Nervous System Learning Outcomes PDF

Detailed Study Guide: Nervous System Learning Outcomes 1. Central Nervous System (CNS) vs. Peripheral Nervous System (PNS) Structure: ○ CNS: Brain (cerebrum, cerebellum, brainstem) and spinal cord; protected by skull, vertebrae, meninges, and cerebrospinal fluid (CSF)...

Detailed Study Guide: Nervous System Learning Outcomes 1. Central Nervous System (CNS) vs. Peripheral Nervous System (PNS) Structure: ○ CNS: Brain (cerebrum, cerebellum, brainstem) and spinal cord; protected by skull, vertebrae, meninges, and cerebrospinal fluid (CSF). ○ PNS: All neural tissue outside CNS, including cranial nerves (12 pairs), spinal nerves (31 pairs), and sensory and motor fibers. Function: ○ CNS: Integration and control center; interprets sensory input, plans and coordinates motor output, and stores information. ○ PNS: Sensory Division: Transmits sensory input from receptors to CNS. Motor Division: Transmits motor commands from CNS to effectors. 2. Motor (Efferent) vs. Sensory (Afferent) Components Sensory (Afferent): ○ Input pathways; carry signals from sensory receptors to CNS. ○ Subdivided into: Somatic Sensory: External stimuli (e.g., pain, temperature, pressure). Visceral Sensory: Internal stimuli (e.g., organ stretch, chemical changes). Motor (Efferent): ○ Output pathways; carry commands from CNS to muscles/glands. ○ Subdivided into: Somatic Motor: Voluntary; skeletal muscle activation. Autonomic Motor: Involuntary; smooth muscle, cardiac muscle, and gland regulation. 3. Nervous System as a Control System Functional Steps: 1. Sensory Receptors: Detect stimuli (e.g., photoreceptors in eyes, mechanoreceptors in skin). 2. Afferent Pathways: Sensory neurons send signals to CNS. 3. Control Center (CNS): Processes input, formulates response (e.g., reflex centers in spinal cord, higher processing in brain).  4. Efferent Pathways: Motor neurons transmit commands from CNS to effectors. 5. Effector Organs: Muscles or glands carry out response (e.g., contraction, secretion). 4. Somatic vs. Autonomic Motor Divisions Somatic Motor Division: ○ Single neuron pathway. ○ Voluntary control of skeletal muscles. ○ Neurotransmitter: Acetylcholine (ACh). Autonomic Motor Division: ○ Two-neuron chain (preganglionic and postganglionic neurons). ○ Involuntary control of smooth/cardiac muscle and glands. ○ Divided into: Sympathetic: Prepares body for stress ("fight or flight"). Parasympathetic: Promotes rest and recovery ("rest and digest"). 5. Neuron Anatomy Components: ○ Cell Body (Soma): Contains nucleus and organelles. Chromatophilic substance (Nissl bodies): Clusters of rough ER for protein synthesis. ○ Dendrites: Receive incoming signals; highly branched for input from multiple sources. ○ Axon: Transmits action potentials to other neurons or effectors. Axon Hillock: Cone-shaped region; initiates action potentials. 6. Types of Neurons Sensory (Afferent): ○ Function: Transmit sensory input to CNS. ○ Structure: Pseudounipolar (one process splits into peripheral and central branches). Interneurons (Association Neurons): ○ Function: Connect sensory and motor neurons; process information. ○ Location: Entirely within CNS.  ○ Structure: Multipolar. Motor (Efferent): ○ Function: Transmit motor commands from CNS to effectors. ○ Structure: Multipolar. 7. Neuroglial (Glial) Cells CNS Glial Cells: ○ Astrocytes: Blood-brain barrier; regulate extracellular environment. ○ Oligodendrocytes: Myelinate CNS axons. ○ Microglia: Phagocytes; remove debris. ○ Ependymal Cells: Line ventricles; produce and circulate CSF. PNS Glial Cells: ○ Schwann Cells: Myelinate PNS axons; aid in repair. ○ Satellite Cells: Support cell bodies in ganglia. Myelination: ○ CNS: Oligodendrocytes wrap multiple axons. ○ PNS: Schwann cells wrap single axon; nodes of Ranvier enable saltatory conduction. 8. Resting Membrane Potential (RMP) Established By: ○ Sodium-potassium ATPase pump (3 Na⁺ out, 2 K⁺ in). ○ K⁺ leak channels. Key Concepts: ○ Depolarization: Membrane potential becomes more positive (Na⁺ influx). ○ Repolarization: Membrane potential returns to resting state (K⁺ efflux). ○ Hyperpolarization: Membrane potential becomes more negative. 9. Graded vs. Action Potentials Graded Potentials: Localized changes in membrane potential; vary in size. Action Potentials: Rapid, all-or-none depolarization; propagate along axons. 10. Synaptic Transmission Steps:  ○ Action potential arrives at axon terminal. ○ Voltage-gated Ca²⁺ channels open. ○ Synaptic vesicles release neurotransmitter into cleft. ○ Neurotransmitter binds to postsynaptic receptors. Excitatory/Inhibitory Postsynaptic Potentials: ○ EPSPs: Depolarizing signals. ○ IPSPs: Hyperpolarizing signals. 11. Spinal Cord Anatomy and Reflexes Gross Anatomy: ○ Cervical/Lumbar Enlargements: Contain motor neurons for limbs. ○ Conus Medullaris: Tapered end of spinal cord. ○ Cauda Equina: Nerve roots extending below spinal cord. Reflex Arc Components: ○ Receptor → Sensory neuron → Integration center → Motor neuron → Effector. 12. Memory and Alzheimer’s Disease Memory: ○ Short-term: Temporary increase in synaptic efficiency. ○ Long-term: Synaptic remodeling, new dendritic spines. Alzheimer’s Disease: ○ Amyloid plaques, tau protein tangles, neuron death; impaired memory and cognition.