neuro

Question 2

What are the four main classes of glial cells?

Answer 2

• Astrocytes
• Oligodendrocytes
• Microglia
• Ependymal cells

Each class has distinct functions and characteristics in the nervous system.

Question 3

What is the primary role of astrocytes?

Answer 3

Regulate the chemical environment and maintain the integrity of the blood-brain barrier (BBB).

Astrocytes fill spaces between neurons and influence neurite growth.

Question 4

What is reactive astrocytosis?

Answer 4

A response to tissue damage where astrocytes multiply and form a ‘glial scar’.

This can lead to abnormal proliferation and potential tumors.

Question 5

What do oligodendrocytes do?

Answer 5

Insulate axons in the central nervous system (CNS) to increase the speed of action potentials.

They can form internodal myelin fibers for multiple nerve fibers.

Question 6

How do oligodendrocytes affect neuronal growth?

Answer 6

They inhibit neuronal growth, contributing to failure of brain repair after damage.

This is significant in disorders like central demyelination.

Question 7

What role do microglia play in the CNS?

Answer 7

Mediating the immune response and acting as antigen-presenting cells.

They also interact with T helper cells and are involved in synaptic remodeling.

Question 8

What is the function of ependymal cells?

Answer 8

Involved in the production and movement of cerebrospinal fluid (CSF).

They line cavities and ventricles in the brain.

Question 9

How do glial cells differ from neurons?

Answer 9

• Smaller in size
• Do not generate action potentials
• Do not have axons
• Can divide and multiply

These differences highlight their distinct roles in the nervous system.

Question 10

What is one disease associated with astrocyte pathology?

Answer 10

Reactive astrocytosis leading to glial scar formation.

This can indicate underlying tissue damage.

Question 11

What is the main function of microglia?

Answer 11

Mediating the immune response within the CNS.

They play a crucial role in brain health and disease.

Question 12

Fill in the blank: Astrocytes contribute to the integrity of the _______.

Answer 12

blood-brain barrier (BBB)

This is essential for protecting the brain from harmful substances.

Question 13

True or False: Ependymal cells are involved in the production of CSF.

Answer 13

True

They facilitate the movement of cerebrospinal fluid.

Question 14

What is reactive astrocytosis?

Answer 14

Astrocytes multiply, increase process length, change staining properties, and become phagocytic

This occurs in response to tissue damage and can lead to the formation of a ‘glial scar’.

Question 15

What tumors can astrocytes and oligodendrocytes form?

Answer 15

• Astrocytoma (astrocytes)
• Oligodendrogliomas (oligodendrocytes)
• Ependymomas (ependymal cells)

These tumors arise from abnormal proliferation of glial cells.

Question 16

What is central pontine myelinosis?

Answer 16

A consequence of rapid changes in serum vs CSF electrolyte balance

This condition affects the myelin in the central pons.

Question 17

How do astrocytes respond to local neuron activation?

Answer 17

They release molecules like lactate, which can be used as an energy source by neurons

Lactate is particularly important during high energy demand.

Question 18

What is the role of lactate in astrocyte-neuron interactions?

Answer 18

Astrocytes overproduce lactate, release it into the extracellular space for neurons to use as energy

Neurons convert lactate into pyruvate to produce energy.

Question 19

What are astrocytes thought to act as?

Answer 19

Intero-receptors

They sense environmental changes and modulate local neuronal networks through gliotransmitter release.

Question 20

What are two examples of astrocyte functions related to neuronal activity?

Answer 20

• Role in central chemo-sensitivity and regulation of breathing
• Maintenance of central perfusion pressure via mechano-sensitivity

These functions highlight their importance in physiological responses.

Question 21

How do astrocytes detect changes in pH?

Answer 21

They detect changes via acid-sensing ion channels (BASICs)

Elevated CO2 levels lead to lower pH, which astrocytes in specific brain regions can sense.

Question 22

What is the role of astrocytes in maintaining neuronal excitability?

Answer 22

They modulate extracellular glutamate levels and ionic concentrations, particularly potassium

This is crucial for maintaining proper neuronal excitability in response to CO2-induced pH changes.

Question 23

What determines the electrical activity of a neuron?

Answer 23

The flow of ions through ion channels

The combination of these ion currents shapes neuronal behavior at rest and during action potentials.

Question 24

What is the typical structure of ion channels?

Answer 24

Composed of similar protein molecules that assemble to form a pore

The subunit composition varies, affecting the channel’s properties.

Question 25

How is the equilibrium potential calculated?

Answer 25

Using the Nernst equation: Eion = -61.5 mV/Z * Log10(C_out/C_in) ## Footnote This equation considers both chemical and electrical potential energy.

Question 26

What determines the ion selectivity of ion channels?

Answer 26

The nature of the R groups lining the pore

Question 27

How is the equilibrium (reverse) potential calculated?

Answer 27

Using the Nernst equation: Eion = 61.5mV/Z * log10([C out]/[C in])

Question 28

What does the Goldman equation describe?

Answer 28

Membrane potential when more than one ion is involved

Question 29

What is the significance of the value 61.5 in the Nernst equation?

Answer 29

It is taken for 37 degrees Celsius

Question 30

What do the coefficients P in the Goldman equation account for?

Answer 30

The conductances for different ions

Question 31

What is the unit of conductance?

Answer 31

Siemens, typically pS for neuronal recordings

Question 32

What is the relationship between conductance and resistance?

Answer 32

Conductance (G) is the reverse of Resistance

Question 33

What is the purpose of IV plots in neurophysiology?

Answer 33

To calculate channel conductance and visualize current movement

Question 34

In an IV plot, how is the influx of positive ions represented?

Answer 34

As inward current looking down

Question 35

What technique is used to study ion channels?

Answer 35

Electrophysiology

Question 36

What does the patch clamp technique allow researchers to do?

Answer 36

Manipulate potential across the membrane and apply drugs

Question 37

What is measured in single-channel patch clamp recordings?

Answer 37

Current through a single ion channel

Question 38

What does whole-cell recording measure?

Answer 38

The ionic current across the entire membrane

Question 39

What is the purpose of excised patch recordings?

Answer 39

To measure the activity of a single channel in isolation

Question 40

What are inside-out and outside-out patches used for?

Answer 40

Studying channel properties and response to environments

Question 41

What is the function of the voltage-clamp technique?

Answer 41

To keep the membrane potential constant

Question 42

True or False: The slope on the IV plot can be used to calculate channel conductance.

Answer 42

True

Question 43

Fill in the blank: At rest, _______ conductance is high, sodium is low.

Answer 43

Potassium (K)

Question 44

Fill in the blank: If channels for an ion are closed, conductance is _______.

Answer 44

0

Question 45

What is the purpose of a voltage clamp?

Answer 45

To maintain the membrane potential at a constant while measuring the resulting current. ## Footnote Crucial for studying ion channels and observing how ion currents vary with voltage changes.

Question 46

What does a current clamp measure?

Answer 46

The membrane potential while injecting a constant current. ## Footnote Used more to study action potentials (APs).

Question 47

How stable is the resting membrane potential in real neurons?

Answer 47

Very perfectly stable, constantly modified by various currents. ## Footnote Includes 'leak' currents, 'persistent' sodium currents, and synaptic inputs.

Question 48

What role do ion channels play in the flow of ions?

Answer 48

They have an aqueous pore that facilitates the flow of ions by substituting for water. ## Footnote Ions must be the appropriate size for this interaction.

Question 49

What is the significance of carbonyl residues in ion channels?

Answer 49

They form a selective filter and must interact with ions of the appropriate size. ## Footnote Arranged to complement the size and hydration energy of specific ions.

Question 50

What is the role of potassium channels?

Answer 50

Responsible for resting membrane potential generation. ## Footnote Inward rectifier K channels pass K into the cell better than out.

Question 51

How many transmembrane domains do inward rectifier K channels have?

Answer 51

2 transmembrane domains.

Question 52

What is the function of tandem pore channels?

Answer 52

They provide baseline 'leak' conductance and have little or no inward rectification. ## Footnote Operate at a slower scale and do not open and close fast during action potentials.

Question 53

What regulates some leak channels?

Answer 53

Various factors, such as second messengers and G-proteins.

Question 54

What is the mechanism of positive feedback in action potentials?

Answer 54

Depolarization leads to the opening of voltage-gated sodium channels, resulting in further depolarization. ## Footnote Strong influx of sodium channels further depolarizes the membrane and opens more channels.

Question 55

What causes the fast dynamics of action potentials?

Answer 55

Positive feedback mechanism involving depolarization and sodium currents.

Question 56

Fill in the blank: The inward rectifier K channel passes K into the cell ______ than out.

Answer 56

better

Question 57

True or False: The presence of persistent sodium currents is thought to underlie the oscillatory behavior of respiratory circuits in the brain stem.

Answer 57

True

Question 58

What happens to voltage gated sodium channels at positive potentials?

Answer 58

They become inactivated, limiting the maximal frequency of action potentials. ## Footnote This is the basis of the absolute 'refractory' period.

Question 59

What role do delayed rectifiers play in neurophysiology?

Answer 59

They help prevent oscillations in the network.

Question 60

What is the function of refrectoriness?

Answer 60

It prevents retrograde propagation of action potentials.

Question 61

What is the role of voltage gated potassium channels?

Answer 61

They open with a delay to help repolarization and can cause 'afterhyperpolarisation' which limits excitability.

Question 62

What is the difference between passive and active conduction?

Answer 62

Passive conduction does not use energy and operates over short distances, while active conduction involves action potentials that are regenerative and conducted along axons.

Question 63

How is information coded in active conduction?

Answer 63

Information is coded as frequency or timing and is directional.

Question 64

How do excitatory synapses contribute to action potential initiation?

Answer 64

They increase the chance of action potentials occurring by depolarizing the post-synaptic membrane.

Question 65

How do inhibitory synapses affect action potentials?

Answer 65

They hyperpolarize the cell, inhibiting action potentials and allowing the cell to return to its resting potential.

Question 66

What is spatial integration in synaptic integration?

Answer 66

It is the adding together of EPSPs generated by many different dendrite synapses simultaneously.

Question 67

What is temporal integration in synaptic integration?

Answer 67

It is the adding together of rapidly fired EPSPs from a single synapse.

Question 68

Why do some synapses have more influence than others?

Answer 68

Due to synaptic plasticity, location, and specialization.

Question 69

What is transduction in the context of sensory receptors?

Answer 69

Transduction refers to the act of sensory information changing into a biochemical signal that can be processed by the brain.

Question 70

What types of stimuli can be transduced?

Answer 70

Pain, temperature, pressure, chemicals, and light.