Human Physiology Exam 2 Content Fall 2024 PDF

BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Chapter 8 Organization of the nervous system Cells of the nervous system Electrical signals in neurons Cell-to-cell communication in the nervous system...

BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Chapter 8 Organization of the nervous system Cells of the nervous system Electrical signals in neurons Cell-to-cell communication in the nervous system 50 Physiology of the Nervous System (NS) Controlling, regulatory, and communicating system Regulating and maintaining homeostasis Uses electrochemical communication 51 1 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Anatomy of the NS 52 What is the difference between a nerve and a neuron? 53 2 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Organization of the PNS 54 Neurons are the Functional Unit of the NS Smallest, repeating structure that performs the functions of the overall system Signal input Dendrites and cell body (soma) Integration Axon hillock (initial segment) Output signal Axon (nerve fiber) and axon terminal Synapse Junction between pre- and post-synaptic cell 55 3 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Figure 8.2 56 Ganglion (PNS) / Nucleus (CNS) Nerve (PNS) / Tract (CNS) 57 4 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Neurons: Functional & Structural Categories Figure 8.2 58 Glial Cells Provide Support for Neurons PNS Glial Cells Schwann cells Form insulating myelin sheaths Nodes of Ranvier Satellite cells Supportive capsules in a ganglion 59 5 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 PNS Glial Cells 60 Figure 8.5 61 6 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 CNS Glial Cells Figure 8.5 62 CNS Glial Cells Figure 8.5 63 7 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Electrical Signals in Neurons 64 Ion Movement Creates Electrical Signals Alteration in the membrane permeability of ions Voltage changes can be classified as graded or action potentials (APs) Figure 5.24 65 8 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 66 What determines the magnitude and sign of the resting membrane potential (RMP)? 1. Na+/K+-ATPase pump Net loss of positive charge 2. Anionic intracellular proteins Unequally distributed and impermeable 3. Membrane permeability Na+ and K+ Leak channel subtype and amounts 67 9 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 RMP 68 Ohm’s Law I=V Voltage or potential difference (V) Intra- vs. extra-cellular separation of charge R Current (I) Transmembrane flow of charge Na+ influx and K+ efflux Resistance (R) Hindrance to flow Phospholipid bilayer and ion channel gating 69 10 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Electrical Signals: Nernst Equation Describes the membrane potential that a single ion would produce if the membrane were permeable to only that ion 70 Electrical Signals: Nernst Equation for Na+ 71 11 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Equilibrium Potentials K+ efflux through leak channels major contributor to the RMP 72 Graded Potentials Reflect Stimulus Strength Graded Potentials Cell type All Signal distance Short Initiated by Stimulus gating of ion channels Amplitude of signal Varies with stimulus strength Change in Depolarization or hyperpolarization membrane potential Threshold No Suprathreshold Greater (amplitude) current change from RMP stimuli Subtypes Receptor, pacemaker, postsynaptic 73 12 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 74 Figure 8.7 75 13 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Subthreshold Graded Potential Figure 8.7 76 Threshold Graded Potential Figure 8.7 77 14 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 APs Travel Long Distances APs Cell type Excitable Signal distance Long Initiated by Opening of voltage-gated Na+ channels Amplitude of signal Same, all-or-none Change in membrane potential Depolarization Threshold -55 mV Suprathreshold stimuli Increased frequency Subtypes No 78 Wave of electrical signal at constant amplitude 79 15 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Action Potential Figure 8.9 80 Figure 8.9 81 16 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Na+ and K+ Move across the Membrane during APs Graded stimuli Membrane depolarizes to threshold at the trigger zone of the axon hillock Rising phase Voltage-gated Na+ channels (VGNaC) open Rapid Na+ influx further depolarizes cell 82 VGNaC at RMP 83 17 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 VGNaC: Graded Depolarizing Current Opens the Activation Gate 84 VGNaC: Na+ Influx 85 18 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Figure 8.9 86 VGNaC: Inactivation Gate Closes the Pore at the Peak of an AP Simultaneously, the slower voltage-gated K+ channels (VGKC) open allowing efflux Figure 8.10 87 19 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 VGKCs Mediate the Falling Phase of the AP & the After-hyperpolarization Figure 8.9 88 VGNaC: Reset Following K+-mediated Membrane Repolarization 89 20 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Refractory Periods Delay of 1-2 msec between consecutive APs Prevents backward conduction Absolute refractory period Na+ gates resetting Relative refractory period Suprathreshold stimulus is required 90 Figure 8.12 91 21 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 AP Conduction Rates Diameter of axon Larger axons are faster Degree of myelination Myelinated axons are faster Continuous vs. saltatory conduction 92 Continuous Conduction TIME 1 TIME 2 Figure 8.14 93 22 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Continuous Conduction TIME 2 TIME 3 Figure 8.14 94 Saltatory Conduction Figure 8.16 95 23 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Cell-to-Cell Communication in the Nervous System We will focus on the chemical axo-dendritic type of synapse 96 Neurotransmitter Release Figure 8.19 97 24 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Neurocrines Generic terminology for any molecule secreted by a neuron 98 ACh Synthesized choline + acetyl coenzyme A Nicotinic cholinergic receptors (NAChR) Skeletal muscle, autonomic neurons, CNS Monovalent cation channels Na+ and K+ Muscarinic (M) cholinergic receptors Smooth and cardiac muscle, endocrine and exocrine glands, CNS GPCR 99 25 BIOL 3730 HUMAN PHYSIOLOGY EXAM 2 CONTENT FALL 2024 Termination of Neurotransmitter Activity 1. Diffusion Out of the synaptic cleft 2. Enzymatic catabolism 3. Uptake Presynaptic axon terminal Glial cells Figure 8.19 100 101 Figure 8.20 26