of bone that consists of lattice of delicate slivers of bone called spicules and trabeculae. Although calcified and hard, it is named for its spongelike appearance.
spongy bone
A general term for soft tissue that occupies the marrow cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger central canals.
bone marrow
In a child, the marrow cavity of nearly every bone is filled with ____ _____ ________. It is often described as hemopoietic tissue.
red bone marrow
In adults, most of the red marrow turns into fatty ______ ____ ________, like the fat at the center of a ham bone.
yellow bone marrow
The formation of bone is called ____________.
ossification or osteogenesis
This type of ossification produces the flat bones of the skull and most of the clavicle.
intramembranous ossification
This is a process in which a bone develops from a preexisting cartilage model. It begins around the sixth week of fetal development and continues into a person’s 20s. Most bones of the body develop this way, including the vertebrae, ribs, sternum, scapula, pelvic girdle, and bones of the limbs.
endochondral ossification
A thin wall of cartilage separating the primary and secondary marrow cavities at one or both ends of the bone. Serves as a growth zone for bone elongation.
epiphyseal plate
Bones grow in two directions: ________ and ________.
length and width
The epiphyseal plate consists of typical hyaline cartilage in the middle, with a transitional zone on each side where cartilage is being replaced by bone. The transitional zone, facing the marrow cavity, is called the __________.
metaphysis
This is the region farthest from the marrow cavity, which typically consists of hyaline cartilage with resting chondrocytes, not yet showing any signs of transformation into bone.
Zone of reserve cartilage
This region is a little closer to the marrow cavity where chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae.
Zone of cell proliferation
This is the region where chondrocytes cease to multiply and begin to hypertrophy. The walls of the matrix between lacunae become very thin.
Zone of cell hypertrophy
In this region, minerals are deposited in the matrix between the columns of lacunae and calcify the cartilage.
Zone of calcification
In this region, within each column, the walls between the lacunae break down and the chondrocytes die. This converts each column into a longitudinal channel , which is immediately invaded by blood vessels and marrow from the marrow cavity. Osteoblasts then line up along the walls of these channels and begin depositing concentric lamellae of matrix, while osteoclasts dissolve temporarily calcified cartilage.
Zone of bone deposition
Cartilage growth from within, by the multiplication of chondrocytes and deposition of new matrix in the interior is called __________ ________.
interstitial growth
In the late teens to early twenties, all the cartilage of the epiphyseal plate is depleted and the primary and secondary marrow cavities unite into one cavity. This junctional region is filled with spongy bone, and the site of the epiphyseal plate is marked with a line of slightly denser spongy bone called the _________ _____.
epiphyseal line
The deposition of new tissue at the surface is called ____________ _______.
appositional growth
This law states that the architecture of a bone is determined by the mechanical stresses placed upon it, and the bone thereby adapts to withstand those stresses.
Wolff’s law of bone
A crystallization process in which calcium, phosphate, and other ions are taken from the blood plasma and deposited in bone tissue, mainly as needlelike crystals of hydroxyapatite. This process begins in fetal ossification and continues throughout life.
mineral deposition (mineralization)
Hydroxyapatite crystals form only when the product of calcium and phosphate concentration in the tissue fluids reaches a critical value called the _________ ________.
solubility product
Osseous tissue sometimes forms in the lungs, brain, eyes, muscles, tendons, arteries, and other organs. Such abnormal calcification of tissues is called _______ ___________.
ectopic ossification
A calcified mass in an otherwise soft organ such as the lungs is called a ________.
calculus
The process of dissolving bone is called ________ _________. It releases minerals into the blood and makes them available for other uses. This process is carries out by the osteoclasts.
mineral resorption
The osteoclasts secrete an enzyme that digests the collagen of the bone matrix called _____ _________. This enzyme is named for its ability to function in a highly acidic environment.
acid phosphatase
A calcium deficiency which causes excessive excitability of the nervous system and leads to muscle tremors, spasms, or tetany is called ___________.
hypocalcemia
The inability of the muscle to relax is called ________. This begins to occur as the plasma calcium concentration falls to 6 mg/dL.
tetany
A blood calcium excess is called __________. At 12 mg/dL and higher this condition causes depression of the nervous system, emotional disturbances, muscle weakness, sluggish reflexes, and sometimes cardiac arrest.
hypercalcemia
Calcium homeostasis is regulated by 3 hormones:
- calcitriol
- calcitonin
- parathyroid hormone
A form of vitamin D produced by the sequential action of the skin, liver, and kidneys. It behaves as a hormone and its principle function is to raise the blood calcium concentration.
calcitriol
In what 3 ways does calcitriol raise blood calcium concentration?
- Increases calcium absorption by the small intestine
- Increases calcium resorption from the skeleton-Calcitriol binds to osteoblasts, which release another chemical messenger called RANKL, the ligand for RANK on the surfaces of osteoclast producing stem cells. The messenger stimulates the stem cells to differentiate into osteoclasts. The new osteoclasts then liberate calcium and phosphate ions from bone.
- Weakly promotes the reabsorption of calcium ions by the kidneys, so less calcium is lost in the urine.
Without calcitriol, calcium and phosphate levels in the blood are too low for normal deposition and the result is a softness of the bones. In children, this condition is called ________ and in adults is called _____________.
Children-rickets
Adults-osteomalacia
Is secreted by C cells (clear cells) of the thyroid gland when the blood calcium concentration rises too high, and it lowers the concentration by two principle mechanisms.
Calcitonin
In what two ways does calcitonin lower blood calcium concentration?
- Osteoclast inhibition
2. Osteoblast stimulation
Is secreted by the parathyroid glands when blood calcium is low. A mere 1% drop in blood calcium level doubles the secretion of this hormone.
Parathyroid hormone (PTH)
Parathyroid hormone raises the blood calcium level by four mechanisms:
- PTH binds to receptors on the osteoblasts, stimulating them to secrete RANKL, which in turn raises the osteoclast population and promotes bone resorption.
- PTH promotes calcium reabsorption by the kidneys so less calcium is lost in the urine.
- PTH promotes the final step of calcitriol synthesis in the kidneys, thus enhancing the calcium-raising effect of calcitriol.
- PTH inhibits collagen synthesis by osteoblasts, thus inhibiting bone deposition.
Bone disorders are among the concerns of the branch of medicine known as __________.
orthopedics
A break in a bone caused by abnormal trauma to a bone.
stress fracture
A break in a bone weakened by some other disease, such as bone cancer or osteoporosis.
pathological fracture
A fracture in which the bone pieces remain in proper anatomical alignment.
nondisplaced fracture
A fracture in which at least one bone piece is shifted out of alignment with the other.
displaced fracture
A type of fracture in which a bone is broken into three or more pieces.
comminuted fracture
A fracture in which the bone is completely broken on one side but merely bent on the opposite side.
greenstick fracture
The healing process of fractures occurs in what four stages?
- Formulation of hematoma and granulation tissue.
- Formation of soft callus.
- Conversion of hard callus.
- Remodeling.
A procedure in which the bone fragments are manipulated into their normal positions without requiring surgery.
closed reduction
Involves the surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments.
open reduction
The most common bone disease characterized by a loss of bone mass, increasing susceptibility to fractures, and sometimes deformity of the vertebral column.
osteoporsis
