Overview of the Nervous System
The Nervous System
Central Nervous System Brain Spinal Cord
Somatic Nervous System innervation
Sympathetic Nervous System Preganglionic neurons: from CNS to ganglia short fibers acetylcholine (ACh) cholinergic Postganglionic neurons: from ganglia to effector long fibers norepinephrine (NE) noradrenergic 1:20
Parasympathetic Nervous System Preganglionic neurons: from CNS to ganglia long fibers Acetylcholine (ACh) cholinergic Postganglionic neurons: from ganglia to effector short fibers 1:4
Animal Cell Chromatin
Axonal Membrane of a Neuron
Ion Channels Cell membrane proteins that pass ions in and out of the cell Voltage-Gated Ion Channels gates are regulated by membrane voltage Chemical-Gated Ion Channels (also called Receptors) gates are regulated by neurotransmitters Iontotropic fast Metabotropic (G-protein coupled) requires second messenger cascade slow
Chemical-Gated Ion Channels Iontotropic Metabotropic
Electrochemical Gradient Inside the Cell More K+ Less Na+ Outside the Cell More Na+ Less K+ Ion Flow Mantra: Na+ In, K+ out
Depolarization/Hyperpolarization
Action Potential Phases 2 Rapid 3 1 Threshold 4 Phase Ion responsible Ion Channel Responsible 1. Threshold Na+ Chemical-gated Na+ channel 2. Rapid Depolarization Na+ Voltage-gated Na+ channel 3. Repolarization K+ Voltage -gated K+ channel 4. After Hyperpolarizatoin K+ Na+/K+ pumps
Na+/K+ Pumps After the Action Potential, Na+/K+ pumps move Na+ ions back out of the cell and move K+ ions back into the cell The movement is against the concentration gradient of each ion so it requires energy (ATP) The pumps move 3 Na+ ions for every 2 K+ ions
Unmyelinated Propagation
Myelinated Propagation
Synaptic Action Voltage-gated Ca2+ channels Synaptic Potentials: EPSP IPSP
Synaptic Potentials Excitatory Postsynaptic Potential (EPSP) triggered by excitatory neurotransmitters open ligand-gated Na+ channels allows Na+ to flow inside the cell causing a slight depolarization of the postsynaptic cell moves the postsynaptic cell closer to firing an action potential Inhibitory Postsynaptic Potential (IPSP) triggered by inhibitory neurotransmitters open ligand-gated K+ channels or Cl- channels allows K+ to flow out of the cell or Cl- to flow inside the cell causing a slight hyperpolarization of the postsynaptic cell moves the postsynaptic cell further from firing an action potential
The Battle to -55mV IPSP EPSP
Brain Organization
Spinal Cord Anatomy Dorsal Ventral Dorsal Horn: Sensory information in Ventral Horn: Motor information out
Brainstem Brainstem: arousal center (ARAS) sensory in pathway motor out pathway Midbrain Superior Colliculus Inferior Colliculus Pons REM sleep Medulla breathing center cardiac center
Ascending Reticular Activating System (ARAS) Arousal Center
Cranial Nerves I. Olfactory II. Optic III. Oculomotor IV. Trochlear smell II. Optic vision III. Oculomotor eye movement IV. Trochlear V. Trigeminal face movement mastication VI. Abducens VII. Facial face/tongue movement VIII. Vestibulocochlear hearing/balance IX. Glossopharyngeal taste/swallowing X. Vagus parasympathetic NS XI. Accessory neck movement XII. Hypoglossal tongue movement swallowing Cranial Nerves
Cerebellum Motor Coordination Fine tuning of: sensory systems emotions learning and memory Autism decreased cerebellum size
Thalamus and Hypothalamus relay station Hypothalamus regulation center
Nucleus Reticularis Thalami NRT: GABA cells Gatekeeper
Hypothalamic Nuclei hunger/thirst blood pressure/heart rate blood pressure/shivering stress satiety sex memory reproduction thermoregulation reproduction circadian rhythms
Limbic System Emotion Rewards Memory smell aggression fear learning recognition memory smell recognition? memory
Basal Ganglia Movement Parkinson’s Disease cell death in substantia nigra
Cortical Lobes Frontal: Strategy and Planning Motor area Parietal: Somatosensory area Temporal: Audition, Language Occipital: Vision