BIOL 111 Lecture Notes - Lecture 16: Myocyte, Hexapoda, Centipede

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Types of skeletons hydrostatic skeleton ex: cnidarians worms shell-less mollusks exoskeleton ex: shelled mollusks arthropods endoskeleton ex: echinoderms vertebrates. Muscular skeletal systems in arthropoda: skeletal muscles, need a resistor to act against (i. e. , a skeleton) b, are often found in antagonistic pairs act in opposite directions. Muscles can only pull, not push (e. g. , biceps/triceps) Muscle: organ: muscle tissue and connective tissue, muscle fibre: multinucleate cell; contains many myofibrils, myofibrils are composed of protein bundles sarcomeres are contractile unit of a myofibril. What happens when spike reaches neuromuscular junction: action potential reaches synapse (neuromuscular junction, voltage-gated ca++ channels open and ca++ flows into presynaptic terminal. Increased [ca++] leads to fusion of synaptic vesicles containing neurotransmitter with presynaptic membrane (neurotransmitter at neuromuscular junction is acetylcholine) Transmitter reaches receptor proteins on postsynaptic membrane via diffusion. Contraction of sarcomere is caused by sliding of thick between thin filaments filaments: at low [ca++], the myosin heads can"t bind to the actin filaments.