The Nervous System

Plasticity

• The brain's special capacity for change.

Nervous System

• The body’s electrochemical communication circuitry.
• It is made up of billions of connecting cells.

Central Nervous System

• Consists of the brain and spinal cord.
• It contains more than 99% of the body's nerve cells.

Peripheral Nervous System

• A network of nerves connects the brain and spinal cord to other body parts.
• It brings information to and from the brain and spinal cord.
• It carries out commands from the central nervous system.

Somatic Nervous System

• Contains sensory nerves.
• It conveys information from skin and muscles to the central nervous system about pain and temperature.

Autonomic Nervous System

• A body system that takes messages to and from the body’s internal organs.
• Monitors breathing, heart rate, and digestion.

Sympathetic Division

• Arouses the body to mobilize it for action and is involved with experiencing stress.

Parasympathetic Division

• Calms the body.

Stress

• An individual's responses to environmental stressors.

Stressors

• Circumstances and events that threaten individuals and tax their coping skills.
• These cause physiological changes to ready the body to handle the assault of stress.

Neurons

• Nerve cells that handle the information processing function.
• They send signals through chemicals; the brain contains 100 billion neurons.

Dendrites

• Fibers project from a neuron.
• They receive information from other neurons and orient it toward the cell body.

Cell Body

• Contains the nucleus.
• It directs the manufacture of substances a neuron needs for growth and maintenance.

Axon

• Carries information away from the cell body towards other cells.

Myelin Sheath

• A layer of fat cells that encases and insulates most axons.

Resting Potential

• The stable, negative charge of an inactive neuron.

Action Potential

• The brief wave of positive electrical charge that sweeps down the axon.

All-or-Nothing Principle

• Once an electrical impulse reaches a certain level of intensity, it fires and moves all the way down the axon without losing any intensity.

Synapse

• Tiny spaces between neurons, also called synaptic gaps.

Neurotransmitters

• Chemical substances stored in tiny sacs within the neuron's terminal buttons.
• Involved in transmitting information across a synaptic gap to the next neuron.

Acetylcholine

• Stimulates neuron firing and is involved in muscle action, learning, and memory.
• A deficiency is related to Alzheimer’s disease.

GABA

• Helps keep many neurons from firing and controls the precision of signals from neuron to neuron.
• Low levels are associated with anxiety.

Glutamate

• Excites many neurons to fire and is especially involved in learning and memory.
• Too much can overstimulate the brain and trigger migraines or seizures.

Norepinephrine

• Excites the heart, intestines, and urogenital tract.
• Stimulated by stress, and makes you very alert.
• Low levels are associated with depression, while too much is associated with a manic state.

Dopamine

• Helps control voluntary movement.
• Outgoing behavior is associated with more dopamine.
• Low levels are associated with Parkinson’s, and problems regulating it are associated with schizophrenia.

Serotonin

• Involved in the regulation of sleep, mood, attention, and learning.
• Key in maintaining neuroplasticity, which allows the brain to change.
• Low levels are associated with depression.

Endorphins

• Reduce feelings of pain and elevate pleasure.

Oxytocin

• Related to love and social bonding, and common in parents meeting their new baby.

Agonist

• A drug that mimics or increases a neurotransmitter's effect.

Antagonist

• A drug that blocks a neurotransmitter's effects.

Hindbrain

• Located at the back and lowest part of the brain.

Medulla

• Begins where the spinal cord enters the skull.
• Involved in breathing, heart rate, and the regulation of reflexes.

Cerebellum

• Two rounded structures important for coordination.

Brain Stem

• Located deep in the brain and connects to the spinal cord.
• Cells inside it determine alertness and regulate basic survival functions such as breathing, heartbeat, and blood pressure.

Midbrain

• Contains Reticular Formation.

Reticular Formation

• A diffuse collection of neurons involved in stereotyped patterns of behavior of walking, sleeping, and turning towards a noise.

Forebrain

• Contains the Limbic system, Amygdala, Hippocampus, Thalamus, Basal Ganglia, Hypothalamus and Cerebral Cortex.

Limbic System

• A network of structures central to emotion, memory, and reward processing.

Amygdala

• Involved in identifying objects necessary for survival, such as food, mates, and social rivals.
• Associated with fear and rage.

Hippocampus

• Plays a special role in the storage of memories.

Thalamus

• Sorts information and sends it to appropriate places for further integration and interpretation.

Basal Ganglia

• Controls and coordinates voluntary movements and habitual behaviors.

Hypothalamus

• Monitors pleasure related to eating, drinking, sexual behavior, emotion, stress, and reward.
• Responds by influencing the secretion of hormones and regulates the body’s internal states.

Cerebral Cortex

• The outer layer of the brain responsible for the most complex mental functions such as thinking and planning.

Frontal Lobes

• (Including prefrontal cortex) involved in higher cognitive functions like planning, reasoning, and self-control.
• Acts like a control system, monitoring and organizing thinking.
• Personality, intelligence, and control of voluntary muscles.

Parietal Lobes

• Involved in spatial location, attention, and motor control.

Temporal Lobes

• Involved in hearing, language processing, and memory, and has connections to the limbic system.

Occipital Lobes

• Structures located at the back of the head that respond to visual stimuli.
• Interprets what you see

Somatosensory Cortex

• Processes information about body sensations.

Motor Cortex

• Processes information about voluntary movement.

Corpus Callosum

• Connects the brain’s two hemispheres and relays information between the two sides.

Stem Cells

• Unspecialized cells that can develop into specialized cells in the body.

Brenda Milner

• Earned degrees in psychology and was interested in the brain.
• Proved there are different memory systems.
• Considered the founder of clinical neuropsychology.

Explore the central and peripheral nervous systems, including the somatic and autonomic systems. Understand how the sympathetic and parasympathetic divisions work. These systems are part of the body's electrochemical communication circuitry.