Unit 3: Human Genetics, Cells of the Nervous System, Parts of the Nervous System, The Brain and Spinal Cord, The Endocrine System

Flashcards for review of key vocabulary and concepts.

All-or-None Law

An action potential either fires completely or not at all, without partial firing. Similar to a gun trigger or a toilet flush

Left Hemisphere Functions

Handles logic, language, and math, especially in right-handed individuals.

Right Hemisphere Functions

Deals with spatial skills, facial recognition, and aesthetic perception.

Inhibitory Messages

Reduce the likelihood that a neuron will fire by hyperpolarizing the membrane.

Thalamus

Relay station for sensory information (except smell), directing it to appropriate brain areas.

Myelin Sheath

Fatty layer that insulates axons, speeding up the transmission of electrical impulses.

Neuroplasticity

Brain's ability to adapt by forming new neurons, connections, or reorganizing areas for different functions across the lifespan.

Central and Peripheral Nervous System (CNS)

Includes the brain and spinal cord. The peripheral nervous system (PNS) connects the CNS to the rest of the body.

Peripheral Nervous System (PNS)

Connects the CNS to the rest of the body.

Parasympathetic Nervous System

Calms the body after stress, restoring rest and digestion functions.

Somatic Nervous System

Controls voluntary movements and transmits sensory info to the CNS, like moving muscles or feeling touch.

Hypothalamus

Regulates vital behaviors such as eating, drinking, body temperature, and sexual activity; maintains homeostasis.

Split-Brain Patients

Individuals with a severed corpus callosum show differences in how each brain hemisphere processes information.

Lateralization

Certain brain functions are more dominant in one hemisphere than the other (e.g., language is usually left-lateralized).

Nervous & Endocrine System Relationship

They influence each other; the hypothalamus links them, coordinating hormonal and neural responses.

Hippocampus

Essential for forming new long-term memories; damage here causes anterograde amnesia.

Action Potential Polarity Shift

During action potential, the neuron's interior becomes positive, switching from resting negative charge.

Somatic Nervous System - Conscious Control

Handles activities like moving your arm or reacting to touch—actions you're aware of.

Fight-or-flight & PNS

Reactions to danger involve motor responses (somatic system) and arousal (autonomic system-specifically sympathetic).

Cerebral Cortex Functions

Involved in reasoning, memory, and emotion; breathing is controlled by the brainstem, not the cortex.

EEG (Electroencephalography)

Brain imaging technique records electrical activity via scalp electrodes, useful in diagnosing epilepsy and some learning disorders; monitors real-time function

PET scan

Shows brain activity with radioactive tracers.

CT scan

X-ray image of brain structure.

fMRI

Tracks brain activity via blood flow.

Sickle-cell anemia

Red blood cells become crescent-shaped, block blood flow, cause pain and damage.

Darwin’s theory of natural selection

Best-suited organisms survive and reproduce; poorly suited ones die off.

Evolutionary psychology

Studies universal behavior patterns that evolved over time.

Behavioral genetics

Studies how genes and environment cause individual differences today.

Chromosomes

Long DNA strands that carry genetic information.

DNA

Helix-shaped molecule made of base pairs.

Genotype

A person’s genetic makeup.

Phenotype

Observable traits from genes and environment.

Genetic “parent” definition

Individual who provides sperm or egg (gamete cell).

Homozygous

Two same alleles for a gene.

Heterozygous

Two different alleles for a gene.

Recessive allele

Only expressed if both alleles are recessive.

Dominant allele

Expressed even with one copy

Polygenic traits

Traits controlled by multiple genes (e.g., height, skin color, weight).

Mutation

Sudden, permanent change in a gene.

Range of reaction

Genes set limits; environment decides where you fall within them.

Gene-environment correlation

Genes influence your environment, and environment affects gene expression.

Genes and behavior

Linked to traits like personality, depression, schizophrenia.

Glial cells

Support neurons; help with communication, insulation, nutrients, and waste.

Neurons

Process and send information in the nervous system.

Neuron membrane

Semipermeable; controls what goes in and out.

Soma (cell body)

Contains the nucleus of the neuron.

Dendrites

Receive signals from other neurons.

Axon

Sends signals away from the soma.

Terminal buttons

End of axon; release neurotransmitters.

Myelin sheath

Insulates axon, speeds up signal transmission.

Nodes of Ranvier

Gaps in myelin sheath; help signals travel faster.

What happens if myelin is damaged?

Slows or blocks neuron signals; causes problems like fatigue, loss of control.

Synaptic cleft

Small gap between neurons where communication occurs.

Neurotransmitters

Chemicals that carry signals across the synaptic cleft.

Receptors

Protein sites on neurons that bind neurotransmitters (like a key in a lock).

Membrane potential

Electrical charge difference across the membrane that powers the neuron.

Resting potential

Neuron’s “ready” state; ions are waiting to move.

Sodium (Na⁺) in resting state

More concentrated outside the neuron.

Potassium (K⁺) in resting state

More concentrated inside the neuron.

Sodium-potassium pump

Moves 3 Na⁺ out, 2 K⁺ in; keeps cell negatively charged inside.

How does a neuron fire?

Signal opens gates → Na⁺ rushes in → charge rises → neuron fires if it reaches threshold.

Action potential (all-or-none)

Either strong enough to fire or it doesn’t happen at all. No in-between.

Reuptake

Neurotransmitter is pumped back into the neuron to clear the synapse.

Neuronal communication

Electrochemical — electrical inside the neuron, chemical across the synapse.

Biological perspective on disorders

Depression/schizophrenia linked to neurotransmitter imbalances.

Psychotropic medications

Drugs that treat psychiatric symptoms by balancing neurotransmitters.

Agonist

Mimics neurotransmitter at receptor.

Antagonist

Blocks neurotransmitter activity at receptor.

Antipsychotics for schizophrenia

Antagonists for dopamine — block it without activating receptors.

SSRIs

Block serotonin reuptake → more serotonin stays in synapse.

Nervous system divisions

CNS = brain + spinal cord

PNS = connects CNS to body.

Peripheral nervous system (PNS)

Nerves sending signals between CNS and body.

PNS subdivisions

Somatic and autonomic nervous systems.

Somatic nervous system

Voluntary movement; uses motor and sensory neurons.

Efferent vs. Afferent

Efferent = exit CNS; Afferent = arrive at CNS.

Autonomic nervous system

Controls organs and glands automatically.

Sympathetic nervous system

Prepares body for stress (“fight or flight”).

Parasympathetic nervous system

Calms body down; routine body functions.

Fight or flight response

Boosts energy and senses to escape or fight danger.

Brain structure

Complex, 2-sided, divided into lobes.

Spinal cord

Connects brain to body; handles some reflexes.

Brain stem (top of spinal cord)

Controls basics like breathing and digestion.

Spinal segments

30 total; each connects to a specific body part

Reflexes

Some actions come from spinal cord, not brain.

Spinal cord protection

Bony vertebrae and fluid, but still vulnerable.

Neuroplasticity

Brain can change and adapt with experience or injury.

Cerebral cortex

Brain’s surface; has folds (gyri) and grooves (sulci).

Brain hemispheres

Left controls right body side, right controls left.

Left hemisphere

Language, memory, positive emotion.

Right hemisphere

Arousal, negative emotion, pitch.

Corpus callosum

Connects hemispheres; helps them share info.

Forebrain

Largest brain part; includes cortex, thalamus, limbic system.

Frontal lobe

Reasoning, motor control, language; has motor cortex and Broca’s area.

Parietal lobe

Processes touch, temperature, pain; includes somatosensory cortex.

Temporal lobe

Hearing, memory, language; has auditory cortex and Wernicke’s area.

Occipital lobe

Back of brain; processes visual info.

Thalamus

Sensory relay station (except smell).

Limbic system

Emotion and memory (includes amygdala, hippocampus, hypothalamus).

Amygdala

Emotional meaning in memories.

Hippocampus

Learning and memory.