Lecture Week 7 Flashcards
What are the bone cell types?
Osteoblast, Osteocyte, Osteoclast
What do osteoblasts do?
Bone “creating cell”, performs matrix deposition (ossification, osteogenesis)
Take calcium out of blood and put into bone tissue matrix
What is an osteocyte?
Mature bone cell in lacuna
What does an osteoclast do?
Bone “destroying” cell, performs matrix resorption, functions bone remodeling during growth, maxtrix mineral utilization
Take calcium from matrix to bone
Osteoblast process from calcium to blood
Calcium in blood —> calcium in bone matrix
Called matrix deposition
Osteoclast process from blood to calcium
Calcium in blood <—- calcium in bone matrix
Called matrix resorption
Osteon
Central canal (blood vessels and nerves) + concentric lamellae (matrix layers)
Osteocytes live in lacunae
True
How do canaliculi connect?
By neighboring lacunae (tunnels)
How do central canals connect?
by perforating canals
What are lamellae layers around?
Osteon
What does circumferential lamellae mean?
Surrounding around
What are interstitial lamellae?
Layers between osteon
What is the basic structural unit of spongy bone?
Trabeculae
What are trabeculae
Small interconnecting bars or plates that contain osteocytes in lacunae and lamellae
How are nutrients supplied to the osteocytes?
Canaliculi open onto the surface of each trabeculae so nutrients and gases can move in
How many methods of ossification are there?
2
Endochondral Ossification (of most bones)
Bone develops from a hyaline cartilage model, perichondrium of the diaphysis is replaced by bone, chondrocytes die, cartilage matrix breakdown, osteoblasts move in, blood vessels follow, osteoblast deposit bone matrix
Intramembranous ossification (of flat bones)
Bone develops within connective tissue membrane, cells from membrane become osteoblasts, spongy bone forms first then some is converted to compact bone, osteoblasts surrounded by matrix becomes osteocytes, remaining connective tissue forms periosteum, osteoblasts remain under periosteum to thicken bone
How does the bone lengthen in endochondral ossification?
Epiphyseal plates move away from diaphysis
During what month of prenatal development does ossification in long bones begin?
3rd month
During what month of prenatal development do most primary ossification centers will have appeared in diaphysis of bones?
4th month
When do secondary ossification centers appear in epiphysis?
Birth to 5 years
When are nearly all bones completely ossified?
23 years for females
25 years for males
Joint Capsule
Fibrous layer (dense regular connective) that is continuous with periostium
Synovial membrane (areolar) that secretes synovial fluid for lubrication or cushioning
Ligaments
Bind bones together and limit movement
Some are part of fibrous layer, some are separate, some run within joint, some surround
Menisci
Fibrocartilage pads between articulating surfaces that provide cushioning
Bursae
Synovial fluid filled cavities that provide cushioning
Sprains
Damage to dense connective tissue in a join
Takes a long time to heal bc of area being non-vascular
Generally do not heal
Fragments may be removed by arthroscopic surgery
Bursitis
Inflammation from trauma or overuse
ex. tennis elbow
Arthritis
Large number of disorders with joint swelling and pain
2 big types
Osteoarthritis and Rheumatoid Arthritis
Osteoarthritis
Associated with aging, most common form, wearing down of articular cartilage with age
Rheumatoid Arthritis (RA)
Autoimmune disorder that damages both cartilage and bone
May be disfiguring as scar tissue forms during healing
Not associated with aging process
Attacking body
Arthroscopic Surgery
Surgeon inserts camera and light source into joint cavity and uses forceps to grab damaged cartilage that has broken down into pieces
Names of joints (6)
Ball and socket, hinge, gliding, pivot, joint, condyloid
Ball and socket joint
Allows for greatest range of movement
ex. shoulder, hip bone
Condyloid joint
shapes convex and concave
Gliding joint
flat surfaces
ex. found in bones of wrist and tarsals in ankles
Hinge joint
provides little movement
ex. knee joints, elbow
Pivot joint
rotate
ex. shaking head
Saddle joint
look like a saddle, fit together
What are fibrous joints held together by?
Dense regular connective tissue
Synarthrosis
No movement in bones
Amphiarthrosis
Slight movement in bones
Diarthrosis
Bones move freely
What are the three kinds of fibrous joints?
Syndesmosis (interosseus ligament), Suture (sutural ligament), Gomphosis (periodontal ligament)
What are the two kinds of cartilaginous joints?
Synchondrosis (hyaline cartilage), Symphasis (hyaline cartilage/fibrocartilage disc)
