AP Psychology Topic 1.3 - The Neuron and Neural Firing

EQ: How do the structures and functions of typical neurons in the central nervous system affect behavior and mental processes?

I. Neuroanatomy: The Structure and Functions of Nerve Cells - Neurons, the fundamental building blocks of the nervous system, have specialized structures such as dendrites, axons, and synapses that enable them to communicate effectively, influencing both behavioral responses and cognitive functions.

Neurons and Glial Cells - Neurons are the fundamental building blocks of the nervous system, responsible for transmitting information throughout the body, while glial cells provide support, protection, and nourishment to neurons, playing a crucial role in maintaining homeostasis and facilitating communication.
The Reflex Arc - The reflex arc is a neural pathway that controls a reflex action, consisting of a sensory neuron that transmits signals from sensory receptors to the spinal cord, an interneuron that processes the information, and a motor neuron that carries commands to muscles, allowing for quick responses to stimuli without direct involvement of the brain.
Neural Structure - Neural structure refers to the organization and intricacies of neurons, including their components such as the cell body, dendrites, and axon, which play key roles in the transmission of electrical impulses and communication with other neurons.

II. Neural Transmission

The Process of Neural Transmission - Neural transmission involves the generation and propagation of electrical impulses, known as action potentials, along the axon, followed by the release of neurotransmitters from the axon terminals into the synaptic cleft, where they bind to receptors on the postsynaptic neuron, facilitating communication between neurons.
Functions of Neurotransmitters - Neurotransmitters serve several critical functions, including relaying signals between neurons, modulating mood and behavior, influencing bodily functions such as heart rate and digestion, and regulating various physiological processes by activating corresponding receptors in target cells.
The Endocrine System and Behavior - The endocrine system plays a pivotal role in regulating behavior by releasing hormones into the bloodstream, which can influence emotions, stress responses, and overall mood, as well as interact with neurotransmitters to modulate the effects of neural transmission.

III. Effect of Psychoactive Drugs on Behavior and Mental Processes

Psychological and Physiological Effects of Psychoactive Drugs on Neurotransmitters - Psychoactive drugs can alter the normal functioning of neurotransmitters by mimicking their structure, blocking their receptors, or increasing their release, leading to significant changes in mood, perception, and overall cognitive functioning.
Drug Categories - Psychoactive drugs can be categorized based on their effects on the central nervous system, which include:
- Stimulants: These drugs increase neural activity and elevate mood, energy, and alertness (e.g., caffeine, nicotine, amphetamines).
- Depressants: These substances reduce neural activity and lower anxiety, leading to feelings of relaxation (e.g., alcohol, benzodiazepines).
- Hallucinogens: These drugs distort perception and can lead to altered sensory experiences (e.g., LSD, psilocybin).
- Opioids: These substances provide pain relief and can induce feelings of euphoria (e.g., morphine, heroin).
Psychoactive Drugs and Dependence or Addiction - Psychoactive drugs can lead to dependence or addiction through their effects on neurotransmitter systems, resulting in tolerance, withdrawal symptoms, and compulsive use despite negative consequences.

IV. Key Terms

Central Nervous System - The part of the nervous system that includes the brain and spinal cord, controlling most functions of the body and mind.
Glial cell - Supportive cells in the nervous system that help maintain and protect neurons.
Interneuron - A type of neuron found in the brain and spinal cord that connects sensory and motor neurons and processes information.
Motor neuron - Neurons that carry signals from the brain and spinal cord to muscles to create movement.
Myelin - A fatty substance that surrounds and insulates axons, helping speed up the transmission of electrical signals.
Neuron - The basic unit of the nervous system that transmits information throughout the body.
Neurotransmitter - Chemicals that transmit signals across a synapse from one neuron to another.
Peripheral Nervous System - The part of the nervous system that includes all the nerves outside the central nervous system, connecting it to the rest of the body.
Reflex arc - The simple neural pathway that controls reflex actions, allowing quick responses to stimuli without brain involvement.
Sensory neuron - Neurons that carry signals from sensory receptors (like touch or pain) to the central nervous system.
Synapse - The junction where one neuron communicates with another, usually via neurotransmitters.
Acetylcholine (ACh) - A neurotransmitter involved in muscle movement and memory.
Action potential - A rapid change in electrical charge that travels along the axon of a neuron, allowing it to transmit a signal.
Adrenaline - A hormone released during stress or excitement that increases heart rate and energy.
All-or-nothing principle - The concept that a neuron either fires completely or not at all; there’s no in-between.
Depolarization - The process of changing the electrical charge of a neuron to cause it to fire an action potential.
Dopamine - A neurotransmitter associated with pleasure, reward, and motivation.
Endorphin - A group of neurotransmitters that act as natural pain relievers and mood enhancers.
Excitatory neurotransmitter - A type of neurotransmitter that increases the likelihood of a neuron firing.
Fight-flight-or-freeze response - The body's automatic response to perceived danger, preparing for action.
GABA (gamma aminobutyric acid) - An inhibitory neurotransmitter that helps to calm brain activity.
Ghrelin - A hormone that stimulates appetite and plays a role in hunger regulation.
Glutamate - The main excitatory neurotransmitter in the brain involved in learning and memory.
Hormone - Chemical messengers in the body that regulate various physiological processes.
Hypothalamus - A part of the brain that links the nervous system to the endocrine system, regulating many bodily functions including temperature and hunger.
Inhibitory neurotransmitter - A neurotransmitter that decreases the likelihood of a neuron firing.
Leptin - A hormone that helps regulate body weight by signaling fullness.
Long-term potentiation (LTP) - A long-lasting enhancement in signal transmission between two neurons that results from repeated stimulation, important for learning and memory.
Melatonin - A hormone that regulates sleep-wake cycles.
Multiple sclerosis (MS) - A disease in which the immune system attacks the protective covering of nerves (myelin), affecting communication between the brain and the body.
Myasthenia gravis (MG) - A chronic autoimmune disorder that affects the connection between nerves and muscles, leading to muscle weakness.
Norepinephrine - A neurotransmitter involved in arousal and alertness; it’s also a hormone that helps regulate blood pressure.
Oxytocin - A hormone that plays a role in social bonding, reproduction, and childbirth.
Pituitary gland - The master gland of the endocrine system that regulates various hormones and bodily functions.
Refractory period - The short time after a neuron has fired when it cannot fire again.
Resting potential - The state of a neuron when it is not transmitting signals, with a negative electrical charge inside the cell.
Reuptake - The process by which neurotransmitters are reabsorbed by the neuron that released them.
Threshold - The level of stimulation required to trigger an action potential in a neuron.
Serotonin - A neurotransmitter that helps regulate mood, sleep, and appetite.
Substance P - A neurotransmitter involved in the transmission of pain signals.