Unit 2: Biology

Neuron

A nerve cell that transmits electrical signals throughout the body, enabling communication within the nervous system.

Neural communication

The process by which neurons transmit signals to each other through electrical impulses and chemical synapses.

Cell body

The central part of a neuron that contains the nucleus and is responsible for maintaining the cell's functions.

Dendrite

Branch-like structures of a neuron that receive electrical signals from other neurons.

Axon

The long, thread-like part of a neuron that transmits electrical signals away from the cell body to other neurons or muscles.

Myelin sheath

A fatty layer that surrounds the axon of some neurons, speeding up the transmission of electrical impulses.

Glial cells

Supportive cells in the nervous system that assist with neuron function, provide structural support, and aid in maintenance and repair.

Action potential

A rapid, temporary change in the electrical charge across a neuron’s membrane that allows it to transmit an electrical signal.

Depolarization

The process during an action potential where the neuron's membrane potential becomes more positive, allowing the signal to travel.

Threshold

The minimum level of stimulation required to trigger an action potential in a neuron.

Refractory period

The brief period after an action potential during which a neuron is unable to fire another action potential, as it returns to its resting state.

All-or-none response

The principle that a neuron will either fire at full strength or not at all once the threshold is reached.

Synapse

The junction between two neurons, where communication occurs through neurotransmitters.

Neurotransmitter

Chemical messengers released by neurons to transmit signals across synapses to other neurons or target cells.

Reuptake

The process by which neurotransmitters are reabsorbed by the neuron that released them, terminating the signal.

Endorphins

Neurotransmitters that act as natural painkillers and mood enhancers, often released during activities like exercise.

Agonist

A substance that mimics or enhances the effect of a neurotransmitter at its receptor site.

Antagonist

A substance that blocks or inhibits the action of a neurotransmitter at its receptor site.

Nervous system

The complex network of cells and tissues that carries messages between the brain, spinal cord, and the rest of the body to control bodily functions and respond to stimuli.

Nerves

Bundles of fibers that transmit electrical signals between the central nervous system and other parts of the body.

Central nervous system (CNS)

The brain and spinal cord, which process and send out information to the body.

Peripheral nervous system (PNS)

The network of nerves outside the central nervous system that connects the body to the CNS.

Sensory (afferent) neurons

Nerve cells that carry sensory information from sensory receptors to the central nervous system.

Motor (efferent) neurons

Nerve cells that carry signals from the central nervous system to muscles and glands to initiate action.

Interneurons

Nerve cells that connect sensory and motor neurons within the central nervous system, facilitating communication between them.

Somatic nervous system

The part of the peripheral nervous system responsible for voluntary control of skeletal muscles.

Autonomic nervous system

The part of the peripheral nervous system that controls involuntary functions, such as heart rate, digestion, and respiratory rate.

Sympathetic nervous system

The division of the autonomic nervous system that prepares the body for fight-or-flight responses during stressful situations.

Parasympathetic nervous system

The division of the autonomic nervous system that promotes rest-and-digest activities and restores body to a calm state after stress.

Reflex

An automatic, rapid response to a stimulus that does not involve conscious thought, often involving the spinal cord.

Spinal cord

A long, tubular structure of nervous tissue that extends from the brainstem and serves as the main pathway for information between the brain and the body.

Endocrine system

A long, tubular structure of nervous tissue that extends from the brainstem and serves as the main pathway for information between the brain and the body.

Hormones

Chemical messengers produced by endocrine glands that travel through the bloodstream to regulate specific processes in the body.

Adrenal gland

Endocrine glands located on top of the kidneys that produce hormones like adrenaline and cortisol, important for stress response.

Pituitary gland

A small gland located at the base of the brain that controls other endocrine glands and regulates growth, metabolism, and reproduction.

Lesion

A damaged or abnormal area of tissue in the body, often used to describe damage to the brain or nervous system.

Electroencephalogram (EEG)

A test that measures the electrical activity of the brain by placing electrodes on the scalp to detect brainwave patterns.

Magnetoencephalography (MEG)

A technique that measures the magnetic fields produced by brain activity to study neural functioning in real-time.

CT (computer tomography) scan

A medical imaging technique that uses X-rays and computer processing to create detailed cross-sectional images of the body, including the brain.

PET (positron emission tomography) scan

A type of imaging that uses radioactive substances to visualize and measure brain activity, blood flow, and other processes in the body.

MRI (magnetic resonance imaging)

A non-invasive imaging technique that uses magnetic fields and radio waves to produce detailed images of organs and tissues, including the brain.

fMRI (functional MRI)

A type of MRI that measures brain activity by detecting changes in blood flow and oxygenation in response to neural activity.

Brain stem

The part of the brain that connects the brain to the spinal cord and controls vital functions like heart rate, breathing, and sleep cycles.

Medulla

The lower part of the brainstem that controls autonomic functions such as breathing, heart rate, and blood pressure.

Thalamus

A brain structure that acts as a relay station for sensory information, directing it to appropriate areas of the brain for processing.

Reticular formation

A network of neurons in the brainstem involved in regulating sleep, alertness, and arousal.

Cerebellum

A brain structure located at the back of the head that coordinates voluntary movements, balance, and motor control.

Limbic system

A group of structures in the brain involved in emotions, memory, and behavior regulation, including the amygdala and hippocampus.

Amygdala

An almond-shaped structure in the brain involved in processing emotions, particularly fear, and emotional memory.

Hypothalamus

A small brain region that regulates vital functions like temperature, hunger, thirst, and the release of hormones from the pituitary gland.

Hippocampus

A brain structure involved in forming and storing long-term memories and spatial navigation.

Cerebral cortex

The outermost layer of the brain, responsible for higher-level functions such as thinking, perception, and decision-making.

Frontal lobe

The region at the front of the brain involved in reasoning, planning, motor control, problem-solving, and aspects of personality.

Parietal lobe

The region of the brain located behind the frontal lobe, responsible for processing sensory information related to touch, spatial awareness, and coordination.

Occipital lobe

The region at the back of the brain primarily responsible for processing visual information.

Temporal lobe

The region of the brain located on the sides, involved in auditory processing, memory, and emotional responses.

Motor cortex

The area of the frontal lobe responsible for planning, controlling, and executing voluntary movements.

Somatosensory cortex

The area of the parietal lobe that processes sensory information from the body, such as touch, temperature, and pain.

Association areas

Regions of the cerebral cortex that are involved in higher mental functions, such as thinking, memory, language, and perception, and integrate sensory input.

Plasticity

The brain's ability to reorganize itself by forming new neural connections in response to learning, experience, or injury.

Neurogenesis

The process of generating new neurons (nerve cells) in the brain, particularly in areas like the hippocampus, which is involved in learning and memory.

Corpus callosum

A large bundle of nerve fibers that connects the two hemispheres of the brain and allows communication between them.

Split brain

A condition resulting from the surgical severing of the corpus callosum, often to treat epilepsy, leading to a lack of communication between the brain's two hemispheres.

Brain hemisphere

One of the two symmetrical halves of the brain (left and right), each responsible for different functions and processing information.

Consciousness

The state of being aware of and able to think about one's own existence, thoughts, and environment.

Cognitive neuroscience

The field of study that explores the relationship between cognitive processes (like memory, perception, and decision-making) and brain function.

Dual processing

The theory that the brain processes information on two levels: one conscious and deliberate (explicit) and the other unconscious and automatic (implicit).

Blindsight

A phenomenon where individuals who are clinically blind due to damage to the visual cortex can still respond to visual stimuli, despite not being consciously aware of them.

Parallel processing

The ability of the brain to process multiple pieces of information simultaneously, such as handling different aspects of a visual scene (color, movement, shape) at the same time.

Sequential processing

The process of handling one piece of information at a time, typically used in tasks that require focused attention, like problem-solving or language comprehension.

Behavior genetics

The study of how genetic and environmental factors influence behavior and traits.

Heredity

The passing of traits and genetic information from parents to offspring through genes.

Environment

The external factors, including physical, social, and cultural influences, that affect an individual's development and behavior.

Nature-nurture

The debate over the relative influence of genetics (nature) and environment (nurture) on human traits and behaviors.

Chromosome

A thread-like structure made of DNA and proteins that carries genetic information in the form of genes.

Deoxyribonucleic acid (DNA)

The molecule that contains the genetic instructions used in the growth, development, and functioning of all living organisms.

Gene

A segment of DNA that contains the instructions for making proteins, which determine the traits of an organism.

Genome

The complete set of genetic material in an organism, including all of its genes.

Identical (monozygotic) twins

Twins that develop from a single fertilized egg that splits into two, sharing 100% of their genetic material.

Fraternal (dizygotic) twins

Twins that develop from two separate eggs fertilized by two different sperm, sharing about 50% of their genetic material, like regular siblings.

Genetic relatives

People who are related through shared genetic material, such as biological parents and children or siblings.

Environmental relatives

People who are related through shared environments, such as adoptive family members.

Heritability

The proportion of variation in a trait among individuals in a population that is due to genetic differences.

Interaction

The way in which genetic and environmental factors work together to influence a person's traits or behavior.

Molecular genetics

The study of the structure and function of genes at the molecular level, including how they are inherited and how they influence traits.

Molecular behavioral genetics

A subfield of genetics that studies the relationship between genes and behavior by examining how genetic variations influence psychological traits and behaviors.

Epigenetics

The study of changes in gene expression that do not involve alterations to the underlying DNA sequence, often influenced by environmental factors and lifestyle.