This lesson covers:
- How muscles cause movement
- Antagonistic muscles
How muscles cause movement
Our body is comprised of approximately 640 skeletal muscles.
These muscles are linked to bones by strong cords known as tendons.
- Muscles contract to create movement, pulling on the tendon which pulls on the bone.
- This action causes the bone to move in the direction the muscle contracts.
Antagonistic muscles
For the body to move, most muscles that cause movement are arranged in pairs on opposite sides of a joint.
These pairs are known as antagonistic muscles, which are essential for controlling movement.
- When one muscle contracts, the opposing muscle relaxes.
- The contracting muscle shortens and pulls on its attached tendon.
- This tendon pulls on the bone, causing movement at the joint.
- The relaxing muscle lengthens to allow the movement.
The biceps and triceps are antagonistic muscles
The action of the biceps and triceps allow your arm to move around your elbow joint.
- To bend the arms – The biceps contract while the triceps relax.
- To straighten the arms – The triceps contract, pulling in the opposite direction, while the biceps relax.
Practice Quiz
1. What is the muscular system?
Answer: The muscular system is composed of approximately 640 skeletal muscles that work together to enable movement, maintain posture, and support bodily functions.
2. How do muscles cause movement?
Answer: Muscles cause movement by contracting and pulling on tendons, which then pull on bones, causing the bones to move at the joints.
3. What are tendons?
Answer: Tendons are strong, fibrous cords that connect muscles to bones, allowing the force generated by muscle contraction to be transferred to the skeleton.
4. What are antagonistic muscles?
Answer: Antagonistic muscles are pairs of muscles that work opposite each other to control movement. When one muscle contracts, the opposing muscle relaxes.
5. How do antagonistic muscles work?
Answer: When one muscle of the pair contracts and shortens, it pulls on the tendon and bone to cause movement. Simultaneously, the opposing muscle relaxes and lengthens to allow the movement.
6. What are examples of antagonistic muscle pairs?
Answer: Examples include the biceps and triceps in the arms, the quadriceps and hamstrings in the legs, and the flexor and extensor muscles in the forearms.
7. How do the biceps and triceps work together?
Answer: To bend the arm at the elbow, the biceps contract while the triceps relax. To straighten the arm, the triceps contract while the biceps relax.
8. What is muscle contraction?
Answer: Muscle contraction is the process where muscle fibers shorten and generate force, causing movement or maintaining posture.
9. What are the different types of muscle tissue?
Answer: The three types of muscle tissue are skeletal muscle (voluntary movement), cardiac muscle (heart function), and smooth muscle (involuntary functions in organs).
10. What is the role of skeletal muscle?
Answer: Skeletal muscle is responsible for voluntary movements, posture, and stability. It attaches to bones and works in pairs to produce movement.
11. How does the nervous system control muscles?
Answer: The nervous system sends electrical signals (nerve impulses) to muscles, triggering muscle contraction and coordinating movement.
12. What is the sliding filament theory?
Answer: The sliding filament theory explains how muscles contract. Actin and myosin filaments within muscle fibers slide past each other, shortening the muscle and generating force.
13. What is muscle tone?
Answer: Muscle tone is the continuous and passive partial contraction of muscles, which helps maintain posture and readiness for action.
14. What is a muscle twitch?
Answer: A muscle twitch is a brief, involuntary contraction of a muscle or group of muscles, often caused by sudden stimulation or stress.
15. What causes muscle fatigue?
Answer: Muscle fatigue occurs when muscles are overworked and unable to contract efficiently, often due to depletion of energy stores, accumulation of waste products, and reduced oxygen supply.
16. How does regular exercise affect the muscular system?
Answer: Regular exercise strengthens muscles, increases endurance, improves muscle tone, and enhances overall muscular efficiency.
17. What is the function of cardiac muscle?
Answer: Cardiac muscle, found in the heart, contracts rhythmically and involuntarily to pump blood throughout the body.
18. What is the role of smooth muscle?
Answer: Smooth muscle is found in the walls of internal organs and blood vessels. It contracts involuntarily to regulate functions like digestion, blood flow, and respiration.
19. What is muscle hypertrophy?
Answer: Muscle hypertrophy is the increase in muscle size and strength due to regular resistance training and exercise.
20. What is muscle atrophy?
Answer: Muscle atrophy is the decrease in muscle mass and strength due to inactivity, aging, or disease.
21. How do muscles repair after injury?
Answer: After injury, muscles repair through a process of inflammation, regeneration of muscle fibers, and remodeling of muscle tissue.
22. What are fast-twitch muscle fibers?
Answer: Fast-twitch muscle fibers contract quickly and powerfully but fatigue rapidly. They are used in short bursts of high-intensity activities like sprinting.
23. What are slow-twitch muscle fibers?
Answer: Slow-twitch muscle fibers contract more slowly but are resistant to fatigue. They are used in endurance activities like long-distance running.
24. What is the importance of flexibility in the muscular system?
Answer: Flexibility allows muscles to move through their full range of motion, reducing the risk of injury and improving overall movement efficiency.
25. What is a muscle strain?
Answer: A muscle strain is an injury where muscle fibers are stretched or torn, often due to overuse, overstretching, or excessive force.
26. How can muscle strains be prevented?
Answer: Muscle strains can be prevented by warming up before exercise, stretching regularly, maintaining proper technique, and avoiding overexertion.
27. What is the function of the quadriceps?
Answer: The quadriceps, located at the front of the thigh, are responsible for extending the knee and are essential for activities like walking, running, and jumping.
28. What is the role of the hamstrings?
Answer: The hamstrings, located at the back of the thigh, are responsible for flexing the knee and extending the hip, important for movements like running and climbing.
29. What are the major muscles in the upper body?
Answer: Major upper body muscles include the pectorals (chest), deltoids (shoulders), biceps (front of upper arm), triceps (back of upper arm), and latissimus dorsi (back).
30. What are the major muscles in the lower body?
Answer: Major lower body muscles include the quadriceps (front of thigh), hamstrings (back of thigh), gluteals (buttocks), and calf muscles (lower leg).
31. What is the function of the deltoid muscle?
Answer: The deltoid muscle, located on the shoulder, is responsible for lifting the arm away from the body and rotating the shoulder.
32. How do muscles maintain body temperature?
Answer: Muscles generate heat during contraction, which helps maintain body temperature. Shivering is an involuntary muscle contraction that produces heat in cold conditions.
33. What is muscle endurance?
Answer: Muscle endurance is the ability of a muscle to sustain repeated contractions over a period of time without becoming fatigued.
34. What is muscle strength?
Answer: Muscle strength is the maximum amount of force a muscle or group of muscles can generate during a single contraction.
35. How does aging affect the muscular system?
Answer: Aging can lead to a decrease in muscle mass, strength, and endurance, as well as reduced flexibility and slower muscle repair.
36. What are common muscular system disorders?
Answer: Common disorders include muscular dystrophy, myasthenia gravis, fibromyalgia, and muscle cramps.
37. What is muscular dystrophy?
Answer: Muscular dystrophy is a group of genetic disorders characterized by progressive weakness and degeneration of skeletal muscles.
38. What is myasthenia gravis?
Answer: Myasthenia gravis is an autoimmune disorder that causes weakness and fatigue of skeletal muscles due to disrupted communication between nerves and muscles.
39. What is fibromyalgia?
Answer: Fibromyalgia is a chronic condition characterized by widespread muscle pain, fatigue, and tenderness in specific areas of the body.
40. What causes muscle cramps?
Answer: Muscle cramps can be caused by overuse, dehydration, electrolyte imbalances, poor circulation, and certain medical conditions.
41. How can muscle cramps be prevented?
Answer: Muscle cramps can be prevented by staying hydrated, maintaining a balanced diet, stretching before and after exercise, and avoiding overexertion.
42. What is the role of calcium in muscle function?
Answer: Calcium is essential for muscle contraction, as it facilitates the interaction between actin and myosin filaments within muscle fibers.
43. What is the role of ATP in muscle contraction?
Answer: ATP (adenosine triphosphate) provides the energy necessary for muscle contraction and relaxation by fueling the interaction between actin and myosin filaments.
44. How does resistance training affect muscles?
Answer: Resistance training increases muscle strength, size, and endurance by stimulating muscle fibers to grow and adapt to increased workload.
45. What is the role of the trapezius muscle?
Answer: The trapezius muscle, located in the upper back and neck, helps move, rotate, and stabilize the shoulder blades and supports head and neck movements.
46. What are the effects of dehydration on muscles?
Answer: Dehydration can lead to muscle cramps, fatigue, decreased performance, and impaired muscle function.
47. What is the function of the pectoral muscles?
Answer: The pectoral muscles, located in the chest, are responsible for movements of the shoulder joint, such as flexion, adduction, and internal rotation of the arm.
48. What is DOMS (Delayed Onset Muscle Soreness)?
Answer: DOMS is muscle pain and stiffness that occurs 24 to 72 hours after intense or unfamiliar exercise, caused by microscopic damage to muscle fibers.
49. How can DOMS be managed?
Answer: DOMS can be managed by rest, gentle stretching, massage, hydration, and using over-the-counter pain relievers if necessary.
50. What is the role of the abdominal muscles?
Answer: The abdominal muscles support the trunk, allow movement and rotation of the torso, assist in breathing, and help protect internal organs.