Movement and Locomotion

Flashcards for key vocabulary terms related to movement and locomotion in animals, covering muscle function, locomotion methods, and environmental constraints.

Muscle cells

Specialized to actively contract and produce tension.

ATP in muscles

Muscles convert the chemical energy of ATP into mechanical energy.

Actin

A protein subunit particularly high in concentration in skeletal and cardiac muscle cells.

Myosin

A long rod-shaped molecule of two protein chains critical for muscle contraction.

Myosin Head

The globular part of the heavy meromyosin end of a myosin molecule.

Troponin and Tropomyosin

Regulate the interaction of actin with myosin.

Striated muscle

A muscle type divided into skeletal and cardiac muscle.

Smooth muscle

One of the two major types of muscle.

Sarcomere

Highly ordered array of thick myosin and thin actin filaments.

Z line

The point to which actin molecules are attached at each end of the sarcomere.

M band

The location where myosin filaments are held in place within the sarcomere.

Sarcotubules

Form a ring around each sarcomere and are called t-tubules.

Sarcoplasmic reticulum (SR)

Intracellular membrane system between adjacent t-tubules that forms a sheath around each sarcomere.

Sliding Filament Model

Mechanism for muscle contraction where sarcomere contraction occurs due to the sliding movement of adjacent thin actin filaments and thick myosin filaments.

ATPase Activity

Myosin head has this, enabling the cross-bridges between actin and myosin for filament sliding.

Actin-Myosin Regulation

In vertebrate striated muscle, this interaction is regulated by Ca2+.

Tropomyosin

Prevents cross-bridge formation with myosin heads.

Troponin

Attached to tropomyosin and has 3 subunits; Ca2+ binding causes a structural change, allowing myosin heads to bind to actin.

Acetylcholine (Ach)

Skeletal muscles are stimulated to contract by the release of this.

Muscle Relaxation

Occurs when Ca2+ is returned to the sarcoplasmic reticulum and acetylcholinesterase removes ACh from the neuromuscular junction.

Rheobase

Threshold voltage for a very long duration impulse that elicits a response.

Isometric contraction

One of the two types of muscle contraction.

Isotonic contraction

One of the two types of muscle contraction.

Latency period

Delay between the electrical stimulation and the first increase in tension in a muscle.

Active state

Period of force generation by a sarcomere.

Summation

Occurs if a second twitch is initiated while the muscle is still generating tension from the first twitch.

Tetany

Continual summation of twitches caused by a series of successive contractions.

Locomotion

Methods dependent on the environment animals inhabit: Aquatic, Terrestrial, Aerial.

Crawling

A type of terrestrial locomotion used by snakes.

Walking and Running

Terrestrial locomotion where body mass is supported on a few points of contact with the substrate.

Cursorial Locomotion

Evolutionary trend to towards this, involving major structural change in limb design and vertical flexion of the vertebral column.

Gait

Pattern of limb movement which varies between animals and with speed.

Relative phase (RF)

Between the cycle for each foot during locomotion.

Duty factor (DF)

The fraction of time that the foot is on the ground while walking or running.

Plantigrade

Foot posture where the entire sole of the foot is on the ground.

Digitigrade

Foot posture where digits support the weight.

Unguligrade

Foot posture where animals travel on the tips of the toes.

Hopping and Jumping

Movement with both legs in phase and a low duty factor.

Metabolic cost of locomotion

Depends on velocity and generally increases linearly with velocity for terrestrial locomotion.

Net cost of transport (COTnet)

The energy required to move a certain distance, a good measure of energetic costs of locomotion.

Burrowing

Has a very high metabolic cost of transport.

Aquatic Locomotion

Principles differ from terrestrial locomotion; fluid density provides buoyant force, creating drag and lift.

Thrust force

Generated by pushing against the external fluid medium for swimming.

Reynold's number (Re)

Ratio of inertial forces to viscous forces; important for determining thrust generation.

Drag forces

Experienced by objects moving through fluid, direction is parallel to the direction of fluid flow.

Lift

Force exerted on an object by a fluid perpendicular to the fluid motion.

Aerial Locomotion

Animals that glide or fly use drag and lift for propulsive force.

Gliding

Decrease in altitude generates the air movement.

Flapping Flight

Flying birds, bats and insects that use muscular energy to generate aerodynamic lift.