PSIO 201 - Unit 2

each bone is an

organ

what does a bone contain that classifies it as an organ?

bone CT, blood vessels and nerves, lymphatic vessels, cartilage CT, and connective tissue coverings

skeletal system functions

support, protection, leverage, mineral homeostasis (storage and release), triglyceride storage, hemopoiesis

Hemopoiesis

red and white blood cell formation. found in red marrow!

where is triglyceride stored in bones?

yellow marrow

importance of mineral homeostasis?

critical for keeping blood calcium levels regulated.

axial skeleton

apendicular skeleton

how many bones are in the human body?

206

long bones

longer than they are wide

short bones

cube shaped bones. equal in l and w

flat bones

thin, flattened, and usually curved

irregular bones

vertebrae and facial bones

seasmoid bones

round bone typically around a joint

sutural bones

tiny bones between cranial bones

pneumatized bones

a bone that is hollow or contains many air cells

Diaphysis of long bone

shaft

epiphysis of long bone

Metaphysis of long bone

Periosteum (long bone)

outer lining of bone

Endosteum (long bone)

inner lining of bone

medullary cavity

cavity within the shaft of the long bones filled with bone marrow

compact bone

dense bone connective tissue on the outside (hard covering)

spongy bone

porous bone on the inside in the epiphysis

what two components are important for bone growth and remodeling?

endosteum and periosteum

Articulation

joint. point of contact of two bones together, bones and cartilage, and bones and teeth.

study of joints

arthrology

kinesiology

study of body movement

the more stable the joint is the ____ mobility (and vice versa)

less mobility

joint classifications via anatomical structure

fibrous, cartilaginous, synovial

joint classifications via function

synarthrosis, amphiarthrosis, and diarthrosis.

Synarthrosis

immovable joint

Amphiarthrosis

slightly movable joint

Diarthrosis

freely movable joint

true or false: all diarthrosis joints are synovial?

true

synovial joints

Freely movable joints with synovial fluid.

fibrous joints

generally immovable

cartilaginous joints

bones held together by cartilage

synovial fluid does what?

lubricates joint, provides nutrients for cartilage, and absorbs shocks

osteoarthritis (OA)

overuse (bone on bone contact) - degenerative disease

rheumatoid arthritis

Chronic autoimmune disease which attacks the healthy joint tissue causing inflamed joints

The shoulder is an example of which type of synovial joint?

the most free moving = least stable

how many muscles does the shoulder rely on to keep it stable?

4

what cushions the joint in the knee?

medial and lateral menisci

name the 2 intracapsular ligaments of the knee

anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)

ACL

anterior cruciate ligament of the knee; prevents forward movement

PCL

posterior cruciate ligament of knee; prevents backward movement

what test can be done to see if you've injured your ACL or PCL?

drawer test!

Osteology

study of bone tissue

what makes up connective tissue?

cells and extracellular matrix

cells within bone connective tissue

osteogenic cells, osteoblasts, osteocytes, and osteoclasts.

osteogenic cell

what does an osteogenic cell do?

develops into an osteoblast

osteoblast

what does an osteoblast do?

builds new bone (bone formation), builds matrix (collagen fibers), initiates calcification (taking calcium from blood and depositing it in bone).

osteocyte

what does an osteocyte do?

maintains bone health, found in lacunae.

osteoclast

from myeloid tissue

what do osteoclasts do?

break down damage (resorption)

sealing zone (SZ) of osteoclast

blue portion - seals itself to the bone

ruffled border (RB) of osteoclast

red portion - "teeth" which increase surface area and releases enzymes and acids (for breakdown)

functional secretory domain (FSD) of osteoblast

green portion - where trancytosis occurs, recycling of nutrients from the cell pushing it back out into the blood stream.

goals of bone remodeling

strength for loading, lightness for mobility

in class example of bone remodeling

tennis player! repeated movement, increased loading, bones must be strengthened for their function.

steps of bone remodeling

1. Activation

2. Resorption

3. Reversal

4. Formation

5. Quiescence

extracellular marix of bone connective tissue contains what two components?

ground substance and fibers (collagen)

ground substance contains

glycoproteins (polysaccharide + protein)

GAG's are negatively charged, so what does it do?

traps water! like in hyaluronic acid skincare.

collagen fibers

helical form, provide strength, resistant to forces/tension

what is type 1 collagen made of?

polypeptide chains, using 3, creating a tropocollagen chain.

what do tropocollagens make?

microfibrils, which then create fibrils, and then fibers

inorganic compounds of the ECM

water (25%) and hydroxyapatite (calcium minerals secreted by osteoblasts)

why is the organization of organic and inorganic compounds important in bones?

it gives structure. mineralized fibrils are extremely strong, and collagen fibers contain lots of mineralized fibrils.

collagen provides

flexibility

minerals provide

firmness

collagen: organic or inorganic?

organic

minerals: organic or inorganic?

inorganic

rickets

inorganic compound deficiency, calcium deficiency due to lack of vitamin d. bowed legs.

scurvy

organic compound deficiency, lack of vitamin c, brittle bones that can fracture easily.

spongy bone and compact bone are similar in their

chemical composition

spongy bone organization

irregular lattice called trabeculae, osteocytes in lacunae

locations of spongy bone

epiphysis of long bones, medullary cavity (where marrow is), insides of smaller bones (packing)

functions of spongy bone

withstand forces in many directions, lightens skeletal system, contains red marrow for hemopoiesis

organization of compact bone

solid network in rings called osteons

location of compact bone

externally around all bones, diaphysis of long bones

function of compact bone

gives long bones the ability to withstand forces

osteon

A

central canal

where vessels and nerves run through to provide nutrients

lamellae

layers surrounding the osteon

canaliculi

small canals surrounding osteocyte

why are osteons arranged with each lamallae having alternating collagen fibers?

allows for the bone to withstand pressure, and have twisting force.

soft spot bones in infants include which of the following?

all the above

ossification

replacement of connective tissue by bone, continuous in development before and after birth.

intramembranous ossification

direct replacement of tissue (mesenchyme) to bone, done within the membrane.

what bones form via intramembrane ossification?

crahead, face, sternum, clavicles.

heterotropic bone formation (intramembrane ossification)

bones that feel stress which stimulates its formation. including sesamoid bones like the kneecaps

step 1 of intramembranous ossification

development of ossification center: osteoblasts secrete organic material

step 2 of intramembranous ossification

calcification: osteoblasts secrete calcium which hardens the ECM

step 3 of intramembranous ossification

formation of trabeculae: ECM develops trabeculae and it fuses making spongy bone

step 4 of intramembranous ossification

development of periosteum: spongy bone turns into compact bone