Skeletal Tissues Flashcards
What comprises a part of the skeleton where flexibility is required?
Cartilage
What is the template for bone formation?
Cartilage
What does cartilage consist of?
Dense network of collagen fibers and elastic fibers embedded in a jelly like ground substance of chondroitin sulfate.
What is the strength of the cartilage due to?
Collagen fibers
What is the resilience (plasticity) of cartilage due to?
Chondroitin sulfate
Cells of mature cartilage are? and are derived from what?
Chondrocytes
Chondroblasts
Where do chondrocytes reside?
In spaces called lacunae (little lakes)
What is most cartilage covered by?
Dense, irregular connective tissue called perichondrium
After becoming vascularized, the perichondrium becomes the?
Periosteum
True or False
Cartilage has blood vessels
False
Where does cartilage have nerves?
The perichondrium
What is relatively inactive, grows slowly, and heals poorly? Why?
Cartilage
Lack of intrinsic blood supply and confinement of chondrocytes to lacunae.
What are the types of cartilage?
Hyaline
Fibrocartilage
Elastic
What is the most abundant type of cartilage?
Hyaline cartilage
Hyaline cartilage covers what?
The ends of long bones and parts of the ribs, nose, trachea, bronchi, and larynx.
What does hyaline cartilage provide for joint movement?
A smooth surface
What is fibrocartilage made of?
Thick bundles of collagen fibers, very strong, and tough cartilage.
Fibrocartilage typically occurs as a ______-_____ segment of ________ between bones.
Disc-shaped
Cartilage
What does elastic cartilage consist of?
Chondrocytes located in a threadlike network of elastic fibers.
What parts does the elastic cartilage make up?
External ear and epiglottis
What are the functions of bone tissue?
Support of soft tissues Protection of internal organs Assistance in movement Mineral homeostasis Blood cell production Triglyceride storage
What is mineral homeostasis?
Storage of calcium and phosphorus
What is triglyceride storage?
Yellow bone marrow is adipose connective tissue.
What is the diaphysis of the bone?
Shaft of body
What is the Epiphyses of bone?
Distal and proximal ends
What is the metaphysis?
Where the diaphysis and epiphyses meet.
What is the epiphyseal plate?
At the metaphysis of a growing bone
What is the articular cartilage?
Hyaline cartilage covering the epiphyses
What is the periosteum?
Dense irregular connective tissue that covers the bone (except for the articular cartilage)
What is the marrow cavity?
Space inside the diaphysis
What is the endosteum?
Membrane lining the marrow cavity
What does the bone matrix consist of?
Water-25%
Collagen- 25%
Calcium- 50% (hydroxyapatite- Ca phosphate and Ca carbonate)
What are stem cells that can divide and differentiate into osteoblasts?
Osteogenic cells
What secrete bone matrix; become osteocytes?
Osteoblasts
What are mature bone cells; regulate the composition of bone matrix?
Osteocytes
What release enzymes that digest bone matrix for remodeling of bone?
Osteoclasts
Regions of the bone may be categorized as?
Compact Bone (AKA cortical bone) Spongy Bone (AKA cancellous bone, trabecular bone)
Most of the skeleton is this type of bone?
Compact bone
True or False
Both compact and spongy bone may be present within the same bone.
True
Compact Bone contains units called?
Osteons or Haversian systems formed from concentric lamellae
What are concentric lamellae?
Rings of calcified matrix
What are interstitial lamellae?
Between osteons are left over fragments of older osteons.
What encircles the bone beneath the periosteum?
Outer circumferential lamellae
What encircles the medullary cavity?
Inner circumferential lamellae
What are small spaces between the lamellae which house osteocytes?
Lacunae
What are small channels filled with extracellular fluid connecting the lacunae?
Canaliculi
Blood and lymphatic vessels found in the osteon’s?
Central Canal
These allow transit of these vessels to the outer cortex of the bone.
Perforating Canals
True or False
Spongy bone has osteons
False
What does spongy bone have instead of osteons?
Trabeculae.
What is trabeculae?
Lamellae arranged in a lattice of thin columns
What does trabeculae of the spongy bone support and protect?
The red bone marrow
Helps bones resist stresses without breaking.
Where are trabeculae oriented?
along lines of stress
What is hematopoiesis and where does it occur?
Blood cell production and occurs in spongy bone.
What is inside each trabecula of spongy bone?
Lacunae
What does the lacunae contain?
Osteocytes that nourish the mature bone tissue from the blood circulating through the trabeculae.
What is the interior of the long bones made up of?
Spongy bone.
What does spongey bone do to the overall weight of the bone?
Lessens it
What is ossification (osteogenesis)?
Process of forming new bone.
What are the four situations of bone growth?
Formation of bone in an embryo
Growth of bones until adulthood
Remodeling of bone
Repair of fractures
Beginning at the 6th week of embryonic development, occurs by what two methods?
Intra-membranous ossification
Endochondral Ossification
What does intra-membranous ossification produce?
Spongy bone.
The bone may subsequently be remolded to form compact bone.
What is Endochondral ossification?
Process whereby cartilage is replaced by bone. Forms both compact and spongy bone.
What is the simpler of the two methods of bone formation?
Intra-membranous ossification
What is intra-membranous ossification used in forming?
the flat bones of the skull, mandible, and clavicle.
What cell does bone form from and what stage does it skip?
From mesenchymal cells that develop within a membrane. They skip a cartilage stage.
True or False
Intra-membranous ossification has many ossification centers.
True
Endochondral ossification is the method used in the formation of?
Most bones, especially long bones.
What does endochondral ossification involve when it comes to the development of the bone? How many centers of growth are there?
It replaces cartilage by bone
There is one primary and two secondary centers of growth.
When is ossification contributing to bone length usually complete by (age)?
18-21 years of age
What is bone remodeling?
The ongoing replacement of old bone tissue by new bone, which involves:
Bone resorption
Bone deposition
In bone remolding, what is the removal of minerals and collagen fibers from bone by osteoclasts?
Bone resorption
In bone remolding, addition of minerals and collagen fibers to bone by osteoblasts?
Bone deposition
If too much new bone tissue is formed the bones become?
abnormally thick and heavy (acromegaly
Excessive loss of calcium in bone growth and remolding does what?
Weakens the bones, as occurs in osteoporosis
If there is not a balance between the actions of osteoclasts and osteoblasts, what may happen to bone?
Acromegaly
Weakened bones
Bones become too soft, as seen in diseases rickets and osteomalacia.
Bone remodeling removes injured bone and replaces is with?
New bone
What provides for strengthening of bone tissue to meet demands placed on it by new or heavy loads?
Bone remodeling
Which bone is more resistant to fracture, new bone or old bone?
New bone
True or False
Bone remodeling does not support calcium homeostasis
False
What is experienced during bone remodeling that better support based on stress patterns?
Alternation of bone shape
What is formed during the first step of a fracture and repair of a bone?
Formation of a fracture hematoma occurring 6-8 hours after injury.
What is the fracture hematoma a result of?
Blood vessels breaking in the periosteum and in osteons.
The second and third step of fracture and Repair, involves the formation of?
A callus (takes a few weeks to 6 months).
How is the fibrocartilaginous callus formed?
Phagocytes remove cellular debris and fibroblasts deposit collagen to form a fibrocartilaginous callus
What is followed by the formation of fibrocartilaginous callus?
Osteoblasts forming a bony callus of spongey bone.
What is the final step of fracture and repair that take several months is called remodeling?
Spongy bone is replaced by compact bone
The fracture line disappears, but evidence of the break remains.
Vitamin A stimulates the activity of?
Osteoblasts
Vitamin C is needed for synthesis of?
Collagen
Vitamin D is essential for?
Healthy bones
What does vitamin D promote?
the absorption of calcium from foods in the GI tract into the blood.
Vitamins K and B12 are needed for synthesis of?
Bone proteins
What is required for synaptic transmission, muscle contraction, and blood clotting?
Calcium
What stores 99% of the body’s calcium?
Bone
The reserve of calcium in the bone, is used to regulate the what in the blood?
The level of calcium
What does the parathyroid hormone do?
Promotes resorption of bone matrix
Prevents loss of calcium in the urine
Promotes Vitamin D (calcitriol) formation
Calcitonin is produced by what cells of what gland? What does it do?
Parafollicular cells of the thyroid gland
Lowers blood calcium levels by inhibiting bone resorption
What are the two main ways that the blood calcium can be increased due to the regulation of blood calcium concentration?
Release of calcium from bone matrix and retention of calcium by the kidneys
What is a point of contact between two bones, between bone and cartilage, or between bone and a tooth?
Joints
What are bones attached by?
Fibrous connective tissue.
In fibrous joints, what is a thin layer of fibrous connective tissue.
Sutures
In fibrous joints, more space than a suture; more fibrous connective tissue?
Syndesmoses
In fibrous joints, teeth in sockets of upper and lower jaw.
Gompgoses
Joint components of this are connected by cartilage
Cartilaginous
What are the types of cartilaginous joints?
Synchondroses
Symphyses
What are some characteristics of cartilaginous joints?
Fibrocartilage or hyaline cartilage
No synovial cavity
Little or no movement.
In cartilaginous joints, AKA primary cartilaginous joints Hyaline cartilage connecting bones’ cartilage may ossify with age
Synchondroses
In cartilaginous joints, AKA secondary cartilaginous joints: fibrocartilage connecting bone.
Symphyses
What joints are most moveable?
Synovial joints
What joint has an articular capsule: dense irregular and regular connective tissue?
Synovial joints
What membrane lines the synovial joint that secrets synovial fluid?
Synovial membrane
In the synovial joint, what allows for diffusion of nutrient and wastes?
Synovial fluid
What joint has articular cartilage: covers epiphyses of bone?
Synovial Joints
The articular cartilage of the synovial joints is not covered by what membrane?
The synovial membrane
What discs may synovial joints contain?
Articular discs (also called menisci)
