Liberty A&P Chapter 6 Skeletal System
Define Endosteum (table 6.1)
This connective tissue membrane lining the inner cavities of the bone
Osteochondral progenitor cells are stem cells that can become _______________________________ or ___________________________________.
osteoblasts or chondrocytes
Describe the structure of hyaline cartilage
-Population of cells scattered through matrix of protein fibers -Embedded in gel-like ground substance that includes proteoglycans, but not calcium -Resilient and flexible -High percentage of water -Highly compressible and good shock absorber -Avascular and contains no nerves -Includes chondroblasts, chondrocytes, and perichondrium
Name and describe the events occurring in the four zones of the epiphyseal plate. Explain how the epiphyseal plate remains the same thickness while the bones increases in length.
1. zone of rest-cartilage attaches to the epiphysis.2. zone of proliferation-new cartilage is produced on the epiphyseal side of the plate as the chondrocytes divide and form stacks of cells.3. zone of hypertrophy-chondrocytes mature and enlarge.4. zone of calcification-matrix is calcified and the chondrocytes die. The thickness of the epiphyseal plate does not increase because the rate of cartilage growth on the epiphyseal side of the plate is equal to the rate of cartilage replacement by bone on the diaphyseal side of the plate.
Define hydroxyapatite (Bone Matrix)
A mineral of the apatite group that is the main inorganic constituent of tooth enamel and bone
Which is the type of hyaline cartilage that covers the ends of bones where they come together to form joints. It has no perichondrium, blood vessels, or nerves.
Articular Cartilage
Within joints, the end of a long bone is covered with hyaline cartilage called___________________________________
Articular Cartilage
What are the spaces between trabecular filled with?
Bone Marrow and Blood Vessels
Define spongy bone (table 6.1)
Bone having many small spaces; found mainly in the epiphysis; arranged into trabeculae
what are the five functions of the skeletal system?
Body Support, Organ Protection, Body Movement, Mineral Storage, and Blood cell production
Describe the effects of aging on bones
Bone matrix is lost and bones become more brittle spongy bone loss results from thinning and loss of trabeculae. Compact bone loss mainly occurs from the inner surface of bones and involves formation of fewer osteons Loss of bone increases the risk for fractures and causes deformity, loss of height, pain, stiffness, and loss of teeth
Why is it important for bone remodeling to occur?
Bone remodeling converts woven bone into lamellar bone and functions in bone growth, changes in bone shape, adjustment of the bone to stress, bone repair, and calcium ion regulation of the body
What are the four components of the skeletal system?
Bones, Cartilage, Tendons, and ligaments.
provides a firm yet flexible support within certain structures such as the nose, external ear, thoracic cage, and trachea
Cartilage
Name the components of bone matrix, and explain their contribution to bone flexibility and bones' ability to bear weight.
Cartilage -
Relate the importance of cartilage to the structure of the skeletal system
Cartilage connective tissue is important because it provides support, but is less rigid than bone. It also allows for some flexibility of movement, but has more stability than muscle. The extracellular matrix of cartilage is produced by cells called chondroblast
In cross section, an osteon resembles a circular target; the bulls eye of the target would be the____________________________
Central Canal
What are the outer surfaces of compact bone formed by?
Circumferential Lamellae
What has more matrix and is denser with fewer pores than spongy bone?
Compact Bone
Explain the structural differences between compact and spongy bone
Compact bone is made of densely packed hysoxyaphite and spongey bone is porous, consisting of criss crossing plates called trabecule
what is the diaphysis composed primarily of?
Compact bone, surrounding a hollow center called the medulla cavity.
Circular layers of bone matrix that surround the central canal on bone
Concentric Lamellae
Define Red Marrow (table 6.1)
Connective tissue in the spaces of spongy bone or in the medullary cavity; the site of blood cell production
Define Compact bone (table 6.1)
Dense bone with few internal spaces organized into osteons; forms the diaphysis and covers the bone of the epiphyses
List the bones, or parts of bones, that develop from each type of ossification
Endochondral - All of the bones of the body, except for the flat bones of the skull, mandible, and clavicles, are formed through endochondral ossification. In long bones, chondrocytes form a template of the hyaline cartilage diaphysis. Intramembranous - It is involved in the formation of the flat bones of the skull, the mandible, and the clavicles. Ossification begins as mesenchymal cells form a template of the future bone.
What can a person do to be protected from the effects of aging on the skeletal system?
Exercise, healthy eating, and healthy habits (no smoking,excessive drinking, etc)
Describe the components of the extracellular bone matrix and state the function of each scribe the components of the extracellular bone matrix and state the function of each.
Extracellular matrix, which is made up of an organic matrix (30%) containing proteoglycans (but less than cartilage), glycosaminoglycans, glycoproteins, osteonectin (anchors bone mineral to collagen) and osteocalcin (calcium binding protein).
Define Yellow Marrow (table 6.1)
Fat stored within the medullary cavity or in the spaces of spongy bone
Give an example of each of the shapes of bones
Flat - Sternum, ribs, scapulae, cranial bones Short - Carpals, tarsals Long - Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges Irregular - Vertebrae, facial bones Sesamoid - Patellae
Flat bones
Flat bones - interior framework of spongy bone sandwiched between two layers of compact bone - ribs, skull bones, scapulae, sternum
Define epiphyseal plate (table 6.1)
Hyaline cartilage between the diaphysis and epiphysis; its growth allows for growth in bone length
Name the three types of cartilage and explain which type is more closely associated with bone
Hyaline, Fibrocartilage, and elastic Hyaline is most intimately associated with bone. most bones develop form hyaline cartilage, produce a matrix that contains collagen, which provides strength, and proteoglycans, which make cartilage resistant by trapping water.
Define appositional growth (type of cartilage growth)
In Appositional growth chodroblasts in the perichondrium add new cartilage to the outside edge of existing cartilage.
What is between the osteons in compact bone?
Interstitial Lamellae
Irregular bones
Irregular - not elongated and no diaphysis and some may have a small epiphysis in certain areas, mirros long bone compositions minus the above, -- vertebrae
Explain how illness or malnutrition can affect bone growth. How do vitamins D and C affect bone growth?
It affects the rate of cell proliferation or the production of collagen and other matrix components. Without vitamin D children can get a disease called rickets, this is resulting from reduced mineralization of the bone matrix. Vitamin C deficiency results in bones and cartilage that are deficient in collagen because collagen synthesis is impaired.
What is mature bone that is organized into thin, concentric sheets or layers approximately 3-7 micrometers thick?
Lamellar Bone
Define Medullary cavity (table 6.1)
Large cavity within the diaphysis
Strong bands of fibrous connective tissue that hold bones together
Ligaments
Long bones
Long Bones - support weight and moidfacilitate movement, are longer than they are wide, include the femur (longest bone in the body, and relatively small bones in the fingers. Located mostly in the appendicular skeleton and include bones in the lower limbs = tibia, fibula, femur, metatarsals, and phalanges. And in the upper limbs = The humerus, radius, ulna, metacarpals, and the phalanges.
Osteoblasts release these - they contain high concentrations of Ca2+ and PO43-
Matrix Vesicles
What cells give rise to osteochondral progenitor cells?
Mesenchymal Stem Cells
The formation of new bone by osteoblasts is called ____________________________ or _____________________________
Ossification or Osteogenesis
What is the process of removing old bone and adding new bone?
Ossification/osteogenesis
What kinds of cells are derived from osteochondral progenitor cells?
Osteoblasts
Define Periosteum (table 6.1)
Outer, double-layered connective tissue membrane with ligaments and tendons attached to bone through the periosteum; blood vessels and nerve pathways; the periosteum is where bone grows in diameter
Describe how parathyroid hormone and calcitonin influence bone health and calcium homeostasis.
PTH - site of action = Kidney Tubules and bone cells Hormonal action - Activate calcitriol
many bones contain cavities filled with this - these give rise to blood cells and platelets
Red Bone Marrow
many bones contain cavities filled with this - this gives rise to blood cells and platelets
Red Bone Marrow
What are red and yellow bone marrows and where are they located in a child and in an adult?
Red Marrow - connective tissue in the spaces of spongy bone or in the medullary cavity; the site of blood cell production Yellow Marrow - Fat stored within the medullary cavity or in the spaces of spongy bone - Red Marrow is located in the spaces between the bones in a fetus. It can be found in the flat and long bones such as hip bones, vertebrae, ribs, shoulder blades, and skull
Short bones
Short Bones - not elongated and no diaphysis, may have a small epiphysis in certain places, mirrors long bone minus the above. - Carpals of the wrist (scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium), and the tarsals in the ankles (talus, calcaneus, navicular, cuboid, lateral cuniform, inetermediate cuneiform, and medial cuneiform)
Define Diaphysis (table 6.1)
Shaft of the bone
What types of cells give rise to osteoclasts?
Stem cells from red bone marrow
skeletal muscles attach to bones by these - they are strong bands of connective tissue
Tendons
During bone formation and growth, bones develop from centers of ossification the primary ossification center is in the ______________________________-
The Diaphysis
Outline the process of intramembranous ossification
The direct conversion of mesenchymal tissue into bone is called intramembranous ossification. This process occurs primarily in the bones of the skull. In other cases, the mesenchymal cells differentiate into cartilage, and this cartilage is later replaced by bone.
What is an epiphysis?
The ends of long bones
Explain the types of cartilage growth
There are 2 types: Appositional and interstitial growth. In Appositional growth chodroblasts in the perichondrium add new cartilage to the outside edge of existing cartilage. In interstitial growth, chondrocytes in the center of the tissue divide and add more matrix in-between the existing cells (figure 6.2)
Outline and explain the steps in bone repair (4 steps)
There are four stages in the repair of a broken bone: 1) the formation of hematoma at the break, 2) the formation of a fibrocartilaginous callus, 3) the formation of a bony callus, and 4) remodeling and addition of compact bone.
How do blood vessels from the periosteum or medullary cavity enter the bone?
Via Perforating Canals
Describe the factors that affect bone growth
Vitamin D. necessary for proper absorption of calcium. Growth Hormone. stimulates division of cartilage cells at epiphyseal plate. kissing Hormones. stimulate ossification of epiphyseal plate. physical exercise. stresses bones, stimulating bone tissue to strengthen and thicken.
Describe how new osteons are produced as bone increases in width
When a bone grows in width slowly, the surface of the bone becomes smooth as osteoblasts from the periosteum lay down even layers of bone to form circumferential lamellae. The circumferential lamellae break down during remodeling to form osteons.
What effect does aging have on the quality and quantity of bone matrix?
With age, bone matrix is lost and the matrix become more brittle
Describe the structure of woven and lamellar bone
Woven - The collagen fibers are randomly oriented in many directions. After woven bone formation, osteoclasts break down the woven bone and osteoblasts build new matrix Lamellar - is mature bone that is organized into thin, concentic sheets or layers approximately 3-7 micrometers thick called Lamellae. In general, the collagen fibers of one lamella lie parallel to one another, but at an angle to the collagen fibers in the adjacent lamellae. Osteocytes, within their lacunae, are arranged in layers sanwiched between lamellae.
Where are trabeculae oriented?
along stress lines
The functional unit of the long bone is
an Osteon
What are the two types of cartilage growth?
appositional and interstitial
Where are osteochondral progenitor cells are located?
arise from mesenchymal stem cells (MSC) in the bone marrow.
Osteoblasts
bone forming cells with an extensive endoplasmic reticulum and numerous ribosomes. they produce collagen and proteoglycans which are packaged into vesicles by the Golgi apparatus and released from the cell by exocytosis.
In Bone cell development connective tissue develops embryologically from mesenchymal cells. Some of the mesenchymal cells become __________________ _________________, some of which replicate and become more specialized cell types.
bone tissue
Name the spaces that are occupied by osteocyte cell bodies and cell extensions.
caniliculi = extensions lacunae = cell bodies
Hyaline cartilage ______________________________produce a matrix surrounding themselves
chondroblasts
by the time the matrix has surrounded a chondroblast, the cell has differentiated into a ____________________, a rounded cell that occupies a space called a ____________________ within in the matrix.
chondrocyte, lacuna
What is the zone of hypertrophy?
chondrocytes mature and enlarge
Define Epiphysis (table 6.1)
end of the bone
When bone stops growing in length, the epiphyseal plate becomes ossified and is called the ___________________________________________
epiphyseal line
What is the zone of resting cartilage?
farthest away from medullary cavity of diaphysis and nearest the epiphysis, consists of small chondrocytes and matrix of hyaline cartilage
What is the ruffled border?
fingerlike processes of the osteoclast that act to increase the surface area of the cell. The ruffled border extends into the subosteoclastic zone and facilitates delivery of digestive enzymes a
What is the epiphyseal plate and where is it located?
growth plate - Hyaline cartilage between the diaphysis and epiphysis; its growth allows for growth in bone length
How is calcium moved into and out of bone?
if blood calcium levels get low, the bone releases calcium to replenish the loss. And vise versa
How are osteocytes, within their lacunae, arranged
in concentric rings around a Central (haversian) canal
What does spongy bone consist of?
interconnecting rods or plates of bone called trabeculae. Between the trabeculae are spaces, which in life are filled with bone marrow and blood vessels
How do osteocytes retain their connections to neighboring osteocytes?
via their cell extensions
Describe the steps or endochondral ossification
(clean)Bones Cant Pop During Exercise Bone Collar Formation Cavitation Periosteal Bud Invasion Diaphysis Elongation Epiphiseal Ossification
Explain the differences in structure between long bones and flat, short, and irregular bones
Flat bones - interior framework of spongy bone sandwiched between two layers of compact bone - ribs, skull bones, scapulae, sternum Short Bones - not elongated and no diaphysis, may have a small epiphysis in certain places, mirrors long bone minus the above. - Carpals of the wrist (scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium), and the tarsals in the ankles (talus, calcaneus, navicular, cuboid, lateral cuniform, inetermediate cuneiform, and medial cuneiform) Irregular - not elongated and no diaphysis and some may have a small epiphysis in certain areas, mirros long bone compositions minus the above, -- vertebrae Sesamoid - bones reinforce tendons, small round bones are commonly found in the tendosn of hands, knees, and feet. Sesamoid bones function to protect tendons from stress and wear. The patella is an example of a sesamoid bone. Long Bones - support weight and moidfacilitate movement, are longer than they are wide, include the femur (longest bone in the body, and relatively small bones int he fingers. Located mostly in the appendicular skeleton and include bones in the lower limbs = tibia, fibula, femur, metatarsals, and phalanges. And in the upper limbs = The humerus, radius, ulna, metacarpals, and the phalanges.
What happens in bone when blood calcium levels decrease? When blood calcium levels increase?
when blood clacium decreases is is called Hypocalcemia When it increases is is called hypercalcemia
What is the zone of calcification?
very thin and contains hypertophied chondrocytes and calcified cartilage matrix. The hypertrophied chondrocytes die, and blood vessels from the diaphysis grow into the area. The connective tissue surrounding the blood vessels contains osteoblasts from the endosteum
Osteocyte in a lacuna with cell extensions in the canaliculi
via tiny channels called Caniliculi
Define callus
the material of repair in fractures of bone which is at first soft or cartilaginous in consistency, but is ultimately converted into true bone and unites the fragments into a single piece
Classify bones according to their shape
Flat bones - interior framework of spongy bone sandwiched between two layers of compact bone - ribs, skull bones, scapulae, sternum Short Bones - not elongated and no diaphysis, may have a small epiphysis in certain places, mirrors long bone minus the above. - Carpals of the wrist (scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium), and the tarsals in the ankles (talus, calcaneus, navicular, cuboid, lateral cuniform, inetermediate cuneiform, and medial cuneiform) Irregular - not elongated and no diaphysis and some may have a small epiphysis in certain areas, mirros long bone compositions minus the above, -- vertebrae Sesamoid - bones reinforce tendons, small round bones are commonly found in the tendosn of hands, knees, and feet. Sesamoid bones function to protect tendons from stress and wear. The patella is an example of a sesamoid bone. Long Bones - support weight and moidfacilitate movement, are longer than they are wide, include the femur (longest bone in the body, and relatively small bones int he fingers. Located mostly in the appendicular skeleton and include bones in the lower limbs = tibia, fibula, femur, metatarsals, and phalanges. And in the upper limbs = The humerus, radius, ulna, metacarpals, and the phalanges.
Compare the structure of a long bone with those of flat, short, and irregular bones. Explain where compact and spongy bones are found in each type.
Long bones, such as the femur, are longer than they are wide. Short bones, such as the carpals, are approximately equal in length, width, and thickness. Flat bones are thin, but are often curved, such as the ribs. Irregular bones such as those of the face have no characteristic shape.
Differentiate among the characteristics and functions of osteoblasts, osteocytes, and osteoclasts.
Osteoblast - derived from osteochondral progenitor cells, bone-forming cells, have an extensive endoplasmic reticulum and nurmerous ribosomes. They produce collagen and proteoglycans, which are packaged into vesicles by the Golgi apparatus and released from the cell by exocytosis. Osteoblasts also release matrix vesicles. Osteocytes -derived from osteblasts, Once an osteoblast has secreted enough bone matrix to become surrounded by it the cell is then referred to as an osteocyte. Retain their connections to neighboring osteocytes through their cell extensions. Osteocytes become relatively inactive, compared with most osteoblasts, but it is possible for them to produce the components needed to maintain the bone matrix. The spaces without matrix but occupied by the osteocytes bodies are called Lucunae, and the spaces occupied by the osteocyte cell extensions are called Canaliculi Osteoclasts - derived form red blood marrow, are bone destroying cells,perform reabsorbtion/break down of bone that mobilizes crucial CA2+ and phosphate ions for use in many metabolic processes. Most carry out reabsorption through a multistep process
List each type of bone cell and give the function and origin of each.
Osteoblast - derived from osteochondral progenitor cells, bone-forming cells, have an extensive endoplasmic reticulum and nurmerous ribosomes. They produce collagen and proteoglycans, which are packaged into vesicles by the Golgi apparatus and released from the cell by exocytosis. Osteoblasts also release matrix vesicles. Osteocytes -derived from osteblasts, Once an osteoblast has secreted enough bone matrix to become surrounded by it the cell is then referred to as an osteocyte. Retain their connections to neighboring osteocytes through their cell extensions. Osteocytes become relatively inactive, compared with most osteoblasts, but it is possible for them to produce the components needed to maintain the bone matrix. The spaces without matrix but occupied by the osteocytes bodies are called Lucunae, and the spaces occupied by the osteocyte cell extensions are called Canaliculi Osteoclasts - derived form red blood marrow, are bone destroying cells,perform reabsorbtion/break down of bone that mobilizes crucial CA2+ and phosphate ions for use in many metabolic processes. Most carry out reabsorption through a multistep process
Name the hormone that is the major regulator of Ca2+ levels in the body What stimulate the secretion of this hormone?
PTH/ Parathyroid Hormone
Define Articular cartilage (table 6.1)
Thin layer of hyaline cartilage covering a bone where it forms a joint (articulation) with another bone
What happens to the epiphyseal plate and the articular cartilage when bone growth ceases?
The rate of growth is controlled by hormones, which will be discussed later. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops. All that remains of the epiphyseal plate is the epiphyseal line
What are osteoblasts derived from?
They are derived from osteochondral progenitor cells (OPCs) Osteo = bone Chondr = cartilage
Define hematoma
is a localized mass of blood released from blood vessels but confined within an organ or a space. When a bone is fractured, the blood vessels in the bone and surrounding periosteum are damaged and a hemotoma forms.
What is woven bone remodeled into?
is remodeled into more permanent lamellar bone
Woven Bone
is the first type of bone that osteoblasts form during ossification. It is fairly weak bone because the collagen fibers are randomly oriented in many directions.
What is the zone of proliferation?
new cartilage is produced on the epiphyseal side of the plate as the chondrocytes divide and form stacks of cells
Describe the formation of new bone by appositional growth.
occurs when the cartilage model also grows in thickness due to the addition of more extracellular matrix on the peripheral cartilage surface, which is accompanied by new chondroblasts that develop from the perichondrium.
Once an osteoblast has secreted enough bone matrix to become surrounded by it the cell is then referred to as an ______________________
osteocytes
most cartilage is covered by a protective connective tissue sheath called the ________________________________________ which is a double layered outer layer of dense irregular connective tissue containing fibroblasts.
perichondrium Reticular Layer
