Bones (Exam 2) Flashcards
What is the study of bones?
Osteology
What is the major producer of blood cells?
Red bone marrow
The connective tissue that makes up bones is called
osseous tissue
Thin, often curved, bones are classified as what shape?
Flat bone
What shape is the humerus?
Long bone
What bone shape are vertebrae classified as?
Irregular
What are the functions of the skeletal system?
Protection, blood formation, acid-base balance, support
What bone shape are the carpal bones of the wrist?
Short
Which osseous tissue is found at the surface of all bones?
Compact
Most long bones are found in
the limbs
Stem cells in developing bone that gives rise to osteoblasts are called
osteogenic cells
Hydroxyapatite makes up part of the _________ component of the bony matrix
Inorganic
What are the layers of the bony matrix in compact bone tissue called?
Lamellae
Within compact bone, a central canal is found at the center of
an osteon
T/F Compact bone comprises most of the diaphysis of a long bone
True
T/F Osteogenic cells are stem cells in the endosteum, periosteum, and central canals that can become chondrocytes
False
T/F Spongy bone is primarily made up of osteons
False
The layers of bony matrix arranged around the central canal of an osteon are called
Concentric lamellae
In longitudinal views, osteons are
cylinders
Where is red bone marrow found in the bones of a child?
Almost all bones
Which structures in the spongy bone line up along the bone’s stress lines?
Trabeculae
The basic structural unit of compact bone is
osteon
Fatty bone marrow that no longer produces blood cells is
yellow bone marrow
In adults, which bone marrow is limited to the axial skeleton, pectoral, and pelvic girdles, and proximal heads of the humerus and femur?
Red bone marrow
What are the methods of ossification that occur in the development of the skeletal system?
Endochondral and intramembranous
Lacunae are located between concentric rings of compact bone tissue called
Lamellae
What is the function of yellow bone marrow?
Energy storage
The bones of the skull are formed by which type of ossification?
Intramembranous
Where does bone formation occur during endochondral ossification?
Hyaline cartilage model
An increase in the length of a long bone occurs through the process of
Interstitial growth
During bone remodeling, the cells that remove unnecessary bone mass are called
osteoclasts
Mineral deposition into bones begins when?
In fetal ossification
As a flat bone is produced by intramembranous ossification, which cells are responsible for the resorption of bone tissue that carves out the spongy bone’s trabeculae?
Osteoclasts
The cartilage that is the tissue that is replaced with bone during endochondral ossification is
hyaline cartilage
What is low blood calcium called?
Hypocalcemia
Which type of bone growth occurs within cartilage and results in bone elongation?
Interstitial
Which mineral is more closely regulated by the body?
Calcium
Where do the calcium and phosphate used to mineralize bone come from?
Blood
Hormones that affect bone growth and development
Calcitonin, parathyroid hormone, testosterone, estrogen
High blood calcium levels
Hypercalcemia
A mass of blood in the tissue
Hematoma (bruise)
How does calcitriol affect blood phosphate levels?
It raises them
_______ has a greater effect on bone growth
Estrogen
What often causes the loss of bone mass seen in osteoporosis in older women?
A loss of estrogen
Which cells have a ruffled border and secrete hydrochloric acid?
Osteoclasts
The marrow cavity of an adult bone may contain
Myeloid tissue
The spurt of growth in puberty results from cell proliferation and hypertrophy in
The epiphysial plate
Osteoclasts are most closely related by common descent, to
Blood cells
The walls between cartilage lacunae break down in the zone of
Bone deposition
Which of these is not an effect of PTH?
Rise in blood phosphate lvel
A child jumps to the ground from the top of a playground jungle gym. His leg bones do not shatter mainly because they contain
Collagen fibers
One long-bone meets the other at its
epiphysis
Calcitriol is made from
7-dehydrocholesterol
One sign of osteoporosis is
A spontaneous wrist fracture
Osteocytes contact each other through channels called ______ in the bone matrix
Canaliculi
A bone increases in diameter only by _____ growth, the addition new surface lamellae
Appositional
Seed crystals of hydroxyapatite form only when the levels of calcium and phosphate in the tissue exceed the _____
Solubility product
calcium deficiency called ______ can cause death by suffocation
Hypocalcemia
cells that secrete collagen and stimulate calcium phosphate deposition
Osteoblasts
The most active form of vitamin D, produced mainly by the kidneys is
Calcitriol
The transitional region between epiphysial cartilage and the primary marrow cavity of a young bone is called the
Metaphysis
A pregnant, poorly nourished woman may suffer a softening of the bones called
Osteomalacia
The flat cranial bones are composed of compact bone only, with no spongy bone
The flat cranial bones have a middle layer of spongy bone called the diploe
In endochondral ossification, bone tissue is formed by the calcification of pre-existing cartilage
Cartilage is removed and replaced by bone, not calcified and transformed into bone
Osteoblasts are multipotent stem cells
Osteoblasts give rise only to osteocytes and are therefore unipotent
The protein of the bone matrix is called hydroxyapatite
Hydroxyapatite is the major mineral of bone; the major protein is collagen
Osteocytes are nourished by blood capillaries in the canaliculi of the osteons
Osteons have blood vessels in their central canals, not in the canaliculi
Vitamin D promotes bone deposition, not resorption
The major effect of vitamin D is bone resorption though it promotes deposition
Parathyroid hormone stimulates bone deposition by osteoblasts
PHT indirectly promotes resorption, not deposition
Name at least five tissues found in the bone:
Marrow cavity, spongy bone, articular cartilage (hylaine), perforating fibers, nutrient foramina, yellow bone marrow
List three or more functions other than supporting the body and protecting some internal organs
Electrolyte balance, acid-base balance, blood formation, and movement
Sternum, scapula, and hip bone
Flat bone
Humerus, radius, ulna, femur, tibia, and fibula
Long bone
Carpals and tarsals
Short bone
Vertebra, sphenoid, and ethmoid bones of the skull
Irregular bone
Shaft
Diaphysis
Head
Epiphysis
Growth zone
Epiphyseal plate
Fibrous covering
Periosteum
Three organic components of the bone matrix
Collagen,carbohydrate, and glyoproteins
What does hemopoietic tissue mean?
Tissue that produces blood cells, so red bone marrow
The ___________ is an example of bone as an organ; ___________ bone is an example of bone as a tissue.
Femur;Spongy
Which one of the following bone cells would have the greatest number of lysosomes?
Osteoclasts
Mature bones are remodeled throughout life via a process known as __________.
Appositional growth
Synthesized by the combined action of the skin, kidneys, and liver, _________ promotes bone resorption but is also necessary for bone deposition.
Calcitriol
In hyaline cartilage, the cells that produce new matrix are called
Chondroblasts
Chondrocytes receive nutrients in this manner
Diffusion through matrix
This flexible strength of bone is attributed to
collagen fibers
Osteochondral progenitor cells give rise to
Osteoblasts and condroblasts
T/F Nutrients travel to osteocytes in this order:
1. blood vessels in the medullary cavity
2. central canal
3. canaliculi
4. perforating (volkmann’s) canals
5. cytoplasm of the osteocytes
False
Endochondral ossification begins during
fetal development
T/F Bones produced by intramembranous or endochondral ossification are indistinguishable because both initially produce woven bone which is then remodeled
True
This can be said of intramembranous ossification
- it forms the frontal and parietal bones
- fontanels are found between skull bones
- osteoblasts lay down matrix around collagen fibers
In this zone of the epiphyseal plate, new cartilage is produced as the chondrocytes divide and form stacks of cells
Proliferation
T/F Growth in bone width occurs in this order
1. osteoblasts lay down bone to form ridges with grooves in between
2. grooves are changed into tunnels
3. concentric lamellae are made
4. an osteon is produced
True
When a fracture is healing, these cells move into the fracture site and tear down the damaged bone
Osteoclasts
Bone remodeling is involved in
- Bone growth
- Changes in bone shape
- Calcium regulation in the body
- Bone repair
T/F The definition of bone remodeling is the construction of bone around blood vessels forming an osteon
False
This process of bone repair requires the longest amount of time
Bone remodeling
If a fracture occurs in the diaphysis of a long bone, the structure that forms between the ends of the bone, as well as the medullary cavity, is called
Internal callus
These kinds of fractures are complete fractures in which the bone breaks into multiple pieces
Comminuted
This kind of tissue has many small spaces, is found mainly in the epiphysis, and is arranged into trabeculae
Cancellous (spongy) bone
This hormone, which is secreted by the anterior pituitary, increases bone growth by stimulating interstitial cartilage growth and appositional bone growth
Growth
Vitamin C deficiency causes this disorder which is characterized by ulcerations, hemorrhage, and poor wound healing
Scurvy
This hormone stimulates an increased number of osteoclasts which increases blood calcium levels
Parathyroid (PTH)
This structure covers the outer surface of bones and serves as an attachment site for tendons and ligaments
Periosteum
These kinds of bones contain air-filled sinuses which are lined with mucous membranes
Irregular and flat bones
What is the functional significance of a long bone being wider at the epiphyses than at the diaphysis?
The wider epiphyses provide surface area for muscle attachment and bone articulation, while the narrowness of the diaphysis minimizes weight.
Which zones account for a child’s growth in height?
Zones of cell proliferation and cell hypertrophy
The most active form of vitamin D is
Calcitriol
Osteoblastic activity in children is stimulated by the hormone
Calcitonin
When blood calcium levels drop, glands embedded in the posterior thyroid secrete _______ hormone, which stimulates osteoclastic activity
Parathyroid
The hormone ________ influences both resorption and deposition of bone
Calcitriol
Vitamin D stimulates the absorption of dietary calcium from the
digestive system
The outcome of increased blood calcium is
- Osteoclastic activity
- Calcitriol
- Parathyroid hormone
- Increased bone resorption
- Inhibition of osteoblasts
- Increased urinary excretion of phosphate
The outcome of decreased blood calcium:
- Osteoblastic activity
- Living at a northern latitude
- Increased use of sunblock
- Calcitonin
Compact Bone
- Made up of osteons
- Also called dense bone
- Visible, obvious, central canals
- Found in greater proportion in the bone diaphyses
Spongy Bone
- Composed of trabeculae
- Convey strength with lightweight
- Found in greater proportions in flat bones
- Gaps between ossified material are filled with marrow
- Arranged along the lines of forces that are encountered
- Found in greater proportions in the bone epiphysis
Organic
- Collagen
- Glycosaminoglycans
- Proteoglycans
- Glycoproteins
- Provides flexibility
- Resists tensile (pulling) forces
Inorganic
- Hydroxyapatite
- Calcium carbonate
- Provides hardness
- Resists compressive (pushing) forces
Not all compact bone is organized around a central canal with concentric lamellae. Lamellae found in the inner and outer boundaries of dense bone run parallel to the bone surface. These lamellae are called
Circumferential
The hydrogen ion pump in osteoclasts became blocked. You would expect the osteoclasts to
Be unable to digest either minerals or collagen
In order for mineralization to begin, two steps must occur. These steps are
the solubility product must be reached and the inhibitors are neutralized.
A fracture of the distal end of the radius and ulna is called a
Colles
The ___ forms by endochondral ossification.
Humerus
A soft callus forms during
The healing of a fracture
Bones that serve as levers and are moved by skeletal muscle to produce movement are termed
Long bones
Fat is stored in
the medullary cavity of long bones.
T/F Each osteocyte of compact bone is supplied by blood capillaries in its lacuna.
False
Bone tissue can be described as
dense, hard connective tissue
Sesamoid bones are found embedded in
tendons
Which category of bone is among the most numerous in the skeleton?
long bone
Long bones enable body movement by acting as a
lever
The diaphysis contains
fat storage
Which of the following occurs in the spongy bone of the epiphysis?
hematopoiesis
Which of the following are incapable of undergoing mitosis?
osteoblasts and osteocytes
Which cells do not originate from osteogenic cells?
osteoprogenitor cells
found in compact bone and cancellous bone?
lamellae
The area of a bone where the nutrient foramen passes forms what kind of bone marking?
a hole
thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber
articular cartilage
where two bone surfaces meet
articulation
channels within the bone matrix that house one of an osteocyte’s many cytoplasmic extensions that it uses to communicate and receive nutrients
canaliculi
layer of spongy bone, that is sandwiched between two the layers of compact bone found in flat bones
diploe
delicate membranous lining of a bone’s medullary cavity
endosteum
spaces in a bone that house an osteocyte
lacunae
small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment
nutrient foramen
primary cell in mature bone; responsible for maintaining the matrix
osteocyte
undifferentiated cell with high mitotic activity; the only bone cells that divide; they differentiate and develop into osteoblasts
osteogenic cell
channel that branches off from the central canal and houses vessels and nerves that extend to the periosteum and endosteum
perforating canal
bone markings where part of the surface sticks out above the rest of the surface, where tendons and ligaments attach
projection
Why is cartilage slow to heal?
because it does not have a blood supply
Why are osteocytes spread out in bone tissue?
Formation of osteoid spreads out the osteoblasts that formed the ossification centers.
In endochondral ossification, what happens to the chondrocytes?
They die in the calcified matrix that surrounds them and form the medullary cavity.
represents the correct sequence of zones in the epiphyseal plate
calcification, maturation, proliferation, reserved
region of the epiphyseal plate that makes new chondrocytes to replace those that die at the diaphyseal end of the plate and contributes to longitudinal growth of the epiphyseal plate
proliferative zone
region of the epiphyseal plate that anchors the plate to the osseous tissue of the epiphysis
reserve zone
region of the epiphyseal plate closest to the diaphyseal end; functions to connect the epiphyseal plate to the diaphysis
zone of calcified matrix
region of the epiphyseal plate where chondrocytes from the proliferative zone grow and mature and contribute to the longitudinal growth of the epiphyseal plate
zone of maturation and hypertrophy
uncalcified bone matrix secreted by osteoblasts
osteoid
manual manipulation of a broken bone to set it into its natural position without surgery
closed reduction
fibrocartilaginous matrix, in the endosteal region, between the two ends of a broken bone
internal callus
surgical exposure of a bone to reset a fracture
open reduction
Wolff’s law, which describes the effect of mechanical forces in bone modeling/remodeling, would predict that ________
a right-handed pitcher will have thicker bones in his right arm compared to his left.
food that is best for bone health
leafy green vegetables
With respect to their direct effects on osseous tissue, which pair of hormones has actions that oppose each other?
calcitonin and parathyroid hormone
Inhibits osteoclast activity and stimulates calcium uptake by bones
Calcitonin
Stimulates absorption of calcium and phosphate from the digestive tract
Calcitriol
When calcium levels are too high or too low, which body system is primarily affected?
the nervous system
most likely to be released when blood calcium levels are elevated
calcitonin
