What happens when muscles work?
They contract (shorten) and pull on bones.
Why can't you sneeze with your eyes open?
Your brain automatically closes them as a protective reflex.
Why do astronauts lose muscle strength in space?
Because there is very little gravity.
Which part of the eye changes shape to help you focus on objects near and far?
The lens
How many liters of blood does the average adult have?
B) 5 liters
A) 1 liter
C) 20 liters
Why is it difficult to read in a dark room?
Not enough light reaches the retina.
Why do we shiver when we are cold?
Muscles contract rapidly to produce heat.
Can a muscle push a bone?
No. Muscles only pull.
Why do your ears pop on an airplane?
Air pressure changes inside and outside the ear.
Which part of your eye detects light?
The retina
Why do your pupils get bigger in the dark?
To let more light into the eye.
Why is drinking water important for your body?
It helps transport nutrients, regulate temperature, and keep organs working.