Cancellous bone is characterized by these needle-like structures.
Trabecullae
The open spaces of the trabecullae is partially filled with...
red bone marrow.
What are the two main structural components of a long bone?
Diaphysis - main shaft
Epiphyses - the ends
What is the main function of long bones?
Function is to provide strong support without cumbersome weight.
What part of long bones will you find red bone marrow?
Epiphyses
What is the main function of the epiphyses of long bones?
Function is to provide attachments for muscles and give stability to joints.
Layer of hyaline cartilage that covers the articular surface of epiphyses.
Articular cartilage
What is the main function of articular cartilage?
Function is to cushion jolts and blows.
This part of the long bone has the following characteristics:
Dense, white, fibrous membrane that covers bone Attaches muscle tendons firmly to bones
Contains cells that form (osteoblasts) and destroy (osteoclasts) bone
Contains blood vessels important in growth and repair
Contains blood vessels that send branches into bone (through volkman’s canals & Haversian canals)
Essential for bone cell survival and bone formation
Periosteum
What is the main function of the periosteum of long bones?
Attaches muscle tendons firmly to bones.
Thin epithelial membrane that lines medullary cavity of long bones.
Endosteum
Spaces inside cancellous bone of a few irregular and flat bones are filled with...
red marrow.
Bone tissue is the most distinctive form of this type of tissue.
Connective tissue
Components of bone tissue that are hard and calcified.
Extracellular components
What characteristic of bone allows it to serve its supportive and protective functions.
Rigidity
What is bone's tensile strength nearly equal to at less than one third the weight.
Cast iron
What are the two general components of bone matrix?
Inorganic salts
Organic matrix
Highly specialized chemical crystals of calcium and phosphate in the bone matrix that contribute to bone hardness.
Hydroxyapatite
Besides calcium and phosphate, what other two inorganic salts are found in the bone matrix?
Magnesium
Sodium
Composite of collagenous fibers and an amorphous mixture of protein and polysaccharides in the organic portion of the bone matrix.
Ground substance
Ground substance is secreted by...
connective tissue cells.
The function of the organic portion of bone matrix is that it...
adds to overall strength of bone and gives some degree of resilience to the bone.
These transverse canals connect to the Haversian canals that run lengthwise through the bone.
Volmann's canals
What are the main functions of osteons?
Osteons permit delivery of nutrients and removal of waste products
What are the four structures that make up each osteon?
Lamella
Lacunae
Canaliculi
Haversian canal
Concentric, cylinder-shaped layers of calcified matrix.
Lamella
Small spaces containing tissue fluid in which bone cells are located between hard layers of the lamella.
Lacunae
Ultrasmall canals radiating in all directions from the lacunae and connecting them to each other and to the Haversian canal.
Canaliculi
Extends lengthwise through the center of each osteon and contains blood vessels and lymphatic vessels.
Haversian canal
How are nutrients delivered and waste products removed in cancellous bone?
Canaliculi
Where do bone cells get their blood supply?
Red bone marrow
Bone-forming cells found in all bone surfaces.
Osteoblasts
Bone cell with the following characteristics:
Bone-destroying cells found also on bone surface Giant multinucleate cells Responsible for the active erosion of bone minerals Contain large numbers of mitochondria and lysosomes
Osteoclasts
Mature, nondividing osteoblast surrounded by matrix, lying within lacunae.
Osteocytes
Osteoblasts synthesize and secrete...
osteoid, an important part of the ground substance.
Collagen fibrils line up in osteoid and serve as a framework for the deposition of calcium and phosphate.
Bone marrow is made of this specialized type of soft, diffuse connective tissue.
Myeloid tissue
Where are blood cells produced?
Red bone marrow
Where are yellow and red bone marrow located?
Found in medullary cavities of long bones (yellow inactive-fat)
The spaces of spongy bone (red-active-hematopoietic tissue)
The two types of bone marrow.
Red
Yellow
True or False. Red marrow is found in virtually all bones in an infant’s or child’s body.
True
As an individual ages, red marrow is replaced by...
yellow marrow.
What does yellow marrow become saturated with?
Fat
Does yellow marrow produce blood cells?
No
What are the main bones in an adult that still contain red marrow?
Ribs
Bodies of the vertebrae
Pelvis
Proximal ends of the humerus and femur
What three instances does yellow marrow alter to red marrow?
Decreased blood supply, such as with anemia
Exposure to radiation
Certain diseases
What are the five main functions of bone?
Support
Protection
Movement
Mineral storage
Hematopoiesis
Term for blood cell formation that is carried out by myeloid tissue.
Hematopoiesis
What percent of calcium reserves are stored in the skeletal system?
98 percent
How is homeostasis of calcium maintained in the blood?
Bone remodeling
What four things make homeostasis of calcium ion concentration essential:
Bone formation, remodeling, and repair
Blood clotting
Transmission of nerve impulses
Maintenance of skeletal and cardiac muscle contraction
What two hormones regulate calcium homeostasis?
Parathyroid hormone
Calcitonin
What hormone is the primary regulator of calcium homeostasis?
Parathyroid hormone
How does parathyroid hormone increases blood calcium levels (3 things)?
Stimulates osteoclasts to initiate breakdown of bone matrix and increase blood calcium levels
Increases renal absorption of calcium from urine
Stimulates vitamin D synthesis
Protein hormone produced in the thyroid gland in response to high blood calcium levels (it decreases blood calcium levels).
Calcitonin
What two things does calcitonin do to decrease blood calcium levels?
Stimulates bone deposition by osteoblasts
Inhibits osteoclastic activity
Is calcitonin as important as parathyroid hormone in the regulation of calcium homeostasis?
Calcitonin is far less important in homeostasis of blood calcium levels than parathyroid hormone.
Combined action of osteoblasts and osteoclasts to mold bones into adult shape.
Osteogenesis
Type of osteogenesis that occurs within a connective tissue membrane.
Intramembranous ossification
Intramembranous ossification is osteogenesis for what two bone types?
Flat bones
Spongy bones
Type of osteogenesis that forms the long bones and compact bone.
Endochondral ossification
Type of osteogenesis where most bones begin as a cartilage model, with bone formation spreading essentially from the center to the ends.
Endochondral ossification
Cartilage plage that is between the epiphysis and the diaphysis and allows growth to occur; sometimes referred to as a growth plate.
Epiphyseal plate
What are the four layers of the epiphyseal plate from top to bottom?
“Resting” cartilage cells —point of attachment joining the epiphysis to the shaft
Zone of proliferation —cartilage cells undergoing active mitosis, causing the layer to thicken and the plate to increase in length
Zone of hypertrophy —older, enlarged cells undergoing degenerative changes associated with calcium deposition
Zone of calcification —dead or dying cartilage cells undergoing rapid calcification
The term that describes the following:
-Bones grow in diameter by the combined action of osteoclasts and osteoblasts
-Osteoclasts enlarge the diameter of the medullary cavity
-Osteoblasts from the periosteum build new bone around the outside of the bone
Bone remodeling
Blood clot occurring immediately after the fracture, is then resorbed and replaced by callus.
Fracture hematoma
This initiates repair of fractures.
Vascular damage
Specialized repair tissue that binds the broken ends of the fracture together.
Callus
Is cartilage vascular or avascular?
Avascular
How do chondrocytes receive oxygen and nutrients?
Diffusion
What is responsible for appositional cartilage growth?
Inner cellular layer of the perichondrium
What are the three types of cartilage?
Hyaline
Elastic
Fibrocartilage
What is the most common type of cartilage?
Hyaline
This type of cartilage covers the articular surfaces of bones.
Hyaline
This type of cartilage forms the costal cartilages, cartilage rings in the trachea, bronchi of the lungs, and the tip of the nose.
Hyaline
Type of cartilage that forms external ear, epiglottis, and eustachian tubes
Elastic cartilage
Strongest type of cartilage.
Fibrocartilage
Type of cartilage that occurs in symphysis pubis and intervertebral disks.
Fibrocartilage
What are three functions of cartilage?
Gristle-like nature permits cartilage to sustain great weight or serve as a shock absorber
Strong yet pliable support structure
Permits growth in length of long bones
Name the type of cartilage growth:
-Cartilage cells divide and secrete additional matrix
-Seen during childhood and early adolescence while cartilage is still soft and capable of expansion from within
Interstitial or endogenous growth
Cartilage growth following following mitosis and secretion of matrix by chondrocytes; interstitial growth of epiphyseal plate results in growth in length of long bones.
Interstitial or endogenous growth
What are the two types of cartilage growth?
Interstitial or endogenous growth
Appositional or exogenous growth
Name the type of cartilage growth:
-Chondrocytes in the deep layer of the perichondrium divide and secrete matrix
-New matrix is deposited on the surface, increasing its size
-Unusual in early childhood but, once initiated, continues throughout life
Appositional or exogenous growth
Most bones of the body are formed from cartilage models in a process called...
endochondral ossification.
Calcification of the organic bone matrix occurs when:
complex calcium salts are deposited in the matrix.
Until bone growth in length is complete, a layer of the cartilage, known as the _____, remains between the epiphysis and diaphysis.
epiphyseal plate
Appositional growth of cartilage occurs when chondrocytes begin to divide and secrete...
additional matrix.
Compact bone contains many cylinder-shaped structural units called:
lamellae.
Scapulae are example of ____ bones.
flat
The patella is an example of a ____ bone.
sesamoid
The carpal is an example of a ____ bone.
short
Vertebra is an example of an ____ bone.
irregular
The cells that produce the organic matrix in bone are:
osteoblasts. They secrete osteoid.
The primary ossification center is located in the:
diaphysis.
Secondary ossification centers are located in the:
epyphyses.
Bone loss normally begins to exceed bone gain between the ages of:
35 and 40 years.
When bones have grown their full length, the epypheseal plate...