Anatomy and physiology: skeletal system part 1

six functions of the skeleton

support, movement, protection, electrolyte balance, acid-base balance, blood formation

how many bones are in the adult human skeleton

206 named bones (born with 270 some fuse)

what are the two divisions of skeletal bones

axial skeleton and appendicular skeleton

axial skeleton

center axis

appendicular skeleton

appendages and bones that connect limbs to center axis

what are the different shapes of bones (4)

long bones, short bones, flat bones, irregular bones (clavicle does not fit in any category)

long bones

longer than wide, rigid levers acted upon by muscles

where are long bones located

arms, fingers, legs, feet

where are short bones located

carpals and tarsals

short bones

equal in length and width, glide across one another in multiple directions

flat bones

protect soft organs, curved but wide and thin

where are flat bones located

ribs, sternum, skull bones

irregular bones

elaborate shapes that don't fit into the other categories

where are irregular bones located

vertebrae

bone may be categorized as: (2)

compact or spongy

spongy bone (compact bone)

spongy bone will always have a layer of compact bone around it

diaphysis

long central region of bone

epiphysis

ends of long bones

metaphysis

where epiphyseal growth plate is located

articular cartilage

perforating fibers that connect with joints, hyaline cartilage used to stop bones from rubbing together

periosteum

dense irregular connective tissue, function - protection

medullary cavity

hollow cavity, that reduces mass

endosteum

another layer of tissue with cells that can break bone

yellow bone marrow

fat and energy storage

periosteum covers _____

the majority of the bone

periosteum layers

2 layers
outer - dense irregular connective tissue
inner - cells

periosteum functions

protection, nourishment, attachment for ligaments and tendons

periosteum ligament tissue

dense regular connective tissue

diaphysis description

bone shaft - compact bone

medullary cavity description

filled with yellow marrow, lined by endosteum - a single layer of cells

epiphysis description

proximal and distal ends of bone - mostly spongy bone, filled with red marrow, capped by articular cartilage (hyaline)

metaphysis description

region between diaphysis and epiphysis

epiphyseal plate

hyaline cartilage and growth zone, once you grow the places where growth plates where then is filled in with bone

bone blood supply

well supplied with blood from periosteal arteries and epiphyseal veins

periosteal arteries

accompanied by nerves supply the periosteum and compact bone

epiphyseal veins

carry blood away from long bones

periosteum is rich in what

sensory nerves, through compact bone there are small blood vessels

structure of a flat bone (sandwich construction)

two layers of compact bone enclosing a middle layer of spongy bone

diploe

spongy layer in the cranium that absorbs shock, makes head lighter and protective mechanism

extracellular matrix

surrounds widely separated cells

crystalized mineral salts

calcium phosphate

collagen fiber and crystalized minerals =

bone is flimsy and solid

osteogenesis imperfecta (another name)

brittle bone disease

osteogenesis imperfecta description

genetic defect in collagen

osteogenesis imperfecta type 1

children with some atypical physical characteristics, one (dominant) copy from one patent to have this genetic defect, there is no treatment

osteogenic cells

undergo cell division, produce osteoblasts

osteoblasts

bone-building cells, synthesize extracellular matrix bone tissue

osteocytes

mature bone cells, exchange nutrients and wastes with the blood

osteoclasts

release enzymes that digest the mineral components of bone matrix (resorption), regulates blood calcium level

these cells develop from each other

osteogenic cells -> osteoblasts -> osteocytes

osteoclasts form from

white blood cells that fuse together, break down bone = resorption

compact bone

resists the stresses produced by weight and movement

osteons

repeating structural units of compact bone

osteons consist of what

a central canal with concentrically arranged lamellae, lacunae, osteocytes, and canaliculi

osteocytes (in bone images)

black lines in the cells (osteons)

osteons (central canal)

have a central canal where blood vessels run through

what is around the central canals in osteons

concentric lamellae

what is between the concentric lamellae in osteons

small spaces called lacunae which contain osteocytes

what is around the lacunae in osteons

radiating in all directions are tiny canaliculi filled with extracellular fluid

spongy bone

within each trabeculae are lacunae that contain osteocytes

how are osteocytes nourished

from the blood circulating through the trabeculae

interior bone tissue made up of what

primarily spongy bone

trabeculae of spongy bone (orientation)

oriented along lines of stress, helps bones resist stresses without breaking

lamellae arrangement

arranged in a lattice of thin columns called trabeculae

trabeculae of spongy bone function

support and protect the red bone marrow

spongy bone description

no central canal, it has red bone marrow no need for a central canal