Leah.J
Badges: 13
Rep:
?
#1
Report Thread starter 1 year ago
#1
My A2 bio book says that they work in pairs because "muscles can't push".
when muscles contract, they shorten, so they pull the bone, doesn't that mean that when they relax they move the bone back to its original position? If that's not "pushing" the bone, doesn't it just get the job done ?
0
reply
LuigiMario
Badges: 19
Rep:
?
#2
Report 1 year ago
#2
what an antagonistic question!

wikipedia sshh..Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. An example of an antagonistic pair is the biceps and triceps; to contract, the triceps relaxes while the biceps contracts to lift the arm.
0
reply
anosmianAcrimony
Badges: 20
Rep:
?
#3
Report 1 year ago
#3
When a muscle relaxes, it doesn't actively push the bone back to its original position. Sometimes you need to actively exert force on your environment, rather than just sorta flop against it like a sack of jelly. So each joint has muscles to pull it in both directions.
0
reply
Jpw1097
Badges: 16
Rep:
?
#4
Report 1 year ago
#4
(Original post by Leah.J)
My A2 bio book says that they work in pairs because "muscles can't push".
when muscles contract, they shorten, so they pull the bone, doesn't that mean that when they relax they move the bone back to its original position? If that's not "pushing" the bone, doesn't it just get the job done ?
(Original post by anosmianAcrimony)
When a muscle relaxes, it doesn't actively push the bone back to its original position. Sometimes you need to actively exert force on your environment, rather than just sorta flop against it like a sack of jelly. So each joint has muscles to pull it in both directions.
Exactly, muscles do not push bones. Often when a muscle relaxes, it returns back to its original position because of gravity. Or if it does not return to its original position due to gravity, then the antagonistic muscle will contract to return the bone to the original position. For example, if you contract your biceps (flex the elbow), when you relax, your arm will flop back to its original position. However, if you’re on your side and so gravity is eliminated, you would need to contract your tricep to return the bone back to the neutral position, otherwise the elbow would remain flexed.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

With no certainty that exams next year will take place, how does this make you feel?

More motivated (86)
31.16%
Less motivated (190)
68.84%

Watched Threads

View All