BIOL 152 1st Edition Lecture 16 Outline of Last Lecture I Epithelial Tissue II Connective Tissue III Nervous tissue IV Generation of Neural Impulse Outline of Current Lecture I Synapses II Nervous System Organization III Muscle Tissue IV Contraction Sequence Current Lecture I Synapses Synapses are specialized junctions controlling communication between neurons and other cells There are two types of synapses electrical synapses and chemical synapses During electrical synapses action potentials spread directly from one cell or neuron to the next via gap junctions Chemical synapses involve the conversion of an electrical signal to a chemical signal and then back to an electrical signal Relative to chemical synapses electrical synapses are fast and facilitate synchrony However chemical synapses are better capable of regulating neural impulses II Nervous System Organization The nervous system is found only in the organisms that fall under the eumetozoa clade There are two main nervous systems the central nervous system and the peripheral nervous system The central nervous system includes the brain that interprets stimuli and sends information to nerves throughout the body The peripheral nervous system is composed mainly of sensory and motor neurons and acts simultaneously with the central nervous system III Muscle Tissue Again only the organisms in the eumetozoa clade contain muscles and muscle cells The muscle is composed of contractile cells or fibers that are responsive to movement There are These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute three types of muscle skeletal cardiac and smooth muscle The skeletal and cardiac muscle are striated whereas the smooth muscle in not IV Contraction sequence There are a series of steps that a muscle must undergo in order to contract The first step is the action potential arrives at the nerve muscle synapse then depolarization travels down the T tubules to sarcoplasmic reticulum Calcium is then released from the sarcoplasmic reticulum and the troponin complex binds to the calcium and changes the tropomyosin so that actin can bind to the myosin The myosin head then hydrolyzes the ATP changing the position of the head the myosin then binds to the actin ADP and an inorganic phosphate group are released and the myosin head swings toward the sarcomere center and the actin filaments toward each other The myosin head then binds to an ATP and the head dissociates from the actin
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