PSYC 3601: Biopsychology Quiz #1 Content

Biopsychology

The study of the mechanisms of experience and behavior

Neurons

Conduct electrical impulses called action potentials; the cells of the nervous system

Action Potential

Generated by charge gradients from ions moving in/out of a neuron

What triggers an action potential?

Stimulation from a sensory receptor or another neuron or a response to an absence of stimulation

Membrane

Lines the outside of the neuron

Soma

Contains the nucleus, mitochondria, and endoplasmic reticulum; the body of the cell

Nucleus

Houses genetic material for the cell

Mitochondria

Generates ATP energy for cell use

Endoplasmic Reticulum/Ribosomes

Synthesize proteins for cell use

Dendrites

Branch-like appendages that receive messages from other neurons via neurotransmitters

Axon

This “tube” is where an action potential travels; contains the myelin sheath and nodes of ranvier

Myelin Sheath

Conducts and insulates an action potential

Nodes of Ranvier

Continues an action potential down the axon

Presynaptic Terminals

The end of the axon branches into these; contain vesicles

Vesicles

Sacs of neurotransmitters in the presynaptic terminals; responsible for housing chemical messengers and reuptake

Camillo Golgi

Pioneered the method of staining neurons to study them; believed neurons were one giant unit

Santiago Ramon y Cajal

Utilized Golgi’s method to stain individual neurons to characterize structure and function; proved that neurons are actually individual units, not one giant network, using Golgi’s own methods

Afferent Neurons

Bring signals from the body to the CNS

Efferent Neurons

Bring signals from the CNS to the body

Interneuron

Neither afferent nor efferent to a structure, but contained within that structure; they carry the message along

Local Interneurons

Form circuits with nearby neurons

Relay Interneurons

Connect circuits that are further apart

Sensory Neurons

Input from sensory receptor, sends signals to the CNS (afferent)

Motor Neurons

Take input from the CNS, sends signals to muscles (efferent)

Types of Neuronic Cells

Pyramidal, Medium Spiny, Purkinje, and Von Economo

Oligodendrocytes/Schwann Cells

Provide myelin

Radial Glia

Provide a structure for neuron growth

Microglia

The nervous system’s immune cells

Astrocytes

Fine-tune neural activity by taking up neurotransmitters from synapses; manage blood and glucose flow in the brain

Why is it extra bad when the nervous system is infected?

Neuron regeneration is very limited, so protecting them from viruses, bacteria, and toxins to maintain circuitry are critical

The Blood-Brain Barrier (BBB)

Protects the CNS from harmful things in the bloodstream; only small, fat-soluble molecules (like oxygen) can make it through

Amino Acids

These are used in the CNS for protein construction and the synthesis of some neurotransmitters

Thiamine (B1)

This vitamin allows the CNS to use glucose; without it, neurons die

Korsakoff’s Syndrome

A severe, chronic brain disorder where an individual experiences memory loss, confabulation, and confusion as a result of a lack of thiamine in the brain

What percentage of oxygen and glucose does the CNS use, respectively?

20% and 25%

Selective Permeability

This means only some chemicals are permeable through protein channels; some are refused

Sodium-Potassium Pumps (NaK)

These pumps continually pump 3 sodium ions out of a neuron and 2 potassium ions into a neuron

What does resting potential look like chemically?

A high sodium concentration outside and a high potassium concentration inside

Resting Potential

The neuron at rest; organic atoms create an overall negative charge (-70mV)

Voltage-Gated Channels

These open based on the voltage difference across the membrane; at a certain threshold they will open

Stimulus

Causes an action potential, if it’s strong enough

Slow Depolarization

When some sodium channels are open, but the voltage threshold is not yet reached

Voltage Threshold

-50mV; causes rapid depolarization as the inside of the membrane becomes positively charged

Peak Depolarization

+30mV; this is when sodium channels close and potassium channels open

Repolarization

The neuron is diving back towards -70mV as potassium refills the inside of the membrane

Hyperpolarization

The potassium pumps are slow to close, so the inside of the membrane becomes temporarily too negative

What returns the neuron to resting potential?

NaK pumps

The All or None Principle

The idea that a neuron will fire ONLY if it reaches voltage threshold, and all firings are the same strength; more stimulus does not mean stronger signal

Refractory Period

The neuron can not fire another action potential whilst one is already going, it must rest and return to proper charge (-70mV)

Action Potential Propagation

Once depolarization triggers voltage-gated channels to open, the action potential propagates down the axon to the presynaptic terminals

Why is myelin important?

Keeps ion flow moving in one direction: down the axon

Why are the Nodes of Ranvier important?

The action potential is regenerated here by ions pushed along through the myelin sheath

Saltatory Conduction

The “jumping” of the action potential from node to node; this is much faster and efficient

Continuous Conduction

This occurs on unmyelinated axons; the signal travels slower and can diminish along the way

Back Propagation

The idea that the action potential propagates backward to the dendrites, making them “stronger”

What does ion flow in dendrites trigger?

Dendritic spine growth, which gives dendrites greater surface area, which leads to more information transmission

Differences Between Neurons

Amplitude and velocity does vary between different kinds of neurons

Why do different nerve impulse speeds matter?

The brain has the ability to register small differences in impulse arrival from visual and auditory inputs; for some inputs, it doesn’t matter, however