PSYC 270 Test 1

What is the general layout of the nervous system?

• Central Nervous System [CNS]

• Peripheral Nervous System [PNS]

  • Somatic Nervous System

  • Autonomic Nervous System

    • Parasynthetic Nervous System

    • Sympathetic Nervous System

What does the Central Nervous System manage?


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Brain and spinal cord

What does the Peripheral Nervous System manage?

Nerves

What does the Somatic Nervous System manage?

Voluntary movements of the skeletal muscles

What does the Autonomic Nervous System manage?

Involuntary internal functions like heart rate and digestion

What does the Sympathetic Nervous System manage?


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Drive the “fight-or-flight” response during stress

What does the Parasympathetic Nervous System manage?

Drive the “rest-and-digest” state during calm

What is the function of the Blood Brain Barrier?

It’s a highly selective, semi-permeable border of cells that separate circulating blood from the brain and central nervous system extracellular fluid

What is the difference between neurons and glia cells?

Neurons are primary signaling cells of the nervous system that generate and transmit electrical impulses, while glia cells provide critical physical support, insulation, and nourishment to keep neurons function properly

Which glia cells are apart of the Peripheral Nervous System?

Schwann Cells and Satellite Glia Cells

What are the functions of Schwann Cells?

They insulate axons with myelin to speed up nerve signal conduction and support nerve repair

What are the functions of Satellite Glia Cells?

They wrap around cell bodies of neurons in the PNS to control their local environment and support their health

Which Glia Cells are in the Central Nervous System?

Astrocytes, Oligodendrocytes, Microglia, and Ependymal Cells

What are the functions of Astrocytes?

They are star-shaped glial cells that provide structural, metabolic, and homeostatic support to neurons

What are the functions of Oligodendrocytes?

Their primary function is to produce myelin

What are the functions of Microglia?

They act as the brain and spinal cords first line of defense

What are the functions of Ependymal Cells?

They line the brain’s ventricles and the spinal cord’s central canal to produce, circulate, and monitor cerebrospinal fluid (CSF)

What is the structure of a neuron?

• Cell Body (Soma)

• Cell Membrane (Plasma Membrane)

• Dendrites

• Axon Hillock

• Axon

• Myelin Sheath

• Nodes of Ranvier

• Axon Terminals

What is the function of the Cell Body (Soma) in neurons?

Acts as the metabolic and control center of a neuron, housing the nucleus and producing the proteins and energy required for the cell to survive and function

What is the function of the Cell Membrane (Plasma Membrane) in neurons?

Acts as a dynamic barrier that separates the inside of the cell from the outside environment while creating and passing electrical signals

What are the functions of Dendrites in neurons?

Function as receiving and processing antennas of a neuron, gathering chemical and electrical signals from neighboring nerve cells

What is the function of the Axon Hillock in a neuron?

Acts as a decision making center of the neuron, where it adds up incoming signals to decide if the cell should fire an electrical message

What is the function of an Axon in a neuron?

To transmit electrical and chemical signals away from the neuron’s cell body toward other neurons, muscles, or glands

What is the function of the Myelin Sheath in a neuron?

To insulate nerve fibers (axons) and dramatically increase the speed at which electrical signals travel

What is the function of Node of Ranvier in a neuron?

They’re tiny, bare gaps in the myelin sheath along a neuron’s axon that allows electrical signals to rapidly jump from gap to gap

What is the function of Axon Terminals in a neuron?

To convert an electrical nerve signal into a chemical message and pass it to the next cell

How does information in a single neuron flow?

In one direction, from dendrites —> cell body —> axon —> and out through the axon terminals

What is the definition of Synapse?

The microscopic junction or space where a nerve impulse passes from one cell to another

What does Pre-Synaptic mean?

It relates to the transmitting side of a synapse

What does Post-Synaptic mean?

Relating to the receiving side of a synapse

What is the definition of Neuronal Variability?

The fluctuation in the electrical activity and response patterns of neurons

What are the dimensions and functions of a Unipolar Neuron?

• Dimensions: Has a single short process branching from the cell body that splits into 2 extensions —> one acting as the dendrite and one as the axon

• Functions: Transmits basic sensory information from the body’s outer tissues directly to the spinal cord and brain

What are the dimensions and functions of a Bipolar Neuron?

• Dimensions: Has 2 distinct processes extending from opposite sides of the cell body —> one main dendrite and one main axon

• Functions: Handles specialized sensory signals with high precision and exactness, such as vision in the retina/smell in the nose/hearing in the inner ear

What are the dimensions and functions of a Multipolar Neuron?

• Dimensions: Has 1 single axon and many branching dendrites extending from the cell body (most common type of neuron in vertebrates)

• Functions: Controls ongoing motor commands and complex information integration throughout the central nervous system (CNS)

What are the dimensions and functions of a Multipolar Interneuron?

• Dimensions: A specialized subset of multipolar neurons that feature extensive, complex branching patterns confined entirely within the local circuit of the central nervous system (CNS)

• Functions: Acts as a middleman to connect sensory neurons, motor neurons, and other interneurons, helping the brain process and compute complex signals rather than just routing them directly

What is a Withdrawal Reflex?

An automatic, involuntary protective response that pulls a body part away from a painful or damaging stimulus before the brain even registers the pain (like stopping yourself from touching a hot surface or sharp object)

What are the inputs and outputs for Somatosensory Neurons regarding Withdrawal Reflex?

• Input: Painful or noxious chemical, thermal, or mechanical stimuli detected by specialized receptors called nociceptors in the skin or tissues

• Output: An electrical action potential carried via sensory nerve fiber through the dorsal root into the dorsal horn of the spinal cord, where it synapses into interneurons

What are the inputs and outputs for Motor Neurons regarding Withdrawal Reflex?

• Inputs: Signals relayed from spinal interneurons (which process sensory input; excitatory signals for flexors and inhibitory signals for extensors)

• Output: Motor impulses traveling out of the ventral horn of the spinal cord via alpha motor neurons to stimulate contraction in flexor muscles (pulling the limb away) while also inhibiting extensor muscles (preventing resistance)

What does Resting Membrane Potential set the stage for?

The generation of action potentials and rapid electrical signaling in excitable cells like neurons and muscle cells

What is the value of Resting Membrane Potential?

-70 mV

Define polarization

The property of transverse waves, such as light, that describes the specific direction or geometrical orientation in which the wave’s oscillations occur

What the main ions involved in membrane potential?

Potassium (K^+), Sodium (Na^+), Chloride (Cl^-), and organic anions

What is the concentration gradient

The difference in the amount of a substance (like a solute or gas) between two connected areas

What is the Electrical Gradient?

The difference in electrical charge across a space or cell membrane

How is the resting membrane potential maintained?

By the combined action of the sodium-potassium pump and selective membrane permeability, and potassium leakage channels

How does synaptic communication work?

It’s a process where one neuron passes an electrical or chemical signal to another cell across a small gap called a synapse

What are the steps of Synaptic Communication?

• Action potential arrives

• Calcium enters

• Vesicles release neurotransmitters

• receptors bind chemicals

• channels open

• signal ends

What are post-synaptic potentials?

Temporary changes in the electrical charge of a neuron’s membrane that happen when chemical signals are passed from one cell to another

What are the graded potentials of synaptic communication?

Depolarized (Excitatory) and Hyperpolarized (Inhibitory)

What is the definition of Depolarized (Excitatory) ?

The inside of the cell becomes less negative (more positive) —> bringing the cell closer to firing an action potential

What is the definition of Hyperpolarized (Inhibitory)?

The inside of the cell becomes more negative —> moving the cell further away from firing an action potential

What is the definition of EPSP (Excitatory Postsynaptic Potential)?

A depolarizing graded potential. It makes the inside of the cell more positive, pushing the cell toward firing an action potential

What is the definition of IPSP (Inhibitory Postsynaptic Potential)?

A hyperpolarizing graded potential, making the inside of the cell more negative—> pushing it harder to fire an action potential

What is Action Potential?

It’s a rapid, temporary change in a cell’s electrical voltage that allows neurons to send signals

What is the process of Action Potential?

• Resting state (voltage is about -70mV/ inside of cell has more potassium ions/ outside of cell has more sodium ions/ stable, polarized state)

• Threshold and Depolarization [Rising Phase] (stimulus opens sodium channels, letting positive Na²+ ions to trickle in/ if voltage reaches about -55mV an action potential fires/ Na²+ floods in/ inside of cell flips from negative—>positive (reaching about +40mV-+55mV))

• Repolarization [Falling Phase] (at the peak, sodium channels close and become inactive/ voltage-gated channels open, allows K^+ ions to rush out of the positive cell interior/ losing positive K^+ ions brings the membrane voltage back down toward its negative resting state)

• Hyperpolarization (Undershoot) and Recovery (potassium channels are slow to close, so too many K^+ ions leave/ voltage drops slightly below normal resting level, entering a refractory period, where it’s harder to trigger a new signal/ the sodium-potassium pump actively resets original ion positions, returning the cell to its resting potential)

What is the Refractory Period?

A short recovery time after a cell, organ, or person responds to a stimulus before they can respond again

What is the All or None Law?

A physiological principle stating that an individual nerve or muscle fiber will respond completely to a stimulus, or not at all, regardless of how strong the stimulus is

What is Chemical Transmission?

The biological process where a nerve cell sends signals to another cell across a tiny gap using chemical messengers called neurotransmitters

What are Neurotransmitters?

Chemical messengers that nerve cells use to send signals to other cells across a tiny gap called a syanpse

What are some examples of Neurotransmitters?

• Dopamine

• GABA

• Serotonin

• Glutamate

• Acetylcholine

What is the Threshold of Excitation and what happens when a neuron reaches this point?

-65mV → its a critical voltage level a neuron’s membrane must reach to trigger an action potential → when it becomes positive enough to hit -65mV, the neuron fires an electrical signal down to the axon → if the voltage stays below -65mV, no action potential occurs

What is Spatial vs Temporal Summation?

• Temporal Summation → Happens when a single presynaptic neuron (sending cell) fires signal in rapid succession at one synapse so the voltages add up over time

• Spatial Summation → Happens when multiple presynaptic neurons fire at the same time in different locations on the postsynaptic neuron

What are the effects of myelination?

It dramatically speeds up nerve signals and lowers the energy cost of running the nervous system

What’s an example of a neurodegenerative disease?

Parkinson’s Disease

How are neurotransmitters transported in the synapse?

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They move via specialized packaging, passive diffusion, active transport proteins, and cellular recycling

How do neurotransmitters bind to the synapse?

They bind to specific receptor proteins on the receiving cell membrane after crossing the fluid-filled gap between neurons called the synaptic cleft

What do Neuronal Firing Rates do?

They encode the strength, duration, and specific features of a sensory stimulus through the frequency of action potentials

What are the different stimuli of neuronal firing rates?

• Sensory Inputs

• Synaptic Chemical Signals

• Electrical Charges

• Intrisnic Patterns

What is the sequence of events at the synapse?

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• Action Potential Arrives → a nerve impulse travels down the axon and reaches the presynaptic axon terminal

• Calcium Channels Open → the depolarization of the terminal membrane opens voltage-gated calcium (Ca²+) channels

• Calcium Enters → Calcium ions rush into the presynaptic cell because their concentration is higher outside

• Vesicle Fuse (Exocytosis) → the incoming calcium triggers synaptic vesicles holding neurotransmitters to fuse with the cell membrane

• Neurotransmitters Release → the vesicles empty their chemical contents into the synaptic cleft (tiny gap between neurons)

• Diffusion and Binding → the neurotransmitter molecules float across the gap and bind to receptor proteins on the postsynaptic membrane

• Ion Channels Open/Close → receptor binding alters the membrane potential of the receiving cell, making it either more likely (excitatory) or less likely (inhibitory) to fire an action potential

• Signal Clearance → enzymes break down the remaining neurotransmitters, or transport proteins abosrb them back into the presynaptic cell via reuptake

How is chemical transmission terminated?

By removing or breaking down the neurotransmitter in the synaptic cleft, allowing the receiving cell to reset

What is inactivation in chemical transmission and why is it important?

It’s the process of removing or breaking down neurotransmitters synaptic cleft to stop their action and clear the signal, it’s important because it prevents continuous stimulation of the postsynaptic cell, allowing hte nervous system to reset and accurately transmit rapid, separate

What is reuptake in chemical transmission?

The process where a presynaptic neuron reabsorbs its released neurotransmitters from the synaptic cleft after chemical transmission

What is negative feedback in chemical transmission?

It’s a regulatory mechanism where the output of a signaling pathway inhibits its own further production or release, ensuring that chemical levels remain balanced and stable

What is the difference between Ionotropic and Metabotropic Receptors?

• Structure → ionotropic receptors structure is a ligand-gated channel while metabotropic receptors structure is G-protein coupled receptors

• Mechanism → ionotropic receptors are direct, neurotransmitter binding opens the pore to less ions pass through while metabotropic receptors are indirect, binding activates G-proteins and secondary messengers

• Speed → ionotropic receptors are very fast (milliseconds) while metabotropic receptors are slower (tens of milliseconds to seconds)

• Duration →ionotropic receptors have short-lived effects while metabotropic receptors have longer-lasting effects

• Scope → ionotropic receptors are localized to the immediate area while metabotropic receptors have widespread intercellular effects

What is Electrical Transmission?

A form of rapid neuronal communication where ionic current flows directly from one cell to the next through specialized protein channels called gap junctions

What are the classes of Neurotransmitters and their functions?

• Amino Acids

  • Glutamate → most common excitatory neurotransmitter in the brain, vital for thinking, learning, and memory

  • GABA → main inhibitory neurotransmitter, helps calm brain activity, reduce anxiety, and promote sleep

  • Glycine → an inhibitory neurotransmitter located mainly in the spinal cord, controls reflexes and motor signals

• Monoamines

  • Dopamine → controls reward, working memory, motivation, and smooth muscle movement

  • Serotonin → regulates mood, appetite, and sleep cycles

  • Norepinephrine (noradrenaline) & Epinephrine → regulates arousal, attention, and the body’s fight-or-flight stress response

• Acetylcholine

  • Acts in both the central peripheral nervous system, responsible for triggering muscle contractions and regulating heart rate and secretions in the autonomic system

• Neuropeptides (Peptides)

  • Endorphins → act as body’s natural painkillers and stress relievers

  • Oxytocin & Vasopressin → regulate social bonding, trust, and reproductive behaviors

• Soluble Gases

  • Nitric Oxide and Carbon Monoxide → unconventional, free- diffusing gases that modulate cellular signaling and blood vessel relaxation

What are the general principles of neurotransmitters?

they allow neurons (nerve cells) to communicate with one another and with target tissues like muscles or glands

Which neurotransmitters are agonist vs antagonist to another?

Agonists mimic or enhance a neurotransmitters activity, they fit into a receptor “lock” and turn on. Antagonists fit into the receptor “lock” without turning on, preventing the real neurotransmitter from landing there and activating the cell

• Example : Acetylcholine (ACh) → Agonist: nicotine or black widow poison enhances /mimics ACh action, causing muscle contractions or spasms → Antagonist: curare or atropine block ACh receptors, leading to muscle paralysis or slowed parasympathetic activity

What makes drugs addictive and how may they affect brain function?

they hijack the brain’s natural survival and reward system, artificially forcing massive chemical surges that the brain is not equiopped to hanlde. Overtime the drug use physically alters the brain’s structure and wiring, turning a conscious choice into a compulsive habit

What is the neural basis of addiction?

It’s a chronic brain disorder that hijacks the body’s natural reward, memory, and impulse-control circuits

What are the drug types and their actions and effects?

• Stimulants → increase activity in the central nervous system and sympathetic nervous system, enhancing alertness, attention, energy, and physical performance (reduced appetite, euphoria, insomnia, etc)

• Depressants → slow down the activity of the central nervous system, reducing arousal, stimulation, and messages traveling between the brain and body (could cause confusion, memory loss, drowsiness, etc)

• Opiates → they block pain signals and alter brain chemistry (reduction in physical pain, euphoria, drowsiness, slowed breathing, etc)

• Hallucinogens → they disrupt communication between brain chemical systems, resulting in altered sensory perceptions, intense mood shifts, and distinct physical changes (hallucinations, blending of senses [“hearing colors”], altered perception of time or space, etc)

What is drug tolerance?

A pharmacological condition where the body’s response to a substances decreases with repeated use

What is drug withdrawal?

The physical or mental reaction that happens when a person suddenly stops or cuts back on using a substance like alcohol, prescription medicine, or recreational drugs after using them for a long period of time

What are some common withdrawal symptoms?

Shaking, headaches, trouble focusing, seizures, axniety, etc