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Locomotion and Movement

Locomotion and MovementNEET Zoology · Class 11 · NCERT Chapter 17

3 interactive concept widgets for Locomotion and Movement. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

Muscle types compared

Compare skeletal, smooth and cardiac muscle across location, striations, control, nuclei, branching and fatigue.

Muscle types

Three types of muscle compared: skeletal vs smooth vs cardiac

A side-by-side comparator of skeletal, smooth and cardiac muscle across six features: location, striations, control, nuclei, branching and fatigue. Click each muscle type to highlight it.

Skeletal
Smooth
Cardiac

Feature

Skeletal

Smooth

Cardiac

Location

Attached to bones; limbs, trunk, face

Walls of hollow organs: gut, blood vessels, uterus, bladder

Wall of the heart only

Striations

Striated (alternating light and dark bands)

Non-striated (no visible bands)

Striated (like skeletal muscle)

Control

Voluntary

Involuntary (also called visceral muscle)

Involuntary (like smooth muscle)

Nuclei

Multiple nuclei at the periphery of the fibre

Single central nucleus per cell

Single nucleus (occasionally two)

Branching

Not branched

Not branched

Branched; fibres joined by intercalated discs

Fatigue

Fatigues with sustained contraction

Does not fatigue easily

Never fatigues under normal conditions

Skeletal muscle: key facts

NEET fact

Skeletal muscle is the only voluntary muscle. It is also called striated or somatic muscle. It fatigues with use.

Try this

  • Cardiac muscle is striated but involuntary. Which of the other two types shares each of these properties?
  • Which muscle type has multiple nuclei at the periphery? Why do you think it needs so many nuclei?
  • Only one muscle type is found in the heart. Only one is voluntary. Name them and explain the difference.

Sliding filament walk-through

Step through the sliding filament theory of muscle contraction and watch the sarcomere bands change.

Muscle contraction

Sliding filament theory: muscle contraction step by step

Walk through the 6 steps of muscle contraction from nerve impulse to relaxation. Watch the sarcomere SVG switch between relaxed and contracted states. See which bands change and which stay the same.

1. Signal

2. Ca2+

3. Unblock

4. Pull

5. Reset

6. Relax
I bandA bandI bandMZZH zoneRELAXED

Input

Nerve impulse

Signal

Output

Action potential in the sarcolemma

Nerve Impulse Arrives

Where

Motor nerve and neuromuscular junction

What happens

A motor neuron sends an impulse to the neuromuscular junction. The nerve terminal releases acetylcholine (ACh) into the synaptic cleft. ACh binds to receptors on the sarcolemma, triggering an action potential in the muscle fibre.

NEET fact

ACh is the neurotransmitter at the neuromuscular junction. Myasthenia gravis destroys these ACh receptors.

Try this

  • Click steps 1 to 6 in order. Watch the sarcomere diagram change between relaxed and contracted.
  • In step 5 (Reset), why would a muscle become stiff if it runs out of ATP?
  • Which step unblocks the actin binding sites? What two proteins are involved?

Human skeleton explorer

Explore the axial and appendicular skeleton with bone counts totalling 206, plus the types of joints.

Skeletal system

Human skeleton explorer: 206 bones and joint types

Toggle between the axial skeleton (80 bones) and appendicular skeleton (126 bones). Click each bone group for the count and details. Switch to 'Joint types' to explore fibrous, cartilaginous and synovial joints with examples.

Axial (80 bones)
Appendicular (126 bones)
Joint types

80

Axial skeleton bones

Forms the central axis: skull, vertebral column, ribs and sternum

Skull (22)
Vertebral column (26)
Ribs (24)
Sternum (1)
Hyoid and ear ossicles (7)

22

Skull

8 cranial bones (protect brain) + 14 facial bones. The skull has a single mandible (lower jaw) that is the only movable bone of the skull.

Total skeleton: Axial (80) + Appendicular (126) = 206 bones

Try this

  • Select Axial, then click each bone group in order. Do the counts add up to 80?
  • Switch to Appendicular. Notice that upper and lower limbs each have 60 bones. What bones make up each limb?
  • In the Joints tab, compare ball and socket with hinge joints. Which has the greater range of movement and why?

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