AP Psych Unit 1 (Module 1.1-1.4c) - Biological Bases for Behavior

Neuron

A nerve cell that transmits electrical and chemical messages. Ex: Sensory neurons carry signals from your skin to your brain.

Sensory neurons

Carry information from sensory receptors to the brain/spinal cord. Ex: Detecting heat from a stove.

Motor neurons

Send signals from the brain/spinal cord to muscles or glands. Ex: Moving your hand off the stove.

Interneurons

Connect sensory and motor neurons within the brain/spinal cord. Ex: Spinal interneurons trigger reflexes.

Glial cells

Support, nourish, and protect neurons. Ex: Schwann cells form myelin in the PNS.

Resting potential

The neuron’s stable, negative charge when inactive. Ex: Around –70 mV inside the axon.

All-or-nothing principle

A neuron fires completely or not at all. Ex: Pressing the threshold triggers a full impulse.

Reuptake

Neurotransmitters are reabsorbed by the sending neuron. Ex: SSRIs block serotonin reuptake to treat depression.

Refractory period

Time after firing when a neuron can’t fire again. Ex: Prevents overlapping impulses.

Threshold

Minimum stimulation needed to trigger an impulse. Ex: Enough depolarization causes action potential.

Depolarization

Positive ions enter the neuron, making it more likely to fire. Ex: Sodium ions rushing in.

Neurotransmitter

Chemical messenger across the synapse. Ex: Dopamine influences movement and pleasure.

Excitatory neurotransmitter

Increases likelihood of neuron firing. Ex: Glutamate.

Inhibitory neurotransmitter

Decreases likelihood of neuron firing. Ex: GABA.

Agonist

Mimics neurotransmitter effects. Ex: Morphine mimics endorphins.

Antagonist

Blocks neurotransmitter effects. Ex: Botox blocks acetylcholine.

Acetylcholine (ACh)

Enables muscle movement and memory. Ex: Low ACh in Alzheimer’s.

GABA

Main inhibitory neurotransmitter. Helps regulate anxiety, fear, and stress by making neurons less likely to fire, which can promote a sense of calm, improve sleep, and stabilize mood.

Serotonin

Regulates mood, hunger, and sleep. Ex: Antidepressants increase serotonin.

Dopamine

Influences movement and reward. Ex: Too much = schizophrenia; too little = Parkinson’s.

Endorphins

Natural painkillers and mood boosters. Ex: Released during exercise (“runner’s high”).

Norepinephrine

Controls alertness and arousal. Ex: Low levels = depression.

Glutamate

Main excitatory neurotransmitter; involved in learning. Ex: Too much can cause migraines.

Substance P

Transmits pain signals. Ex: High levels during injury.

Multiple Sclerosis (MS)

Myelin sheath degenerates, slowing signals. Affects the central nervous system, and symptoms can vary widely. Ex: Causes muscle weakness.

Myasthenia Gravis

Immune system attacks ACh receptors. Ex: Leads to muscle fatigue.

Lesions

Destroyed brain tissue used to study function. Ex: Lesioning amygdala affects fear.

fMRI (Functional MRI)

Tracks brain activity via blood flow. Ex: Shows active areas during speech.

EEG (Electroencephalogram)

Records electrical brain activity. Ex: Detects sleep stages.

Brainstem

Controls basic life functions. Ex: Breathing and heartbeat.

Medulla

Regulates heartbeat, swallowing, and breathing. Ex: Damage can cause death

Reticular activating system

Controls arousal and attention, filters information, connects to nerve network. Ex: Helps you wake up.

Cerebellum

Coordinates voluntary and involuntary movement and balance, nonverbal learning/memory, and processes sensory input. Ex: Playing the piano smoothly.

Limbic system

Emotion and motivation center, memory formation. Ex: Includes amygdala and hippocampus.

Thalamus

Sensory relay station to the cortex (all senses except for smell). Ex: Sends visual info to occipital lobe.

Hypothalamus

Regulates bodily maintenance: hunger, thirst, body temp, and drives. Dopamine production, influences in pituitary gland, the four f’s. Ex: Triggers eating when hungry.

Hippocampus

Forms new memories, navigational abilities, helps process explicit/concious memories (facts/events) for storage. Ex: Damage causes amnesia.

Amygdala

Processes intense fear and aggression (emotional memories/experiences). Ex: Overactive amygdala = anxiety.

Split brain procedure

Cuts corpus callosum to reduce seizures. Ex: Right/left hemispheres act independently.

Corpus callosum

Connects brain hemispheres. Communication link! Ex: Integrates functions of both sides.

Occipital lobe

Visual processing cortex. Ex: Damage = blindness/visual hallucinations/distortions.

Parietal lobe

Processes touch and body position, contains somatosensory cortex. Ex: Sensing texture or temperature.

Frontal lobe

Controls planning, judgment, impulse control, social behavior, higher order thinking, and movement. Contains motor cortex. Ex: Used in decision making.

Temporal lobe

Processes hearing and language. Ex: Damage = hearing loss.

Somatosensory cortex

Processes body touch/movement sensations, at the front of the parietal lobes. Ex: Feeling pressure on skin.

Motor cortex

Controls voluntary movements. Ex: Moving your right arm.

Broca’s area

Produces speech. Ex: Damage = trouble speaking/broken sentences.

Wernicke’s area

Comprehends language. Ex: Damage = meaningless speech.

Plasticity

Brain’s ability to reorganize after damage. Ex: Stroke recovery.

Peripheral nervous system (PNS)

Connects CNS to the rest of the body. Ex: Nerves in limbs.

Somatic nervous system

Controls voluntary movement. Ex: Lifting a glass of water.

Autonomic nervous system

Controls involuntary actions. Ex: Heartbeat and digestion.

Sympathetic nervous system

Activates “fight or flight.” Ex: Increased heart rate during stress.

Parasympathetic nervous system

Calms body after stress. Ex: Slows heartbeat after fear passes.

Pituitary gland

Controlled by hypothalamus. Master gland controlling other glands; releases growth hormone. Ex: Oversees puberty hormones.

Adrenaline (epinephrine)

Hormone that boosts alertness and energy in stress. Ex: Adrenaline rush before a race.

Right Hemisphere Functions

• Controls the left hand

• Nonverbal

• Visual-spatial perception

• Music and artistic processing

• Emotional thought and recognition

• Processes the whole

• Pattern and facial recognition

Left Hemisphere functions

• Controls the right hand

• Spoken/written language

• Mathematical calculations

• Logical thought processes/analysis of details

• Reading/making lists