Neuroscience Chapter on Resting Membrane Potential

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Questions and Answers

What is the primary role of thermoreceptors in the body?

Detecting pressure changes

Detecting light intensity

Regulating blood pressure

Sensing heat and temperature variations (correct)

Which submodality of taste is primarily associated with hydrogen ions (H+)?

Salty

Umami

Sour (correct)

Bitter

Which type of afferent fiber is responsible for proprioception?

Ia and II fibers (correct)

Aß fibers

C fibers

Aδ fibers

What type of mechanoreceptor is primarily responsible for detecting sustained stretch?

Ruffini ending (D) Signup and view all the answers

Which mechanoreceptor is activated by light touch and phasic vibration?

Meissner corpuscles (D) Signup and view all the answers

Which type of receptor is primarily involved in pain perception?

Nociceptors (D) Signup and view all the answers

What is the common conduction velocity range for touch sensory afferents like Aß fibers?

35-75 m/s (A) Signup and view all the answers

What is the primary function of the stria vascularis in the cochlea?

To maintain high potassium concentration in endolymph (D) Signup and view all the answers

Which statement best describes the role of outer hair cells?

They enhance sensitivity to sounds and sharpen frequency selectivity (D) Signup and view all the answers

How do auditory nerve fibers encode sound intensity?

Based on firing rate and number of activated fibers (C) Signup and view all the answers

What is the function of the cochlear amplifier?

To increase sensitivity to quiet sounds and sharpen frequency discrimination (C) Signup and view all the answers

Which structure is NOT part of the auditory pathway from the cochlea to the auditory cortex?

Basilar membrane (A) Signup and view all the answers

What type of ions do salt stimuli primarily detect?

Sodium ions (Na+) (A) Signup and view all the answers

Which receptor type is primarily responsible for detecting temperature changes above 30°C?

Warm receptors (A) Signup and view all the answers

What is the function of Golgi tendon organs in the human body?

Detect muscle tension (D) Signup and view all the answers

How do both cold and warm receptors adapt to stimuli?

They exhibit varying response frequencies to sustained stimuli. (C) Signup and view all the answers

What neurotransmitters are primarily used by nociceptors to relay pain signals?

Glutamate and substance P (B) Signup and view all the answers

In stimulus intensity coding, what does frequency coding enable?

Differentiation between stimuli intensities through action potential frequency (C) Signup and view all the answers

What mechanism do acids (sour stimuli) primarily depend on for detection?

Hydrogen ions (H+) (B) Signup and view all the answers

What role do intrafusal fibers play in the muscular system?

Provide proprioceptive information regarding body movement (C) Signup and view all the answers

What triggers the activation of nociceptors?

Intense mechanical pressure, excessive temperatures, and chemical signals (B) Signup and view all the answers

What primarily determines the perception of spatial resolution in sensory coding?

The distance between stimuli (D) Signup and view all the answers

Which type of sensory receptor is best for detecting motion?

Rapidly adapting receptors (B) Signup and view all the answers

What role does lateral inhibition play in sensory perception?

Enhances spatial localization of stimuli (D) Signup and view all the answers

How is sensory information processed in the brain before reaching the cortex?

Via thalamic relay points (A) Signup and view all the answers

What is the purpose of 'descending pathways' in sensory information processing?

To modulate and refine sensory information (A) Signup and view all the answers

What is the main function of slowly adapting receptors in the sensory system?

Maintaining constant sensation monitoring (C) Signup and view all the answers

Which of the following best describes the anatomical components of the eye in relation to vision?

Each component has a specific function in vision (D) Signup and view all the answers

Which statement accurately reflects the characteristics of specific sensory receptors?

They have a functional specialization for designated modalities (A) Signup and view all the answers

What is a key feature of the crossed ascending pathways in sensory processing?

They facilitate hemispheric balance in sensory information (A) Signup and view all the answers

What do mechanoreceptors specifically respond to in the context of touch?

Shape, texture, and vibration (D) Signup and view all the answers

What does frequency, measured in Hertz (Hz), correspond to in sound perception?

Pitch (D) Signup and view all the answers

Which component of the ear is responsible for transmitting sound through the ossicles?

Middle ear (C) Signup and view all the answers

What is the primary function of inner hair cells (IHC) in the auditory system?

Transducing sound into electrical signals (C) Signup and view all the answers

How is the basilar membrane organized in terms of frequency sensitivity?

Tonotopic organization (C) Signup and view all the answers

What ion is predominantly found in endolymph, which influences hair cell function?

Potassium (K+) (A) Signup and view all the answers

What is the threshold of hearing measured in decibels (dB)?

0 dB (C) Signup and view all the answers

Which part of the ear includes the pinna and external auditory canal?

Outer ear (C) Signup and view all the answers

What sound characteristics are perceived as loudness?

Amplitude (C) Signup and view all the answers

What can sound levels exceeding 120 dB cause?

Hearing loss (C) Signup and view all the answers

Which part of the auditory system is involved in the activation of hair cells?

Basilar membrane (C) Signup and view all the answers

Study Notes

Resting Membrane Potential (RMP)

RMP is the difference in charged particle distribution across the cell membrane when it's not stimulated.
A typical RMP is around -70 mV.
Maintenance factors include: diffusion of ions via concentration gradients, electrostatic interactions between charged particles, and ion transport via the Na+/K+ pump.
The Na+/K+ pump actively transports 3 sodium ions out of the cell for every 2 potassium ions brought in, contributing to the intracellular negative charge.
The presence of negatively charged ions (Cl⁻) and proteins inside the cell also establishes the RMP.
The 'salty banana' analogy illustrates the difference in Na⁺ concentration between inside and outside the cell, crucial for understanding RMP.

Ion Transport

The Na+/K+ pump is vital for maintaining RMP.
It utilizes ATP and conformational changes to transport ions against their concentration gradient.

Ion Permeability

The Goldman-Katz equation predicts equilibrium potential for ions when the membrane is permeable to multiple ions.
Typical permeability ratios at rest: PK:PCl:PNa = 1.0 : 0.45 : 0.04.
K⁺ ions have a more substantial effect on RMP due to higher permeability compared to Na⁺.

Factors Influencing Membrane Potential

K⁺ diffusion results in a loss of net positive charge inside the cell.
Active transport of ions (Na+/K+ pump) contributes to a net loss of positive charge.
Electrochemical gradients influence K⁺ movement into the cell.
Changes in voltage across the membrane initiate changes and affect the signaling pathways in neurons.

Action Potentials

Action potentials are crucial for signal propagation in the neuron.
The threshold for firing an action potential is typically around -55mV.
Action potential phases:
- Rest: Neurons are in a steady state with resting membrane potential established.
- Depolarization: Rapid influx of Na⁺ ions, creating a more positive charge.
- Repolarization: K⁺ channels open, driving the membrane potential back to a negative value.
- Refractory Period: The neuron is temporarily less excitable.
- In the absolute refractory period, the cell cannot fire another action potential due to Na⁺ channel inactivation.
- In the relative refractory period, a stronger-than-normal stimulus is required before firing another action potential.

Refractory Periods

Absolute and Relative Refractory periods are key phases that allow neurons to regulate and control actions potentials.
Absolute period: No new action potentials can fire during this phase.
Relative period: A stronger stimulus is required to fire an action potential.

Factors Influencing Membrane Potential, Including Action Potential Phases and Characteristics

The interplay of graded and action potentials sets the stage for neuron communication.
The combined impact of positive and negative charges on a neuron leads to changes in membrane potential.
Action potentials serve as critical signaling units, ensuring information transmission and action through neurons along the axon.

Summary of Membrane and Action Potential Changes

Graded potentials are summed at the axon hillock to trigger action potentials.
Action potentials are generated if the threshold is reached.

Phases of Action Potentials

Rest: Neuron is at a steady state with the resting membrane potential established.
Depolarization: The influx of Na⁺ ions causes the neuron to become less polarized.
Repolarization: K⁺ channels open, facilitating the return to a more negative resting state.
Refractory period: The neuron is temporarily less excitable following an action potential.

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Description

This quiz explores the concepts of resting membrane potential (RMP), focusing on the distribution of ions across the cell membrane when at rest. Key topics include the role of the Na+/K+ pump, ion transport mechanisms, and the significance of ion permeability. Test your understanding of these fundamental neurophysiological principles!