Home
School Syllabus
CBSE
Class XI
Biology
अध्याय 17: गमन एवं संचलन

माध्यम चुनें / Select Medium:

CBSE • कक्षा XI • Biology • अध्याय 17

अनुमानित समय: 45 Mins

प्रगति: अध्ययनरत

गमन एवं संचलन

In Class 11 Biology, "Locomotion and Movement" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्याय CBT ऑनलाइन टेस्ट दें सभी अध्याय देखें

प्रस्तावना अध्याय अवधारणाएँ अध्याय सारांश स्व-मूल्यांकन अभ्यास टेस्ट दें

💪 Have You Ever Wondered?

How do millions of microscopic myosin motor proteins inside your bicep muscle pull actin filaments past each other like oars on a racing galley to lift a 20-kg dumbbell? The Sliding Filament Theory and human skeletal mechanics.

यह अध्याय क्यों महत्वपूर्ण है

In Class 11 Biology, "Locomotion and Movement" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्ययन से पूर्व (आवश्यक ज्ञान)

Muscular system from Class 9.
Bones and joints.
ATP hydrolysis.

इस अध्याय के लक्ष्य

Distinguish between Movements and Locomotion; survey types of movement (Amoeboid, Ciliary, Muscular).
Analyze Skeletal Muscle anatomy: Muscle bundle (Fascicle), Muscle fiber (Sarcolemma, Sarcoplasmic reticulum - calcium storehouse), and Myofibrils.
Describe Sarcomere anatomy: Thick myosin filaments ($A$-band), Thin actin filaments ($I$-band, Troponin, Tropomyosin, $F$-actin), $Z$-line, and $H$-zone.
Explain the Sliding Filament Theory (Huxley): Neuromuscular junction, Acetylcholine, $Ca^{2+}$ binding to troponin, cross-bridge formation and power stroke.
Classify Human Skeletal System: Axial skeleton ($80$ bones: Skull, Vertebral column, Ribs, Sternum) and Appendicular skeleton ($126$ bones: Limbs, Girdles).
Classify Joints: Fibrous (sutures in skull, immovable), Cartilaginous (vertebrae, limited), and Synovial joints (ball and socket, hinge, pivot, gliding, saddle).

अध्याय रूपरेखा एवं प्रगति

1 1. The Sarcomere: Functional Unit o...

2 2. The Sliding Filament Mechanism

3 3. Human Skeleton ($206$ Bones) & S...

सम्पूर्ण सैद्धांतिक एवं वैचारिक अध्ययन

1. The Sarcomere: Functional Unit of Contraction

A muscle fiber contains parallel myofibrils divided into functional repeating units called Sarcomeres bounded by two $Z$-lines:
• Thin Filament (Actin): Two helical strands of $F$-actin wrapped by Tropomyosin; complex protein Troponin masks the active myosin-binding sites at rest.
• Thick Filament (Myosin): Composed of meromyosin subunits with a globular head (possessing ATPase enzyme activity) and tail.
• $A$-band: Anisotropic (myosin length, constant!); $I$-band: Isotropic (actin only); central gap with no actin overlap is the $H$-zone.

2. The Sliding Filament Mechanism

Action potential arrives at Neuromuscular Junction → releases Acetylcholine.
Depolarization spreads across sarcolemma into Sarcoplasmic Reticulum, releasing a flood of $\mathbf{Ca^{2+}}$ ions!
$\mathbf{Ca^{2+}}$ binds to Troponin-C, changing its conformation to unmask active binding sites on actin.
Myosin heads hydrolyze ATP ($ATP \to ADP + Pi$), form Cross-Bridges with actin, and execute a Power Stroke, pulling actin filaments toward the center of the sarcomere:
• $I$-bands shorten, $H$-zone disappears, distance between $Z$-lines decreases, but $A$-band remains unchanged!

3. Human Skeleton ($206$ Bones) & Synovial Joints

Axial ($80$ bones): Skull ($22$ bones), Vertebral column ($26$ vertebrae), Ribs ($12$ pairs: 7 true, 3 false, 2 floating), Sternum ($1$).
Appendicular ($126$ bones): Upper and lower limbs ($60 + 60$), Pectoral girdle ($4$), Pelvic girdle ($2$).
Synovial Joints (Fluid-filled synovial cavity): Ball-and-socket (shoulder/hip), Hinge (knee/elbow), Pivot (Atlas-Axis), Gliding (carpals), Saddle (thumb).

Locomotion and Movement - Key Biological & Anatomical Model

अध्याय का सार संक्षेप एवं 10 मुख्य निष्कर्ष

मुख्य बिंदु 1

Sarcomere Unit: Contractile segment bounded between adjacent Z-discs.

मुख्य बिंदु 2

Troponin Calcium Gate: Calcium binding shifting tropomyosin to expose myosin catalytic docking sites.

मुख्य बिंदु 3

Sliding Filament Power Stroke: Myosin head tilt sliding thin actin filaments without changing filament length.

मुख्य बिंदु 4

Red vs White Fibres: Myoglobin-rich aerobic fatigue-resistant fibers vs glycolytic fast-twitch fibers.

मुख्य बिंदु 5

Synovial Cavity: Lubricated friction-free articulation permitting wide angular joint movement.

स्व-मूल्यांकन अभ्यास (Check Your Understanding)

मूल वैचारिक स्पष्टता की जांच के लिए नैदानिक प्रश्न। पहले स्वयं हल करें, फिर उत्तर देखें।

Describe the Sliding Filament Theory of muscle contraction. What structural changes occur in the sarcomere during contraction?

उत्तर एवं व्याख्या देखें

उत्तर: Proposed by A.F. Huxley and H.E. Huxley: Muscle contraction occurs through the sliding of thin actin filaments over thick myosin filaments towards the center of the sarcomere. During contraction: (1) The $I$-bands shorten, (2) The $H$-zone shortens and disappears, (3) The distance between $Z$-lines decreases (sarcomere shortens), (4) The $A$-band retains its length unchanged.
Thin actin slides over thick myosin; I-band and H-zone shorten, A-band stays constant.

What is the role of Calcium ions ($Ca^{2+}$) and ATP in muscle contraction?

उत्तर एवं व्याख्या देखें

उत्तर: $Ca^{2+}$ ions released from the sarcoplasmic reticulum bind to the regulatory protein Troponin on actin filaments, triggering a conformational change that unmasks the myosin-binding sites on actin. ATP binds to the myosin head and is hydrolyzed by myosin ATPase into ADP and Pi, providing the energy to form a cross-bridge and execute the power stroke pulling actin.
Ca2+ unmasks actin binding sites; ATP hydrolysis powers myosin cross-bridge stroke.

Differentiate between Red muscle fibers and White muscle fibers.

उत्तर एवं व्याख्या देखें

उत्तर: Red muscle fibers: Rich in myoglobin, high mitochondrial density, rich capillary network, slow-twitch, perform aerobic respiration without fatigue over long durations (e.g. flight muscles in migratory birds). White muscle fibers: Low myoglobin, fewer mitochondria, abundant sarcoplasmic reticulum, fast-twitch, rely on anaerobic glycolysis, fatigue rapidly due to lactic acid accumulation.
Myoglobin-rich aerobic fatigue-resistant vs fast-twitch anaerobic easily fatigued.

Classify the three main types of joints found in the human body with an example of each.

उत्तर एवं व्याख्या देखें

उत्तर: (1) Fibrous (Immovable) Joints: Dense fibrous connective tissue with zero movement (e.g. Sutures between flat skull bones), (2) Cartilaginous (Slightly Movable) Joints: Connected by cartilage with limited movement (e.g. Joints between adjacent vertebrae), (3) Synovial (Freely Movable) Joints: Fluid-filled synovial cavity permitting extensive movement (e.g. Ball-and-socket shoulder joint).
Fibrous (skull sutures), Cartilaginous (vertebrae), Synovial (ball-and-socket).

Name the bones that constitute: (i) Cranium, (ii) Pectoral girdle, (iii) Pelvic girdle.

उत्तर एवं व्याख्या देखें

उत्तर: (i) Cranium (8 bones): 1 Frontal, 2 Parietal, 2 Temporal, 1 Occipital, 1 Sphenoid, 1 Ethmoid. (ii) Pectoral girdle (4 bones): 2 Clavicles (collar bones) and 2 Scapulae (shoulder blades). (iii) Pelvic girdle (2 coxal bones): Each formed by fusion of Ilium, Ischium, and Pubis.
Cranium (8 bones), Pectoral (clavicle + scapula), Pelvic (coxal bones: ilium, ischium, pubis).

अध्याय का अध्ययन पूर्ण हुआ?

अभ्यास के लिए तैयार?

ऑनलाइन CBT टेस्ट देकर तैयारी का मूल्यांकन करें

झारखण्ड बोर्ड परीक्षा पैटर्न पर आधारित बहुविकल्पीय प्रश्नों का ऑनलाइन टेस्ट दें। तुरंत परिणाम, समय विश्लेषण और प्रत्येक प्रश्न का विस्तृत हल प्राप्त करें।

फाउंडेशन टेस्ट

15 MCQs • मूल अवधारणाएँ

एडवांस्ड टेस्ट

15 MCQs • HOTS और ट्रैप्स