Lecture 5: Osseous Tissue Flashcards
Osseous Tissue
Bone Tissue
Functions of the Skeletal System
Support, Storage of Minerals, Storage of Lipids, Blood Cell Production, Protection, Leverage
Support of the Skeletal System
Body weight,
Muscles
Storage of Minerals in Skeletal System
Calcium and Phosphate ions (also needed in blood),
Provide Strength
Storage of Lipids in Skeletal System
Store Energy, Yellow Marrow (fat tissue),
Blood Cell Production in Skeletal System
Red Marrow (replen the lost blood cells)
Protection in Skeletal System
Protects organs
Leverage in Skeletal System
Force of motion/allow for movement
How Are Bones Classified?
Shape,
Internal Tissue Organization,
Bone Markings
Long Bones
Upper/Lower Extremities,
Long and thin,
Arms, legs, hands, feet, fingers, toes
Flat Bones
Thin with parallel surface,
Skull, sternum, ribs, scapulae
Sutural Bones
Small and irregular,
Bones in a suture,
Between flat bones of the skull
Irregular Bones
Complex Shapes,
Spinal Vertebrae,
Pelvic Bone,
Short Bones
Small and thick,
Ankle and wrist
Sesamoid Bones
Small and flat,
Inside tendons near joins of knees, hands, and feet
Bone Depression/Groove
Fossa,
Sulcus
Bone Projection/Processes
Connections to other bones
Bone Projections Where Tendons and Ligaments Attach:
Spine, Line, Crest, Tubercle, Tuberosity, Trochanter
Bone Projections Where Other Bone Articulations Occur:
Head, Condyle, Trochlea, Facet, Articular Process
Openings in Bones
Where blood vessels and nerves pass through the bone,
Foramen, Canal, Meatus, Fissure
Diaphysis of Long Bone
Shaft of bone,
Heavy wall of compact bone,
Central space (medullary cavity),
Epiphysis of Long Bone
Wide part at each end of bone,
Articulation with other bones,
Mostly spongy bone,
Covered with compact bone
Metaphysis of Long Bone
Where diaphysis and epiphysis meet
Epiphyseal Plates
Growth Plates,
Where active (growing) mitosis is occurring,
Typically in metaphysis (growth plates),
When plates close the person stops growing,
Able to determine age,
Close at different times depending on each bone
Structure of Flat Bone
2 Layers of compact bone covering spongy bone,
No marrow activity
Bone Matrix
Nonliving part of bone,
Made of Type 1 Collagen and Hydroxyapatite Crystals
How is Bone Matrix Made?
Collagen fibers provide a framework for a hydroxyapatite crystal to form on,
Tough but flexible
4 Types of Cells in Bones
Osteocytes,
Osteoblasts,
Osteoprogenitor Cells,
Osteoclasts
Osteocytes
Maintain bone matrix, Live in small pockets, Between the layers of matrix, Connect to adjacent cells by cytoplasmic extensions, Have gap junctions
Lacunae
Pockets where osteocytes live
Canaliculi
Tunnels to connect to neighboring lacunae
Gap Junctions of Lacunae
‘Holes’/Pores that canaliculi go out of lacunae from
Osteoblasts
Produce new bone, Immature bone cell, Secrete matrix compounds (osteogenesis), Contains Osteoid, Surrounded by bone and become osteocytes locked in the lacunae, Type 1 Collagen and Hydroxyapatite
Osteoid
Matrix produced by osteoblasts, but not yet calcified to form bone
Osteoprogenitor Cells
Stem cells that divide to produce osteoblasts,
Located in the Endosteum and Periodsteum,
Assist in fracture repair
Endosteum
Lining of the medullary cavity,
Layer of osteoprogenitor cells covering spongy bone,
Bottom/inside
Periosteum
Outer layer of fibrous tissue, inner layer of osteoprogenitor cells and osteoblasts,
Separates bone from other tissues,
Continuous with tendons and ligaments,
More likely to fracture bone around attachment than rip the tendon,
Tendons weave through bone to hold muscle
Osteoclasts
Break down bone,
Secrete acids and protein-digesting enzymes,
Most active in marrow,
Dissolve bone matrix,
Derived from stem cells that produce macrophages,
Used to get calcium from blood,
Always active along with osteoblasts
Osteolysis
Breakdown of bone
Compact Bone
Contains osteon, central canal and perforating canals
Osteon
Basic unit of compact bone,
Cylinder of tissue and blood vessels,
Can travel the length of entire bone,
Only in compact bone
Central Canal of Compact Bone
At center of each osteon,
Contain capillary and venule,
Provides nutrients to osteons
Perforating Canals
Vascular canals,
Pass through bone perpendicularly to long axis of bone,
Horizontal to supply central canal with nutrients
Concentric Lamellae
Rings of osteon,
Contains concentric layers around central canal
Circumferential/Outer Lamellae
Rings of bone tissue around outer surface of bone,
Allow for diameter growth in bone,
Around all osteons together (fill up empty space)
Spongy Bone
Contains trabeculae, Does not have osteons, Red bone marrow fills the space, Lightens bones, Provides strength
Trabeculae
Rods of calcified collagen,
Spongelike appearance formed by rods and plates
Bone Marrow
Occupies the medullary cavity in diaphysis of long bones or trabecular of spongy bone
Red Marrow
Produces Blood Cells,
Found in vertebrae, ribs, sternum, pelvic girdle, proximal heads of femur and humerus
Yellow Marrow
Fat storage
Ossification
Bone growth before birth,
Intramembranous,
Endochondral
Intramembranous Ossification
Within a membrane,
Bones grow in the dermis from the connective tissue,
Flat bones (skull, mandible, clavicle),
No cartilage template
Endochondral Ossification
Cartilage template laid down,
Osteocytes and osteoblasts form and create bone on the template
Primary Center of Endochondral Ossification
Blood vessels go into bone carrying osteoblasts with them to produce new bone,
Osteoclasts invade center to hollow out the middle of diaphysis
Secondary Center of Endochondral Ossification
Blood vessels go into the epiphysis and osteoblasts start making the ends
Interstitial Bone Growth
Length of bone
Appositional Bone Growth
Width of bone
Hormones that Control the Calcium Balance in Blood
Calcitriol,
Parathyroid glands,
Calcitonin
Calcitriol
Tells cells how to behave,
Stimulates intestine to absorb calcium,
Promotes osteoclast activity,
Increase blood calcium levels to maintain homeostasis
Parathyroid Hormone
Parathyroid glands,
Stimulates osteoclast activity,
Promotes calcium resorption in kidneys,
Promotes calcitriol synthesis in kidneys,
Inhibits bone deposition by osteoblasts,
Increase blood calcium levels to maintain homeostasis
Calcitonin
Reduces osteoclast activity,
Increases number and activity of osteoblasts,
Most important in children and development,
Decrease blood calcium levels to maintain homeostasis
4 Steps of Fracture Repair
- Formation of fracture hematoma (connection of blood)
- Cells of periosteum and endosteum divide rapidly and create an internal and external callus made of cartilage which is then replaced with bone
- Osteoblasts continue to replace cartilage and form complete bridge of bone from internal to external callus
- Remodeling by osteoclasts and osteoblasts takes up to a year (removing of the callus)
Cranial Bones
Enclose the cranial cavity,
Contains the brain, fluids, blood vessels, nerves, and membranes
Superficial Facial Bones
Muscle attachment
Deep Facial Bones
Separate the oral and nasal cavities,
form the nasal septum
Sinuses
Frontal,
Ethmoidal,
Sphenoidal,
Maxillary
Ribs
Mobile,
Absorb shock,
Affect the width and depth of thoracic cage
