Bones in Space
What environment do astronauts experience aboard the International Space Station?
microgravity
The average adult human body contains this many bones.
206
This dense, hard tissue forms the strong outer layer of a bone.
compact bone?
Nicknamed “The Builder,” this cell produces new bone
osteoblast
The skull protects this organ.
brain
Astronauts in microgravity may lose approximately this percentage of bone mass each month.
1–2%
The skull, vertebral column, ribs, and sternum belong to this division of the skeleton.
axial skeleton?
This type of bone tissue has a porous, honeycomb-like appearance.
spongy bone
Nicknamed “The Demolisher,” this cell breaks down old or damaged bone.
osteoclast
Besides supporting your body, bones work with muscles and joints to perform this function.
movement
Bones receive less of this in microgravity because they don't have to support as much body weight.
mechanical loading/stress
The arms, legs, shoulder girdle, and pelvic girdle belong to this division.
appendicular skeleton
This type of bone marrow produces red blood cells, white blood cells, and platelets.
red bone marrow
Nicknamed “The Monitor,” this mature bone cell senses mechanical stress.
osteocyte
A patient has a problem producing new blood cells. Doctors might investigate this tissue inside their bones.
red bone marrow
Astronauts do this extensively in space to help slow muscle and bone loss.
exercise
The femur belongs to this bone-shape category.
Long bone
This type of marrow stores fat and is commonly found in the medullary cavity of adult long bones.
yellow bone marrow
Osteoblasts, osteocytes, and osteoclasts work together in this continuous process of breaking down and rebuilding bone.
bone remodeling
A doctor examines the expanded end of a patient's femur. What part of the long bone are they examining?
epiphysis
Explain why astronauts lose bone mass in microgravity
less mechanical loading causes bone remodeling to become unbalanced, so more bone is removed than replaced
This type of bone has a complex shape that doesn't fit into the long, short, or flat categories. Vertebrae are an example.
irregular bone
This hollow space inside the shaft of a long bone contains yellow marrow in adults
medullary cavity
An astronaut has increased osteoclast activity and decreased osteoblast activity. What will happen to their bone mass?
bone mass will decrease / their bones will become weaker
An astronaut returns to Earth after losing significant bone density. Why could this be dangerous?
their weakened bones suddenly have to support their full body weight under Earth's gravity?