nervous system unit ap psychology 2025

heredity

the transmission of traits from parents to their offspring

eugenics

the practice of improving the human race by selectively mating people with specific desirable traits

glial cells

cells in the nervous system that support, nourish, and protect neurons

sensory (afferent) neurons

neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord.

motor (efferent) neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

interneurons

neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs

reflexive arc

consists of a sensory, neuron that conducts nerve impulses from a receptor to the spinal cord, where it connects directly or via an interneuron to a motor neuron that carries the impulses

depolarization

the reduction of electric potential across a cell membrane. if the stimulus exceeds the excitatory threshold, an action potential is generated, propagating a nerve impulse // the loss of the inside/outside charge difference

refractory period

a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

resting potential

the electric potential across the plasma membrane of a neuron representing an excess of negatively charged ions on the inside of the membrane // positive-outside/negative inside state

action potential

a neural impulse; a brief electrical charge that travels down an axon // temporary inflow of positive ions is the impulse

reuptake

a neurotransmitter’s reabsorbtion by the sending neuron

multiple sclerosis

central nervous system disease causing inflammation and scarring of the myelin sheath, damaging nerves and disrupting neural transmission.

myasthenia gravis

autoimmune disorder in which antibodies attack ACh receptors at the neuromuscular junction, causing faulty transmission of nerve impulses

excitatory neurotransmitter

depolarize postsynaptic neurons, increasing the likelihood of an action potential.

inhibitory neurotransmitter

hyperpolarize postsynaptic neurons, making action potentials less likely by increasing the negative charge inside the cell.

psychoactive drug

a chemical substance that alters the brain, causing changes in perceptions and moods

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug’s effect

addiction

compulsive substance use that continue despite harmful consequences

withdrawal

discomfort/distress that follows discontinuing an addictive drug/behavior

limbic system

forebrain neural system that includes amygdala, hypothalamus, hippocampus, and pituary gland; emotions and drives

pituitary gland

secrets hormones which regulate the production of other hormones “master gland of the endocrine system”

hypothalamus

autonomic functions (4 Fs: feeding, fighting, fleeing, and fornication). linked to emotion and reward

cerebral cortex

layer of gray matter that covers the outside of the cerebral hemisphere associated with higher cognitive function (language, learning, perception, planning)

somatosensory cortex

cerebral cortex area at front of parietal lobes that registers body touch and movement sensation

prefrontal cortex

most anterior part of cerebral cortex functions in attention, planing, working memory, expression of emotions, and appropriate social behavior

motor cortex

a cerebral cortex area at the rear of the frontal lobes that controls voluntary movements

split brain

condition resulting from surgery that isolates the brain’s 2 hemispheres

aphasia

impairment of language usually caused by damage to Broca’s area (speech production) and/or Wernicke’s Area (speech understanding)

contralateral hemispheric organization

refers to the brain's structure where each hemisphere primarily controls the opposite side of the body. ex. left hemisphere controls right side, right hemisphere controls left side.

EEG

an amplified recording of the waves of electrical activity sweeping across the brain’s surface, measured by electrodes placed on the scalp

fMRI

a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. show brain function as well as structure

lesion

tissue destruction; may occur naturally (disease, trauma), during surgery, or experimentally (using electrodes to destroy brain cells)