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Multiple Choice Questions - mcqs -Neurons
Neurons generate and propagate nerve impulses. Some parts of the neurons receive signals from other neurons whereas some other parts propagate these impulses to other neurons.
The action potential arise from a region that resembles a mound on one side of the cell body in a neuron.
Action potentials are transmitted rapidly by the successive activation of regions that extends from the cell body to the axon terminals.
Neurotransmitters are chemicals which help in the transmission of impulses from a neuron to a cell across the synapse.
They participate in electro-chemical communication from one nerve cell to another or one nerve cell to various organs in the body.
Neuron as the Basic Functioning Unit
Nervous system is the fast communication system in the body. It is organised into central nervous system and the peripheral nervous system. The functioning unit of the nervous system is the nerve cell or neuron.
Schwann cells are glial cells that wrap around the nerve fiber in the peripheral nervous system
The myelin sheath is fatty and consists of layers of lipids, including cholesterol and phospholipids, separated by thin layers of protein. There are periodic gaps in the myelin sheath on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses. Impulses to jump from this gap to gap in a process known as saltatory conduction
Sodium-potassium pump is a protein found in many cells that maintains the concentration of potassium ions [K+] and sodium ions [Na+]. The most abundant intracellular ion is potassium and the most abundant extracellular ion is sodium. The pump is activated by external concentration of [K+] and internal concentration of [Na+].
Graded potentials result from the changes in the membrane potential caused by movement of ions across the cell membrane.
Graded potential may be excitatory or inhibitory and do not behave like action potentials. Graded potential decay over short distances from the point of initiation and depending upon the type of ion channel involved, it may excite or inhibit a neuron. Action potentials are the fully developed nerve impulses generated at the axon hillock and travel through the entire length of axons.
Multiple Choice Questions (mcqs) on Neuronsview quiz statistics
Refractory period is the minimum period of time required for the same area of axon membrane to generate a second action potential
The depolarisation beginning at the axon hillock spreads sequentially to the nodes of Ranvier “downstream” from the hillock
Myelin sheath influences the transmission of impulses. Without myelin the entire surface of axon membrane has to sequentially depolarise and repolarise needing more time.The fastest transmission of action potential occur with large diameter myelinated axons.
Neurons communicate with other cells by way of synapses. Synapses are special sites where a presynaptic neuron releases neurotransmitters which will get attached to receptors in the postsynaptic neuron. Neurons extend terminals to many other celss and receive input from other neurons which will form nerve pathways.