Chapter 7: Osseous Tissue

Question 1

Functions of the Skeleton

Answer 1

• Support
• Protection
• Movement
• Electrolyte Balance
• Acid-Base Balance
• Blood Formation

Question 2

The hardening process of matrix in osseous tissue is called what?

Answer 2

mineralization or calcification

Question 3

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_______ ______.

Answer 3

flat bones

Question 4

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.

Answer 4

long bones

Question 5

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.

Answer 5

short bones

Question 6

Other bones that do not fit in the categories of other bones such as the vertebrae and three tiny ear bones.

Answer 6

irregular bones

Question 7

Shaft of a bone

Answer 7

diaphysis

Question 8

Head at each end of bone

Answer 8

epiphysis

Question 9

The joint surface where one bone meets another is covered with a layer of hyaline cartilage called the______ _______.

Answer 9

articular cartilage

Question 10

Blood vessels penetrate into the bone through minute holes called ________ _________.

Answer 10

nutrient foramina

Question 11

Bone is covered with a sheath called _________.

Answer 11

periosteum

Question 12

Collagen fibers of the outer layer that penetrate into the bone matrix are called ___________ _______.

Answer 12

perforating fibers

Question 13

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 ___________.

Answer 13

endosteum

Question 14

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 _____________ ________.

Answer 14

epiphyseal plate

Question 15

The spongy layer in the cranium is called ______.

Answer 15

diploe

Question 16

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 _________ ______.

Answer 16

osteogenic cells

Question 17

Bone forming cells are called _________.

Answer 17

osteoblasts

Question 18

Former osteoblasts that have become trapped in the matrix they have deposited that reside in lacunae that are connected canaliculi are called __________.

Answer 18

osteocytes

Question 19

Functions of osteocytes

Answer 19

• Resorb bone matrix
• Deposit bone matrix
• Contribute to the homeostatic maintenance of both bone density & blood concentrations of calcium and phosphate ions
• Strain sensors

Question 20

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 __________.

Answer 20

osteoclasts

Question 21

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 __________ _________.

Answer 21

ruffled border

Question 22

The pits that osteoclasts often reside in that they have etched into the bone surface are called _________ _____.

Answer 22

resorption bays or Howship lacunae

Question 23

Crystallized calcium phosphate

Answer 23

hydroxyapatite

Question 24

A combination of two basic structural materials that can combine the optimal mechanical properties of each component is called a _________.

Answer 24

composite

Question 25

Onionlike layers of matrix concentrically arranged around a central canal (haversian canal) and connected with each other by canaliculi are called ___________ __________.

Answer 25

concentric lamellae

Question 26

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.

Answer 26

osteon

Question 27

Along their length, central canals are joined by transverse or diagonal passages called __________ ______.

Answer 27

perforating canals or Volkmann canals

Question 28

The inner and outer boundaries of dense bone are arranged in _______________ __________ that run parallel to the bone surface.

Answer 28

circumferential lamellae

Question 29

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 _________ ________.

Answer 29

interstitial lamellae

Question 30

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.

Answer 30

spongy bone

Question 31

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.

Answer 31

bone marrow

Question 32

In a child, the marrow cavity of nearly every bone is filled with ____ _____ ________. It is often described as hemopoietic tissue.

Answer 32

red bone marrow

Question 33

In adults, most of the red marrow turns into fatty ______ ____ ________, like the fat at the center of a ham bone.

Answer 33

yellow bone marrow

Question 34

The formation of bone is called ____________.

Answer 34

ossification or osteogenesis

Question 35

This type of ossification produces the flat bones of the skull and most of the clavicle.

Answer 35

intramembranous ossification

Question 36

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.

Answer 36

endochondral ossification

Question 37

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.

Answer 37

epiphyseal plate

Question 38

Bones grow in two directions: ________ and ________.

Answer 38

length and width

Question 39

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 __________.

Answer 39

metaphysis

Question 40

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.

Answer 40

Zone of reserve cartilage

Question 41

This region is a little closer to the marrow cavity where chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae.

Answer 41

Zone of cell proliferation

Question 42

This is the region where chondrocytes cease to multiply and begin to hypertrophy. The walls of the matrix between lacunae become very thin.

Answer 42

Zone of cell hypertrophy

Question 43

In this region, minerals are deposited in the matrix between the columns of lacunae and calcify the cartilage.

Answer 43

Zone of calcification

Question 44

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.

Answer 44

Zone of bone deposition

Question 45

Cartilage growth from within, by the multiplication of chondrocytes and deposition of new matrix in the interior is called __________ ________.

Answer 45

interstitial growth

Question 46

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 _________ _____.

Answer 46

epiphyseal line

Question 47

The deposition of new tissue at the surface is called ____________ _______.

Answer 47

appositional growth

Question 48

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.

Answer 48

Wolff's law of bone

Question 49

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.

Answer 49

mineral deposition (mineralization)

Question 50

Hydroxyapatite crystals form only when the product of calcium and phosphate concentration in the tissue fluids reaches a critical value called the _________ ________.

Answer 50

solubility product

Question 51

Osseous tissue sometimes forms in the lungs, brain, eyes, muscles, tendons, arteries, and other organs. Such abnormal calcification of tissues is called _______ ___________.

Answer 51

ectopic ossification

Question 52

A calcified mass in an otherwise soft organ such as the lungs is called a ________.

Answer 52

calculus

Question 53

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.

Answer 53

mineral resorption

Question 54

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.

Answer 54

acid phosphatase

Question 55

A calcium deficiency which causes excessive excitability of the nervous system and leads to muscle tremors, spasms, or tetany is called ___________.

Answer 55

hypocalcemia

Question 56

The inability of the muscle to relax is called ________. This begins to occur as the plasma calcium concentration falls to 6 mg/dL.

Answer 56

tetany

Question 57

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.

Answer 57

hypercalcemia

Question 58

Calcium homeostasis is regulated by 3 hormones:

Answer 58

- calcitriol - calcitonin - parathyroid hormone

Question 59

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.

Answer 59

calcitriol

Question 60

In what 3 ways does calcitriol raise blood calcium concentration?

Answer 60

1. Increases calcium absorption by the small intestine 2. 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. 3. Weakly promotes the reabsorption of calcium ions by the kidneys, so less calcium is lost in the urine.

Question 61

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 _____________.

Answer 61

Children-rickets | Adults-osteomalacia

Question 62

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.

Answer 62

Calcitonin

Question 63

In what two ways does calcitonin lower blood calcium concentration?

Answer 63

1. Osteoclast inhibition | 2. Osteoblast stimulation

Question 64

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.

Answer 64

Parathyroid hormone (PTH)

Question 65

Parathyroid hormone raises the blood calcium level by four mechanisms:

Answer 65

1. PTH binds to receptors on the osteoblasts, stimulating them to secrete RANKL, which in turn raises the osteoclast population and promotes bone resorption. 2. PTH promotes calcium reabsorption by the kidneys so less calcium is lost in the urine. 3. PTH promotes the final step of calcitriol synthesis in the kidneys, thus enhancing the calcium-raising effect of calcitriol. 4. PTH inhibits collagen synthesis by osteoblasts, thus inhibiting bone deposition.

Question 66

Bone disorders are among the concerns of the branch of medicine known as __________.

Answer 66

orthopedics

Question 67

A break in a bone caused by abnormal trauma to a bone.

Answer 67

stress fracture

Question 68

A break in a bone weakened by some other disease, such as bone cancer or osteoporosis.

Answer 68

pathological fracture

Question 69

A fracture in which the bone pieces remain in proper anatomical alignment.

Answer 69

nondisplaced fracture

Question 70

A fracture in which at least one bone piece is shifted out of alignment with the other.

Answer 70

displaced fracture

Question 71

A type of fracture in which a bone is broken into three or more pieces.

Answer 71

comminuted fracture

Question 72

A fracture in which the bone is completely broken on one side but merely bent on the opposite side.

Answer 72

greenstick fracture

Question 73

The healing process of fractures occurs in what four stages?

Answer 73

1. Formulation of hematoma and granulation tissue. 2. Formation of soft callus. 3. Conversion of hard callus. 4. Remodeling.

Question 74

A procedure in which the bone fragments are manipulated into their normal positions without requiring surgery.

Answer 74

closed reduction

Question 75

Involves the surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments.

Answer 75

open reduction

Question 76

The most common bone disease characterized by a loss of bone mass, increasing susceptibility to fractures, and sometimes deformity of the vertebral column.

Answer 76

osteoporsis