1.3 The Neuron and the Neuron Firing
Neurons and glial cells are the building blocks of our nervous system, making all our behaviors and mental processes possible. These specialized cells talk to each other through electrical and chemical signals, creating complex networks that process info and make us do stuff.
Neural transmission is like a game of telephone, but with precise steps from resting potential to action potential firing. Neurotransmitters and hormones are the chemical messengers that influence our behavior and mental states. Psychoactive drugs can mess with these processes, affecting how neurotransmitters work and changing our behavior.
quick cram review
neurons send signals to control behavior and thinking; glial cells support them.
neural transmission is how neurons communicate using electrical and chemical signals.
psychoactive drugs change behavior by affecting neurotransmitters (stimulants → speed up activity, depressants → slow down activity, hallucinogens → change perception, opioids → relieve pain)
Neuron structures and functions
Neural cells in behavior
Neurons and glial cells work together as the basic functional units of the nervous system. While neurons are the primary information processors, glial cells provide essential support that enables proper neural function.
Neurons are specialized cells that:
Transmit information via electrical and chemical signals
Form complex networks for information processing
Connect to create neural circuits
Glial cells perform several critical support functions:
Create structural scaffolding for neural networks
Insulate neurons to enhance signal transmission
Facilitate communication between neurons
Remove waste products to maintain healthy function
Together, these neural cells enable all behavior and mental processes, from basic sensory input to complex decision-making and motor output.
Spinal cord reflex arc
The reflex arc demonstrates a simple but essential neural circuit that enables rapid, automatic responses without brain involvement. This process occurs in the spinal cord and involves multiple types of neurons working in sequence.
Example: Quickly pulling your hand away from a hot stove before consciously feeling pain
Key components of the reflex arc:
Sensory neurons detect initial stimulus (heat)
Interneurons relay information within the spinal cord
Motor neurons activate muscles for response (pulling the hand away)
Entire process occurs before conscious awareness
Neural transmission process
Neural transmission mechanisms
Neural transmission follows a precise sequence that enables neurons to communicate effectively. This process begins with the resting state and proceeds through several distinct phases.
The basic sequence includes:
Maintenance of resting potential (negative charge inside cell)
Stimulus reaches threshold
Action potential fires (all-or-nothing principle)
Depolarization occurs
Refractory period follows
Reuptake completes the cycle
Disruptions to this process can cause various disorders:
Multiple sclerosis: Damage to the insulation (myelin) around neurons impairs signal transmission
Myasthenia gravis: Antibodies attack receptors for the neurotransmitter acetylcholine, weakening muscle contractions
🚫 Exclusion Note: The sodium-potassium pump will not be covered on the AP Psych exam.
Neurotransmitter functions
Neurotransmitters serve as the chemical messengers ✉ of the nervous system, each with specific roles in neural communication.
Excitatory neurotransmitters increase likelihood neural firing:
Glutamate (most common in brain)
Norepinephrine (increases arousal alertness)
Inhibitory neurotransmitters decrease likelihood of neural firing:
GABA (main inhibitory transmitter, balances out excitation)
Serotonin (regulates mood, sleep, and appetite)
Some neurotransmitters have both excitatory and inhibitory effects:
Dopamine (motivation, reward, and motor control)
Acetylcholine (muscle contractions, learning and memory)
Endorphins (natural pain relief and euphoria-inducers)
Substance P (pain signaling from body to brain)
🚫 Exclusion Note: The AP Psych exam will only cover the neurotransmitters listed above.
Hormones in behavior
Hormones act as chemical messengers throughout the body, similar to neurotransmitters but produced by glands and traveling via bloodstream to influence behavior and mental processes.
The key hormones affecting behavior and mental-processes include:
Adrenaline (epinephrine): triggers "fight-or-flight" response during stress
Leptin: controls feelings of fullness to regulate appetite and body weight
Ghrelin: stimulates hunger and food-seeking behavior
Melatonin: regulates sleep cycles based on light exposure
Oxytocin: promotes social bonding, trust, and maternal behavior
🚫 Exclusion Note: The AP Psych exam will only cover the hormones listed above. 🚫 Exclusion Note: Specific information about the glands of the endocrine system is beyond the scope of the AP Psych exam.
Psychoactive drugs and behavior
Drug effects on neurotransmitters
Psychoactive drugs interact with neurotransmitter systems in several ways to alter neural communication and behavior.
Three main mechanisms of action:
Agonists mimic or enhance neurotransmitter effects, ✅ neural firing
Example: Opioids like heroin and morphine mimic endorphins
Antagonists block neurotransmitter effects, 🚫 neural firing
Example: Caffeine blocking adenosine
Reuptake inhibitors block the reabsorption of neurotransmitters back into the releasing neuron, prolonged neurotransmitter activity
Example: Antidepressants like Prozac are serotonin reuptake inhibitors, helping to elevate mood
Psychological and physiological effects
Different classes of psychoactive drugs produce distinct effects on behavior and mental processes.
Stimulants increase arousal and activity:
Mild: caffeine, nicotine
Potent/addictive: cocaine, amphetamines
Depressants reduce neural activity and have sedating effects:
Alcohol affects judgment, coordination, and memory
Benzodiazepines (Xanax, Valium) treat anxiety and sleep issues
Hallucinogens alter perception:
Marijuana contains THC which affects sensory processing, judgement, and memory
LSD and psilocybin ("magic mushrooms") can cause vivid hallucinations and feelings of dissociation from reality
Opioids are powerful pain relievers that also induce euphoria and relaxation
Prescription versions treat severe pain (OxyContin, Vicodin)
Illegal forms like heroin carry high risks (Heroin)
Drug tolerance and addiction
Drug tolerance develops as the brain adapts to repeated drug exposure, requiring larger doses to achieve the same effects. This adaptation reflects the brain's attempt to maintain balance despite the drug's presence.
Addiction involves:
Compulsive drug use despite negative consequences
Activation of brain reward systems, reinforcing the behavior
Withdrawal symptoms upon cessation:
Physical symptoms (nausea, tremors)
Psychological symptoms (anxiety, cravings)
Severity varies by drug type and usage pattern
Neurotransmitter VS Hormone.
Neurotransmitters: Chemicals that transmit signals across a synapse from one neuron to another, playing a critical role in mood regulation and perception.
Hormones: Chemicals released into the bloodstream that affect various body functions, including stress response and metabolic processes, often influencing behavior and mood.