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Chapter 1: The Living World
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Chapter 2: Biological Classification
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3
Chapter 3: Plant Kingdom
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4
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5
Chapter 5: Morphology of Flowering Plants
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Chapter 6: Anatomy of Flowering Plants
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Chapter 7: Structural Organization in Animals
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Chapter 8: Cell: The Unit of Life
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Chapter 19: Excretory Products and their Elimination
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Chapter 20: Locomotion and Movement
10 questions
Q1
Define sliding filament theory of muscle contraction.
Q2
Describe the important steps in muscle contraction.
Q3
Write true or false. If false change the statement so that it is true.
(a) Actin is present in thin filament.(b) H-zone of striated muscle fibre represents both thick and thin filaments.
(c) Human skeleton has 206 bones.
(d) There are 11 pairs of ribs in man.
(e) Sternum is present on the ventral side of the body.
21
Chapter 21: Neural Control and Coordination
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Chapter 22: Chemical Coordination and Integration
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Question
Medium
Solving time: 5 mins
Describe the important steps in muscle contraction.
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Text solution
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During skeletal muscle contraction, the thick filament slides over the thin filament by a repeated binding and releases myosin along the filament. This whole process occurs in a sequential manner.
Step 1:
Muscle contraction is initiated by signals that travel along the axon and reach the neuromuscular junction or motor end plate. The neuromuscular junction is a junction between a neuron and the sarcolemma of the muscle fibre. As a result, acetylcholine (a neurotransmitter) is released into the synaptic cleft by generating an action potential in the sarcolemma.
Step 2:
The generation of this action potential releases calcium ions from the sarcoplasmic reticulum in the sarcoplasm.
Step 3:
The increased calcium ions in the sarcoplasm lead to the activation of actin sites. Calcium ions bind to the troponin on actin filaments and remove the tropomyosin, wrapped around actin filaments. Hence, active actin sites are exposed and this allows myosin heads to attach to this site.
Step 4:
In this stage, the myosin head attaches to the exposed site of actin and forms cross bridges by utilizing energy from ATP hydrolysis. The actin filaments are pulled. As a result, the H-zone reduces. It is at this stage that the contraction of the muscle occurs.
Step 5:
After muscle contraction, the myosin head pulls the actin filament and releases ADP along with inorganic phosphate. ATP molecules bind and detach myosin and the cross bridges are broken.
Step 6:
This process of formation and breaking down of cross bridges continues until there is a drop in the stimulus, which causes an increase in calcium. As a result, the concentration of calcium ions decreases, thereby masking the actin filaments and leading to muscle relaxation.
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Practice more questions from Biology (NCERT)
Q1
Define sliding filament theory of muscle contraction.
Q2
Describe the important steps in muscle contraction.
Q3
Write true or false. If false change the statement so that it is true.
(a) Actin is present in thin filament.(b) H-zone of striated muscle fibre represents both thick and thin filaments.
(c) Human skeleton has 206 bones.
(d) There are 11 pairs of ribs in man.
(e) Sternum is present on the ventral side of the body.
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| Question Text | Describe the important steps in muscle contraction. |
| Updated On | Jun 5, 2023 |
| Topic | Locomotion and Movement |
| Subject | Biology |
| Class | Class 11 |
| Answer Type | Text solution:1 Video solution: 1 |
| Upvotes | 129 |
| Avg. Video Duration | 3 min |
