Electrical Signals in Animals

Flashcards based on Electrical Signals in Animals lecture notes.

What type of tissue is nervous tissue?

A type of tissue in the body

What are the two main types of signals neurons use to communicate?

Electrical and chemical signals

What are simple clusters of neurons called?

Ganglia

Where does the processing of information take place in the nervous system?

Ganglia or brain

What are the branched extensions of a neuron that receive signals from other neurons called?

Dendrites

What is the typically long extension of a neuron that transmits signals to other cells?

Axon

What is the cone-shaped base of an axon called?

Axon hillock

What are the chemical messengers that transmit information across the synapse?

Neurotransmitters

What is the junction between an axon and another cell called?

Synapse

What is the cell that sends information across a synapse called?

Presynaptic cell

What is the cell that receives information across a synapse called?

Postsynaptic cell

What are the cells that nourish or insulate neurons called?

Glia or glial cells

What are the three main stages of information processing in the nervous system?

Sensory input, integration, and motor output

What type of neurons transmit information from sensors to the brain or ganglia?

Sensory neurons

What type of neurons integrate information in the brain or ganglia?

Interneurons

What type of neurons trigger muscle or gland activity?

Motor neurons

What does the central nervous system (CNS) consist of?

Brain and spinal cord

What is the function of the peripheral nervous system (PNS)?

Carries information into and out of the CNS

What do the bundled neurons of the PNS form?

Nerves

What is the voltage across a cell's plasma membrane called?

Membrane potential

What is the membrane potential of a neuron not sending signals called?

Resting potential

What do changes in membrane potential act as?

Signals for transmitting and processing information

What do sodium-potassium pumps use to maintain ion gradients?

ATP

Where is the concentration of K+ highest in a mammalian neuron at resting potential?

Inside the cell

Where is the concentration of Na+ highest in a mammalian neuron at resting potential?

Outside the cell

What type of potential energy do concentration gradients represent?

Chemical potential energy

What happens when ion channels open in the plasma membrane?

Chemical potential is converted to electrical potential

At resting potential, does a neuron contain more open K+ or Na+ channels?

More open K+ channels

What is the major source of membrane potential?

Buildup of negative charge within the neuron

What type of channels open or close in response to stimuli?

Gated ion channels

What is hyperpolarization?

An increase in magnitude of the membrane potential

What causes hyperpolarization?

K+ diffuses out of the cell

What is depolarization?

A reduction in the magnitude of the membrane potential

What causes depolarization?

Na+ diffuses into the cell

What are graded potentials?

Changes in polarization where the magnitude of the change varies with the strength of the stimulus

What is an action potential?

A massive change in membrane voltage

What are two characteristics of action potentials?

Constant magnitude and all-or-none

What type of channels are responsible for action potentials?

Voltage-gated ion channels

What happens to voltage-gated Na+ channels during the rising phase of an action potential?

They open and Na+ flows into the cell

What happens during the falling phase of an action potential?

Voltage-gated Na+ channels become inactivated; voltage-gated K+ channels open, and K+ flows out of the cell

What is the refractory period?

A period after an action potential when a second action potential cannot be initiated

What causes the refractory period?

Temporary inactivation of the Na+ channels

Where is the action potential usually generated?

Axon hillock

In what direction do action potentials travel?

Toward the synaptic terminals

What prevents action potentials from traveling backwards?

Inactivated Na+ channels

What increases the speed of an action potential?

Axon's diameter

What is the myelin sheath?

Insulation around axons

What cells make myelin sheaths in the CNS?

Oligodendrocytes

What cells make myelin sheaths in the PNS?

Schwann cells

What are the gaps in the myelin sheath called?

Nodes of Ranvier

What is saltatory conduction?

Action potentials jump between the nodes of Ranvier

What is an electrical synapse?

Electrical current flows from one neuron to another through gap junctions

What is a chemical synapse?

Chemical neurotransmitter carries information between neurons

Where are neurotransmitters synthesized and packaged?

Synaptic vesicles located in the synaptic terminal

What triggers the release of neurotransmitter?

Action potential

What happens after neurotransmitter diffuses across the synaptic cleft?

It is received by the postsynaptic cell

What does direct synaptic transmission involve?

Binding of neurotransmitters to ligand-gated ion channels

What does neurotransmitter binding cause?

Ion channels to open, generating a postsynaptic potential

How are neurotransmitters cleared from the synaptic cleft?

Diffusion, inactivation by enzymes, or recapture into the presynaptic neuron

What is the role of acetylcholinesterase?

Enzymatic breakdown of neurotransmitter in the synaptic cleft

What is reuptake?

Reuptake of neurotransmitter by presynaptic neuron

What is the function of Acetylcholine?

Muscle stimulation, memory formation, and learning

What Neurotransmitter are Glutamate, GABA and Glycine classified as?

Amino Acids

What Neurotransmitter are Norepinephrine, Dopamine, and Serotonin classified as?

Biogenic Amines

What are Substance P and Met-enkephalin classified as?

Neuropeptides

What is Nitric oxide classified as?

Gases

What is the definition of 'Nodes of Ranvier'?

Gaps in the myelin sheath on the axon of a neuron where action potentials are regenerated.

Explain the process of repolarization in a neuron.

Repolarization is the stage where the membrane potential returns to its resting value after depolarization, primarily due to the outflow of potassium ions (K+).

What role do voltage-gated calcium channels play in synaptic transmission?

Voltage-gated calcium channels open in response to depolarization, allowing calcium ions (Ca2+) to enter the presynaptic terminal, which triggers the release of neurotransmitters.

How does an excitatory postsynaptic potential (EPSP) affect the postsynaptic neuron?

An EPSP depolarizes the postsynaptic membrane, making the neuron more likely to fire an action potential.

What is the function of glial cells in the nervous system?

Glial cells provide support, insulation, and protection for neurons, as well as maintain the extracellular environment.

Describe the role of the sodium-potassium pump in maintaining the resting potential.

The sodium-potassium pump actively transports sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, maintaining the ion gradients necessary for the resting potential.

What is the difference between a graded potential and an action potential?

A graded potential is a local change in membrane potential that varies in magnitude, while an action potential is an all-or-none, rapid depolarization and repolarization of the membrane.

Explain the concept of 'threshold' in the context of action potentials.

Threshold is the minimum depolarization needed to trigger an action potential. Once the threshold is reached, an action potential will fire.

How does myelin increase the speed of action potential conduction?

Myelin insulates the axon, allowing action potentials to 'jump' between the Nodes of Ranvier, a process called saltatory conduction, which greatly increases conduction speed.

What is a neurotransmitter?

A neurotransmitter is a chemical messenger that transmits signals from a neuron to a target cell across a synapse.

What role does the synapse play in neuronal communication?

The synapse is the junction between two neurons (or between a neuron and a target cell) where communication occurs through the release and reception of neurotransmitters.

What is meant by the term 'resting membrane potential'?

Resting membrane potential refers to the electrical potential difference across the plasma membrane of a neuron when it is not actively transmitting a signal. It is typically around -70mV.

What is the significance of the sodium-potassium pump in maintaining neuronal function?

The sodium-potassium pump is crucial for maintaining the proper ion concentrations inside and outside the neuron, which is essential for establishing the resting membrane potential and enabling action potentials.

How is the intensity of a stimulus encoded by neurons?

The intensity of a stimulus is encoded by neurons through the frequency of action potentials. Stronger stimuli trigger more frequent action potentials.

What is the role of the axon hillock in a neuron?

The axon hillock is the region where the decision to fire an action potential is made. It has a high density of voltage-gated sodium channels and is the site where action potentials are initiated.

What are the key characteristics distinguishing nerve cells from other kind of cells?

Nerve cells communicate and transmit electrical and chemical information throughout the body.

What are the factors that influence the rate of nerve signal transmission?

Axon diameter and myelination, as myelination increases the velocity of signal transmission.

Why are there both electrical and chemical synapsis?

Chemical synapses allow for various modulation and control, whereas electrical synapses provide direct, quick transmission.

In what ways do neurotransmitters affect postsynaptic neurons?

Neurotransmitters can generate inhibitory or excitatory postsynaptic potentials depending on the receptors they bind to.

What physiological purposes does neuronal integration serve?

Neuronal integration enables the nervous system to manage complex information by averaging excitatory and inhibitory signals, determining if an activity potential is launched.

What is the function of glial cells in the nervous system?

Support, insulation, and regulation of the neuronal environment are provided by glial cells.

What role do ion channels play in the action potential?

In the action potential, voltage-gated ion channels regulate the flow of ions, allowing for membrane depolarization and repolarization.

What processes maintain the resting membrane potential?

The sodium-potassium pump and potassium leak channels play a vital role in maintaining the resting membrane potential.

How do neurons encode the intensity of stimuli?

Neurons encode data about a stimuli's intensity via action potential frequency.

What are the key characteristics that differentiate electrical synapses from chemical synapses?

Gap junctions permit direct ion current flow in electric synapses, whereas neurotransmitters are released in chemical synapses.

Describe the roles of major molecules like neurotransmitters and ion channels during synaptic transmission.

For the action potential to be initiated and propagated, precise ion channels and neurotransmitters are required in synaptic transmission.

What are the roles of sensory, motor, and interneurons?

The nervous system's main purposes are accomplished by sensory neurons via receiving sensory input, interneurons via processing data, and motor neurons.

Describe glial cells effect on the neural system.

glial cells which comprise astrocytes, oligodendrocytes, and microglia, are critical for neuron maintenance, myelination, and immunological defense.

How do myelination and saltatory conduction influence nerve signal transmission?

This greatly speeds up signal transmission by allowing action potentials to jump across myelinated sections from one Node of Ranvier to the next.

How are a potential created at rest and why is it important?

The sodium-potassium pump and ion channels maintain the resting membrane potential, which is vital for neuronal excitability and signaling.

Which steps are involved in creating an action possibility?

Depolarization, repolarization, and hyperpolarization are the phases in action potential generation that are crucial for signal transmission.

How neurotransmitters cross synapses?

Neurotransmitters move through synapses, where they connect to receptors and generate inhibitory or excitatory potentials in postsynaptic neurons.

In the control and coordination of body activities, what is the significance of neuronal circuits and pathways.

Fundamental to numerous physiological functions is the organization and coordination of neurons through neuronal circuits and pathways.

How does a cell respond to neurotransmitter binding?

Ion channels open and neurotransmitter binding causes postsynaptic potential generation, which influences neuron excitability.