Neurons and Neurotransmission

• The nervous system's basic building blocks are neurons and glial cells.

Neuron Structure

• Dendrites receive information from other neurons.
• The axon transmits electrical charge
• The cell body contains the nucleus and other organelles.
• The myelin sheath is a fatty substance that insulates axons and speeds up neural transmission.
• A synapse is a gap between two neurons where neurotransmitters are released.

Neural Transmission

• Action potential is the electrical charge that travels down the axon of a neuron.
• A neuron at rest has a charge of -70 mV inside the cell relative to the outside.
• The refractory period is when a neuron is unable to fire again immediately.
• Sodium (Na⁺) ions rush into the neuron during action potential, making it more positive.

Neurotransmitters

• Acetylcholine is associated with muscle control and memory.
• A deficiency in acetylcholine is linked to Alzheimer’s disease.
• Dopamine is primarily involved in motivation and pleasure.
• Low levels of dopamine are associated with Parkinson’s disease.
• Glutamate is the primary excitatory neurotransmitter in the brain.
• Too much glutamate can result in seizures.
• Serotonin plays a key role in mood regulation and is targeted by SSRIs.

Drugs and the Nervous System

• An agonist mimics or enhances a neurotransmitter’s effects.
• Cocaine primarily affects dopamine.
• Opioids act as agonists for endorphins.
• Naloxone (Narcan) is used to block opioid overdose effects.

Divisions of the Nervous System

• The Central Nervous System (CNS) consists of the brain and spinal cord.
• The Peripheral Nervous System (PNS) connects the CNS to the body's organs and muscles.
• The Somatic Nervous System controls voluntary muscle movements.
• The Autonomic Nervous System (ANS) is responsible for digestion and breathing.
• The Sympathetic Nervous System is activated in stressful situations.
• The Parasympathetic Nervous System helps the body return to a resting state.

Brain Structure: Hindbrain

• The hindbrain is responsible for basic life functions like breathing and heart rate.
• The medulla controls breathing and heart rate.
• The cerebellum is primarily responsible for fine motor coordination.

Brain Structure: Midbrain and Forebrain

• The midbrain is involved in reflexes and movement.
• The forebrain is responsible for complex cognitive functions.
• The thalamus functions as a sensory relay station.
• The hypothalamus regulates hunger, thirst, and body temperature.

Brain Structure: Limbic System

• The limbic system is primarily involved in emotion, motivation, and memory.
• The hippocampus is essential for storing and processing new memories.
• Damage to the hippocampus can result in amnesia and difficulty forming new memories.
• The amygdala is primarily responsible for processing emotions like fear and aggression.
• The basal ganglia play a key role in voluntary movement and habit formation.
• Malfunction of the basal ganglia is linked to Parkinson’s disease.
• The hypothalamus regulates body temperature, hunger, thirst, and sexual behavior.

Cerebral Cortex

• The cerebral cortex is responsible for higher cognitive functions such as thinking, planning, and decision-making.
• The corpus callosum connects the two hemispheres of the brain.
• The cerebral cortex is divided into four lobes.
• The occipital lobe is involved in processing visual information.
• The parietal lobe plays a crucial role in touch and spatial awareness.
• The somatosensory cortex is located in the parietal lobe and maps body sensations such as touch and pain.
• The motor cortex is responsible for controlling voluntary movements.
• The motor cortex is located in the frontal lobe.

Temporal Lobe

• The temporal lobe is primarily involved in hearing and language processing.
• The primary auditory cortex is found in the temporal lobe.
• The left hemisphere of the brain is generally dominant in language and speech processing.
• Broca’s area is responsible for speech production.
• Damage to Broca’s area results in difficulty forming words properly (expressive aphasia).
• Wernicke’s area is responsible for speech comprehension.
• Damage to Wernicke’s area results in an inability to comprehend language (receptive aphasia).

Frontal Lobe

• The frontal lobe is primarily involved in higher cognitive functions like decision-making and planning.
• The frontal lobe is involved in controlling voluntary movement and problem-solving.
• The prefrontal cortex is essential for decision-making and personality.
• Damage to the prefrontal cortex can result in personality changes and poor decision-making.
• The frontal lobe plays a major role in impulse control and reasoning.
• Executive functions, such as planning and organizing, are controlled by the prefrontal cortex.
• The motor cortex, located in the frontal lobe, is responsible for initiating voluntary movements.
• The frontal lobe is also involved in emotional regulation and social behavior.