Skeletal Tissue Flashcards
What is the fxn of cartilage
- Covers articulating surfaces to reduce friction
- template for bone formation
- increases flexibility of the skeleton
Describe fibers that make up cartilage
a dense network of collagen fibers and elastic fibers embedded in a ground substance of chondroitin sulfate.
What fiber gives cartilage its strength?
Collagen
What Substance gives cartilage its plasticity
chondroitin sulfate
True or False cartilage has blood vessels
False
What are the 3 type of cartilage and describe them.
- Hyaline=most common, provides smooth surface for movement. (Think ends of log bones)
- Fibrocartilage= disc shaped, between bones, consist of thick bundles of collagen, very strong, tough (think vertebral discs)
- Elastic cartilage= chondrocytes located in network of elastic fibers, (makes up malleable part of ear)
What are the functions of bone tissues
- Supports soft tissues
- Protects organs
- Movement
- Mineral homeostasis (Ca and P)
- Blood cell production (red marrow)
- Triglyceride storage (yellow marrow)
Diaphysis
shaft or body of a long bone
Epiphysis
distal and proximal ends of the bones
Metaphysis
Where the diaphysis and epiphysis meet
Epiphyseal plate
an area of bone growth at the metaphysis
Articular cartilage
hyaline cartilage covering the epiphysis
Periosteum
dense irregular connective tissue that covers the bone (except articular cartilage)
Marrow cavity
space inside the diaphysis
Endosteum
membrane lining the marrow cavity
What is the make up of water, collagen, and hydroxyapatite
25% water, 25% collagen, 50% hydroxyapatite
Osteogenic cells
stem cells that can divide and change to osteoblast
Osteoblast
secrete bone matrix, become osteocytes
Osteocytes
mature bone cells, regulate bone matrix
Osteoclast
from macrophages, releases enzymes that breakdown bone for remodeling.
What are the 2 types of bones
Compact and spongy
-can be present within the same bone
Define osteons
units of compact bone formed by concentric lamellae
Define concentric lamellae
rings of calcified matrix
Define interstitial lamellae
fragments of older osteons that are between active osteons
Outer circumferential lamellae
lamellae that circles the whole bone, underneath the periosteum
Inner circumferential lamellae
lamellae that circles the marrow(medullary) cavity
Lacunae
small spaces between lamellae which house osteocytes
Canaliculi
small channels filled w/ extracellular fluid connecting lacunae
Where are blood and lymphatic vessels found in the bone.
In the central canal of the osteon
Volkmann’s (perforating) canals
Canals that allow transit of vessels to the outer cortex of the bone
Trabeculae
thin lattice columns in spongy bones that house lacunae
-spongy bones lack osteons
Where does hematopoiesis occur in the bone
red marrow located in spongy bone
In what 4 situations does bone formation occur
- bone formation in the embryo
- growth of bones until adulthood
- Remolding of bone
- repair of fracture
What are the 2 different methods osteogenesis can occur
- Intra-membrane ossification
2. endochondral ossification
Describe the process of intra-membranous ossification
- Simpler of the 2 bone formation methods, produces spongy bone initially
- Bone forms from mesenchymal cells that develop within a membrane
- Many ossification centers
Describe the process of endochondral ossification
- How most long bones are formed
- 1 primary and 2 secondary ossification centers
- Cartilage model forms
- Cartilage model grows
- Primary ossification center forms, and most cartilage tissue is replaced by bone
- Development of the marrow/medullary cavity by osteoclast
- Development of secondary ossification centers at the epiphyses
- Articular cartilage forms
Bone resorption
removal of minerals and collagen fibers from bone by osteoclast
Bone deposition
add minerals and collagen fiber to bone by osteoblast
Acromegaly
excessive bone formation causing abnormally thick and heavy
Osteomalecia
“adult rickets”, new bone is formed during remodeling but fails to calcify
-Usually caused by Vit D def
Rickets
childhood dz, new bone is formed at the epiphyseal plates but fails to osssify.
-Usually caused by Vit D def
Osteoporosis
resorption of bone outpaces deposition, usually caused by depletion of Ca
Osteoarthritis
degeneration of articular cartilage, creating bone on bone contact which results in friction
What are the 5 effects of bone remolding
- removes injured bone
- provides strengthening of bone tissue to meet the demand placed on it
- alteration of shape for better support
- more resistant to fx
- supports Ca homeostatis
What are the 4 steps for fx repair
- 6-8 hrs after injury, formation of fx hematoma
- 3 wks to 6 months, formation of fibro-cartilaginous callus, phagocytes remove cellular debris and fibroblast deposit collagen
- osteoblast form spongy bone callus by ossifying fibro-cartilaginous callus
- Remodeling boney callus, spongey bone replaced by compact bone. Takes several months
What Vitamins are necessary for normal bone metabolism and their fxns.
- Vitamin A= stimulates osteoblast
- Vitamin C=collagen formation
- Vitamin D (Calcitriol)= promotes absorption of Ca in the gut
- Vitamin K and B12= synthesis of bone protein
How much of the body’s Ca is stored in the bone
99%
Effect of Parathyroid Hormone on bone
Increases blood Ca by:
- promotes resorption of bone
- prevents loss of Ca in the urine
- promotes Vit D formation
Effect of Calcitonin on bone
Reduces blood Ca by inhibiting bone resorption
-made by parafollicular cells of the thyroid
What is a fibrous joint and the 3 types
Bone attached by fibrous connective tissue, it allows little movement
- Suture=thin layer of fibrous connective tissue (think skull)
- Syndesmoses= more space and fibrous connective tissue than suture (think between ulna and radius)
- Gomphoses= teeth sockets
What is a cartilaginous joint and the 2 types
Joint connected by cartilage (fibrocartilage or hyaline), NO synovial cavity, little or no movement
- Synchondroses= hyaline cartilage connecting bones, may ossify w/ age. (think epiphyseal plate)
- Symphyses= fibrocartilage connecting bone (think pubic symphysis)
What are the 4 parts of a synovial joint and describe them
- Articular capsule= dense irregular and regular connective tissue that surrounds the joint
- Synovial membrane= lines of articular capsule and secretes synovial fluid
- Synovial fluid= viscous fluid that lubricates the joints and allows diffusion of nutrient/waste
- Articular cartilage= covers epiphyses, not covered by synovial membrane
* may contain articular discs aka menisci
