Neurobiology.1.25
Page 1: Introduction & Purpose
These materials are for BSci 1511 students to assist in exam preparation.
The content may be copyrighted and should only be used for studying within this class context.
Page 2: Overview of Neurobiology
I. Components of the Nervous System
A. Nervous Systems: Networks & Circuits
B. Neurons: The fundamental units of nervous systems.
C. Glia: Supporting cells in the nervous system.
II. Neurons and Nerve Impulses
A. Resting Membrane Potential (Vm)
(1) Concentration differences of ions across membrane.
(2) Differential permeability of the membrane to ions.
B. Electrical Signaling: Action Potentials
(1) Voltage-gated channels and their phases.
(2) Propagation and directionality of signals.
(3) All-or-None principle of action potentials; they are digital signals.
(4) Factors affecting velocity: Axon diameter vs. saltatory conduction.
III. Neurons, Synapses, and Communication
A. Types of Synapses and Neurotransmitters (NTs)
B. Mechanism: “Passing the Baton” between neurons.
C. Integration of signals: Summation of excitatory and inhibitory inputs.
D. Mechanism to stop neural signals.
Page 3: Complexity of the Human Brain
Quote: "If the human brain were so simple that we could understand it, we would be so simple that we couldn’t.” - Emerson Pugh
Highlights specific neuron types in the hippocampus marked by fluorescent proteins.
Page 4: Functions of the Nervous System
It perceives, reacts, communicates, thinks, learns, remembers, and enables consciousness.
Page 5: Nervous System Components
Key Functions:
Sensor: Receives sensory input.
Motor output: Commands muscles and responses.
Effector: Executes responses.
Structural Components:
Peripheral Nervous System (PNS) and Central Nervous System (CNS).
Page 6: Biological Electricity
Luigi Galvani's Experiments
Conducted in the 1780s with frogs; showcased 'animal electricity'.
Demonstrated that frog legs could react through electrical charges.
Page 7: Cultural Reference: Frankenstein
Mary Shelley's novel introduces the concept of electricity as a vital force in the context of life and death.
Contrasts cinematic representation with the literary work regarding the 'spark of life'.
Page 8: Nervous System Complexity
Simple organisms utilize basic nerve networks (nerve nets).
More complex organisms have ganglia, leading to the development of the CNS (brain & spinal cord).
Page 9: Structural Design of the Nervous System
Types of Neurons
Sensory, interneurons, and motor neurons.
Excitable cells include neurons and muscle cells.
Example: Knee-Jerk Reflex
Involves sensory neurons, interneurons, and motor neurons.
Page 10: Neuron Structure
Components
About 100 billion neurons in the human brain.
Parts of a Neuron:
Presynaptic cell: Dendrites (input), Cell body, Axon hillock (initiating signal).
Axon: Transmits impulses to axon termini and postsynaptic cells.
Page 11: Neuronal Morphology
Example structures from different brain regions: cerebellum, retina, cerebral cortex, spinal cord.
Page 12: Types of Neurons
Highlighted pyramidal nerve cells from the cerebrum of cats.
Page 13: Types of Cells: Glia
Functions of Glial Cells
Structural support, nutrient supply (glucose, lactate), forming the blood-brain barrier (BBB), neurotransmitter reuptake, ion homeostasis.
Page 14: Types of Glia
Schwann cells in the PNS and oligodendrocytes in CNS both create myelin sheaths.
Page 15: Myelinated Axon Cross-section (rat)
Illustrates the insulation provided to axons.
Page 16: Resting Membrane Potential
Vm Determinants
(1) Concentration differences of ions across the membrane.
(2) Differential permeability to ions explains how resting Vm is established.
Page 17: Action Potentials
Study of a giant neuron from squid led to insights on electrical signaling in nerves.
Page 18: Membrane Potential Measurement
Diagram showing the use of microelectrodes, voltage recorders, and oscilloscopes.
Page 19: Electrochemical Gradients
Discusses the role of charged molecules and their movement in establishing the resting potential.
Page 20: Equilibrium Potentials
Explanation of how ion concentration relates to membrane potential and the Nernst equation.
Page 21: Calculating Equilibrium Potentials
Overview of K+ and Na+ equilibrium potentials and their contributions to the resting potential.
Page 22: Driving Force for Ions
Difference between ionic equilibrium and membrane potential explains ion flow in neurons.
Page 23: Changes in Ion Permeability
Mechanisms by which the membrane potential (Vm) varies through ion channel activity.
Page 24: Ion Concentration Gradient Maintenance
Role of the Na+/K+ pump in preserving ionic gradients for resting potential and action potentials.
Page 25: Key Components of Electrical Signaling
Details on voltage-gated channels and their functional phases during action potentials.
Page 26: Types of Ion Channels
Ligand-gated vs. voltage-gated channels with implications for nervous signaling.
Page 27: Graded Potential Changes
Differentiation between hyperpolarizations/depolarizations initiated by stimuli.
Page 28: Action Potential Phases
Steps of the action potential illustrated through the functioning of different ion channels.
Page 29: Voltage-gated Channel Dynamics
Specifics on the stages of action potential development as Na+ and K+ channels behave.
Page 30: Action Potential Properties
Notes on propagation speed, duration, and characteristics indicating an all-or-none response.
Page 31: Mechanics of Action Potentials
Analysis of visual data showing action potential generation and propagation dynamics.
Page 32: Conductive Speed in Axons
Comparisons of conduction speeds in giant axons vs. small diameter axons during action potentials.
Page 33: Effects of Myelination
Illustrates how myelin sheaths increase conduction speed through reduced leakage (saltatory conduction).
Page 34: Overview of Synapses
Neuronal Communication
Synapses facilitates communication between neurons and muscle cells.
Page 35: Synapses and Neurotransmitter Function
Highlights the different types of synapses and the neurotransmitter roles in neural communication.
Page 36: Synapse and Memory
Connections between synaptic structures and memory, mentioning the impact of Alzheimer’s Disease.
Page 37: Synaptic Mechanisms in Learning
Insights from Aplysia (sea hare) studies on mechanisms of memory formation.
Page 38: Aplysia and Behavioral Studies
Analysis of specific neuronal responses by sea hare in danger (ink release).
Page 39: Neuron Structure Recap
Review of presynaptic and postsynaptic neuronal structures involved in signal transmission.
Page 40: Synapse Connection Density
Average density of synaptic connections per neuron in human brain dimensions discussed.
Page 41: Structural Complexity of Synapses
Visualization of synaptic connections' structure demonstrating input-output relationship.
Page 42: Neuronal Connections in Drosophila
Discussion focused on the number of neurons and synapses within the insect brain.
Page 43: Synapse Types Overview
Major Categories
Electrical synapses: fast but non-modulated.
Chemical synapses: NT release and diffusion across synaptic cleft (Key neurotransmitters detailed).
Page 44: Neuromuscular Junction Example
Detail of neuromuscular action potential and neurotransmitter release process.
Page 45: ACh Receptor Mechanism
ACh's role in opening Na+ channels and the effects on postsynaptic membranes.
Page 46: Outcome of ACh Depolarization
Describes the exciting or inhibitory outcomes based on the postsynaptic nature (muscle vs. neuron).
Page 47: Excitatory vs. Inhibitory Synaptic Responses
Contrasting effects of NTs on postsynaptic potentials (EPSP vs. IPSP).
Page 48: Axon Hillock Functionality
Critical functionality of the axon hillock for action potential initiation due to the accumulation of EPSPs/IPSPs.
Page 49: Decision Making in Action Potentials
Explanation of how integration of synaptic inputs leads to action potential firing at the hillock.
Page 50: Spatial and Temporal Summation in Synapses
Process by which simultaneous synaptic influences collectively determine postsynaptic responses.
Page 51: Neuronal Integration Mechanism
Neurons' computational ability to integrate inputs and decide on action potentials.
Page 52: Fluorescence Imaging in Neuroscience
Overview of techniques to monitor neuronal activity using fluorescence methods.
Page 53: Types of Chemical Synapse Receptors
Differentiation of metabotropic and ionotropic receptors regarding NT interactions.
Page 54: G-protein Couple Receptor Functionality
Mechanism of adrenergic receptor action in the sympathetic nervous system with Ca++ channels.
Page 55: Termination of Synaptic Signal
Mechanisms Breakdown
NTs are released in brief bursts and quickly removed from synaptic cleft, ceasing action.
Page 56: Sample Questions for Review
Multiple Choice Examples:
Resting neurons and K+ equilibrium potential.
Chloride ion influx implications.
Understanding of temporal summation processes.
Short Answer Question:
Action potential conduction mechanisms in vertebrates vs. invertebrates regarding myelin.
Page 57: Poetic Reflection on Neurons
The creative interpretation of neurology through poetry, merging science with artistic expression.