Membrane Potentials and Ion Channels
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Questions and Answers

The movement of the RMP can be described as follows: ______ is the movement of the potential from the RMP to a less negative value.

Depolarization

The movement of the ______ can be described as follows: Depolarization is the movement of the potential from the RMP to a less negative value.

RMP

Depolarization is the movement of the potential from the ______ to a less negative value.

RMP

Depolarization is the movement of the potential from the RMP to a ______ negative value.

<p>less</p> Signup and view all the answers

Depolarization is the movement of the potential from the RMP to a less ______ value.

<p>negative</p> Signup and view all the answers

Any change in the membrane potential due to a stimulus is known as a ______ potential.

<p>graded</p> Signup and view all the answers

A graded potential can be either a depolarization or a ______.

<p>hyperpolarization</p> Signup and view all the answers

A ______ is a change in membrane potential that makes the inside of the cell more positive.

<p>depolarization</p> Signup and view all the answers

A ______ potential is a type of electrical signal that can travel along a neuron.

<p>graded</p> Signup and view all the answers

The size of a graded potential is ______ to the strength of the stimulus.

<p>proportional</p> Signup and view all the answers

Glycinergic neurons bind to ______ receptors on postsynaptic cells.

<p>ionotropic</p> Signup and view all the answers

These receptors allow ______ to enter postsynaptic cells.

<p>Cl-</p> Signup and view all the answers

Glycinergic neurons are essential for maintaining a balance of excitatory and ______ activity in the spinal cord.

<p>inhibitory</p> Signup and view all the answers

Glycinergic neurons are found in the spinal cord integrating centers that regulate ______ muscle contraction.

<p>skeletal</p> Signup and view all the answers

Glycine is a(n) ______ neurotransmitter.

<p>inhibitory</p> Signup and view all the answers

ON bipolar cells have ______ glutamate receptors.

<p>metabotropic</p> Signup and view all the answers

OFF bipolar cells express ______ glutamate receptors.

<p>ionotropic</p> Signup and view all the answers

Glutamate receptors on ON bipolar cells are ______.

<p>metabotropic</p> Signup and view all the answers

The difference in glutamate receptor types between ON and OFF bipolar cells contributes to different ______ responses.

<p>light</p> Signup and view all the answers

The ______ is a small mass of tissue that includes the pineal gland.

<p>epithalamus</p> Signup and view all the answers

The pineal gland, located in the ______, plays a role in regulating biological rhythms.

<p>epithalamus</p> Signup and view all the answers

The ______ gland is responsible for regulating biological rhythms.

<p>pineal</p> Signup and view all the answers

The pineal gland is involved in the ______ of biological rhythms.

<p>regulation</p> Signup and view all the answers

Biological rhythms are regulated by the ______ gland.

<p>pineal</p> Signup and view all the answers

L cones respond optimally at ______ wavelengths.

<p>long</p> Signup and view all the answers

M cones respond at ______ wavelengths.

<p>medium</p> Signup and view all the answers

S cones are best stimulated at ______ wavelengths.

<p>short</p> Signup and view all the answers

Color blindness results from a ______ mutation in the genes that encode the cone pigments.

<p>recessive</p> Signup and view all the answers

There are three types of ______ that respond to different wavelengths of light.

<p>cones</p> Signup and view all the answers

Flashcards

Resting Membrane Potential (RMP)

The electric potential difference across the cell membrane when the cell is at rest.

Depolarization

The process where the membrane potential becomes less negative than the RMP.

Membrane Potential

The voltage difference across a cell's membrane due to ion distribution.

Electric Potential Difference

The difference in electric charge between two points or areas.

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Ionic Distribution

The arrangement and concentration of ions across a cell membrane.

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Action Potentials

Quick changes in the membrane potential that lead to signal transmission in neurons.

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Graded Potential

A change in membrane potential that varies in size, depending on the strength of the stimulus.

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Hyperpolarization

Increase in membrane potential, making the inside of the cell more negative.

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Stimulus

Any event or change that causes a response in the cell, leading to graded potentials.

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L cones

Photoreceptor cells that respond optimally at long wavelengths, usually associated with red light.

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M cones

Photoreceptor cells that respond optimally at medium wavelengths, typically linked to green light.

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S cones

Photoreceptor cells that are best stimulated by short wavelengths, generally related to blue light.

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Color blindness

A condition resulting from a recessive mutation in genes that affect cone pigments, leading to difficulty in distinguishing colors.

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Cone pigments

Proteins in the photoreceptor cells that absorb specific wavelengths of light, enabling color vision.

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Glycinergic neurons

Neurons that release glycine as a neurotransmitter, involved in inhibiting activity in the spinal cord.

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Ionotropic receptors

Receptors that, when bound by neurotransmitters, allow ions to flow through the cell membrane.

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Cl- ion entry

The process of chloride ions entering a postsynaptic cell through ionotropic receptor binding.

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Excitatory vs Inhibitory balance

The equilibrium between excitatory (activation) and inhibitory (calming) signals in the nervous system.

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Spinal cord integrating centers

Areas within the spinal cord that coordinate sensory and motor information for muscle control.

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ON Bipolar Cells

Bipolar cells in the retina that respond to light; influenced by metabotropic glutamate receptors.

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OFF Bipolar Cells

Bipolar cells in the retina that respond to darkness; influenced by ionotropic glutamate receptors.

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Metabotropic Receptors

Receptors that act through metabolic pathways, affecting cell signaling over a longer term.

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Glutamate

A neurotransmitter that plays key roles in synaptic transmission in the retina.

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Epithalamus

A small mass of tissue in the brain that includes the pineal gland.

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Pineal Gland

A gland within the epithalamus that regulates biological rhythms.

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Biological Rhythms

Natural cycles in the body that regulate functions like sleep-wake patterns.

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Role of Epithalamus

Regulates biological rhythms through the pineal gland's hormone production.

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Melatonin

A hormone made by the pineal gland that helps control sleep patterns.

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Study Notes

Membrane Potentials

  • Different cells have different resting membrane potentials, generally ranging from -40 to -90 mV.
  • The standard resting membrane potential (RMP) is typically -70 mV.
  • Ion movement in and out of the cell causes changes in potential.

Major Ions Across the Plasma Membrane

  • Key ions include Na+, Cl-, and K+.
  • Extracellular concentrations (mmol/L):
    • Na+: 145
    • Cl-: 100
    • K+: 5
  • Intracellular concentrations (mmol/L):
    • Na+: 15
    • Cl-: 7*
    • K+: 150
  • The semipermeable cell membrane controls selective passage of materials into and out of the cell.

Membrane Channels

  • Ligand-gated channels open with chemical triggers (e.g., acetylcholine at the neuromuscular junction).
  • Mechanically-gated channels open due to pressure or deformation.
  • Voltage-gated channels open and close based on membrane potential, crucial for action potential generation and propagation.

Membrane Pumps

  • Ions move against their potential gradient (e.g. a positive ion needing to move to a more positive area) through pumps.
  • The Na+/K+ ATPase pump is an example. It moves 3 sodium ions out of the cell and 2 potassium ions in, generating an electrochemical gradient with net charge of -1 inside the cell.

Action Potentials

  • Graded potentials, depolarizations or hyperpolarizations, result from stimuli.
  • Techniques in medicine sometimes hyperpolarize cells to reduce action potential development.
  • Local anesthetics like procaine and lidocaine block voltage-gated Na+ channels, preventing action potential generation.
  • Some animal toxins also interfere with nerve conduction.
  • The magnitude of graded potentials varies with stimulus strength.

Action Potential Propagation

  • Depolarization: potential moves from RMP to less negative value.
  • Repolarization: potential moves from less neg. value towards RMP.
  • Hyperpolarization: potential moves from RMP to a more negative value.
  • Threshold potential is typically 15mV above RMP (-55mV).
  • Excitability is a neuron's ability to generate an action potential.

Refractory Period

  • The absolute refractory period is the time immediately after an action potential where a second stimulus, no matter how strong, won't generate another action potential. This is because all Na+ channels are already open.
  • The relative refractory period is the time after the absolute refractory period, in which a second action potential can occur but only with a stronger stimulus.

Synapses

  • Synapses are junctions between neurons, either chemical or electrical.
  • Electrical synapses transmit electrical activity directly from one neuron to another
  • Chemical synapses utilize neurotransmitters that pass between pre- and post-synaptic neurons to influence the electrical activity of the receiving neuron
  • Neurotransmitters are stored in vesicles at axon terminals
  • Stimulation causes calcium influx, triggering vesicle relocation and release of neurotransmitters into the synaptic cleft.
  • Neurotransmitters bind to receptors on the postsynaptic membrane, causing either excitation or inhibition.

Synaptic Transmission Termination

  • Neurotransmitter removal is required to end the signal.
  • This occurs through diffusion, enzyme degradation, or reuptake.

Neurotransmitters and Neuromodulators

  • Neurotransmitters facilitate rapid communication between neurons.
  • Neuromodulators regulate slower processes like learning, development, emotions, and motor/sensory activities
  • Acetylcholine (ACh) is found in neuromuscular junctions, acting at muscarinic (G-protein coupled) or nicotinic (ion channel) receptors.

Biogenic Amines

  • Dopamine, norepinephrine, and epinephrine are catecholamines derived from tyrosine, influencing various functions.
  • Serotonin, derived from tryptophan, plays a vital role in regulating mood and other activities.
  • Histamine originates from histidine and participates in various physiological processes.

Amino Acid Neurotransmitters

  • Glutamate and aspartate are primary excitatory neurotransmitters.
  • GABA and glycine are primary inhibitory neurotransmitters. (Other types of neurotransmitters are not covered in the document provided)

Overview of the Nervous System

  • The central nervous system (CNS) includes the brain and spinal cord.
  • The peripheral nervous system (PNS) includes afferent (sensory) and efferent (motor) divisions.
  • The brain comprises the forebrain, cerebellum, and brainstem.
  • The forebrain has cerebral hemispheres with the outer cortex and underlying structures (e.g. Basal Nuclei).
  • The cerebellum is involved in coordination and balance.
  • The brainstem controls basic life functions.

Cranial Nerves

  • The brainstem contains nuclei associated with 10 of the 12 pairs of cranial nerves.
  • Several cranial nerves have both motor and sensory functions.

Sensory Physiology

  • Sensory receptors, categorized as mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, or nociceptors, transduce stimuli into signals.
  • Sensory signals undergo coding and adaptation.

Other Significant Points

  • Drugs affect synaptic transmission through various mechanisms.
  • Drugs like NSAIDs and Morphine have various impacts.
    • The blood-brain barrier protects the brain from harmful substances.
    • Meninges, cerebrospinal, fluid (CSF) coat, support and protect central nervous system.
    • Hyperalgesia and Analgesia affect pain perception

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Description

Explore the intricacies of membrane potentials, focusing on different cell types and their resting potentials. This quiz covers major ions across the plasma membrane, the types of channels involved, and the role of membrane pumps in maintaining potential gradients.

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