Unit 2: Bones (Review)

resorption

the process in which parathyroid hormone (PTH) stimulates osteoclasts to collapse bone tissue.

• Blood calcium increases, bone density decreases.

deposition

The process in which the calcitonin hormone stimulates the osteoblast to diffuse calcium from the bloodstream to build bone tissue.

• Increases bone density, decreases blood calcium

hypocalcemia

low blood calcium levels

hypercalcemia

high blood calcium levels

endochondral ossification

The process in which bone develops from pre-existing cartilage

creates long & short bones

intramembranous ossification

soft connective tissue gets replaced with hard bony tissue

creates flat & irregular bones

osteoporosis

definition: the condition in which bone building does not keep up with bone removal, resulting in weak and brittle bones

symptoms: pathological fracture (bone breaks bcuz it is weakened by disease), easily fractures from trauma, immobility, spinal deformity

treatment: calcium-rich diet, vitamin D supplements, hormone blockers (to stop PTH)

compact bone

feature: dense, without spaces visible, and made of osteons

locations: the outer layer of all bones

functions: provides support and protection

spongy bone

feature: honeycomb-like appearance, lighter in weight (compared to compact bone), and made of trabeculae

locations: inner layer of all bones

functions: provide structure and support without too much-added weight

long bone

description: long, compact bone that covers the marrow cavity (with bone marrow)

function: for movement (acts as levers which are moved by muscles)

examples: arms, legs

flat bone

description: thin, flat bones (usually curved)

function: to protect internal organs

examples: ribs, hips, sternum

short bone

description: cube-shaped bones with equal dimensions made mostly of spongy bone

function: provide support and stability when body is not in movement

examples: wrist, ankle

irregular bone

description: mainly spongy bone covered with thin compact bone

function: protect nervous tissue, anchor points for skeletal muscle attachments or tongue, support

examples: vertebrae, some skull bones

osteocytes

cells inside mature bone tissue that form bones

osteoclasts

cells that collapses bone

osteoblasts

cells that form new bone

periosteum

definition: the outer covering of bones (except the ligament part)

function: helps bone growth by supplying it with what it needs to heal and grow

red marrow

forms blood cells

yellow marrow

forms cartilage and fat; energy storage

bone remodeling

adjustments in bone shape and density to adapt to stress

diaphysis

middle portion of the bone; holds bone marrow

epiphysis

end portions of the bone; responsible for bone growth

axial skeleton

foundational structure

• Skull

• Spine

appendicular skeleton

limbs & what attaches limbs to axial

• legs

• arms

• pelvis

osteons

makes up compact bone

trabeculae

makes up spongy bone

ossification

the formation of bone

the two types are:

1. endochondral

2. intramembranous