Biology 1107 Final Exam Study Guide (University Of Connecticut) 2024

Biology 1107 Final Exam Study Guide (University Of Connecticut) 2024 along the length of the axon c. Action potential needs to be regenerated by the presence of more voltage gated sodium and potassium channels along the length of the axon d. So if axon is damaged, you would not have transmission of AP, it would never drive at the axon terminal and never release a neurotransmitter e. Myelin- a fatty cell type that wraps around the axon, allowing for jumping of action potential along the axon so doesn’t have to regenerate f. Synaptic bouton i. This is an axon terminal that has a special shape ii. Has vesicles and inside contains neurotransmitters g. At the terminal, you’re able to see how the action potential turns into a signal that is released and goes goes into other cells h. Ligands bind to receptors that are off of the soma surface- often associated w ion channels i. Ligand binding signals sodium channels to open, depolarizing it to the threshold j. When neuron depolarizes to threshold, all sodium channels open at once causing massive influx of sodium and depolarization i. Axon hillock- where there’s a lot of voltage gated sodium channels k. When the depolarizing signal arrives at the axon terminal, there are other voltage gated ion channels here such as calcium l. Calcium acts as a chemical signal that binds to calcium receptors which are on the vesicles causing the vesicles to dock at the presynaptic membrane m. Membranes fuse w the membrane and dump their contents into the synaptic cleft (exocytosis) i. Neurotransmitters released into the synapse and act as a ligand n. Typically there is a postsynaptic membrane nearby which can be a dendrite, cell body, or axon of another neuron i. You need receptors for this neurotransmitter for there to be a response period end of story. 10. Be able to explain how EPSPs and IPSPs "sum" within a neuron and affect membrane potential. a. So EPSPs? Excitatory postsynaptic potential. i. Neurotransmitters released by the presynaptic neuron and depolarize the postsynaptic potential ii. It makes action potential more likely iii. Pushes postsynaptic neuron towards the threshold iv. Positive charges enter b. So IPSPs? Inhibitory postsynaptic potential. i. Hyperpolarizes the postsynaptic neuron ii. Makes action potential less likely iii. Pushes postsynaptic neuron away from the threshold iv. Positive charge bye bye baby c. Space and time influence how EPSPs and IPSPs affect membrane potential d. Inputs closer to the axon hillock where there are sodium ion channels have a bigger effect on voltage gated sodium channels getting to the threshold e. Distal dendrite inputs have a lesser effect on the postsynaptic neuron and can diffuse or disintegrate over receding neuron membrane space f. EPSPs and IPSPs sum can cancel out or add together g. If EPSP happens a lone receives depolarization then diffuses no long lasting change in postsynaptic neuron membrane potential h. At later times when arrival is close together of postsynaptic membrane potentials i. If 2 events of signal transduction occur close together they sum helping neuron to reach the threshold ii. All or nothing action potential temporal summation i. EPSP and IPSP can cancel eachother out 11. Be able explain the structure of the neuromuscular junction and of muscle fibers. a. Our bones contract and execute voluntary movement when they receive info from neurotransmitters b. Skeletal muscles consist of bundles of elongated cells called muscle fibers which run the entire length of the muscle c. Muscle fibers (muscle cells) are packed with cylindrical contractile fibers (myofibrils) that run lengthwise in the cell i. Inside muscle fibers are myofibrils, each myofibril consists of thick and thin filaments which contract to allow movement ii. Thick and thin alternate dark and light bands to give muscle fibers a striated appearance, d. Thick filaments- are parallel bundles of myosin molecules, consisting of subunits of a head connected to a long double helix tail i. Head bends toward adjacent thin filament to form a cross bridge ii. Myosin head moves while the tail keeps it connected e. Thin filaments- contain two linear chains of actin molecules wound in a double helix i. Bound to the actin is tropomyosin (long fibrous protein) and troponin- (a three subunit globular protein that binds to tropomyosin at intervals along the thin filaments f. Within muscles are muscle fibers, within fibers are myofibrils, within myofibrils are thick and thin filaments 12. Be able to describe the molecular steps that create muscle contraction. a. One neuron contains acetylcholine that gets exocytosed out through the synapse into the ligand gated channels on the motor neurons which are acetylcholine receptors b. At the arrival of acetylcholine at the receptors, changes happen inside the cell