Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The animal body and how it moves Chapter 42 Tissues, organs, skeleton, muscles Tube within a tube Coelom is internal body cavity, usually subdivided Peritoneal cavity and pleural cavity Skeleton – jointed bones, vertebrae surround nerve cord Cells – tissue – organ – organ system Tissues are groups of cells similar in function Organs – Body structures composed of several different tissues 3 embryonic tissues = endoderm, mesoderm, ectoderm 4 primary tissues epithelial, connective, muscle, nervous Heart = cardiac muscle, connective tissue, epithelial tissue and nerve tissue Organ system = group of organs that performs major activities (digestive system) Necessary for complex activities Epithelial Tissue Epithelial membrane - covers surface of every vertebrate body and lines cavities Substances must enter/exit through Simple – one cell layer thick Regulation Diffusion Stratified – several layers thick Glands develop from invaginated epithelium Muscle Motors of vertebrate body Actin and myosin filaments in cells Smooth and striated (skeletal and cardiac) Nerves can stimulate or regulate Skeletal muscle long, multinucleate Appear to have transverse stripes when viewed in longitudinal section Skeletal = voluntary, smooth and cardiac = invol. stimulated by nerve, amt of contraction can vary Cardiac – smaller, interconnected Connective Tissue From embryonic mesoderm Connective and special connective Abundant extra-cellular material because cells are placed widely apart Matrix -- crystals in bone, plasma in blood © Adipose cells – fat cells © Ligaments, tendons (sc) Cartilage – tissue that does not stretch and is far tougher (sc) Bones – modeled in cartilage – calcified (sc) Blood – abundant extracellular material Extracellular crystallized matrix, spongy bone, compact bone Erythrocytes and leukocytes -blast vs. -cyte Nerve tissue Neurons and supporting cells – neuroglia Produce, conduct electrochemical events – impulse Cell body, dendrite, axon CNS/PNS Ganglia = collection of nerve bodies Skeletal systems Hydrostatic – soft bodied, fluidfilled cavities surrounded by muscles Exoskeleton – rigid hard case, chitin Contract and push fluid Protection, resist bend, muscles attach Molting, limits size Endoskeleton – rigid internal, muscles attach, flexible exterior Cellular, living, repair Vertebrate = axial, appendicular Muscle contractions move bones Contraction and shortening of muscles Joint/articulation = bone meets bone Immovable – skull Slightly movable – bones bridged by cartilage Intervertebral discs – shock absorbers Freely movable – synovial, articulating ends have synovial capsule (diff. mvmts) Actions of muscles Ends of muscle attached to different bones Attached via tendon Origin is stationary Insertion moves when muscle contracts Synergists vs. antagonists Quads and quads vs. hamstrings To shorten – must overcome existing forces (gravity) Isotonic (same strength) bicep curl Isometric (same length) hold stationary Muscle contraction In each muscle are many muscle fibers, each fiber cell has a bundle of myofibrils, myofibrils are made of myofilaments Myofibrils have alternating dark/light bands on myofilaments – appear striated Thick myofilaments = dark, A bands, myosin Thin = light, I band, divided in half by protein (Z line), actin Sarcomere is from Z line to Z line and crosses myosin Thin overlaps thick, but does not meet in center Contraction = muscle shorten because filaments slide closer together = sliding filament mechanism Crossbridges between thick and thin myofilaments Thick is many myosin proteins with myosin heads Thin is many actin proteins in helix Myosin head + ATP binds to actin, makes bent conformation, slides Controlling muscle contractions Muscle relaxed, myosin head is cocked and ready, but does not bind Competitive inhibition from tropomyosin on thin filament Troponin holds tropomyosin in place When Ca++ binds, troponin moves, displacing tropomyosin, allowing myosin head to bind, break ATP, slide Muscles store Ca++ in modified ER – sarcoplasmic reticulum http://www.blackwellpublishing.com/matthews/myosin.html Nerves stimulate contraction Muscles stimulated by motor neurons Somatic motor neurons Axon of nerve cell makes synapse with multiple muscle fibers Neurotransmitter released (acetylcholine) stimulates muscle to create own electrochemical impulses Carried through muscle, stimulates release of Ca++ Stimulation stops, troponin back to place, tropomyosin blocks cross bridge Excitation-contraction coupling Release of Ca++ links excitation of muscle by neuron to perform contraction http://www.blackwellpublishing.com/matthew s/myosin.html Motor unit – one stimulation contracts a unit of muscles (coordination of muscles) Muscle metabolism – More control = smaller motor units (fewer muscle fibers per neuron) (tapping toe vs. moving leg) At rest = aerobic respiration of fatty acids At work = also glycogen and blood glucose ATP needed for slide and to repump Ca++ 45-90 secs = anaerobic, O2 not increased fast enough Muscle fatigue – decrease in force generated after much use Correlated to lactic acid build up Endurance training does not increase muscle size (slower breakdown of glycogen) Modes of locomotion Actively move requires propulsive and control mechanisms Contracting muscles Quantity, quality, position determined by nervous system Appendicular or axial locomotion Water – ciliary, slither, creep, limbs, feet Bouyancy reduces effect of gravity Body shape important to reduce friction and turbulence Swimming = undulation of whole body, posterior or appendicular Land – mollusks, arthropods, vertebrates Mollusks – muscular foot and slime A & V – body raised above ground, appendages push against ground Legs = support and locomotion Arthropods = more legs, less control, less speed Leapers Invertebrates = peristaltic mvmt (resemble eel, but more analogous, not homologous) Air – insects, pterosaurs, birds, bats Flight evolved 4 times Propulsion achieved by pushing down against air Alternates flexor and extensor Contractions stimulate contractions (1000 times per second, faster than nerve impulses) Night vs. day resources Label the sarcomere, thin filaments, thick filaments, M line Label the thick filaments, thin filaments, myosin head, actin helix, describe what tropomyosin does and what troponin does