Neurobio Exam 1

What can we learn from the experiment about neuronal plasticity with prisms on barn owls' eyes?

The experiment demonstrates how the brain can adapt to altered sensory input, showcasing neuronal plasticity.

Who is Patient HM (Henry Molaison) and what does his case teach us?

Patient HM is a famous case in neuroscience that illustrates the role of the hippocampus in memory formation and the distinction between short-term and long-term memory.

What are the main cell types found in the nervous system?

The main cell types are neurons and glial cells, including astrocytes, oligodendrocytes, and microglia.

What was the historical 'great debate' in neuroscience?

The debate involved Santiago Ramón y Cajal and Camillo Golgi regarding whether the nervous system is composed of individual neurons or a continuous network.

What are the parts of a neuron?

The main parts of a neuron include the cell body (soma), dendrites, axon, and axon terminals.

What is an action potential and how does it differ from a graded potential?

An action potential is a rapid, all-or-nothing electrical signal that travels along the axon, while a graded potential is a variable change in membrane potential that can lead to an action potential.

Is there a directionality to information flow within neurons?

• Yes, information flows directionally from dendrites to the cell body and then down the axon to the axon terminals

• In a circuit, flow is from sensory neuron to interneuron to motor neuron

• This helps with efficiency and reduces confusion

• Example of flow in a circuit is between the neurons of the eye

  • photoreceptors → bipolar cell → retinal ganglion cells

Explain the patellar knee-jerk reflex.

• doctor hits above tendon

• dendrtie of sensory neuron in quad muscle spindle recieves info

• That neuron synapses with an exicitatory and inhibitory neuron

• excitatory neuron tells quads to extend

• inhibitory neuron is an interneuorn which synapses with another motor neuron to tell hamstrings not to flex

• all this is a spinal reflex(you don’t need brain)

What are neural circuits?

Neural circuits are networks of interconnected neurons that process specific types of information, consisting of excitatory neurons, inhibitory neurons, and interneurons.

How do we ask neurobiological questions?

• Neurobiological questions can be explored using model organisms and techniques

• Organisms= rats, mice, human, crabs, zebra fish, fruit flies, c. elegans

• techniques= staining of neurons(silver method and fluorescence), optical methods, fMRI, calcium imaging(looks at individual cells), tracing circuits

Why is transport inside neurons necessary?

Transport is necessary to move proteins, organelles, and other materials to different parts of the neuron for proper functioning and maintenance.

Tubulin vs Actin

• Micro tubers have hollow are and are much stronger/larger

• actin is smaller, its 2 standed

What is interesting about the larval zebrafish escape response?

• The larval zebrafish escape response is notable for its rapid reflexive action, which can be studied to understand neural circuits and motor control.

• mauthner cell= interneuron

How are proteins generated and trafficked in a cell?

Proteins are synthesized in the endoplasmic reticulum and trafficked to specific locations via vesicles through processes like exocytosis and endocytosis.

What is the purpose of the cytoskeleton?

• Props up inside of cell

• Allows movement of things

• Cytoskeleton proteins= actin and tubulin

What are motor proteins and their functions?

• They move things around(they are the amazon trucks)

• highway/road is tubulin/actin

• Motor proteins: myosin, kinesin, dynein

Myosin

• Associated with muscle contraction

• only “walks” on actin

Kinesin

• Anterograde

Dynein

• retrograde

What is the difference between active and passive transport?

Active transport requires energy to move substances against their concentration gradient, while passive transport occurs along the gradient without energy input.

What are some types transporters?

• ATP driven, light dricen, coupled transporter

• A symporter has different paths but they move in the same direction

How do concentration and electrical gradients function?

Concentration gradients drive the movement of ions from areas of high concentration to low concentration, while electrical gradients influence ion movement based on charge differences across the membrane.

What are the important ions in a cell and their concentrations?

Key ions include Na+, K+, and Cl-, with Na+ being higher outside the cell, K+ higher inside, and Cl- varying based on the cell type.

What is the Equilibrium potential of an ion?

The Equilibrium potential is the membrane potential at which there is no net movement of a specific ion across the membrane.

How do we calculate the Equilibrium potential?

• nerst equation

• Ex = (RT/ zF) ln ([X]out [X]in)

  • r is constant

  • f is constant

  • z is valency

  • T is temperature

What are the Equilibrium potentials of Na+, K+, and Cl-?

• Na+= +60 mV

• Cl-= -55 mV

• K+= -85 mV

How do we calculate the membrane potential of a neuron at rest?

The resting membrane potential is calculated using the Goldman equation, which incorporates the permeability of the membrane to different ions.

Goldman equation

• Vm= resting membrane potential

• px is permeability

What is the resting membrane potential and why is it around -70 mV?

The resting membrane potential is the electrical potential difference across the membrane of a neuron at rest, typically around -70 mV, primarily due to the distribution of Na+ and K+ ions and the permeability of the membrane to these ions.

What is driving force in the context of ion movement?

Driving force refers to the difference between the membrane potential and the equilibrium potential for a specific ion, influencing the direction and magnitude of ion flow across the membrane.

Ohm’s Law

• relares current, voltage and resistance

• V= IR

Time Constant

• How a signal changes over time

• draw graph

• T= Rm* Cm

  • Rm= resistance of membrane

  • Cm= capacitance of membrane

• Bigger t= slower

• Passive property

• Slower processing= integration

• Faster processing= more restrictive

• about speed

Length Constant

• How a signal changes over distance until amplitude degrades 37% of original aplitude

• Lamba= square root(dRm/ 4Ri)

  • Rm= resistance of membrane

  • Ri is internal resistance

How does an action potential propagate along an axon?

An action potential propagates along an axon through the sequential opening and closing of voltage-gated ion channels, leading to depolarization and repolarization of the membrane.

How does a voltage-gated Na+ channel work?

A voltage-gated Na+ channel opens in response to depolarization, allowing Na+ ions to flow into the cell

it inactivates shortly after opening, contributing to the refractory period.

What is the refractory period in relation to Na+ channels?

The refractory period is the time during which a neuron cannot fire another action potential, primarily due to the inactivation of voltage-gated Na+ channels.

What is myelin and how does it contribute to faster signal propagation?

Myelin is a fatty substance that insulates axons, allowing for faster signal propagation by reducing capacitance and increasing the speed of electrical impulses.

How do myelin sheaths work in series to increase conduction velocity?

Myelin sheaths increase conduction velocity by allowing action potentials to jump between nodes of Ranvier, minimizing signal loss and speeding up transmission.

What is saltatory conduction?

Saltatory conduction is the process by which action potentials jump from one node of Ranvier to another along a myelinated axon, enhancing the speed of signal transmission.

What does a single channel recording reveal about voltage-gated ion channels?

Single channel recordings provide insights into the behavior of individual voltage-gated ion channels during depolarization, allowing for the study of channel kinetics and function.

What is the patch clamp technique?

The patch clamp technique is a method used to study the ionic currents of individual ion channels by isolating a small patch of membrane.

How do ions pass through voltage-gated channels?

Ions pass through voltage-gated channels via a selectivity filter that allows specific ions to enter based on size and charge, while blocking others.

Why do we need so many ion channels?

We need many ion channels to regulate various physiological processes, and they exhibit evolutionary relationships that reflect their diverse functions in cellular signaling.