Bone Biology Flashcards
The human skeleton is composed of ___ bones
206
When does the bone mass in the skeleton reach maximum density?
30 years old
Skeleton at birth contains how many bones?
300
Adult skeleton contains how many bones?
206
What is the axial skeleton?
- skull vertebral column, rib cage
- visceral skeleton (lower jaw, upper jaw, branchial arches, hyoid bone)
What is the appendicular skeleton?
bones of upper and lower limbs
The classification of human skeleton bones can be characterized by 5 shapes, what are they?
- long
- short
- flat
- irregular
- sesamoid
What is the function of long bones?
support weight and facilitate movement
What is the shape of short bones?
cube-shaped
What is the function of flat bones?
protect the internal organs
These type of bones have complex shapes
irregular bones
These type of bones reinforce tendons
sesamoid bnes
Long bones have a tubular bone shaft which consists of
bone collar surrounding a hollow medullary cavity
The hollow medullary cavity is filled with what?
yellow bone marrow in adults
What are the epiphyses? What do they consist of?
- found at ends of bone
- consist of internal spongy bone covered by a layer of compact bone
What is the epiphyseal line and where it is located?
- located between epiphyses and diaphysis
- remnant of epiphyseal plate
What is the external surface of the bone covered by?
periosteum which has the blood supply
What is the internal surface of the bone lined by?
endosteum which is a connective tissue membrane
Describe the general structure of short, flat, and irregular bones.
- thin plates of periosteum (outside)
- endosteum-covered spongy bone (inside) which houses bone marrow between trebeculae
How do you differentiate between cortical bone and trabecular bone?
- trabecular bone has holes
- cortical bone has no holes
Describe the general blood supply of long bones
- diaphyseal nutrient artery: most important for long bone
- diaphyseal nutrient artery divides into ascending and descending branches –> supply inner 2/3 or cortex and medullary cavity
- metaphyseal and epiphyseal arteries –> supply the ends of bones
- periosteal arterioles –> supply outer layers of cortical bone
Describe the general bone supply of large irregular bones, short bones, and flat bones
- superficial blood supply from periosteum
- form large nutrient arteries which penetrate into medullar bone
The periosteum and large nutrient arteries of the large irregular bones, short bones and flat bones ___ freely.
anastamose
**EXAM QUESTION ** What are the 6 functions of the human skeleton?
- support
- supports softer tissues
- provides points of attachment for skeletal muscles - protection
- internal organs, preventing injury (ex. cranial bones for brain, vertebrae for spinal cord, ribcage for heart and lungs) - assisting movement
- skeletal muscles attached to bones –> muscles contract –> bones move - resevoir for mineral
- Ca and P
- when minerals needed, bone releases minerals in the blood to balance minerals in body - storage of energy
- with age, red bone marrow –> yellow bone marrow
- yellow blone marrow consists mainly of adipose cells and few blood cells - production of blood cells
- red bone marrow inside larger bone cells which produce blood cells
What are the four major bone cells?
- osteoblasts
- osteoclasts
- osteocytes
- osteoprogenitor cells
What are osteoblasts? (7 points)
“build bone”
- form new bone
- come from bone marrow
- related to structural cells
- found on surface of new bone
- one nucleus
- produce new bone called “osteoid” made of collagen and protein
- control calcium and mineral deposition
What are osteoclasts (7 points)?
- “chew bone”
- dissolve the bone
- come from bone marrow
- related to white blood cells
- formed from two or more cells that fuse together
- more than one nucleus
- found on surface of bone mineral next to dissolving bone
What are osteocytes?
- cells inside the bone
- come from osteoblasts
- new bone will surround osteocytes
- not isolated because they send out long branches to connect other osteocytes
- can sense pressures or cracks in bone and help to direct where osteoclasts will dissolve the bone
Osteocytes form a complicated network within bone called the
lacuna-canaliculi system
What is the origin and function of osteoprogenitor cells?
origin
- mesenchymal stem cells
function
- low strain and high oxygen tension –> osteoblasts
- intermediate strain and low oxygen tenstion –> cartilage
- high strain - fibrous tissue
Skeletal development begins during the ____ of gestation and continues into the _____.
first trimester
postnatal years
Skeletal development occurs through two distinct processes, what are they?
- intramembranous ossification –> osteoblast
- endochondral ossification
–> chondrocyte
What is intramembranous ossification?
- osteoblasts line surface of the bone (lining cells)
- develop bone marrow cavity
- woven bone
What is endochondral ossification?
- hyaline cartilage template formed
- over time replaced by mineralized bone tissue
The epiphyseal growth plate is classified into __ zones
5
What is bone modeling? What is the primary function? Where does it occur?
- formation modeling: formation of bone by osteoblasts
- resporptive modeling: resorption of bone by osteoclasts
primary function
- increase bone mass and mantain/alter bone shape
occurs?
- preexisting bone surface
Differentiate between longitudinal growth and radial bone growth
True or false: During bone remodelling, bone formation and bone resorption must occur at the same location.
True
Bone remodeling can occur upon/within any of the four bone surfaces, what are they?
- periosteal
- endocortical
- trabecular
- intracortical
Compare and contrast modeling and remodeling of the bone
What is Wolff’s Law?
“Bone in a healthy person or animal will adapt to the loads under which it is placed”
According to Wolff’s Law, what happens if loading on a particular bone increases (i.e., baseball player or rower)?
bone will remodel itself over time to become stronger to resist that sort of loading
According to Wolff’s Law, what happens if loading on a bone decreases (i.e., astronauts in space)
the bone will become less dense and weaker due to lack of required for continued remodeling
What are the consequences of tooth loss?
