Axonic Transport and Neurobiology Lecture Review

These flashcards cover axonic transport mechanisms, neuron types, neuroglia of the CNS and PNS, the structure of myelinated axons, gray and white matter organization, and membrane potential characteristics.

What is anterograde movement in axonic transport?

Movement from the soma to the axon and synaptic knobs.

Which types of viruses are associated with retrograde flow?

Rabies and hopes virus.

How is a sensory or afferent neuron defined?

Neurons that carry information and action potentials toward the CNS.

How is a motor or efferent neuron defined?

Neurons that carry motor output from the CNS out to the body.

What is the function of interneurons (association neurons)?

They decipher different sensations and formulate an appropriate response.

Which structural type of neuron is most common in the CNS?

Multipolar neurons.

Where are bipolar neurons found and what is their function?

They are found in the reting of the eye and nose, functioning in special sensation.

What is a unipolar neuron?

A neuron with a single process that divides into two branches.

What is the role of Schwann cells (neurolemmocytes) in the PNS?

They wrap around a portion of only one axon to form a myelin sheath; greater wrapping leads to faster nerve impulse conduction.

What is the primary function of astrocytes in the CNS?

They regulate substances reaching the CNS from the blood (blood-brain barrier) and promote tight junctions.

What is the function of the blood-brain barrier?

It protects neurons from toxic substances and allows the exchange of nutrients and waste products between neurons and blood.

What structures do ependymal cells line?

Brain ventricles and the choroid plexus.

What is the function of the choroid plexus?

It consists of blood vessels that secrete cerebrospinal fluid (CSF).

What is the function of microglia?

They are specialized machrophages that respond to inflammation and phagocytize necrotic tissue and microorganisms.

How do oligodendrocytes differ from Schwann cells in myelin formation?

A single oligodendrocyte can form myelin sheaths around portions of several axons in the CNS.

When does the myelination of axons typically start?

It starts after birth in a top down sequence.

What are the nodes of Ranvier?

Gaps between myelinated sections that are bare regions where the action potential occurs.

In which condition does damage to the myelin sheath and sclerosis occur?

Multiple sclerosis.

What constitutes gray matter and what is its primary function?

It consists of unmyelinated axons, cell bodies, dendrites, and neuroglia, and it performs integrative functions.

What constitutes white matter and what is its function?

It consists of myelinated axons and nerve tracts that propagate action potentials from one area in the CNS to another.

What are groups of cell bodies in the PNS gray matter called?

Ganglia.

What are leak channels and which ions do they favor?

They are always open channels responsible for rest permeability; there are many more for $K^{+}$ and $Cl^{-}$ than for $Na^{+}$.

In what direction does $K^{+}$ move through leak channels when the membrane is at rest?

Because $K^{+}$ is in higher concentration on the inside, it moves out.

How do ligand-gated ion channels operate?

They open or close in response to a ligand, such as Ach.

What is the voltage of a polarized cell at rest?

$-70\,mV$ on the inside relative to the outside.

What is the Typical range for the potential difference of the Resting Membrane Potential?

$-70\,mV$ to $-90\,mV$.