Anatomy and Physiology Chapter 7
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
What are mature bone cells found within lacunae of compact bone called?
Osteocytes
The study of bone is called
Osteology
A degenerative bone disease characterized by a loss of bone mass and an increased risk of fracture is called __________.
Osteoporosis
Other Bone Disorders Notes
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 •Affects spongy bone the most since it is the most metabolically active •Subject to pathological fractures of hip, wrist, and vertebral column •Kyphosis (widow's hump)—deformity of spine due to vertebral bone loss •Complications of loss of mobility are pneumonia and thrombosis
What is the most common and deadly form of bone cancer?
Osteosarcoma
A low blood calcium level stimulates the release of which hormone?
Parathyroid hormone
Parathyroid Hormone Notes
Parathyroid hormone (PTH)—secreted by parathyroid glands on posterior surface of thyroid PTH released when calcium levels low in blood PTH raises calcium blood level by four mechanisms •Stimulates osteoblasts to secrete RANKL, thereby increasing osteoclast population and bone resorption •Promotes calcium reabsorption by kidneys, so less lost in urine •Promotes the final step of calcitriol synthesis in the kidneys, enhancing calcium-raising effect of calcitriol •Inhibits collagen synthesis by osteoblasts, inhibiting bone deposition
A fracture caused by a tumor would be classified as a ___________ fracture.
Pathological
In an adult, which of the following is a bone that does not contain red bone marrow? 1. Radius 2. Rib 3. Sternum 4. Vertebra 5. Skull
Radius
In adults, which bone marrow is limited to the axial skeleton, pectoral and pelvic girdles, and proximal heads of the humerus and femur?
Red
A concerned mother brings her young son to you for a check up. She says he stays indoors on the couch all the time, playing video games, and refuses to drink milk or eat dark green leafy vegetables. You tell her that unless he changes his behaviors, he is at risk for what skeletal disorder?
Rickets
Fractures and Their Repair notes
Stress fracture—break caused by abnormal trauma to a bone (example: in a fall) Pathological fracture—break in a bone weakened by disease (such as bone cancer or osteoporosis) •Usually caused by a stress that would not break a healthy bone Fractures classified by structural characteristics •Direction of fracture line•Break in the skin•Multiple pieces -Example: comminuted—three or more pieces
Which of the following is not considered a weight bearing activity? 1. Walking 2. Running 3. Swimming 4. Jumping rope 5. Pedaling a bike
Swimming
Where does the calcium and phosphate used to mineralize bone come from?
The blood
In the human body, where is 99% of the calcium found?
The bones
osteomalacia
The softening of the bones in adults due to calcium depletion
True or false: Compact bone comprises most of the diaphysis of a long bone.
True (Spongy bone for epiphysis)
In a growth plate, which of the following describes the zone of bone deposition?
Walls between lacunae break down and chondrocytes die. Osteoblasts begin secreting bone matrix.
Which zone of the epiphyseal plate is located the closest to the marrow cavity?
Zone of bone deposition
In which zone of the epiphyseal plate are chondrocytes multiplying and aligning into longitudinal columns of flattened lacunae?
Zone of cell proliferation
Which zone of the epiphyseal plate is located the farthest from the marrow space?
Zone of reserve cartilage
The skeletal system helps maintain acid-base balance by __________.
absorbing or releasing alkaline phosphate and carbonate salts
Epiphysial plate (growth plate)
area of hyaline cartilage that separates epiphyses and diaphyses of children's bones •Enables growth in length
Bones in the legs, arms, spine and pelvis grow __________.
at different rates
Osseous tissue is a connective tissue with a hardened matrix that makes up organs called ____________.
bones
Vitamin D, also known as ______, raises the blood calcium level.
calcitriol
Osseous tissue matrix is composed of __________.
calcium phosphate
Mineralization is a process that extracts __________ and __________ from the blood plasma and deposits it into bone.
calcium; phosphate
To help regulate body calcium levels, bone has two reserves. The disadvantage of the stable reserve is that it __________.
cannot easily be exchanged or released into the tissue fluid
If the __________ component of bone is not in adequate amounts, the flexibility of bone will be compromised.
collagen
Osteogenesis imperfecta is due to the deficiency of __________ in the matrix, which makes the bones extremely brittle.
collagen
A __________ fracture is one in which the bone is broken into three or more pieces.
comminuted
By weight, the skeleton is mostly ______ bone.
compact
Which osseous tissue is found at the surface of all bones?
compact
Which osseous tissue is found on the surface of bones and composed of tightly arranged parallel osteons?
compact
Ligaments
connect bone to bone at joints
Bone(osseous tissue)
connective tissue with the matrix hardened by calcium phosphate and other minerals
In longitudinal views, osteons are ______.
cylinders
Compact (dense or cortical) bone
dense outer shell of bone
The layer of connective tissue lining internal surfaces of bones is called ____________.
endosteum
The structure found between the epiphysis and diaphysis in a child and is a site of bone growth is the ___________ plate.
epiphyseal
Where does a long bone grow in length?
epiphyseal plate
Which hormone has a greater effect on bone growth?
estrogen
Periosteum
external sheath covering most of bone
The outer layer of periosteum is a(n) ______.
fibrous layer
Bones are classified as one of four types based on their shape. The bones of the cranium are examples of _________ bones.
flat
Thin, often curved, bones are classified as what shape?
flat
The calcium-phosphate salt that mineralizes bone tissue is called ______.
hydroxyapatite
If a patient has abnormally high blood calcium levels, they are said to have a condition called ______.
hypercalcemia
Epiphysial line
in adults, a bony scar that marks where growth plate used to be
Hydroxyapatite makes up part of which component of the bony matrix?
inorganic
Bones such as the vertebrae are classified as ________ bones.
irregular
What bone shape are vertebrae classified as?
irregular
How does calcitriol affect blood phosphate levels?
it raises them
Articular cartilage
layer of hyaline cartilage that covers joint surface; allows joint to move more freely
Most long bones are found ______.
limbs
What shape is the humerus?
long
Long bones
longer than they are wide; rigid levers acted upon by muscles; crucial for movement
Nutrient foramina
minute holes in bone surface that allows blood vessels to penetrate
Which of the following would directly affect osseous tissue? 1. A Vitamin-C deficiency 2. The overproduction of white blood cells, as in leukemia 3. The malformation of dense regular connective tissue 4. The erosion of articulated cartilage 5. A disorder affecting fibroblasts
1. A Vitamin-C deficiency
Which of the following best describes osseous tissue? 1. A connective tissue with a hardened matrix that makes up bone 2. A connective tissue composed primarily of cartilage matrix and collagen 3. A connective tissue consisting of loosely arranged protein fibers 4. A connective tissue lacking fibers in the extracellular matrix 5. A hardened mineralized matrix devoid of living cells
1. A connective tissue with a hardened matrix that makes up bone
Which of the following best describes a medullary cavity? 1. A hollow cavity within the diaphysis of a long bone 2. An opening through which a blood vessel enters a bone 3. A hollow area within the spongy bone of the epiphysis
1. A hollow cavity within the diaphysis of a long bone
Select all that apply What is the name for a channel that extends longitudinally through the center of an osteon? 1. Central canal 2. Haversian canal 3. Canaliculi canal 4. Medullary canal 5. Perforating canal
1. Central canal 2. Haversian canal
Select all that apply Calcitriol acts on which organs to raise blood calcium levels? 1. Small intestines 2. Bones 3. Kidneys 4. Muscles 5. Brain
1. Small intestines 2. Bones 3. Kidneys
Which of the following is not a component of the skeletal system? 1. Tendons 2. Ligaments 3. Cartilage 4. Flat bones 5. Long bones
1. Tendons
Standard number of bones in the appendicular skeleton
126
total number of true ribs
14
total number of carpals
16
Select all that apply Which two ions are deposited by osteoblasts into the bone matrix? 1. Chlorine 2. Phosphate 3. Potassium 4. Iron 5. Calcium
2. Phosphate 5. Calcium
In which of the following does blood cell production occur? 1. Periosteum 2. Red bone marrow 3. Yellow bone marrow 4. Growth plate
2. Red bone marrow
Total number of metacarpals and metatarsals
20
Standard number of bones in the adult
206
Select all that apply What is the name for a channel that extends longitudinally through the center of an osteon? 1. Canaliculi canal 2. Perforating canal 3. Haversian canal 4. Central canal 5. Medullary canal
3. Haversian canal 4. Central canal
total number of vertebrae
33
Each of the following complications listed below is a result of a homeostatic calcium imbalance. Which would not be life threatening? 1. Inability to maintain the resting membrane potential 2. Declining neuronal communication 3. Decreased blood clotting ability 4. A deficit of appositional bone growth 5. Irregular heart rate
4. A deficit of appositional bone growth
Which describes a nutrient foramen? 1. A small space within cartilage where chondrocytes are found 2. An opening in a bone that conveys nerves into the bony tissue 3. A small fissure-like structure that connects neighboring lacunae 4. An opening into the surface of a bone which allows the passage of blood vessels into bone tissue
4. An opening into the surface of a bone which allows the passage of blood vessels into bone tissue
Number of vertebrae fused together that result in the sacrum
5
At which of the following ages would calcium loss from bone be more than calcium deposits into bone, even when a high calcium diet is eaten? A. 18 months old B. 10 years old C. 18 years old D. 50 years old E. 25 years old
50 years old
total number of phalanges
56
Total number of ossicles
6
Number of tarsals in one extremity
7
total number of cranial bones
8
Standard number of bones in the axial skeleton
80
In the human body, what percentage of calcium in the body is found in the bones?
99
A shorter, seventy-year-old Chinese woman comes to you with a broken hip. Which test do you order to check for osteoporosis?
A bone mineral density test
Cartilage
A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together. Covers many joint surfaces of mature bone
What often causes the loss of bone mass seen in osteoporosis in older women?
A loss of estrogen
Physiology of Osseous Tissue Notes
A mature bone remains a metabolically active organ •Involved in its own maintenance of growth and remodeling •Exerts a profound 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
During fracture healing, cartilage is deposited in granulation tissue to form which of the following?
A soft callus
Which allows the passage of blood vessels into a bone? A. Nutrient foramen B. Perforating canal C. Central canal
A. Nutrient foramen
You have a male patient who is about four feet tall with a normal-sized head and trunk but smaller arms and legs. You deduce that they have what condition?
Achondroplastic dwarfism
Dwarfism Notes
Achondroplastic dwarfism •Long bones stop growing in childhood -Normal torso, short limbs•Failure of cartilage growth in metaphysis •Spontaneous mutation produces mutant dominant allele Pituitary dwarfism •Lack of growth hormone •Normal proportions with short stature
Which tend to attain their full height earlier in life?
Adolescent girls
Where is red bone marrow found in the bones of a child?
Almost all bones
Within compact bone, a central canal is found at the center of which structure?
An osteon
Which type of bone growth involves the deposition of new tissue at the surface?
Appositional
Which type of bone growth occurs within mature bone and results in the bone becoming thicker?
Appositional growth
Bone Widening and Thickening Notes
Appositional growth—occurs at bone surface •Continual growth in diameter and thickness •Intramembranous ossification •Osteoblasts of inner periosteum deposit osteoid tissue -Become trapped as tissue calcifies •Lay down matrix in layers parallel to surface -Forms circumferential lamellae -Osteoclasts of endosteum enlarge marrow cavity
Short bones
Approximately equal in length and width; glide across one another in multiple directions
What is the hyaline cartilage found covering the ends of bones within a joint called?
Articular cartilage
Other Factors Affecting Bone Notes
At least 20 or more hormones, vitamins, and growth factors affect osseous tissue Bone growth especially rapid in puberty and adolescence •Surges of growth hormone, estrogen, and testosterone occur and promote ossification •These hormones stimulate multiplication of osteogenic cells, matrix deposition by osteoblasts, and chondrocyte multiplication and hypertrophy in metaphyses Bone growth especially rapid in puberty and adolescence(Continued) •Girls grow faster than boys and reach full height earlier -Estrogen has stronger effect than testosterone on bone growth •Males grow for a longer time and also taller Anabolic steroids cause growth to stop •Epiphysial plate "closes" prematurely •Results in abnormally short adult stature
Phosphate Homeostasis Notes
Average adult has 500 to 800 g phosphorus with 85 to 90% of it in the bones Normal plasma concentration is 3.5 to 4.0 mg/dl Phosphate is also needed in DNA, RNA, ATP, and phospholipids Phosphate levels are not regulated as tightly as calcium levels Calcitriol raises phosphate levels by promoting its absorption by small intestine PTH lowers blood phosphate levels by promoting its urinary excretion
Which mineral is more closely regulated by the body? A. Phosphate B. Calcium
B. Calcium
Which layer of tissue lines the internal surfaces of a bone? A. Periosteum B. Endosteum C. Perichondrium
B. Endosteum
What is the function of red bone marrow?
Blood cell production
Bone Cells Notes
Bone is connective tissue that consists of cells, fibers, and ground substance Four principal types of bone cells •Osteogenic cells, osteoblasts, osteocytes, and osteoclasts Osteogenic cells—stem cells found in endosteum and inner layer of periosteum •Arise from embryonic mesenchyme; multiply continuously and give rise to most other bone cell types Osteoblasts—bone-forming cells•Form single layer of cells under endosteum and periosteum •Synthesize soft organic matter of matrix which then hardens by mineral deposition (osteogenesis) •Stress stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts which reinforce bone •Secrete hormone osteocalcin •Stimulates insulin secretion of pancreas; increases insulin sensitivity in adipocytes which limits the growth of adipose tissue Osteocytes—former osteoblasts that have become trapped in the matrix they deposited •Lacunae—tiny cavities where osteocytes reside •Canaliculi—little channels that connect lacunae •Cytoplasmic processes of osteocytes reach into canaliculi and contact processes of neighboring cells •Gap junctions allow for passage of nutrients, wastes, signals •Some osteocytes reabsorb bone matrix while others deposit it •Act as strain sensors—when stressed, produce biochemical signals that regulate bone remodeling (shape and density changes that are adaptive) Osteoclasts—bone-dissolving cells found on bone surface •Osteoclasts develop from same bone marrow stem cells that give rise to blood cells (different origin from other bone cells) •Very large cells formed from fusion of several stem cells •Have multiple nuclei in each cell •Ruffled border (large surface area) faces bone •Cells often reside in resorption bays (pits in bone surface) •Dissolving bone (osteolysis) is part of bone remodeling
What are the spaces between trabeculae in spongy bone filled with?
Bone marrow (More specifically, red marrow is found in the spongy bone of the epiphysis of a long bone, whereas yellow marrow is found in the medullary (marrow) cavity of the diaphysis.)
Bone Marrow notes
Bone marrow—soft tissue occupying marrow cavities of long bones and small spaces of spongy bone Red marrow (myeloid tissue) •Contains hematopoietic tissue—produces blood cells •In nearly every bone in a child •In adults, found in skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur Yellow marrow found in adults •Fatty marrow that does not produce blood •Can transform back to red marrow in the event of chronic anemia
Bone Remodeling Notes
Bone remodeling (absorption and deposition) occurs throughout life—10% of skeleton per year •Repairs microfractures, releases minerals into blood, reshapes bones in response to use and disuse •Wolff's law of bone: architecture of bone determined by mechanical stresses placed on it -Remodeling is a collaborative and precise action of osteoblasts and osteoclasts -Bony processes grow larger in response to mechanical stress
Which of the following describes the lacunae of osseous tissue? A. Tiny canals radiating from the osteocytes B. Hollow canals in the center of osteons C. Spaces between lamellae that contain osteocytes
C. Spaces between lamellae that contain osteocytes
Which hormone inhibits osteoclasts and stimulates osteoblasts to lower blood calcium levels?
Calcitonin
Calcitonin Notes
Calcitonin—secreted by C cells (clear cells) of thyroid gland when blood calcium levels rise too high Lowers blood calcium concentration in two ways: •Inhibits osteoclasts thereby reducing bone resorption •Stimulates osteoblasts to deposit calcium into bone Important in children, weak effect in adults •Osteoclasts more active in children due to faster remodeling May inhibit bone loss in pregnant and lactating women
Calcitriol Notes
Calcitriol—most active form of vitamin DProduced by actions of skin, liver, and kidneys •Epidermal keratinocytes use UV radiation to convert •7-dehydrocholesterol to previtamin D3; warm sun on skin converts this to vitamin D3 •Liver adds hydroxyl group converting that to calcidiol •Kidney adds hydroxyl group converting that to calcitriol Calcitriol is a hormone that raises blood calcium level •Mainly, it increases calcium absorption by small intestine •It also increases calcium resorption from the skeleton -Stimulates osteoblasts to release RANKL, a chemical that stimulates production of more osteoclasts •It weakly promotes kidney reabsorption of calcium ions, so less lost in urine Calcitriol is also necessary for bone deposition—helping provide adequate calcium and phosphate Inadequate calcitriol results in abnormal softness of bones in children (rickets) and in adults (osteomalacia)
Which mineral is most important throughout life to assist in maintaining strong bones?
Calcium
Calcium Homeostasis Notes
Calcium and phosphate are used for much more than bone structure Calcium needed in neuron communication, muscle contraction, blood clotting, and exocytosis Minerals are deposited in the skeleton and withdrawn when they are needed for other purposes About 18% of skeletal calcium is exchanged with blood each year •Most exists as part of hydroxyapatite, but a little is in a form that is easily exchanged with the blood Normal calcium concentration in blood plasma is 9.2-10.4 mg/dl Hypocalcemia—deficient calcium in blood •Changes membrane potentials and causes overly excitable nervous system and tetany (muscle spasms) -Laryngospasm can cause suffocation •Caused by vitamin D deficiency, diarrhea, thyroid tumors, underactive parathyroid glands •Pregnancy and lactation increase risk of hypocalcemia Hypercalcemia—excessive calcium levels •Makes ion channels less responsive and thus nerve and muscle are less excitable -Can cause emotional disturbance, muscle weakness, sluggish reflexes, cardiac arrest •Hypercalcemia rarely occurs Calcium homeostasis depends on a balance between dietary intake, urinary and fecal losses, and exchanges between osseous tissue Calcium homeostasis is regulated by three hormones: •Calcitriol, calcitonin, and parathyroid hormone
In osseous tissue, the narrow channels connecting neighboring lacunae are called _______.
Canaliculi
__________ is/are found in compact bone but not spongy bone.
Central canals
Which of the following describes the zone of cell hypertrophy in an epiphyseal plate?
Chondrocytes in this zone are no longer dividing, but are enlarging; there is a thinning of lacunae walls.
The Treatment of Fractures Notes
Closed reduction—procedure in which bone fragments are manipulated into their normal positions without surgery Open reduction—involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments Cast—normally used to stabilize and immobilize healing bone Fractures of the femur in children often treated with traction •Aligns bone fragments by overriding force of the strong thigh muscles Hip fractures in older adults are usually pinned and early walking is encouraged •Fractures taking more than 2 months to heal may be treated with electrical stimulation which suppresses effects of parathyroid hormone
Tendons
Connect muscle to bone
What is the purpose of the canaliculi in compact bone? A. To provide a passageway for blood vessels through the center of the long bone B. To provide a passageway for nerves into a long bone C. To provide a passageway for blood vessels into a long bone D. To provide a passageway between the lacunae
D. To provide a passageway between the lacunae
Where is the primary ossification center during endochondral ossification in a long bone?
Diaphysis
Irregular bones
Elaborate shapes that do not fit into other categories
One function of the skeleton is to store calcium and phosphate to help maintain __________ balance.
Electrolyte
What are the two principle forms of ossification that occur in the development of the skeletal system? 1. Membranous and cartilaginous 2. Membranous and intramembranous 3. Endochondral and osteogenic 4. Endochondral and intramembranous
Endochondral and intramembranous
Where do you find osteogenic cells?
Endosteum and periosteum
In adults, what is the remnant of the epiphyseal plate called?
Epiphyseal line
Secondary ossification centers usually appear where in long bones?
Epiphyses
Bone Elongation Notes
Epiphysial plate—cartilage transitions to bone •Functions as growth zone where bone elongates •Has typical hyaline cartilage in the middle with transition zones on each side where cartilage is replaced by bone •Metaphysis is zone of transition facing the marrow cavity This is interstitial growth—growth from within •Bone elongation is a result of cartilage growth within the epiphysial plate •Epiphyses close when cartilage is gone—epiphysial line of spongy bone marks site of former epiphysial plate -Lengthwise growth is finished -Occurs at different ages in different bones
What is the expanded end of a long bone to which tendons and ligaments attach called?
Epiphysis
Osteoporosis Notes
Estrogen maintains bone density in both sexes; inhibits resorption by osteoclasts Postmenopausal white women at greatest risk •Ovaries cease to secrete estrogen •White women begin to lose bone mass as early as age 35; by age 70, average loss is 30% of bone mass •Risk factors: race, age, gender, smoking, diabetes mellitus, diets poor which are poor in: calcium, protein, vitamins C and D Osteoporosis also seen in young female athletes with low body fat causing them to stop ovulating and decrease estrogen secretion Treatments •Estrogen replacement therapy (ERT) slows bone resorption, but increases risk of breast cancer, stroke, and heart disease •Drugs Fosamax, Actonel destroy osteoclasts •PTH slows bone loss if given as daily injection -Forteo (PTH derivative) increases density by 10% in 1 year --May promote bone cancer so use is limited to 2 years •Best treatment is prevention: exercise and a good bone-building diet between ages 25 and 40
True or false: The bone cells responsible for the formation of the organic bone matrix are called chondrocytes.
False Reason: Chondrocytes produce and maintain the cartilaginous matrix. Osteoblasts are the cells that deposit bone matrix and eventually become osteocytes.
True or false: Osteogenic cells are stem cells in the endosteum, periosteum, and central canals that can become chondrocytes.
False (Osteogenic cells are stem cells in the endosteum, periosteum, and central canals that can become osteoblasts rather than chondrocytes)
Another term for a central canal
Haversian canal
Bleeding at the site of a bone fracture results in the formation of a fracture _________, a blood clot.
Hematoma
What is a mass of blood in the tissues called?
Hematoma
Compact Bone Notes
Histology of compact bone reveals osteons (haversian systems) •Concentric lamellae surround a central (haversian) canal running longitudinally •Perforating canals—transverse or diagonal passages •Circumferential lamellae fill outer region of dense bone •Interstitial lamellae fill irregular regions between osteons
___________ cartilage is the tissue which is replaced with bone during endochondral ossification.
Hyaline
Articular surfaces of long bones are covered with which tissue?
Hyaline cartilage
Where does bone formation occur during endochondral ossification?
Hyaline cartilage model
What is the calcium-phosphate salt deposited within bone called?
Hydroxyapatite
What is low blood calcium called?
Hypocalcemia
What do individual bones (organs) consist of?
Individual bones (organs) consist of bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
What does the hormone calcitonin do?
Inhibits osteoclasts and stimulates osteoblasts
An increase in the length of a long bone occurs by the process of ________ growth.
Interstitial
Which type of bone growth occurs within cartilage and results in bone elongation?
Interstitial
The bones of the skull form by which type of ossification?
Intramembranous
What is the hollow space in which an osteocyte resides called?
Lacuna
Lacunae are located between concentric rings of compact bone tissue called what?
Lamellae
What are the layers of bony matrix in compact bone tissue called?
Lamellae
Bones that are longer than they are wide are classified as ___________ bones.
Long
Spongy (cancellous) bone
Loosely organized bone tissue •Found in center of ends and center of shafts of long bones and in middle of nearly all others •Covered by more durable compact bone Side Note (Not related to this card): Skeleton three-fourths compact and one-fourth spongy bone by weight Spongy bone consists of: •Lattice of bone covered with endosteum -Slivers of bone called spicules -Thin plates or beams of bone called trabeculae •Spaces filled with red bone marrow Few osteons and no central canals •All osteocytes close to bone marrow Provides strength with minimal weight •Trabeculae develop along bone's lines of stress
PTH is a hormone released by parathyroid glands in response to which of the following?
Low blood calcium levels
The Matrix Notes
Matrix of osseous tissue averages, by dry weight, about one-third organic and two-thirds inorganic matter Organic matter—synthesized by osteoblasts •Collagen, carbohydrate-protein complexes, such as glycosaminoglycans, proteoglycans, and glycoproteins Inorganic matter •85% hydroxyapatite (crystallized calcium phosphate salt) •10% calcium carbonate•Other minerals (fluoride, sodium, potassium, magnesium) Bone is a composite material—a combination of a ceramic and a polymer •Hydroxyapatite and other minerals are the ceramic and collagen (protein) is the polymer •Ceramic portion allows the bone to support body weight without sagging -Rickets is a disease caused by mineral deficiency and resulting in soft, deformed bones •Polymer (protein) gives some flexibility -Osteogenesis imperfecta (brittle bone disease) results from a defect in collagen deposition
What is the hollow space within the diaphysis of a long bone called?
Medullary cavity
Mineral Deposition and Resorption Notes
Mineral deposition (mineralization)—process in which calcium, phosphate, and other ions are taken from blood and deposited in bone •Osteoblasts produce collagen fibers that spiral the length of the osteon •Fibers become encrusted with minerals -Hydroxyapatite crystals form at solubility product—critical level of calcium times phosphate concentration -First few crystals act as seed crystals that attract more calcium and phosphate from solution •Abnormal calcification (ectopic ossification)—calcification in an otherwise soft organ such as a lung, brain, eye, muscle, tendon, or artery (arteriosclerosis) Mineral resorption—process of dissolving bone and releasing minerals into blood •Performed by osteoclasts at ruffled border •Hydrogen pumps in membranes secrete hydrogen into space between osteoclast and bone surface •Chloride ions follow by electrical attraction •Hydrochloric acid (pH 4) dissolves bone minerals •Acid protease enzyme digests collagen Orthodontic appliances (braces) reposition teeth through resorption and deposit •Tooth moves because osteoclasts dissolve bone ahead of tooth; osteoblasts deposit bone behind the tooth
Which of the following describes the zone of calcification in an epiphyseal plate?
Minerals are deposited between the columns of lacunae.
Bone disorders notes
Orthopedics—branch of medicine dealing with prevention and correction of injuries and disorders of bones, joints, and muscles •Name implies its origin as field treating skeletal deformities in children Includes the design of artificial joints and limbs and the treatment of athletic injuries
If you were having joint problems, which medical specialist would be most likely to help you?
Orthopedist
The connective tissue that makes up bone is called ______ tissue.
Osseous
Bone Growth and Remodeling notes
Ossification continues throughout life with the growth and remodeling of bones Bones grow in two directions • Length • Width
Which bone cells produce the organic bone matrix?
Osteoblasts
Which bone cells produce the soft organic bone matrix?
Osteoblasts
The branch of medicine dealing with bone disorders is ____________.
orthopedics
The process of bone formation is called
ossification
During the healing of a bone fracture, a hard callus is formed by ___________.
osteoblasts
The __________ contain hydrogen pumps that lead to the formation of hydrochloric acid, which is used to dissolve bone minerals in a process called __________.
osteoclasts; mineral resorption
Mature bone cells found within lacunae of compact bone are called ___________.
osteocyte
The basic structural unit of compact bone is the ______.
osteon
The connective tissue surrounding the external surface of a bone is called the __________.
periosteum
What is the major producer of blood cells?
red bone marrow
A(n) __________would not involve damage to the structures that comprise the skeletal system.
ruptured calcaneal (Achilles) tendon
diaphysis
shaft of long bone, composed of compact bone
Bones such as the carpals that have the same length and width are classified as _________ bones.
short
What bone shape are the carpal bones of the wrist?
short
Bone marrow fills the spaces between trabeculae in ______ bone tissue.
spongy
The interior of flat bones is composed of ______ bone.
spongy
Trabeculae and spicules are found in ______ bone.
spongy
______________ bone is always enclosed by more durable compact bone.
spongy
An epiphyseal line is slightly denser ______.
spongy bone
A fracture in a healthy bone caused by abnormal trauma, like a fall, is classified as a _________ fracture.
stress
Functions of the skeletal system
support, protection, movement, storage, blood cell production Support—limb bones and vertebrae support body; jaw bones support teeth; some bones support viscera Protection—of brain, spinal cord, heart, lungs, and more Movement—limb movements, breathing, and other movements depend on bone Electrolyte balance—calcium and phosphate levels Acid-base balance—buffers blood against large pH changes by altering phosphate and carbonate salt levels Blood formation—red bone marrow is the chief producer of blood cells
Mineralization or calcification
the hardening process of bone
Greenstick fractures most commonly occur in children because __________.
their bones contain a higher proportion of collagen
Endosteum
thin layer of reticular connective tissue lining marrow cavity •Has cells that dissolve osseous tissue and others that deposit it
Flat bones
thin, flattened, and usually curved (protect soft organs) Features: •Sandwich-like construction •Two layers of compact bone enclosing a middle layer of spongy bone (inner and outer tables) -Both surfaces covered with periosteum •Diploe—spongy middle layer -Absorbs shock -Marrow spaces lined with endosteum
In an adult, a compound fracture of the __________ could lead to a "fat" embolism entering the blood stream.
tibia
What are the thin plates forming spongy bone called?
trabeculae
Trusses and arches, which help form an internal scaffolding network, are found in __________.
trabecular bone
Long bone features
•Diaphysis—shaft that provides leverage -Marrow cavity (medullary cavity)—space in the diaphysis of a long bone that contains bone marrow •Epiphyses—enlarged ends of a long bone -Strengthen joint and anchor ligaments and tendons •Epiphyses and diaphysis •Compact and spongy bone •Marrow (medullary) cavity •Articular cartilage •Periosteum
Layer Notes
•Outer fibrous layer of collagen •Some fibers continuous with tendons •Perforating fibers—penetrate into bone matrix •Inner osteogenic layer of bone-forming cells •Important to bone growth and healing of fractures