Bones and Cartilage Flashcards
Bones and cartilage are what types of tissue? What characterizes this tissue?
Connective tissue
Come from the mesenchyme and has a lot of ECM
Perichondrium
Layer of dense connective tissue that surrounds cartilage
Resists outward pressure
Functions in growth and repair of cartilage
Characteristics of cartilage
Has perichondrium
Consists primarily of water (mostly in the matrix)
Is a resilient tissue
What cell type makes up cartilage?
Chondrocyte
Hyaline (glass) cartilage
Appears translucent
Most abundant cartilage
Chondrocytes appear spherical
Collagen unit fibril is the ONLY type of fiber in the matrix
Ground substance holds a large amount of water
Provides support through flexibility
Elastic cartilage
Contains many elastic fibers
Yellowish in colour
Able to tolerate repeated bending
Located in epiglottis and cartilage of external ear
Fibrocartilage
Resists strong compression and tension
An intermediate between hyaline and elastic
Located in pubic symphysis, menisci of knee, and anulus fibrosus
Does NOT have the perichondrium
Lacuna
Cavities in the matrix
Cells reside here
Appositional growth
Growth from the outside
Chondroblasts in surrounding perichondrium produce new cartilage
Interstitial growth
Growth from within
Chondrocytes within cartilage divide and secrete new matrux
5 functions of bone
Support and protection
Movement (skeletal muscles use bones as levers)
Mineral storage (reservoir for important minerals like calcium and phosphate)
Blood cell formation (bone contains red marrow)
Energy metabolism (osteoblasts secrete osteocalcin)
Osteocalcin
Secreted by osteoblasts
Can effect tissue sensitivity to insulin and the levels of insulin secretion
Organic versus inorganic components of bone tissue
Organic: 35% - cells, fibers, and ground substance - contribute to flexibility and tensile strength
Inorganic: 65% - mineral salts that invade bony matrix - provide exceptional hardness, resist compression
Osteogenic cells
Stem cells that differentiate into osteoblasts
Osteoblasts
Actively produce and secrete bone matrix
Bone matrix is osteoid
Osteocytes
Keep bone matrix healthy
Osteoclasts
Found within bone tissue
Responsible for resorption of bone - eat it up - bones are constantly being remodelled
Are derived from a line of white blood cells
Secrete hydrochloric acid and lysosomal enzymes
4 types of bones
Long bones
Flat bones
Short bones
Irregular bones
Compact bone
Dense outer later
Contains passage ways for blood vessels, lymph vessels, and nerves
Spongy (cancellous) bone
Internal network of bone
Trabeculae
Little “beams” of bone in spongy bone
Open spaces between trabeculae are filled with marrow
Diaphysis
Shaft of long bones
Epiphysis
Ends of long bones
Periosteum
Outer covering of bone
Helps the bone heal when it is injured
Endosteum
Inner lining of bones
Medullary cavity
Hollow cavity filled with yellow marrow (fat cells)
Diploe
Internal spongy bone of flat bones
Structure of flat bones, short bones, and irregular bones
Contain bone marrow but no marrow cavity
Have diploe
Outer and inner table
Osteons
Also called Haversian system
Long cylindrical structures
Function in support
Structurally resemble rings of a tree in cross section
Rings are made out of the matrix with collagen fibers in it
Contain: lamellae, central canal, perforating canals, and canaliculi
Haversian canal
Central canal
Contains nerves and blood vessels
Volkmann’s canal
Perforating canals
Connect Haversian systems
Canaliculi
Tiny canals
Way for osteocytes to connect to one another
Act like gap junctions
Pass nutrients
Ossification (definition, and 2 different types)
Bone formation
Intramembranous ossification
Endochondral ossification
Intramembranous ossification
Membrane bones
Formed directly from mesenchyme
There is a membrane and then ossification begins on the membrane
Endochondral ossification
All bones except some bones of the skull and clavicles
Bones are modelled in hyaline cartilage
Begins forming late in the second month of embryonic development
Continues forming until early adulthood
In epiphyseal plates of growing bones…
Cartilage is organized for quick, efficient growth
Cartilage cells form tall stacks (chondroblasts at the top of stacks divide quickly)
Pushes the epiphysis away from the stalk to lengthen entire long bone
Growth hormone
Produced by the pituitary gland
Stimulates epiphyseal plates
Thyroid hormone
Ensures that the skeleton retains proper proportions
Sex hormones
Promote bone growth
Later induces closure of epiphyseal plates
Osteoclast
Bone-degrading cell Giant cell with many nuclei Crawls along bone surfaces Breaks down bone tissue Secreted concentrated HCl Lysosomal enzymes are released Derived from hematopoietic stem cells
Osteoporosis
Characterized by low bone mass
Bone resorption outpaces bone deposition
Occurs most often in women after menopause
Osteomalacia
Occurs in adults
Bones are inadequately mineralized
Rickets
Bones are weak
Vitamin D deficiency
Occurs in children
Analogous to osteomalacia
Osteosarcoma
A form of bone cancer
3 places to find fibrocartilages
In the vertebral column
Pubic symphysis
Knee
Everywhere else (except the ear) is hyaline
