Bone Shape & Structure, Tissue, Cells

what is the function of the skeletal organ system?

support and structure

stores calcium, phosphate, and lipids

blood cell production

protection of organs

leverage

how many red blood cells are in the body?

25 trillion cells

how many cells make up the human body?

30 trillion cells

what is the percentage of red blood cells in the human body?

83% red blood cells

what is the average lifespan of a red blood cell?

3-4 months

how many red blood cells does your body make every minute?

3 million red blood cells per minute

how are bones classified?

shape and structure

what are the bone shapes?

sutural

irregular

short

flat

long

sesamoid

why are sutural bones important?

allows no movement

what makes sesamoid bones unique?

does not connect to any other bone; completely surrounded by tendons

what is the structure of a long bone?

diaphysis : shaft of bone made of compact bone with medullary cavity inside

epiphysis : wide part at the end of bone made of spongy bone

metaphysis : where diaphysis and epiphysis meet

what are the advantages of compact bone?

strong and absorbs compressive forces

what are the advantages of spongy bone?

flexible and resilient to bending without breaking

why is having a mix of compact and spongy bone important?

bones are good at resisting compressing forces while allowing the bone to bend without breaking

what is the structure of flat bones?

spongy bone in between two layers of compact bone

what is the percentage of extracellular matrix (protein) in bone?

98% of bone

what is the bone extracellular matrix?

2/3 is calcium phosphate, which is good at resisting compression

1/3 is collagen fibers, which is good at resisting stretch

why is having calcium phosphate and collagen fibers important for bones?

allows bone to be able to resist compression and stretch (very strong)

what percentage of bone mass are specialized cells?

2% of bone

what are the four types of bone cells?

osteogenic cells

osteoblasts

osteocytes

osteoclasts

which three bone cells are related?

osteogenic cells, osteoblasts and osteocytes

which bone cell is closely related to white blood cells?

osteoclasts

what are osteogenic cells?

stem cells that divide to produce osteoblasts

where are osteogenic cells located?

in periosteum and endosteum

what are osteoblasts?

immature cells that produce new bone matrix during osteogenesis (ossification)

how do osteoblasts become osteocytes?

osteoblasts surround itself in bone matrix

what are osteocytes?

mature cells gthat maintains proteins and mineral content of matrix

what is the structure significance of osteocytes?

has cytoplasmic extensions : branch-like structure that allows cell to be contact with bone matrix to maintain healthy level of mineralized collagen

what are osteoclasts?

destroys bone marrow

what is the structure of osteoclasts that allows it to dissolve bone marrow?

multinucleated, so it is able to produce lots of proteins because of DNA. allowing lots of digestive enzymes breaks down bone matrix

why do osteoclasts need to break down bone?

blood needs minerals (calcium)

remodel bone

why is the relationship between osteoblasts and osteoclasts important?

interaction between building and breaking bones maintains healthy bone matrix

what are the structures inside compact bone?

osteon : tree trunk

central canal : allows blood vessels to travel

lamellae : rings of tree trunk

lacunae : pockets where osteons live

what do spongy bones lack?

osteons because it is not as compact

what is the structure of spongy bone?

trabeculae : steel beams that extend through medullary cavity

bone marrow is in between trabeculae

what is the periosteum?

surrounds the outside of bone and is innervated

how does the periosteum of one bone reach the periosteum of next bone?

interwoven / continuous with joint capsule, allowing it to stay continuous with next bone’s periosteum

describe osteoarthritis

gradual loss of cartilage and causes inflammation inside joint

able to feel pain because synovial membrane (innervated) is impacted

what is the endosteum?

hollow structure where bone marrow lives

on internal surface of bone