CHAPTER 48 Animal Movement PPT Notes 5 6 2014 movement a way for animals to respond to stimuli from environment produced by muscle skeletal systems o locomotion movement of entire animal generated by muscle contraction biomechanics study of locomotion in animals skeletal geometry reveals much information about animal posture range of motion skeleton functions forces involved depend on environment on land mainly gravitational inertial forces in water mainly drag forces in air mainly drag forces must be lightweight counter gravity natural selection favors minimizing cost of locomotion rate of oxygen consumption via energy efficient gait at various speeds depending on energy need size of animal ratio of SA to V as animal size larger animals use energy gram body mass distance traveled than smaller animals cost of locomotion with mass weight of animal proportional to V ability of leg bones to support weight proportional to cross sectional area posture may determine locomotion behavior small animals crouch leap large animals locomote gently aquatic animals deal w viscosity of water fluid minimize inertia o movement of one part of animal body relative to whole muscle fibers long slender cells that compose vertebrae skeletal cardiac muscle tissue o myofibrils small strands within muscle cell may be striped striated made of light dark areas called sarcomeres sarcomeres shorten as myofibril contracts lengthen as sarcomere relaxes thick filaments contain myosin head of myosin bound to actin from thin filament catalyzes hydrolysis of ATP Ca2 ions bind to troponin to actin myosin can interact interaction btwn actin myosin is a 4 step process 1 ATP binds to myosin head shape releases myosin from actin 2 ATP hydrolyzed to ADP inorganic phosphate myosin neck straightens head pivots to bind to new myosin head ready for power stroke energized head in cocked position 3 phosphate released neck bends back moves thin filament relative to thick filament 4 ADP released myosin filament ready to repeat actin subunit cycle o o o o two ends of sarcomere pulled closer together through cycle thin filaments contain actin troponin tropomyosin troponin tropomyosin regulate muscle activity block myosin binding sites on actin by forming a complex actin myosin can t slide past each other movement contraction occurs as motor neuron generates action potential that is received muscle cell 1 action potential triggers release of acetylcholine from motor neuron acetylcholine neurotransmitter acetylcholine deposited into synaptic cleft btwn motor neuron muscle cell 2 acetylcholine binds to receptors on muscle cell membrane 5 6 2014 muscle cell depolarized action potentials triggered in fibers 3 4 action potential spreads to interior of fiber via invaginated T tubules of cell membrane T tubule interacts with smooth ER known as sarcoplasmic reticulum protein in in ER shape lets Ca2 ions enter 5 myosin binding sites on actin exposed contraction o o o muscle force proportional to cross sectional area of muscle cell of sarcomeres lined up side by side muscle shape depending on interaction of skeletal muscle systems parallel fibers maximize length change i e sartorious muscle cross section small force length diagonal pennate muscles maximize force i e gastrocnemius 3 types of muscle tissues smooth skeletal cardiac see chapter 42 smooth uninucleate involuntary unbranched unstriated lacks myofibrils sarcomeres thin sheets essential to function of lungs blood vessels digestive system urinary bladder reproductive system contains autonomic motor neurons connected to parasympathetic neurons that release acetylcholine to stimulate contractions in digestive system parasympathetic neurons secrete acetylcholine to slow down heartbeat rest slower rate of depolarization sympathetic neurons and adrenal gland release neurotransmitters that inhibit muscle contraction in digestive tract sympathetic neurons release norepinephrine adrenal glands epinephrine adrenaline these hormones are released during fight or flight exercise to heartbeat blood flow o skeletal striated multinucleate voluntary unbranched longer than smooth cardiac has myofibrils sarcomeres systems perform 4 main functions protection maintenance of body posture re extension of shortened muscles transfer of muscle forces bones joints cartilage tendons ligaments vertebrae skeletons move by s of joint angles controlled by antagonistic muscle groups muscles pull on bones when contracting movement enclose openings of digestive system swallowing defecation urinary system urination voluntary muscles stimulated by somatic motor neurons damage results in paralysis 3 types of fibers slow muscle fibers red in presence of Fe in myoglobin high myoglobin concentration slow oxidation of ATP many mitochondria get ATP from aerobic respiration slow fatigue intermediate muscle fibers pink or red oxidize ATP intermediate rate via glycolysis aerobic respiration few mitochondria intermediate fatigue fast muscle fibers white bc of conc of myoglobin get ATP from glycolysis many mitochondria fast fatigue hydrostatic skeletons still water skeletons hydrostats are made of body wall in tension surrounding fluid tissue under compression pressure allows soft bodied animals to perform main functions o cardiac uninucleate involuntary branched striated contains sarcomeres cells connected end to end via intercalated discs discs contain protein lined openings gap junctions that give direct cytoplasmic connection btwn adjacent muscle cells critical to flow of electrical signals from cell to cell heartbeat muscle contracts when muscle cell is depolarized 5 6 2014 CHAPTER 48 Animal Movement Blue Thread Questions 5 6 2014 Why is the dark band in a sarcomere dark and the light band light Explain which elements in the rope analogy represent the Z discs which are the thin filaments and which elements are the thick filaments Describe the sliding filament model Predict the effect on muscle function of drugs that have the following actions increase acetylcholine release at the neuromuscular junction prevent conformational changes in troponin and block uptake of calcium ions into the sarcoplasmic reticulum Predict whether the breast meat of pigeons which are capable of prolonged flights is composed of dark meat or white meat and explain why there is a color difference between these muscle types If you understand how a hydrostatic skeleton works you should be able to explain how earthworms can push laterally against the
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