Unit 2: Biological Basis of Behavior

Comprehensive vocabulary flashcards covering the biological bases of behavior, including neuroanatomy, neural firing, neurotransmitters, the endocrine system, brain imaging methods, brain structures, and genetic conditions.

Neuroanatomy

The study of the parts and functions of neurons (individual nerve cells) that make up the entire nervous system.

Neuron

An individual nerve cell that serves as the basic communication link in the nervous system, composed of discrete parts including dendrites, a cell body, an axon, and terminal buttons.

Glial Cells

Cells in the nervous system that provide support for neurons by supplying nourishment, removing waste products, and providing insulation around many axons.

Dendrites

Rootlike parts of a neuron that branch out from the cell body to receive messages and make synaptic connections with other neurons.

Cell Body (Soma)

The life-support center of a neuron that contains the nucleus and other structures needed to sustain cell life.

Axon

A wirelike structure extending from the cell body that ends in terminal buttons and transmits electrical signals away from the cell body toward other cells.

Myelin Sheath

A fatty covering surrounding the axon of some neurons that insulates the axon and speeds up neural impulses.

Terminal Buttons

The branched ends of an axon (also called end buttons, terminal branches, or synaptic knobs) that contain vesicles of neurotransmitters.

Synapse

The microscopic space between the terminal buttons of one neuron and the dendrites of the adjacent neuron.

Afferent (Sensory) Neurons

Neurons that carry incoming sensory information from the sensory receptors to the brain and spinal cord.

Interneurons

Neurons located in the brain and spinal cord that take messages from afferent neurons and send them elsewhere in the brain or transmit them to efferent neurons.

Efferent (Motor) Neurons

Neurons that transmit outgoing instructions and motor information from the brain to the rest of the body, including muscles and glands.

Action Potential

A brief change in electrical charge that travels rapidly down the length of an axon at approximately $120\,\text{m/s}$ to trigger neurotransmitter release.

All-or-None Principle

The principle stating that a neuron either fires completely or does not fire at all; if incoming signals push it past its threshold, the impulse is delivered with the same strength every time.

Threshold

The minimum level of neurotransmitter stimulation required to make a neuron's cell membrane permeable to positive ions and trigger an action potential.

Neurotransmitters

Chemical messengers stored inside vesicles within terminal buttons that cross the synaptic gap and bind to receptor sites on postsynaptic dendrites like a key in a lock.

Agonist

A chemical that mimics the action of a neurotransmitter, causing postsynaptic potentials (PSPs).

Antagonist

A chemical that opposes or inhibits the action of a neurotransmitter by blocking postsynaptic potentials (PSPs).

Monoamines

A group of three neurotransmitters consisting of dopamine, norepinephrine, and serotonin.

Dopamine

A monoamine neurotransmitter involved in alertness and voluntary motor movement; degeneration of dopamine neurons is linked to Parkinson's disease, while overactivation is linked to schizophrenia.

Norepinephrine

An excitatory chemical (noradrenaline) that affects arousal and memory, and raises blood pressure by constricting blood vessels.

Serotonin

Known as the 'mood molecule'; a neurotransmitter that regulates sleep, dreaming, mood, hunger, pain, and aggressive behavior.

Acetylcholine (ACh)

A neurotransmitter that plays a key role in muscle movement, functioning as the primary transmitter between motor neurons and voluntary muscles.

Endorphins

Internally produced chemicals structurally similar to opiates that bind to specialized receptors to modulate pain and contribute to feelings of pleasure.

GABA

A primary neurotransmitter that produces inhibitory effects at all synapses, playing a significant role in anxiety, seizures, and sleep regulation.

Central Nervous System (CNS)

The primary division of the nervous system composed entirely of the brain and the spinal cord.

Peripheral Nervous System (PNS)

All nerves lying outside the brain and spinal cord, subdivided into the somatic nervous system and the autonomic nervous system.

Somatic Nervous System

The subdivision of the peripheral nervous system that connects to muscles and sensory receptors to control voluntary body movements.

Autonomic Nervous System

The subdivision of the peripheral nervous system that connects to blood vessels, smooth muscles, and glands to regulate involuntary biological processes.

Sympathetic Nervous System

The branch of the autonomic nervous system that mobilizes the body's resources in response to stress, initiating the fight-or-flight response.

Parasympathetic Nervous System

The branch of the autonomic nervous system responsible for calming the body and restoring normal resting state after a stress response.

Endocrine System

A system of glands controlled by the hypothalamus that secretes hormones into the bloodstream to regulate basic bodily processes.

Pituitary Gland

The master gland of the endocrine system that produces growth hormone and regulates the activation of other endocrine glands.

Thyroid Gland

An endocrine gland that produces hormones regulating metabolism, which is the speed at which the body operates and consumes energy.

Adrenal Glands

Endocrine glands that produce adrenaline, signaling the rest of the body to prepare for emergency fight-or-flight activity.

Electroencephalogram (EEG)

A neuroimaging method that detects broad patterns of brain waves and measures overall electrical activity during various states of consciousness.

Computerized Axial Tomography (CAT / CT)

A neuroimaging method that uses multiple rotating X-ray cameras to construct a detailed three-dimensional picture of the brain's physical structure.

Magnetic Resonance Imaging (MRI)

A structural brain imaging method that uses magnetic fields to evaluate the density and location of brain tissue, generating high-resolution images.

Positron Emission Tomography (PET)

A functional neuroimaging scan that measures the brain's rate of chemical consumption to identify which regions are most active during specific tasks.

Functional MRI (fMRI)

A technique combining elements of MRI and PET scans that tracks blood flow and brain activity alongside detailed structural imaging during cognitive tasks.

Lesioning

The experimental or surgical destruction of a specific area of the brain used to study resulting changes in behavior and function.

Cerebral Cortex

A thin ($1\,\text{mm}$), highly wrinkled outer layer of densely packed neurons covering the cerebrum, responsible for complex cognitive processes.

Frontal Lobes

Cerebral lobes positioned at the top front of the brain behind the eyes, containing the motor cortex and associated with planning, personality, and speech production.

Prefrontal Cortex

The anterior region of the frontal lobe that serves as the brain's central executive, directing abstract thought, pursuing goals, and exercising emotional control.

Motor Cortex

A thin vertical strip of tissue located at the back of the frontal lobe that sends motor commands to muscles to direct voluntary movements.

Parietal Lobes

Cerebral lobes situated behind the frontal lobe that house the sensory cortex and process incoming tactile and bodily sensations.

Sensory Cortex (Somatosensory Strip)

A vertical strip of tissue located behind the motor cortex in the parietal lobe that receives and registers touch sensations from across the body.

Temporal Lobes

Cerebral lobes located along the sides of the brain that house the auditory cortex to interpret sound and assist with speech understanding.

Occipital Lobes

Cerebral lobes situated at the very back of the brain containing the visual cortex, responsible for processing visual input received from the eyes.

Broca's Area

A specialized region situated in the left frontal lobe that controls the muscles required for physical speech production.

Wernicke's Area

A specialized region situated in the left temporal lobe responsible for interpreting and comprehending spoken and written language.

Neuroplasticity

The ability of the brain's neural pathways and synapses to adapt and reorganize throughout life in response to behavioral changes, environment, or physical injury.

Contralateral Control

The cross-wired arrangement of the human nervous system wherein the right cerebral hemisphere controls the left half of the body and vice versa.

Corpus Callosum

The large band of neural fibers connecting the left and right cerebral hemispheres, facilitating direct communication between them.

Split-Brain Patients

Individuals whose corpus callosum has been surgically severed to treat severe epilepsy, preventing interhemispheric transfer of information.

Hindbrain

The evolutionary life-support structure positioned atop the spinal cord that maintains essential biological functions; contains the medulla, pons, and cerebellum.

Medulla

A hindbrain structure located immediately above the spinal cord that regulates vital autonomic functions, including blood pressure, heart rate, and respiration.

Pons

A hindbrain structure positioned above the medulla that connects the hindbrain with the midbrain and forebrain, and aids in controlling facial expressions.

Cerebellum

A hindbrain structure located at the lower rear of the brain responsible for coordinating balance, posture, and habitual motor movements.

Midbrain

A brain region situated between the hindbrain and forebrain that coordinates simple sensory-motor movements and houses the reticular formation.

Reticular Formation

A netlike cluster of nerve cells located in the midbrain that regulates arousal, general body alertness, and attentional focus.

Forebrain

The highest division of the brain regulating thought and reason, containing the limbic system (thalamus, hypothalamus, amygdala, and hippocampus).

Limbic System

A collection of forebrain structures consisting of the thalamus, hypothalamus, amygdala, and hippocampus that regulates emotion, motivation, and memory.

Thalamus

The forebrain's sensory relay station situated atop the brainstem, routing sensory information from the spinal cord to appropriate cortex destinations.

Hypothalamus

A forebrain structure that manages metabolic homeostasis, regulating hunger, thirst, body temperature, sexual libido, and the endocrine system.

Amygdala

A limbic system structure located at the ends of the hippocampal arms that is vital to the processing and experience of basic emotions.

Hippocampus

A limbic system structure vital to the memory system, processing new memories before transferring them to the cerebral cortex for long-term storage.

Turner's Syndrome

A genetic condition characterized by having only a single X chromosome on the 23rd pair, causing short stature, webbed necks, and altered sexual maturation.

Klinefelter's Syndrome

A genetic disorder marked by an extra X chromosome ($\text{XXY}$), which leads to minimal sexual development and distinct personality traits.

Down Syndrome

A genetic disorder resulting from a third chromosome on the 21st pair, producing characteristic physical facial traits and degrees of intellectual disability.