BIO304H5 Chapter Notes - Chapter 2: Exocytosis, Reticular Theory, Potassium Dichromate
Document Summary
Regression on graded vs. action potentials: gradedpotentials fizzle out over time, gradedpotentials can be excitatory(depolarizing) or inhibitory(hyperpolarizing, excitatory post-synaptic potentials = epsps. Action potentials arise when graded potentials activate voltage-gated ion channels: unlike graded potentials, aps don"t dissipate and travel long distances, can travel up to 120 m/s along myelinated (insulated) axons. Aps are driven by voltage-gated na+and k+ion channels: main function of action potentials in neurons, transmit signals along axons, trigger pre-synaptic ca2+influx through voltage-gated calcium channels for the release of neurotransmitters (fast exocytosis) Main function in muscle: drive contraction, main function in endocrine cells, drive secretion of hormones (exocytosis) We didn"t always know that neurons are cells: the cell theory (1838), the cell theory (1838), made possible by technological advances in microscopy, based on combined observations by numerous scientists. 2. the cell is the basic unit of structure and organization in organisms.
