FINAL Exam BIOD 152

Name and describe what is occurring in the neuron cell membrane in section 4 of the diagram. Include the charge of the membrane during this phase. This is phase 4: afterpolarization (hyperpolarization), the potassium gates are slow to clse and that results in an undershoot of the potential, the voltage will drop below -70mV and the return to the restign state beings. At rest, a neuron plasma membrane is: A. -70 mV B. +40 mV C. Hyperpolarized D. Depolarized A. -70 mV Which of the following is false concerning the sodium-potassium pump? A. it maintains the resting phase of an axon B. For every three sodium ions pumped out, two potassium ions are pumped in C. it must remain in constant operation to maintain the resting state D. The overall effect is a negative charge on the outside of the membrane D. The overall effect is a negative charge on the outside of the membrane True or false: A sensory neuron is signaling the body of extreme pain. This means that the strength of the action potential is greater than usual. Explain your reasoning False, there is no variation in the strength of action potentials. (It is an all-or-nothing response). There is variation in the number and frequency of neurons firing Which of the following statements is false concerning the neuromuscular junction? A. Sodium ions release from the presynaptic motor neuron B. Calcium ions release from the sarcoplasmic reticulum to cause muscle contraction C. Sodium channels open on the muscle fibers in response to the neurotransmitter D. The NMJ is found in the peripheral nervous system A. Sodium ions release from the presynaptic motor neuron What prevents continuous stimulation of a nerve synapse and how is this accomplished? The short extension of neurotransmitters in the synpase prevents coninous stimulation. Some synapses contain enzymes that rapidly inactivate neurotransmitters and other synpases rapidly absord the neurotransmitters. What neurotransmitter is found at the neuromuscular junctions? Acetylcholine (ACh) True or False: Action potentials travel in multiple directions within the same neuron. False (only one direction in the same neuron) True or False: Reflexes occur only with conscious intervention from the brain False Fill in the blank: In a reflex, the ____________ neuron conducts nerve impulses along a pathway towards the central nervous system. sensory (afferent) Where is the integration center of a reflex located? CNS (central nervous system) Which of the following is false about reflexes? A. Reflexes do not require higher levels of voluntary processing from the brain B.Regulation of blood sugar by hormones is one example of a reflex C. Some reflexes can be tested to determine injury D. Pulling a hand away from a hot flame is not a reflex; it is entirely voluntary D. Pulling a hand away from a hot flame is not a reflex; it is entirely voluntary What is false about the stretch reflex? A. the effect of the motor signal is to relax a muscle B. The patellar reflex test the stretch reflex of the quadriceps femoris C. The muscle is spindle detects stretch within the muscle D. Stretch reflexes help to decrease the stretch on a muscle A. The effect of the motor signal is to relax a muscle