Muscles and Movement
Muscles pull on bones in antagonistic pairs.
About this topic
Muscles produce movement by contracting. Skeletal muscle is attached to bones by tendons and works in antagonistic pairs: the biceps contracts to bend the elbow while the triceps relaxes, and vice versa. Muscles can only pull, never push. Smooth muscle lines organs and cardiac muscle forms the heart.
Contraction occurs when actin and myosin filaments slide past each other, using ATP. Exercise strengthens muscles, and anaerobic respiration can cause fatigue. Muscle cells contain many mitochondria.
When you lift a cup, the biceps contracts while the triceps relaxes; to straighten, the roles reverse. At the microscopic level, protein filaments, actin and myosin, slide past each other using ATP, which is the sliding filament model. Muscles can only pull, never push, which is why they work in pairs.
Three types exist: skeletal (voluntary), cardiac (found only in the heart, never tires) and smooth (in gut and blood vessel walls, involuntary). Exercise builds muscle, and lack of use causes wasting. Cramps can follow hard exercise and lack of salts. Students sometimes think muscle turns into fat when you stop exercising; they are different tissues, and muscle shrinks while fat can accumulate separately.
Key ideas
- Biceps and triceps
- Skeletal, smooth, cardiac
- Contraction uses ATP
Quick check
Use cases: where Muscles and Movement helps
- Homework: review the key idea behind Muscles and Movement before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Muscles and Movement without notes.
- Visual learning: play with the interactive lab to see how Muscles and Movement changes when you adjust its inputs.
- Teaching a friend: explain Muscles and Movement in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Muscles and Movement?
Muscles pull on bones in antagonistic pairs.
What will I learn in Muscles and Movement?
Biceps and triceps. Skeletal, smooth, cardiac. Contraction uses ATP.
Is Muscles and Movement part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Muscles and Movement lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Muscles and Movement?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.