study question chapter 11 – Flashcards

Schwann cell

The cell shown in E wraps and insulates the soma of neurons within ganglia in the PNS.

Yes, cilia are an indication that the cells they appear on are moving fluids past the surface of the cells.

Microglial cells are small and ovoid with relatively long "thorny" processes. Their processes touch nearby neurons, monitoring their health, and when they sense that certain neurons are injured or are in other trouble, the microglial cells migrate toward them. Where invading microorganisms or dead neurons are present, the microglial cells transform into a special type of macrophage that phagocytizes the microorganisms or neuronal debris.

Astrocytes are the most abundant and diversely functioning glial cells. Examples of their many functions include: anchoring neurons to capillaries, aiding in the exchanges between neurons and blood, guiding the migration of young neurons, and helping control the chemical environment around neurons.

The neuron shown has a many processes (axon and dendrites) that emerge from the cell body. Such neurons typically function as motor neurons or interneurons.

The dendrites and soma of the cell receive signals from other neurons. E would be considered a secretory region, delivering signals to other neurons.

Neurotransmitters are released by secretion from the ends of axonal terminals.

Graded potentials originating in the dendrites and cell body are integrated (summated) at the axon hillock (C). Membrane potentials above threshold at the hillock will open voltage-gated Na+ channels found in the "trigger zone," producing an action potential that proceeds down the axon. ( points to the the end where it connects to the tail )

Voltage-gated Na+ and K+ channels allow for the triggering of an action potential at the axon hillock (C) and its propagation down the axon (D). Receptive regions of neurons are areas characterized by the presence of chemically gated ion channels and other neurotransmitter-binding receptors. ( they are located in the tail and the near the tail

The dendrites provide a large surface area for connections from other neurons. Yes, because of the branching and extensive membrane surface area, there is a large amount of membrane dedicated to synapses with other neurons.

Bundles of neurons are called tracts in the central nervous system. In the peripheral nervous systems, bundles of axons are called nerves.

This is true; a neuron can have only one axon, but the axon may have occasional branches along its length.

Functional classification groups neurons according to the direction in which the nerve impulse travels relative to the central nervous system. Based on this criterion, there are sensory neurons, motor neurons, and interneurons.

Dendrites are the main receptive or input regions, providing an enormous surface area for receiving signals from other neurons.

Unipolar neurons makeup the sensory neurons in the peripheral nervous system.

Yes! The resting membrane potential is the baseline potential that can be recorded across the plasma membrane of an excitable cell prior to excitation.

Yes. Leak channels for Na+ and K+ are ubiquitous, and they allow for the diffusion of these ions across plasma membranes. Some ligand-gated channels do permit Na+ and K+ to passively move across plasma membranes, but they are not present in all cells.

Yes! Also known as the Na+-K+ pump, or simply the pump, this transporter moves three Na+ out of the cell and two K+ into the cell for every ATP it hydrolyzes. This pumping action prevents the Na+ and K+ gradients from running down as these ions passively move through leak channels. The Na+ cotransporter, which uses the energy inherent in the Na+ gradient to transport other ions or molecules (for example, Ca2+ and glucose) across the plasma membrane, is an example of a secondary active transporter. Recall that the Na+ gradient is maintained by the action of the Na+-K+ ATPase. Energy that is liberated during ATP hydrolysis is transformed into the energy of the Na+ gradient. Na+ cotransporter mechanisms do not maintain the Na+ and K+ gradients.

Yes! The concentration gradient and the large number of K+ leak channels allow for rather robust K+ diffusion out of a cell. In contrast, the concentration gradient and the relatively few Na+ leak channels allow for much less Na+ diffusion into a cell.

Yes! The inside surface of the plasma membrane accumulates more negative charge because of the presence of Na+ and K+ gradients and the selective permeability of the membrane to Na+ and K+.