Astrocytes Are named after asteroids as they are very small

Astrocytes.... Are named after asteroids as they are very small neurons which circle other neurons like asteroids Can limit Neurotransmitter diffusion Take-up/remove Neurotransmitter May participate in the \"Tri-partate Synaspe\" Of the above.. One statement is true Two statements are true Three statements are true All statements are true None of the statements are true After firing a short burst of action potentials in an axon, researchers observe a larger EPSP in the postsynaptic cell, and this effect seems to last a few tens of milliseconds. According to the favored hypothesis for this phenomenon, the presynaptic terminal most likely has ___________. elevated intracellular calcium concentration lowered intracellular calcium concentration elevated intracellular sodium concentration reduced intracellular sodium concentration elevated intracellular magnesium concentration The rising phase of an action potential is largely due to... Opening of voltage-gated Na^+ channels K^+ channel inactivating and delayed opening of Na^+ channels Na^+ channels inactivating and delayed opening of K^+ channels Activation of both Na^+ and K^+ channels increasing total ionic flux none of the above Which of the following regarding the voltage gated sodium channel is FALSE: Has a region known as a selectivity filter Has a voltage sensor consisting of positively charged amino acids Is always open when the membrane is depolarized above threshold Must undergo a conformational change in order for the pore to open Is concentrated at the Nodes of Ranvier

Solution

3. Astrocytes are the cells that exist in star shape. These cells cover the surface of the brain and nonsynaptic regions of the neurons. They produce a supportive frame work for CNS and also stimulate the formation of blood-brain barrier. They are involved in nourishment of neurons and secrete the growth stimulants. These cells also influence the synaptic signaling between neurons and help to regulate the composition of extra cellular fluid in the CNS. These cells produce scar tissue to replace the damaged nervous tissue. They take up and release the neurotransmitters and are also involved in tripartite synapse. option b is correct.

4. . EPSP do not have sufficient magnitude to bring the postsynaptic neuron to threshold. Summation of EPSPs generated by multiple pre-synaptic action potentials is required to generate an action potential in a postsynaptic neuron. The synaptic inputs to generate action potentials are dependent on voltage dependent channels. Options b and c are correct.

5. Na⁺ enters cell, causing explosive depolarization to +30mV, which generates rising phase of action potential. Therefore, opening of voltage gated Na⁺ channels cause rise in action potential. Option a is correct.

6. Voltage gated sodium channels open by sensing changes in the membrane potential but not by undergoing conformational changes. Option d is correct.