Psych

Study Guide: Neurons, the Nervous System, and Related Topics

I. Neurons and the Nervous System

a. Neuron Diagram and Parts

• Dendrites: Branch-like structures that receive messages from other neurons.

• Axon: Long fiber that transmits signals from the neuron to other cells.

• Myelin Sheath: Fatty layer that insulates the axon, speeding up signal transmission.

• Synaptic Terminal: End of the neuron that sends signals to other neurons.

• Synaptic Gap: Space between the synaptic terminal and the next neuron where neurotransmitters are released.

• Terminal Buttons: Small knobs at the end of the axon that release neurotransmitters.

• Vesicles: Small sacs in the terminal buttons that store neurotransmitters.

• Neurotransmitters: Chemical messengers that transmit signals across the synaptic gap.

b. Multiple Sclerosis

• Cause: The immune system attacks the myelin sheath, leading to damaged nerves.

• Symptoms: Fatigue, muscle weakness, vision problems, coordination issues, and more.

c. Nervous System Diagram

• Central Nervous System (CNS): Composed of the brain and spinal cord, it controls most bodily functions.

• Peripheral Nervous System (PNS): Connects the CNS to limbs and organs.

  • Somatic Nervous System: Controls voluntary muscle movements.

  • Autonomic Nervous System: Regulates involuntary functions like heartbeat and digestion.

    • Sympathetic Nervous System: Activates the "fight or flight" response during stressful situations.

    • Parasympathetic Nervous System: Promotes the "rest and digest" response, calming the body.

II. Neural Signaling

a. Electrochemical Communication

• Explanation: Neurons communicate through electrical signals (action potentials) and chemical signals (neurotransmitters).

b. Excitatory vs. Inhibitory Neurotransmitters

• Excitatory: Increase the likelihood of the receiving neuron firing an action potential (e.g., Glutamate).

• Inhibitory: Decrease the likelihood of an action potential (e.g., GABA).

c. Neurotransmitters and Functions

• GABA: Inhibitory, reduces neural activity (calming effect).

• Glutamate: Excitatory, involved in learning and memory.

• Dopamine: Influences movement, emotion, and reward pathways.

• Serotonin: Regulates mood, appetite, and sleep.

• Norepinephrine: Controls alertness and arousal.

• Acetylcholine: Important for muscle function and memory.

• Endorphins: Relieve pain and induce euphoria.

• Substance P: Transmits pain signals.

d. Locations of Neurotransmitters

• GABA, Glutamate, Dopamine, Serotonin, etc.: Found in various brain regions such as the hippocampus, amygdala, and cerebellum.

e. Diseases Associated with Neurotransmitters

• GABA: Anxiety disorders.

• Glutamate: Schizophrenia.

• Dopamine: Parkinson's disease, addiction.

• Serotonin: Depression.

• Norepinephrine: Mood disorders.

• Acetylcholine: Alzheimer's disease.

• Endorphins: Linked to pain disorders.

• Substance P: Chronic pain.

f. Epilepsy

• Explanation: A neurological disorder causing recurrent seizures due to abnormal electrical activity in the brain.

g. Myasthenia Gravis Symptoms

• Symptoms: Muscle weakness, difficulty breathing, and problems with eye movement.

h. Alzheimer’s Disease

• Neurotransmitter: Acetylcholine.

• Brain Part: Hippocampus.

III. Endocrine System

a. Role of the Endocrine System

• Function: Releases hormones that regulate metabolism, growth, and mood.

b. Hormones and Functions

• Oxytocin: Promotes social bonding and maternal behaviors.

• Ghrelin: Stimulates hunger.

• Leptin: Inhibits hunger, regulating energy balance.

• Melatonin: Regulates sleep-wake cycles.

• Adrenaline: Increases heart rate and energy during stress.

IV. Action Potential

a. Action Potential

• Definition: A brief electrical charge that travels down the axon.

• Process: Sodium ions rush into the cell, causing depolarization, followed by potassium ions exiting, repolarizing the neuron.

b. Threshold of Excitation

• Definition: The level of depolarization needed to trigger an action potential.

c. Resting Potential

• Definition: The negative charge inside the neuron when it is not transmitting signals.

d. Depolarization

• Definition: The process where the neuron's membrane potential becomes more positive, leading to an action potential.

e. All-or-None Law

• Definition: A neuron either fires completely or not at all.

f. Refractory Period

• Definition: A period immediately following an action potential when the neuron is unable to fire again.