Schooling · Class 11 · Biology · Locomotion and Movement · Chapter on a page
CBSE Class 11 · Biology · NCERT Biology
Locomotion and Movement: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 27 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Movement occurs at cellular, organ…
- Three types of muscle tissue exist…
- A skeletal muscle fibre is a…
- Muscle contraction follows the…
- The human skeleton has 206 bones in…
- Joints are classified by the degree…
- Skeletal disorders include arthritis…
- Formulas and facts
- Sarcomere boundaries
- Sliding filament mechanism
- Role of calcium ions
- ATP requirement
- Axial skeleton count
- Appendicular skeleton count
- Types of synovial joints
- Worked examples
- Identifying sarcomere changes during…
- Counting vertebrae in the human spine
- Identifying joint types
- Watch out for
- Thinking the A-band shortens during…
- Confusing movement with locomotion
- Believing cardiac muscle is…
- Counting 206 bones in children
- Forgetting calcium's role and only…
What this chapter is about
Locomotion and movement are fundamental properties of living organisms. Movement refers to any change in the position of body parts or internal structures, while locomotion is the voluntary movement of the entire organism from one place to another. This chapter explains how humans and other animals move, focusing on the muscular and skeletal systems that make this possible.
Key ideas
- Movement occurs at cellular, organ and organism levels; locomotion is the coordinated movement of the whole body from place to place, requiring specialised structures like limbs, cilia or flagella.
- Three types of muscle tissue exist in vertebrates: skeletal muscle (voluntary, striated, attached to bones), smooth muscle (involuntary, non-striated, found in visceral organs), and cardiac muscle (involuntary, striated, found only in the heart).
- A skeletal muscle fibre is a multinucleate cell containing myofibrils, which are made of repeating units called sarcomeres; the sarcomere is the functional unit of muscle contraction.
- Muscle contraction follows the sliding filament theory: thin actin filaments slide over thick myosin filaments, shortening the sarcomere; this requires calcium ions, ATP and the regulatory proteins troponin and tropomyosin.
- The human skeleton has 206 bones in adults, divided into the axial skeleton (skull, vertebral column, ribs, sternum) and the appendicular skeleton (limbs and girdles).
- Joints are classified by the degree of movement allowed: fibrous joints (immovable, like skull sutures), cartilaginous joints (slightly movable, like intervertebral discs), and synovial joints (freely movable, like the knee).
- Skeletal disorders include arthritis (joint inflammation), osteoporosis (reduced bone density), gout (uric acid crystals in joints), and muscular dystrophy (progressive muscle weakness).
Formulas and facts to remember
- Sarcomere boundaries: A sarcomere extends from one Z-line to the next Z-line in a myofibril; it contains A-band (dark), I-band (light) and H-zone.
- Sliding filament mechanism: Actin filaments slide inward over myosin; the A-band remains constant in length, the I-band and H-zone shorten during contraction.
- Role of calcium ions: Calcium released from the sarcoplasmic reticulum binds to troponin, exposing active sites on actin for myosin head attachment.
- ATP requirement: ATP binds to the myosin head, causing it to detach from actin; ATP hydrolysis re-cocks the head for the next power stroke.
- Axial skeleton count: 80 bones (skull 22, vertebral column 26, ribs 24, sternum 1, hyoid 1, ear ossicles 6).
- Appendicular skeleton count: 126 bones (upper limbs 60, lower limbs 60, pectoral girdle 4, pelvic girdle 2).
- Types of synovial joints: Ball-and-socket (shoulder, hip), hinge (elbow, knee), pivot (atlas-axis), gliding (wrist), saddle (thumb base), condyloid (knuckles).
- Muscle proteins: Actin and myosin are contractile proteins; troponin and tropomyosin are regulatory proteins.
Common mistakes
- Thinking the A-band shortens during contraction → The A-band stays constant; only I-band and H-zone shorten.
- Confusing movement with locomotion → Movement is change in position of any body part; locomotion is movement of the whole organism from place to place.
- Believing cardiac muscle is voluntary because the heart beats rhythmically → Cardiac muscle is involuntary; its rhythmic contraction is intrinsic and not under conscious control.
- Counting 206 bones in children → The 206-bone count applies to adults; children have more bones because some fuse later.
- Forgetting calcium's role and only mentioning ATP → Both calcium ions (to expose binding sites) and ATP (for myosin head detachment and re-cocking) are essential for contraction.
Quick revision
- Sarcomere = Z-line to Z-line; contains A-band, I-band, H-zone.
- Sliding filament theory: actin slides over myosin; needs Ca²⁺ and ATP.
- Human adult skeleton: 206 bones (80 axial + 126 appendicular).
- Synovial joints are freely movable; types include ball-and-socket, hinge, pivot.
- Skeletal muscle is voluntary and striated; smooth muscle is involuntary and non-striated; cardiac muscle is involuntary and striated.
- Common disorders: arthritis, osteoporosis, gout, muscular dystrophy.