Animal LocomotionAnimal LocomotionSkeletal & Muscular SystemsSkeletal & Muscular Systems

Learning Objectives Learning Objectives (3/12/08)(3/12/08)

1.1. Describe the types of skeletons that Describe the types of skeletons that support and enable movement in support and enable movement in animals, with examples.animals, with examples.

2.2. Describe how muscles exert force Describe how muscles exert force against skeletal elements to maintain against skeletal elements to maintain posture and produce movement.posture and produce movement.

3.3. Compare the structure and function of Compare the structure and function of the three types of muscle tissue.the three types of muscle tissue.

4.4. Differentiate between whole muscle Differentiate between whole muscle contraction and contraction of a single contraction and contraction of a single muscle cell, including the sliding filament muscle cell, including the sliding filament theory of muscle contraction.theory of muscle contraction.

Musculoskeletal MachinesMusculoskeletal Machines The skeleton and muscles work together in The skeleton and muscles work together in lever systemslever systems

– Muscles can only shorten by contraction, they cannot Muscles can only shorten by contraction, they cannot actively elongate. actively elongate.

– An external force is needed to stretch a muscle back to An external force is needed to stretch a muscle back to its resting length.its resting length.

– Opposing muscle sets provide this external force. Opposing muscle sets provide this external force.

Hydrostatic SkeletonsHydrostatic Skeletons

Fluid held in internal Fluid held in internal compartments as a compartments as a hydraulic fluid hydraulic fluid transfers force transfers force between opposing between opposing muscle sets. muscle sets.

As muscles contract, As muscles contract, internal volume internal volume remains the same, so remains the same, so the opposing muscle the opposing muscle set must stretch.set must stretch.

This stretch creates This stretch creates the potential to do the potential to do workwork

How do soft-bodied animals like worms and other forms How do soft-bodied animals like worms and other forms that lack rigid skeletons operate opposing muscles?that lack rigid skeletons operate opposing muscles?

Hydrostatic SkeletonHydrostatic Skeleton

Sea anemones (Phylum ?) have cylindrical fluid-filled bodies that function as a hydrostatic skeleton.

They have both circular and longitudinal muscle that contract against the fluid in their gastrovascular cavity.

Sea Anemone Body ShapesSea Anemone Body Shapes

Nematode WormsNematode Worms

Roundworms have only Roundworms have only longitudinal muscleslongitudinal muscles, , innervated by two nerve cords, and use a innervated by two nerve cords, and use a hydrostatic skeletonhydrostatic skeleton..

Their body can assume curved and S-shaped Their body can assume curved and S-shaped configurations to help them move through soil configurations to help them move through soil and other media. and other media.

Name the closed, water-filled body cavity that acts as the hydroskeleton.

nematode locomotion

Annelid WormsAnnelid WormsEach segment in the worm Each segment in the worm

body can act as an body can act as an independent hydrostatic independent hydrostatic skeleton.skeleton.

This permits much more This permits much more complex changes in body complex changes in body shape. shape.

The head is extended The head is extended forward by contraction of forward by contraction of circular muscles.circular muscles.

A wave of contraction of A wave of contraction of longitudinal muscles then longitudinal muscles then anchors the segments anchors the segments near the head.near the head.

earthworm locomotion

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Polychaete WormsPolychaete WormsContraction of longitudinal muscles on one side of a segment stretches the longitudinal muscles on the other side.

polychaete worm swimming

Parapodia act like paddles to push each segment toward the rear of the animal.

ExoskeletonsExoskeletonsExoskeletons are hardened outer surfaces to which internal muscles are attached.Increased leg length allows greater speed and power in locomotion (simple lever systems).

Multiple, long legs create a potential problem of tripping over one’s legs.

Centipedes and crustaceans have staggered activity in their legs to prevent tripping.

More advanced forms (e.g. crustaceans and insects) fuse segments and reduce the number of legs.

p. 1068

EndoskeletonsEndoskeletons

Endoskeletons are internal, articulated systems of rigid supports consisting of bone and cartilage to which muscles are attached.What are some of the advantages associated with endoskeletons, over exoskeletons?

How could you improve the efficiency of the lever system for arm flexion?

p. 1068

Lever SystemsLever Systems Muscles and bones work Muscles and bones work

together around joints as together around joints as systems of levers.systems of levers.

Lever systems of muscles Lever systems of muscles and skeletons can be and skeletons can be designed either for power designed either for power oror speed. speed.

The ratio of load arm The ratio of load arm (resistance) to power arm (resistance) to power arm (effort) determines the (effort) determines the power.power.

A low load arm to power A low load arm to power arm ratio provides high arm ratio provides high power but low speedpower but low speed

A high load arm to power A high load arm to power arm ratio provides high arm ratio provides high speed but lower power.speed but lower power.

Power L:P = 2

Speed L:P = 5

What is the functional unit of contraction in a muscle fiber? Circle and/or label one in this diagram.

What is a myofibril?

Internal organization of a muscle cell

What is stored within cisternae of muscle cells?

Each t-tubule is an extension of the ________________.

p. 1072

Organization of Myofilaments in a Organization of Myofilaments in a SarcomereSarcomere

A sarcomere within a myofibril

= actin= actin= myosin= myosin

p. 1070

myofibril

Events at Events at the NMJthe NMJ

Is the release of neurotransmitter active transport or passive transport?

Is the influx of Na+ ions by active transport or passive transport?

How does the influx of Na+ ions change the transmembrane electrochemical potential?

p. 1072

Are the calcium channels in cisternae voltage-gated or chemically-gated?

Besides Ca+2, what must also be present in order for myosin to bind to actin?