BIOL 2420 - Human Physiology: Neurons and Supporting Cells Flashcards

Vocabulary-style flashcards covering neuron anatomy, neuroglia, action potentials, synaptic transmission, and neurotransmitters based on lecture notes.

Neurons

The basic cells of the nervous system that form the central nervous system (CNS) and peripheral nervous system (PNS).

Axon hillock

A specialized part of the neuron cell body that connects to the axon, where action potentials are often initiated.

Pseudounipolar neuron

A type of neuron where a single process extends from the cell body and branches into two directions.

Schwann cells

PNS neuroglia, also called neurolemmocytes, that produce myelin sheaths around myelinated axons and surround all PNS axons to form a neurilemmal sheath.

Satellite cells

Supporting cells in the PNS that support the functions of neurons within sensory and autonomic ganglia.

Oligodendrocytes

CNS neuroglia that form myelin sheaths around central axons, producing the "white matter" of the CNS.

Microglia

CNS neuroglia that phagocytose pathogens and cellular debris.

Astrocytes

CNS neuroglia that cover capillaries and induce the blood-brain barrier (BBB), interact metabolically with neurons, and modify the extracellular environment.

Ependymal cells

Cells that form the epithelial lining of brain cavities and the central canal of the spinal cord; they cover capillaries to form choroid plexuses that produce cerebrospinal fluid.

Neurotrophins

Molecules upon which nerve regeneration largely depends.

Depolarization

A change in membrane potential where the cell becomes more positive, such as from $-70\,mV$ to $+30\,mV$.

Hyperpolarization

An inhibitory change in membrane potential where the inside of the cell becomes more negative than the resting membrane potential.

Resting Membrane Potential (RMP)

The stable voltage maintained by neurons, typically around $-70\,mV$.

Absolute Refractory Period

A period during an action potential when the membrane cannot respond to another stimulus due to inactivated $Na^+$ channels.

Relative Refractory Period

A period during an action potential when a second action potential can be triggered but requires a stronger stimulus due to continued outward diffusion of $K^+$.

Connexin proteins

Proteins that form gap junctions through which electrical impulses travel between adjacent cells.

Synaptotagmin

The protein to which $Ca^{2+}$ likely binds after entering the axon terminal to trigger neurotransmitter release.

SNARE complexes

Protein complexes that vesicles bind to before releasing neurotransmitters via exocytosis into the synaptic cleft.

EPSP (Excitatory Postsynaptic Potential)

Graded depolarizations caused by the inward diffusion of $Na^+$ through chemically gated channels.

IPSP (Inhibitory Postsynaptic Potential)

Localized hyperpolarizations caused by inhibitory neurotransmitters that move the membrane potential further from the threshold.

Spatial Summation

The process where the release of neurotransmitters from multiple neurons simultaneously produces a combined EPSP to reach the threshold.

Temporal Summation

The process where successive releases of neurotransmitters from a single neuron produce a combined EPSP over time.

Nicotinic ACh receptors

Ligand-gated acetylcholine receptors that act as ion channels.

Muscarinic ACh receptors

GPCR-gated acetylcholine receptors that utilize G-proteins.

Acetylcholinesterase (AChE)

An enzyme in the synaptic cleft that breaks down acetylcholine into acetate and choline.

Monoamine Oxidase (MAO)

An enzyme responsible for the inactivation of most monoamine neurotransmitters after reuptake.

Serotonin

A monoamine derived from $\text{l-tryptophan}$ that regulates mood, behavior, appetite, and circulation.

Dopamine

A monoamine involved in the Nigrostriatal and Mesolimbic systems.

Glutamic Acid

An amino acid that produces EPSPs and has three specific receptor types.

GABA and Glycine

Inhibitory amino acid neurotransmitters that hyperpolarize the postsynaptic membrane via ligand-gated receptors.

Endocannabinoids

Short-chain fatty acids that act as retrograde neurotransmitters to inhibit the release of other neurotransmitters.

Nitric Oxide

A gas neurotransmitter that activates $cGMP$ to cause smooth muscle relaxation.

Synaptic Plasticity

The ability of synapses to change in response to activity, encompassing long-term potentiation and long-term depression.