Physiological Psychology Quiz 1

Study guide for the first quiz of phys psych

Do action potentials jump along myelinated axons?

No, action potentials do not jump; they regenerate at voltage-gated sodium channels located at the nodes of Ranvier.

Do action potentials occur in dendrites?

No, action potentials do not occur in dendrites.

How are action potentials created in neurons?

Through voltage-activated ion channels whose permeability depends on the voltage difference across the membrane.

How are endothelial cells related to the blood-brain barrier?

They are joined so tightly that almost nothing can pass between them.

How do axons facilitate the transport of ions across cell membranes?

Axons are well insulated, which reduces energy needed for ion transport and minimizes cross-talk between neurons.

How do neurons code the difference between weak and strong stimuli?

By differences in timing, specifically the frequency or rhythm of action potentials.

How do patients with Guillain-Barre Syndrome typically recover?

Patients usually improve spontaneously, but recovery can take up to a year, with some experiencing residual weakness or pain.

How do symptoms of multiple sclerosis typically manifest?

Symptoms usually persist for days or weeks and then remit, varying across attacks.

How do water molecules pass through the blood-brain barrier?

They pass passively through special protein channels that regulate their flow.

How does myelin affect action potential conduction?

It allows for saltatory conduction, where the current leaps from one Node of Ranvier to the next, increasing speed.

How does the body maintain electrical neutrality?

By having a separation of positive and negative charges in different areas, creating a potential to generate electricity.

How does the brain's energy consumption relate to the blood-brain barrier?

The brain consumes a lot of glucose and oxygen, and active transport across the blood-brain barrier requires significant energy.

How does the electrical gradient affect the inside of a neuron?

It makes the inside more negative compared to the outside.

How does the frequency of action potentials relate to stimulus strength?

A weak stimulus results in a low frequency of action potentials, while a strong stimulus results in a high frequency.

How does the thickness of axons affect action potentials?

Current flows more easily through thicker axons, resulting in faster action potentials.

How many axons do neurons typically have?

Neurons have no more than one axon.

List some common symptoms of multiple sclerosis.

Symptoms include fatigue, visual disorders, numbness, dizziness, bladder and bowel dysfunction, weakness, tremor, impaired mobility, sexual dysfunction, slurred speech, spasticity, swallowing disorders, chronic pain, depression, and cognitive difficulties.

What are common symptoms of gliomas?

Common symptoms include headaches, nausea, vomiting, drowsiness, and seizures.

What are glia and their relationship to neurons?

Glia are smaller than neurons and are almost equal in number, with several types performing distinct functions.

What are graded potentials?

Membrane potentials that vary in magnitude, depolarizing or hyperpolarizing in proportion to the stimulation.

What are interneurons?

Neurons whose dendrites and axons are completely contained within a brain region.

What are local neurons?

Neurons that have no axons, exchange information with close neighbors, do not produce action potentials, and produce graded potentials.

What are potential causes of multiple sclerosis?

Potential causes include infection by a virus, trauma, and exposure to heavy metals.

What are presynaptic terminals?

The end points of an axon responsible for releasing chemicals to communicate with other neurons.

What are protein channels in neuron membranes responsible for?

Permitting charged ions such as sodium, potassium, calcium, and chloride to cross through the membrane.

What are the functions of astrocytes?

Astrocytes control blood flow to brain areas, synchronize neuronal activity, and may contribute to learning and memory.

What are the initial symptoms of Guillain-Barre Syndrome?

Initial symptoms include weakness and tingling in the legs, which can spread to the arms and cause breathing problems.

What are the main ions involved in the resting state of a neuron?

Sodium, potassium, calcium, and chloride.

What are the major components of a neuron?

Soma (cell body), Dendrites, Axon, Presynaptic Terminals, Postsynaptic Receptors.

What are the nodes of Ranvier?

Short unmyelinated sections of myelinated axons.

What are the two main types of cells in the human brain?

Neurons and Glia.

What are the two phases of the refractory period in neurons?

Absolute refractory period and relative refractory period.

What are two disadvantages of having a blood-brain barrier?

1. Most potentially therapeutic drugs, such as anti-tumor agents and anti-virals, cannot cross it. 2. Active transport of chemicals across the barrier requires a lot of energy.

What can diffuse directly across the neuron cell membrane?

Small uncharged fat-soluble chemicals such as water, oxygen, and carbon dioxide.

What can result from alterations in sodium channel function?

Pathological conditions such as seizures, neuronal death during strokes, and effects from toxins like tetrodotoxin and batrachotoxin.

What characterizes the absolute refractory period?

It lasts from depolarization to repolarization, ensuring each action potential is a unique all-or-nothing event.

What creates the resting membrane potential in neurons?

The resting membrane potential is created by the difference in charge between the inside of the neuron, which is negatively charged, and the positively charged extracellular surroundings.

What does it mean for a neuron to have a membrane potential of 0?

It is neither hyperpolarized nor depolarized.

What does the concentration gradient refer to in neurons?

The difference in the concentration of ions across cell membranes.

What does the soma of a neuron contain?

The nucleus, mitochondria, ribosomes, and other structures found in other types of cells.

What does the term 'electrical polarization' refer to in neurons?

The difference in electrical charge across the membrane, with the inside being negative relative to the outside.

What does the term 'resting potential' indicate about a neuron's state?

It indicates that the neuron is not currently firing an action potential.

What factors influence the speed of action potential conduction?

Pathway type, axon diameter, and myelination.

What happens during depolarization in a neuron?

During depolarization, sodium channels open, allowing sodium to rush into the cell, increasing the internal charge and potentially reaching +40mV.

What happens during repolarization of a neuron?

Voltage-gated potassium channels open, allowing potassium ions to flow out, rebalancing the charges.

What happens during spontaneous firing in neurons?

Neurons can fire action potentials at a consistent rate without external stimulation.

What happens to neurons in the brain when they are infected by viruses?

They are killed and do not regenerate.

What happens to potassium during the relative refractory period?

Potassium is flowing out of the cell at a more rapid than normal rate.

What happens to the electrical signals recorded from neurons?

They are recorded to analyze the neuron's activity, often requiring noise reduction techniques.

What happens to the membrane potential during an action potential?

The membrane potential rapidly depolarizes and can reach up to +40mV.

What happens to the resting potential when a neuron is stimulated?

The resting potential remains stable until the neuron is stimulated.

What happens when sodium channel gates are closed after an action potential?

It takes time for the gates to reopen, contributing to the refractory period.

What initiates the biological chain reaction during an action potential?

The rapid depolarization and opening of voltage-gated sodium channels initiate the biological chain reaction.

What initiates the opening of voltage-gated sodium channels in a neuron?

A local current strong enough to change the voltage around the channels.

What ions are primarily involved in establishing the resting membrane potential?

The outside has a lot of positively charged sodium ions, while the inside has some positively charged potassium ions and many negatively charged proteins.

What is a glioma?

Glioma is a cancer originating in glial cells, making up 80% of malignant brain tumors.

What is a localized change in membrane potential due to weak stimuli called?

A graded potential.

What is an action potential?

An electrical signal (pulse) that allows a neuron to communicate information to other neurons.

What is an electrochemical gradient?

An electrochemical gradient is the difference in charge and concentration of ions across a membrane.

What is depolarization (hypopolarization) in a neuron?

A change in a cell's membrane potential that makes it less polarized, resulting in a smaller absolute value.

What is glioblastoma multiforme?

Glioblastoma multiforme is the most common brain tumor in adults, a type of astrocytoma with a median survival of about 14 months.

What is Guillain-Barre Syndrome?

Guillain-Barre Syndrome is a rare inflammatory disease that damages the myelin sheath in the peripheral nervous system.

What is hyperpolarization in a neuron?

A change in a cell's membrane potential that makes it more polarized, resulting in a greater absolute value.

What is hyperpolarization in the context of neuronal action potentials?

A brief phase where the membrane voltage drops to -75mV due to excessive potassium ion flow.

What is known about the cause of multiple sclerosis?

The exact cause is unknown, but it is hypothesized to be an autoimmune disease influenced by genetic and environmental factors.

What is meant by a neuron being polarized?

A neuron is said to be polarized when it has a negative membrane potential.

What is meant by the term 'selectively permeable' in relation to neuron membranes?

It means that some chemicals can pass through the membrane more freely than others.

What is multiple sclerosis?

Multiple sclerosis is a disease characterized by the destruction of the myelin sheath and the formation of hard sclerotic plaques.

What is myelin and its function?

Myelin is an insulating material composed of fats and proteins that facilitates the conduction of information down the axons.

What is required for active transport systems in the blood-brain barrier?

ATP is required to pump glucose, hormones, vitamins, and amino acids across the membrane.

What is saltatory conduction?

The process where action potentials jump between Nodes of Ranvier, increasing conduction speed.

What is the absolute refractory period?

The first part of the period during which the membrane cannot produce another action potential.

What is the all-or-none law in relation to action potentials?

The amplitude and velocity of an action potential are independent of the stimulus intensity.

What is the all-or-nothing phenomenon in action potentials?

The all-or-nothing phenomenon means that once the threshold is reached, an action potential occurs fully or not at all.

What is the analogy used to describe the propagation of action potentials?

The propagation of action potentials is analogous to the telegraph system, where repeater stations regenerate electrical signals.

What is the blood-brain barrier?

A mechanism that surrounds the brain and blocks most chemicals from entering.

What is the conduction velocity of action potentials affected by?

The diameter of the axon and whether it is myelinated.

What is the consequence of a neuron being in the refractory period?

The neuron resists another action potential and cannot respond to stimuli.

What is the current treatment for Guillain-Barre Syndrome?

Treatment includes plasmapheresis and intravenous immunoglobulin to manage symptoms.

What is the definition of membrane potential?

The measurement of potential energy generated by separated charges in a neuron, measured in millivolts (mV).

What is the difference between graded potential and action potential?

Graded potential is a small, localized change in membrane potential due to weak stimuli, while action potential is a large change in membrane potential that sends a signal along the axon.

What is the effect of a high concentration of sodium ions outside the neuron?

It contributes to the electrical gradient, making the inside more negative.

What is the effect of tetrodotoxin on neurons?

It blocks voltage-gated sodium channels, preventing action potentials from occurring.

What is the electrical polarization of a neuron?

The inside of the membrane is slightly negative with respect to the outside.

What is the formula for current in relation to voltage and resistance?

Current is equal to voltage divided by resistance.

What is the function of an afferent axon?

It brings information into a brain region.

What is the function of an efferent axon?

It carries information away from a brain region.

What is the function of oligodendrocytes and Schwann cells?

They build myelin sheaths around axons, supply nutrients, and Schwann cells guide regenerating axons in the periphery.

What is the function of sodium-potassium pumps in neurons?

Sodium-potassium pumps distribute ions by pumping two potassium ions into the cell and three sodium ions out, creating a more positively charged outside.

What is the function of the axon in a neuron?

To transmit information to other neurons, glands, or muscles.

What is the function of topographic maps in the brain?

They represent visual and auditory stimuli through neuron firing patterns.

What is the function of voltage-activated ion channels?

They open in response to specific voltage ranges, allowing ions to flow across the membrane.

What is the impact of scorpion and tarantula venom on neurons?

They can impair voltage-gated sodium channels, affecting neuronal excitability.

What is the impact of the blood-brain barrier on drug delivery for therapeutic purposes?

It limits the ability of many therapeutic drugs to reach the brain.

What is the main treatment for multiple sclerosis?

The main treatment for multiple sclerosis is Interferon ß.

What is the most common cause of rapidly developing paralysis?

Guillain-Barre Syndrome.

What is the myelin sheath?

An insulating material composed of fats and proteins that covers the axons of many types of neurons.

What is the primary characteristic of local neurons?

They do not produce action potentials.

What is the primary function of neurons?

To receive information from and transmit it to other neurons.

What is the primary function of the blood-brain barrier?

To block incoming viruses, bacteria, or other harmful material from entering the brain.