Nervous System Fundamentals and Physiology

Flashcards covering the subdivisions of the nervous system, neuron structure, neuroglial cells, membrane potentials, and synaptic transmission based on the lecture transcript.

The Central Nervous System (CNS) consists of the brain and the __________, both of which are enclosed in bony coverings.

Spinal cord

In the Peripheral Nervous System (PNS), a __________ is a bundle of nerve fibers wrapped in connective tissue.

Nerve

Approximately __________ of all neurons are interneurons, which are confined to the CNS.

$$90\%$$

The ability of a neuron to respond to stimuli such as environmental changes is known as __________.

Excitability

The __________ is the cell body of a neuron, containing a single central nucleus and Nissl bodies.

Soma

The product of the breakdown of worn-out organelles that accumulates in neurons with age is called __________.

Lipofuscin

The single __________ arises from the axon hillock and is responsible for the rapid conduction of nerve signals.

Axon

__________ neurons are the most common structural type, characterized by having many dendrites and one axon.

Multipolar

__________ axonal transport moves organelles and enzymes at speeds up to $400\,mm/day$.

Fast anterograde

The glial cells responsible for forming the blood-brain barrier (BBB) and regulating brain tissue fluid are __________.

Astrocytes

In the CNS, __________ form myelin sheaths around many nerve fibers.

Oligodendrocytes

__________ are macrophages formed from monocytes that concentrate in areas of infection or trauma within the CNS.

Microglia

The myelin sheath is composed of $20\%$ protein and __________ lipid.

$$80\%$$

The gaps between segments of the myelin sheath are known as __________.

Nodes of Ranvier

Signal conduction speed in large, myelinated fibers reaches up to __________.

$$120\,m/sec$$

Regeneration of peripheral nerve fibers can occur only if the soma and the __________ tube remain intact.

Neurilemmal

A typical neuron has a resting membrane potential of __________.

$$-70\,mV$$

The Na+/K+ pump requires a great deal of __________ to function, pumping out 3 Na+ for every 2 K+ it brings in.

ATP

Unlike action potentials, local potentials are __________, meaning they vary in magnitude based on stimulus strength.

Graded

An action potential is triggered only if the local potential reaches a threshold of __________.

$$-55\,mV$$

The period of resistance to stimulation during which no stimulus will trigger a new action potential because Na+ gates are open is the __________ refractory period.

Absolute

In myelinated fibers, nerve signals travel via __________ conduction, jumping from one Node of Ranvier to the next.

Saltatory

Neurotransmitters such as epinephrine, norepinephrine, and dopamine are classified as __________.

Catecholamines

Chains of 2 to 40 amino acids that act at lower concentrations and have longer-lasting effects are called __________.

Neuropeptides

An inhibitory __________ synapse triggers the opening of Cl- channels, leading to hyperpolarization of the postsynaptic membrane.

GABA-ergic

The enzyme __________ is responsible for degrading acetylcholine in the synaptic cleft to terminate the signal.

Acetylcholinesterase

The ability of the nervous system to process, store, and recall information through chemical synapses is called __________.

Neural integration