Nervous System Overview

The two major divisions of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

The four lobes of the cerebral hemisphere are the frontal, parietal, temporal, and occipital lobes.

The functional unit of the nervous system is the neuron.

<p>Dendrites extend from the cell body to receive incoming signals and process them before sending information to the soma.</p> Signup and view all the answers

<p>Action potentials are typically generated at the initial segment of the axon.</p> Signup and view all the answers

<p>The myelin sheath insulates the axon, increasing the speed of impulse transmission.</p> Signup and view all the answers

<p>The two components of the autonomic nervous system are the sympathetic and parasympathetic nervous systems.</p> Signup and view all the answers

<p>The brainstem includes the midbrain, pons, and medulla oblongata.</p> Signup and view all the answers

<p>Schwann cells wrap around the axon to form the myelin sheath, which insulates the axon.</p> Signup and view all the answers

<p>At the nodes of Ranvier, the axon is unmyelinated, allowing action potentials to 'jump' between these nodes for faster conduction.</p> Signup and view all the answers

<p>Neurons generate local (non-propagated) potentials and propagated action potentials.</p> Signup and view all the answers

<p>The Na+/K+ ATPase pump actively moves Na+ out of the cell and K+ into the cell, maintaining the concentration gradients necessary for membrane potential.</p> Signup and view all the answers

<p>The resting membrane potential of neurons is typically around -70 mV.</p> Signup and view all the answers

<p>An action potential is an electrochemical signal that transmits impulses, occurring when there's a change in voltage across the membrane and a threshold level of stimulus is reached.</p> Signup and view all the answers

<p>The unequal distribution of ions, particularly higher K+ concentration inside the cell and higher Na+ concentration outside, is crucial for establishing the resting membrane potential.</p> Signup and view all the answers

<p>K+ moves out of the neuron when K+ channels are open due to the concentration gradient driven by the higher K+ concentration inside the cell.</p> Signup and view all the answers

<p>The All-or-None law states that an action potential either occurs fully or not at all.</p> Signup and view all the answers

<p>During depolarization, voltage-gated Na+ channels open, allowing Na+ ions to rush into the cell, causing further depolarization.</p> Signup and view all the answers

<p>The absolute refractory period occurs from the start of the action potential until part of repolarization, where no stimulus can trigger another action; during the relative refractory period, a stronger than normal stimulus can initiate a response.</p> Signup and view all the answers

<p>During repolarization, voltage-gated K+ channels open, allowing K+ ions to exit the cell, which causes the membrane potential to decrease.</p> Signup and view all the answers

<p>Weak stimuli require a longer duration to trigger an action potential, while strong stimuli can evoke a response with a shorter duration.</p> Signup and view all the answers

<p>Hyperpolarization is when the membrane potential becomes more negative than resting level, occurring after the K+ channels close.</p> Signup and view all the answers

<p>Threshold intensity is the minimum strength of a stimulus needed to trigger an action potential, determining whether a neuron fires.</p> Signup and view all the answers

<p>Na+ channels inactivate after the membrane potential approaches +60 mV, preventing further influx of Na+ and contributing to the repolarization phase.</p> Signup and view all the answers

<p>An action potential will not be generated if the stimulus is subthreshold.</p> Signup and view all the answers

<p>Decreased Na+ outside the cell lowers the strength of the action potential but minimally impacts the resting membrane potential.</p> Signup and view all the answers

<p>Saltatory conduction involves depolarization jumping from one node of Ranvier to the next, facilitated by the insulating effect of myelin.</p> Signup and view all the answers

<p>Hyperkalemia lowers the threshold for action potential, making neurons more excitable.</p> Signup and view all the answers

<p>Glial cells support neurons by holding them in place, supplying nutrients, insulating them, and removing pathogens.</p> Signup and view all the answers

<p>Hypokalemia hyperpolarizes the membrane, making it more negative and reducing the likelihood of an action potential.</p> Signup and view all the answers

<p>Decreased Ca2+ increases membrane excitability, while increased Ca2+ decreases it.</p> Signup and view all the answers

<p>Nodes of Ranvier allow for the circular current flow necessary for saltatory conduction in myelinated axons.</p> Signup and view all the answers

<p>The BBB primarily separates the central nervous system from peripheral blood circulation.</p> Signup and view all the answers

<p>Neurotrophins support the growth, survival, and function of neurons.</p> Signup and view all the answers

<p>Schwann cells release growth-promoting factors that guide axonal sprouting towards the distal stump.</p> Signup and view all the answers

<p>Peripheral nerve regeneration is more successful due to the presence of growth-promoting factors and viable connective tissues.</p> Signup and view all the answers

<p>Axons in the CNS form short sprouts, but rarely recover or form new synapses.</p> Signup and view all the answers

<p>Astrocytic proliferation and scar formation are two such factors.</p> Signup and view all the answers

<p>Neurotrophins produced by the distal stump promote axonal growth during regeneration.</p> Signup and view all the answers

<p>Inflammatory responses lead to immune cell invasion and create a hostile environment for regeneration.</p> Signup and view all the answers