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bio 162 animal movement objectives

Terms in this set (14)

describe the structure of skeletal muscle at levels ranging from a whole muscle to the contractile filaments within sarcomeres
sarcomere composed of Z disk (edges), thick filaments (myosin), and thin filaments (actin)
describe the mechanism by which skeletal muscle contracts and relaxes
when a sarcomere contracts, the thick filaments (myosin) and thin filaments (actin) slide past one another.

calcium ions bind to troponin, moving the troponin-tropomyosin complex and exposing the myosin binding sites. the myosin head then binds to a subunit on the actin thin filament, using the production and hydrolization of ATP to perform this sliding mechanism (lets go and binds to a new subunit on the actin thin filament)
which ion regulates contraction and relaxation
calcium ions
give a step-by-step description of the process by which a motor neuron stimulates contraction of a skeletal muscle cell, beginning with an action potential traveling down the motor neuron and ending with relaxation of the muscle. Pay attention to the role of Na+, K+, and Ca2+ ions in both the neuron and the muscle
1. depolarization of motoneuron axon terminal (voltage-gated Ca2+ channels open)
2. vesicles containing a neurotransmitter, acetylcholine, fuse with nerve cell membrane
3. acetylcholine receptors open and conduct Na+ ions
4. an EPSP occurs in the muscle cell
5. voltage-gated Na+ channels open in the muscle cell membrane near the neuromuscular junction
6. an action potential is conducted along the T-tubule. DHPR detects voltage changes
7. ryanodine receptors open
8. SR Ca2+ release channels open. [Ca2+] rises in the muscle cell cytoplasm
9. Ca2+ binds to troponin
10. tropomyosin rotates into the groove of the thin filament (out of the way of the myosin binding site)
11. myosin head goes through the cross-bridge cycle and hydrolyzes ATP
12. Ca2+ dissociates from troponin and actively transported to SR by SR Ca2+ ATPases
compare and contrast the three different types of vertebrate muscle
smooth muscle: the unstriated muscle tissue that lines the intestine, blood vessels, and some other organs. consists of tapered, unbranched cells that can sustain long contractions. involuntary and has a single nucleus

cardiac muscle: the muscle tissue of the vertebrate heart; responsible for pumping blood. consists of long, branched fibers that are electrically connected and that initiate their own contractions. involuntary with 1 or 2 nuclei

skeletal muscle: the muscle tissue attached to the bones of the vertebrate skeleton. consists on long, unbranched muscle fibers with a characteristic striped (striated) appearance. voluntary and multinucleate
compare and contrast the three fiber types of vertebrate skeletal muscle
slow oxidative: a type of skeletal muscle that is red due to the abundance of myoglobin, generates ATP by oxidative phosphorylation (many mitochondria), and contracts slowly but does not fatigue easily

fast glycolytic: a type of skeletal muscle fiber that is white (low [myoglobin]), generates ATP by glycolysis (few mitochondria), and contracts rapidly but fatigues easily

fast oxidative: type of skeletal muscle fiber that is pink (high [myoglobin]), generates ATP by both glycolysis and aerobic respiration (many mitochondria), and has contracticle properties in between slow oxidative and fast glycolytic
distinguish between an endoskeleton, exoskeleton, and hydrostatic skeleton, and give an example of an animal that has each of these types of skeletons
endoskeleton: have rigid structures inside the body (ex. frogs)

exoskeleton: have rigid structures outside of the body (ex. arthropods (crabs))

hydrostatic skeleton: use hydrostatic pressure of enclosed body fluids or soft tissues to support the body (ex. earthworms)
name one function of cartilage
cushions the joint
name three functions of bone
protect the internal organs
provide support for the body
provide a brace for muscles to pull against
discuss how muscles, bones, tendons, and ligaments work together to allow an animal to move.
bones and cartilage do a good job of resisting compression (pushing) and bending, whereas tendons and ligaments do a good job of resisting tension (pulling). these structures interact with muscle in ways that enable the efficient transmission of muscle forces and shape changes
give examples of how joint lever systems (a) can alter the direction of the force applied by muscular contraction and (b) how they can alter the speed and force exerted by a muscle.
bone transmits the forces exerted by the thigh muscles to the foot - such as when the extension of your leg enables you to kick a ball
describe some of the forces exerted on moving animals by the environment
lift counteracts gravity in the air (important when flying)

drag resists forward motion through fluids

gravitational force experienced by an animal is its weight. weight is important on land because most terrestrial animals must hold themselves up to move forward

buoyancy supports the animal's weight in the water
discuss how body size affects animal locomotion
small animals locomotive in a more crouched posture and make great leaps, while large animals like elephants are more straight-legged, so that their skeletons, rather than their muscles, can support their body weight. larger animals also locomote more gently. if a house cat were enlarged to the size of an elephant, it would break its own bones when trying to pounce
compare the cost of locomotion for the three major methods of locomotion (flying, swimming, running)
flying: must overcome drag and must generate enough lift to counteract gravity

swimming: must overcome drag

running: usually dominated by gravitational, must overcome inertial forces
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