Skeletal & Muscular Systems Animal Locomotion Skeletal & Muscular Systems

Learning Objectives (3/11/09) Support and movement Reason (Food,Weather,Protection) Motile and Non motile

Movement Organ Phylum Protozoa Heterotrophic or autotrophic Most motile Eukaryotes Unicellular Movement Flagellates(chlamydomonas) Ciliates(paramecium) Pseudopodia (Amoeba)

Important points of movement propulsion, Support stability

Movement Bones+cartilage+muscles

Types of Skeleton Exoskeleton

(ligament).

Hydrostatic Skeletons How do soft-bodied animals like worms and other forms that lack rigid skeletons operate opposing muscles? p. 1046 Fluid held in internal compartments as a hydraulic fluid transfers force between opposing muscle sets. As muscles contract, internal volume remains the same, so the opposing muscle set must stretch. This stretch creates the potential to do work

Hydrostatic 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.

Nematode Worms See p. 694 Roundworms have only longitudinal muscles, innervated by two nerve cords, and use a hydrostatic skeleton. Their body can assume curved and S-shaped configurations to help them move through soil and other media. Name the closed, water-filled body cavity that acts as the hydroskeleton. nematode locomotion

Annelid Worms Each segment in the worm body can act as an independent hydrostatic skeleton. This permits much more complex changes in body shape. The head is extended forward by contraction of circular muscles. A wave of contraction of longitudinal muscles then anchors the segments near the head. earthworm locomotion See p. 724

Exoskeletons Exoskeletons 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. 1046

Endoskeletons 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. 1046

Lever Systems Muscles and bones work together around joints as systems of levers. Lever systems of muscles and skeletons can be designed either for power or speed. The ratio of load arm (resistance) to power arm (effort) determines the power. A low load arm to power arm ratio provides high power but low speed A high load arm to power arm ratio provides high speed but lower power. Power L:P = 2 Speed L:P = 5

Internal organization of a muscle cell What is stored within cisternae of muscle cells? What is a myofibril? p. 1072 Internal organization of a muscle cell What is the functional unit of contraction in a muscle fiber? Circle and/or label one in this diagram. Each t-tubule is an extension of the ________________.

Organization of Myofilaments in a Sarcomere A sarcomere within a myofibril p. 1070 myofibril = actin = myosin Organization of Myofilaments in a Sarcomere

Events at the NMJ p. 1072 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?

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?