B3.3 Muscle and motility (HL) Notes

Internal Movement

Movement that occurs within the body of all living organisms, essential for processes like nutrient distribution and waste removal.

Locomotion

Movement from one location to another, enabling organisms to find resources and evade predators.

Motile Organisms

Organisms that actively move to find food or escape from danger, characterized by adaptations such as skeletal and muscular systems.

Sessile Organisms

Organisms that remain fixed in one location for most of their lives, still exhibiting small-scale movements for feeding and reproduction.

Cytoplasmic Streaming

Movement of cytoplasm within unicellular organisms like amoeba, aiding in nutrient transport and locomotion.

Cross-Bridge Formation

The attachment of myosin heads to actin filaments during muscle contraction, initiated by calcium release.

Power Stroke

The movement where myosin heads pivot and pull actin filaments towards the center of the sarcomere, powered by ATP.

Titin

The largest protein in the human body, acting as a molecular spring to restore sarcomere length and prevent overstretching.

Antagonistic Muscles

Muscle pairs that work in opposition; when one contracts, the other relaxes, facilitating smooth and controlled movements.

Motor Unit

A motor unit consists of a single motor neuron and all the muscle fibers it innervates, transmitting signals for contraction.

Neuromuscular Junction (NMJ)

The synapse where a motor neuron communicates with a muscle fiber, releasing acetylcholine to initiate contraction.

Lever

A rigid structure (bone) that pivots around a fulcrum (joint) to produce movement.

Range of Motion (ROM)

The extent to which bones of a joint can move in relation to one another, influenced by joint structure and surrounding tissues.

Intercostal Muscles

Muscles located between the ribs that coordinate inhalation and exhalation through their alternating contractions.

Blowhole

The opening on the top of a marine mammal's head for breathing, allowing them to ventilate their lungs efficiently while swimming.

Streamlining

The adaptation of marine mammals' body shapes to reduce water resistance and enhance swimming efficiency.