Chapter 2 - The Nervous System Notes PDF

Chapter 2 - The Nervous System Notes Learning Objectives ​ Understand the structure and function of neurons and glial cells. ​ Learn about different types of neurons and their roles. ​ Explore the divisions of the nervous system. ​ Understand brain structures and their functions....

Chapter 2 - The Nervous System Notes Learning Objectives ​ Understand the structure and function of neurons and glial cells. ​ Learn about different types of neurons and their roles. ​ Explore the divisions of the nervous system. ​ Understand brain structures and their functions. ​ Learn about genetics and its impact on neuroscience. Cells of the Nervous System Neurons ​ Fundamental units of the nervous system (~90-100 billion in the human brain). ​ Generate action potentials and release neurotransmitters to communicate. ​ Process motor, sensory, and cognitive information. Structure of a Neuron ​ Dendrites: Receive signals from other neurons. ​ Soma (Cell Body): Contains the nucleus and cellular components. ​ Axon: Transmits signals away from the soma. ​ Axon Terminals: Release neurotransmitters into the synapse. Functional Types of Neurons ​ Sensory Neurons (Afferent): Carry sensory information to the CNS. ​ Interneurons: Connect neurons within the same neural region. ​ Motor Neurons (Efferent): Carry signals away from the CNS to muscles/glands. Glial Cells ​ Oligodendrocytes: Form myelin in the CNS. ​ Astrocytes: ○​ Form the blood-brain barrier. ○​ Respond to neuronal injury (gliosis). ○​ Provide nutrients for neurotransmitter synthesis.  ○​ Maintain ion balance. ​ Microglia: Act as immune cells, removing waste. ​ Ependymal Cells: Produce cerebrospinal fluid (CSF). The Nervous System: Terminology & Divisions ​ Neuraxis: The central axis of the nervous system. ​ Directional Terms: ○​ Anterior - Posterior (Front - Back) ○​ Dorsal - Ventral (Top - Bottom) ○​ Medial - Lateral (Middle - Side) ○​ Superior - Inferior (Above - Below) Peripheral Nervous System (PNS) ​ Somatic Nervous System: Controls voluntary muscle movements. ​ Autonomic Nervous System (ANS): Controls involuntary functions. ○​ Sympathetic Nervous System: "Fight or flight" (releases norepinephrine). ○​ Parasympathetic Nervous System: "Rest and digest" (releases acetylcholine). ○​ Enteric Nervous System: Regulates digestion. Central Nervous System (CNS) ​ Hindbrain: ○​ Medulla: Regulates breathing, heart rate, reflexes. ○​ Pons: Connects brain regions, affects arousal/sleep. ○​ Cerebellum: Controls balance, coordination, and motor timing. ​ Midbrain: ○​ Superior Colliculus: Controls visual tracking. ○​ Inferior Colliculus: Processes auditory information. ○​ Substantia Nigra: Dopamine production, movement regulation (Parkinson’s disease). ○​ Ventral Tegmental Area (VTA): Important for reward processing. ○​ Periaqueductal Gray (PAG): Regulates pain, rich in endorphins. ​ Forebrain: ○​ Thalamus: Sensory relay station. ○​ Hypothalamus: Regulates hormones, hunger, temperature, etc. ○​ Limbic System: Controls emotion and memory. ​ Cingulate Gyrus: Processes pain and emotions. ​ Hippocampus: Memory formation. ​ Amygdala: Fear and aggression. ​ Olfactory Bulb: Processes smells.  ○​ Nucleus Accumbens: Part of the reward system. ○​ Cerebral Cortex: Higher cognitive functions. ​ Occipital Lobe: Vision. ​ Temporal Lobe: Hearing, language. ​ Parietal Lobe: Sensory processing. ​ Frontal Lobe: Decision-making, personality, movement. ○​ Basal Ganglia: Stabilizes voluntary movement and regulates habitual movement. Cerebral Blood Flow & Cerebrospinal Fluid (CSF) ​ Cerebral Blood Flow: Essential for normal brain function. ​ Blood-Brain Barrier (BBB): Controls substances entering the brain from the bloodstream. ​ Cerebrospinal Fluid (CSF): ○​ Produced in the ventricles. ○​ Provides cushioning and nutrient transport. ○​ CSF analysis helps in drug and neurotransmitter studies. Genetics & the Nervous System DNA & Gene Expression ​ Nucleus contains 46 chromosomes, made of DNA. ​ Genes: Segments of DNA that determine traits. ​ Polymorphisms: Gene variations that influence traits like enzyme production and neurotransmitter levels. Epigenetics ​ Gene expression can be modified without changing DNA sequence. ​ Methylation = Tightly wound DNA (gene off). ​ Acetylation = Loosely wound DNA (gene on). Genetically Modified Organisms (GMOs) ​ Transgenic Animals: Modified to study gene function. ○​ Global (whole-body gene change) vs. Conditional (specific area/time change). CRISPR-Cas9 Gene Editing ​ A technique to edit genes or turn them on/off. ​ Could be used for treating genetic disorders.