Chapter 9: The Central Nervous System

Terminology for Parts of the Nervous System

• Central Nervous System (CNS): Consists of the brain and spinal cord; responsible for integrating sensory information and responding accordingly.

• Peripheral Nervous System (PNS): All neural tissue outside the CNS; connects the CNS to limbs and organs.

• Gray Matter: Regions with neuron cell bodies, dendrites, and unmyelinated axons; involved in processing and integration.

• White Matter: Regions with myelinated axons; responsible for communication between different CNS areas.

Neuronal Structures and Their Functions

• Cell Body (Soma): Contains the nucleus and organelles; metabolic center of the neuron.

• Dendrites: Receive incoming signals from other neurons.

• Axon: Conducts electrical impulses away from the cell body.

• Axon Hillock: Site where action potentials are initiated.

• Synaptic Terminals: Release neurotransmitters to communicate with other cells.

Types of Glial Cells and Their Functions

• Astrocytes: Maintain blood-brain barrier, regulate ion/nutrient environment, and support neurons.

• Oligodendrocytes: Myelinate CNS axons, increasing conduction speed.

• Schwann Cells: Myelinate PNS axons.

• Microglia: Immune defense in CNS.

• Ependymal Cells: Line ventricles, produce cerebrospinal fluid (CSF).

Nernst and Goldman-Hodgkin-Katz Equations

• Nernst Equation: Calculates equilibrium potential for a single ion.

• Goldman-Hodgkin-Katz Equation: Calculates membrane potential considering multiple ions.

Relative Ion Concentrations

• Inside Cell: High K+, low Na+, low Cl-

• Outside Cell: High Na+, high Cl-, low K+

Action Potential Events

• Resting membrane potential maintained by Na+/K+ ATPase.

• Depolarization: Na+ channels open, Na+ influx.

• Repolarization: K+ channels open, K+ efflux.

• Hyperpolarization: K+ channels remain open briefly.

• Return to resting potential.

Example: Action potential graph shows rapid depolarization, repolarization, and hyperpolarization phases.

Factors Affecting Action Potential Speed and Neuron Excitability

• Axon diameter (larger = faster conduction).

• Myelination (myelinated = faster via saltatory conduction).

• Temperature (higher = faster up to a point).

Neurotransmitter Classes and Examples

• Amino Acids: Glutamate (excitatory), GABA (inhibitory), Glycine (inhibitory).

• Biogenic Amines: Dopamine, norepinephrine, serotonin.

• Peptides: Substance P, endorphins.

• Others: Acetylcholine (ACh; excitatory at neuromuscular junction).

Receptor Types and Effects

• Ionotropic Receptors: Ligand-gated ion channels; fast response (e.g., nicotinic ACh receptor).

• Metabotropic Receptors: G-protein coupled; slower, modulatory effects (e.g., muscarinic ACh receptor).

• EPSP (Excitatory Postsynaptic Potential): Depolarizes membrane, increases likelihood of action potential.

• IPSP (Inhibitory Postsynaptic Potential): Hyperpolarizes membrane, decreases likelihood of action potential.

Synaptic Events and Neurotransmitter Release

• Action potential arrives at axon terminal.

• Voltage-gated Ca2+ channels open; Ca2+ influx triggers vesicle fusion and neurotransmitter release.

• Release can be increased by higher Ca2+ influx or decreased by presynaptic inhibition.

Neuron Pathways

• Convergent Pathways: Multiple neurons synapse onto a single neuron.

• Divergent Pathways: One neuron branches to synapse on multiple neurons.

Summation of Graded Potentials

• Spatial Summation: Multiple simultaneous inputs from different locations.

• Temporal Summation: Rapid, repeated inputs from a single source.

Long-Term Potentiation (LTP)

• Persistent strengthening of synapses based on recent activity.

• Involves NMDA receptor activation, Ca2+ influx, and increased synaptic efficacy.

Example: LTP is a cellular mechanism underlying learning and memory.

Chapter 10: Brain Structure and Function

Brain Regions and Functions

• Cerebrum: Higher cognitive functions, voluntary movement, sensory perception.

• Cerebellum: Coordination of movement and balance.

• Diencephalon: Thalamus (relay center), hypothalamus (homeostasis).

• Brainstem: Midbrain, pons, medulla; controls vital functions (breathing, heart rate).

Meninges and CSF Production

• Meninges: Dura mater, arachnoid mater, pia mater; protect CNS.

• CSF: Produced by choroid plexus; cushions brain, removes waste.

Spinal Cord Structure

• Central gray matter (butterfly shape) surrounded by white matter.

• Dorsal roots (sensory input), ventral roots (motor output).

White and Gray Matter Terminology

• CNS: Nuclei (gray), tracts (white).

• PNS: Ganglia (gray), nerves (white).

Cortical Areas and Lobes

• Frontal Lobe: Motor cortex, executive functions.

• Parietal Lobe: Somatosensory cortex.

• Temporal Lobe: Auditory cortex, memory.

• Occipital Lobe: Visual cortex.

Perception

• Interpretation of sensory information by the brain.

Diffuse Modulatory Systems

• Noradrenergic: Originates in locus coeruleus; attention, arousal.

• Serotonergic: Raphe nuclei; mood, emotion.

• Dopaminergic: Substantia nigra, ventral tegmental area; reward, movement.

• Cholinergic: Basal forebrain, brainstem; learning, memory.

Limbic System Functions

• Emotion, motivation, memory formation.

• Includes amygdala, hippocampus, cingulate gyrus.

Memory Types and Brain Regions

• Short-term Memory: Prefrontal cortex.

• Long-term Memory: Hippocampus (formation), cortex (storage).

• Procedural Memory: Basal ganglia, cerebellum.

Sleep States

• REM Sleep: Dreaming, muscle atonia.

• Non-REM Sleep: Restorative, slow-wave activity.

• Sleep interacts with immune, endocrine, and cognitive systems.

Cranial Nerve Functions

• 12 pairs; control sensory and motor functions of head and neck.

Hypothalamus Functions

• Homeostasis: temperature, hunger, thirst, circadian rhythms, endocrine regulation.

Chapter 11: Sensory Physiology

Sensory Receptor Types and Adequate Stimuli

• Mechanoreceptors: Touch, pressure, vibration.

• Thermoreceptors: Temperature changes.

• Photoreceptors: Light (vision).

• Chemoreceptors: Chemical stimuli (taste, smell).

• Nociceptors: Painful stimuli.

Sensory Pathways

• Each sense has a specific pathway to the brain (e.g., visual pathway: retina → optic nerve → thalamus → visual cortex).

Tonic vs. Phasic Receptors

• Tonic: Slow-adapting, respond as long as stimulus is present.

• Phasic: Rapidly adapt, respond to changes in stimulus.

Somatic Sense Modalities

• Touch, temperature, pain, proprioception.

Somatosensory Nerve Fiber Classes

Gate Control Theory of Pain

• Non-painful input (e.g., touch) can inhibit pain signals in the spinal cord.

Gustation Cell Properties

• Taste cells respond to sweet, sour, salty, bitter, umami.

• Each cell type has specific receptors for its modality.

Ear Structure and Function

• Outer Ear: Collects sound.

• Middle Ear: Transmits vibrations via ossicles.

• Inner Ear: Cochlea (hearing), vestibular apparatus (balance).

Sound Transduction

• Sound waves → tympanic membrane vibration → ossicles → cochlear fluid movement → hair cell activation → electrical signal.

Vestibular Apparatus Function

• Semi-circular Canals: Detect rotational movement.

• Otolith Organs (utricle, saccule): Detect linear acceleration and head position.

Light Focusing and Eye Structure

• Cornea and lens focus light onto retina (fovea centralis: highest acuity, contains cones).

• Photoreceptors (rods and cones) transduce light into electrical signals.

Abnormal Eye Conditions

• Myopia: Nearsightedness.

• Hyperopia: Farsightedness.

• Astigmatism: Irregular curvature of cornea/lens.

• Cataracts: Clouding of lens.

Chapter 12: Autonomic and Somatic Motor Control

Autonomic Nervous System (ANS) Divisions

Autonomic Control Centers

• Located in hypothalamus, brainstem (medulla, pons).

Neuromuscular Junction Structure

• Motor neuron terminal, synaptic cleft, muscle fiber membrane (motor end plate).

• ACh released, binds to nicotinic receptors, triggers muscle action potential.

Chapter 13: Muscle Physiology and Movement Control

Skeletal Muscle Terminology

• Origin: Attachment to stationary bone.

• Insertion: Attachment to movable bone.

• Flexor: Decreases joint angle.

• Extensor: Increases joint angle.

• Agonist: Main muscle causing movement.

• Antagonist: Opposes agonist.

Microscopic Muscle Structure

• Myofibrils: Bundles of actin and myosin filaments.

• Sarcomere: Functional unit; Z-line to Z-line.

• Sarcoplasmic Reticulum: Stores Ca2+.

Muscle Twitch Events

• Action potential → Ca2+ release → cross-bridge cycling → contraction → Ca2+ reuptake → relaxation.

Energy Molecules for Skeletal Muscle

• ATP (immediate source), creatine phosphate, glycogen, fatty acids.

Muscle Fatigue Types and Causes

• Central Fatigue: CNS origin (motivation, neurotransmitter depletion).

• Peripheral Fatigue: Muscle fiber origin (ion imbalance, ATP depletion).

Types of Muscle Contraction

• Isometric: Tension without length change.

• Isotonic: Muscle changes length (concentric: shortens, eccentric: lengthens).

Muscle Fiber Types and Properties

Muscle Disorders

• Muscular Dystrophy: Genetic, progressive muscle weakness.

• Myasthenia Gravis: Autoimmune, affects neuromuscular junction.

Smooth Muscle Contraction and Relaxation

• Ca2+ binds to calmodulin, activates myosin light chain kinase, cross-bridge cycling.

• Relaxation: Dephosphorylation of myosin, Ca2+ removal.

Comparison: Skeletal, Cardiac, and Smooth Muscle

Chapter 14: Control of Body Movement

Types of Reflexes

• Monosynaptic: Single synapse (e.g., stretch reflex).

• Polysynaptic: Multiple synapses (e.g., withdrawal reflex).

Proprioception and Structures Involved

• Muscle Spindles: Detect muscle stretch.

• Golgi Tendon Organs: Detect muscle tension.

• Joint Receptors: Detect joint position.

Phases of Voluntary Movement Control

• Planning: Cortex, basal ganglia, cerebellum.

• Initiation: Motor cortex.

• Execution: Motor neurons, muscles.

Example: Reaching for an object involves planning (premotor cortex), initiation (primary motor cortex), and execution (spinal cord, muscles).

Additional info: Where details were not explicit in the study guide, standard academic context was added for completeness (e.g., specific neurotransmitter examples, muscle fiber types, and equations).