Quiz #1- Psy 327 Part II

Unit 1: Neurons & Glia

What are the two major cell types in the brain?

Neurons and glia.

What are neurons specialized for?

Rapid, long-distance communication and information processing in the nervous system.

What are neurons?

The primary information-processing elements of the nervous system.

What does it mean that neurons are highly polarized cells?

They have structurally different regions that allow them to receive, process, and transmit information.

What electrical signal do neurons generate?

Action potentials

What percentage of brain cells are glia?

Approximately 90% of cells in the brain.

What percentage of brain volume do glia make up?

About 50% of brain volume.

What is the primary function of glia?

They support neurons and regulate the environment around them.

Do glial cells typically generate action potentials?

No. Glia typically do not generate action potentials.

What is the function of the cell membrane?

It separates the intracellular (inside) and extracellular (outside) environments and is essential for electrical signaling.

What is the function of the nucleus?

It stores and protects genetic material (DNA) and acts as the cell's control center.

What is the function of the mitochondria?

They are the cell's main energy-producing organelles, converting nutrients into usable energy.

What is the cytoplasm?

The gel-like fluid that fills the cell, suspends organelles, and provides an environment for biochemical reactions.

What is the cell membrane?

A continuous, highly selective boundary that separates the cell's internal and external environments.

Why is the cell membrane important for neurons?

It controls the movement of ions across the membrane, which is essential for electrical signaling.

Is movement through an open ion channel active or passive?

ions move through the channel without the cell directly using energy to push them through

What determines whether an ion can pass through a channel?

Ion selectivity — the channel's structure determines which ions can fit and pass through.

What is an open channel?

A membrane protein channel that is open and allows specific ions to pass through.

What is an ion electrochemical gradient?

What is an ion electrochemical gradient?

What determines the movement of ions through an open channel?

Three key factors:

• The channel must be open

• The ion must fit/selectively pass through the channel

• The electrochemical gradient determines the direction of movement

What is DNA often described as?

The “blueprint” for making cellular proteins.

How is DNA organized inside the nucleus?

into chromosomes

How does the nucleus control cellular activities?

by regulating gene expression—which proteins are made, when they are made, and how much is made.

Why are proteins important to cells?

Nearly everything the cell does depends on proteins.

What do proteins do as enzymes?

They speed up and regulate biochemical reactions.

What role do proteins play as receptors and channels?

they help cells receive signals and control the movement of substances/ions across the membrane

What structural role do proteins play?

they provide structure & support for cells and tissues

What role do proteins play in transport?

They help move substances within cells and across cell membranes.

How are proteins involved in synaptic plasticity?

Proteins help neurons change the strength and connections of synapses, allowing the nervous system to adapt and learn.

What are the main functions of neurons?

Neurons process and transmit information.

What is a distinctive feature of neurons?

they have distinct receiving and transmitting zones.

In what direction does information generally flow through a neuron?

One direction: receiving → integrating → transmitting.

What is the input zone of a neuron?

the area that receives chemical signals from other cells.

What is the integration zone of a neuron?

The area that sums/integrates incoming signals to determine whether to trigger an action.

What are the functional zones of a neuron and what does each do?

• Input zone → receives signals

• Integration zone → sums signals and determines whether to respond

• Conduction zone - transmits the electrical signal over distance

• Output/transmitting zone → sends information to other cells

what happens in the transcription process? where does it happen?

[NUCLEUS]

DNA is unravelled and transcribed into complementary messenger (mRNA)

DNA —> mRNA

what happens in the translation process? where does it happen?

[RIBOSOME in Cytoplasm]

mRNA is read by ribosome, transfer RNA (tRNA) adds amino acids to build the protein

mRNA —> Polypeptide

what happens in the processing process? where does it happen?

[Rough ER & Golgi]

polypeptide folded into functional protein, packaged and sent to final destination

polypeptide —> functional protein

what are the 3 steps of protein synthesis in a cell?

1. transcription

2. translation

3. processing

What are dendrites?

Branching structures that extend into nearby tissue and receive chemical signals from other cells.

What is the function of dendritic spines?

They massively increase the synaptic contact area, allowing more connections with other neurons.

What is the function of the soma (cell body)?

It integrates incoming signals from all synaptic inputs to the cell.

What type of electrical signals does the soma produce?

Action potentials

What is the axon hillock?

The neuron's “trigger zone”, where incoming synaptic signals are converted into an action potential.

Why is the axon hillock especially good at triggering action potentials?

t has a high density of voltage-gated sodium (Na⁺) channels

What are axon collaterals?

branches of the axon that allow a signal neuron to send signals to multiple targets

What are terminal buttons?

the output zones of neurons where electrical signals trigger the release of neurotransmitters.

What is a multipolar neuron?

A neuron with one axon and many dendrites.

What are multipolar neurons designed to do?

Integrate large numbers of inputs.

Where are multipolar neurons commonly found?

In the cortex, spinal cord, brainstem, basal ganglia, and cerebellum.

What is a bipolar neuron?

A neuron with one axon and one dendrite.

What are bipolar neurons designed to do?

directly relay information

Where are bipolar neurons commonly found?

in sensory systems, especially the retina.

What is a unipolar neuron?

A neuron with a single extension that branches.

What are unipolar neurons designed to do?

Rapidly transmit sensory information.

Where are unipolar neurons commonly found?

Throughout the peripheral nervous system (PNS), particularly in the skin and muscles.

what is the basic flow of information through a neuron?

dendrites → soma → axon hillock → axon → terminal buttons

receive → integrate → trigger → transmit → release neurotransmitter

What are astrocytes?

Star-shaped glial cells that support neurons and help regulate their environment.

What is one important function of astrocytes related to energy?

They extract glucose to help provide energy for neurons.

How do astrocytes physically support neurons?

They help hold neurons in place and provide structural support.

What are microglia?

The macrophages of the brain—immune cells that provide the brain's primary immune response.

What are the main functions of microglia?

They clean up damaged tissue and help coordinate swelling and inflammation.

What are oligodendrocytes?

Glial cells that produce myelin in the CNS.

Where are oligodendrocytes found?

Exclusively in the central nervous system (CNS).

How do oligodendrocytes differ from Schwann cells?

One oligodendrocyte can myelinate segments of multiple axons, while a Schwann cell myelinates segments of one axon.

Why is myelin important?

it allows more efficient communication along axons and supports axon health

What are Schwann cells?

Glial cells that produce myelin in the PNS.

Where are Schwann cells found?

Exclusively in the peripheral nervous system (PNS).

What does a Schwann cell myelinate?

It wraps a myelin segment around a single axon.

What are the functions of Schwann cells?

They support axons and can promote axon regeneration after injury.