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UGA BIOL 1108 - Animal Forms

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BIOL 1108 1nd Edition Lecture 12 Outline of Last Lecture I. Learning Objectives II. In The NewsIII. Starch and CelluloseIV. Plant History Outline of Current Lecture I. Learning ObjectivesII. In The News #8III. Electrical Signals IV. Resting Potential to Action Potential Current LectureI. Learning Objectives1. Describe the range of vertebrate nervous systems 2. Describe information processing 3. Identify neuron structure and function 4. Describe the basis of membrane potential 5. Be able to: describe what an action potential is, including – depolarization – hyperpolarization II. In The News: “In what ways does our understanding of giraffes not measure up?”- Maternal Behavior: mourning over died offspring (social groups like elephants?)- Male Behavior: show sexual features depending on the presence of other males. Fighting (necking) sexual selection (evolution)- Circulatory system: thick blood vessels to avoid fainting - Ecological impacts: seed distributers- Physiology: testosterone= androgen fluctuates based on sexual activityThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Body temperature averages around 38 degrees (endothermic)III. Electrical Signals a. TOPHAT: Which has more vertebrae, a giraffe or a mouse?i. They are the same (all animals have 7 vertebrae)b. Anatomy of a Neuron- The functional unit of the nervous system is the neuron - Dendrites- receives the signals - Cell body- contains organelles- Axon Hillock- signals are generated - Myelin sheath (Schwan Cell)- insulation and increase speed - Node of Ranvier- gap helps signals leap down the axon- Axon- transmits signal from cell to cell- Axon Terminal- connects cell to dendrites of another cellc. Membrane Potential- The charged difference or voltage (mV) between the inside and outside of the axon.- Two factors that influences membrane potential is ion concentration (diffusion) and electrical force.- The negative charge inside the axon is built up through active transporto Resting potential (when no signals are being sent at all) is between -60 mV and -80 mV Why is the axon resting membrane potential -70 mV?- There are more potassium channels than there are sodiumchannels. So potassium is going to leave the cell and sodium is going into the cell. The net movement of potassium out of cell, positive charges leave cell --> negative net loss Sodium in the outside also is positive and remains on the outside creating a positive gradient.- Number of sodium and potassium attempt to balance through diffusion. More diffusion out than in the cell- Using ATP as energy to transport sodium out and the potassium in the celld. TOPHAT: At which phase does depolarization first occur?i. B) At graded potential e. TOPHAT: An action potential is triggered when the membrane potential reaches:i. +55 mVf. Equilibrium Potential (Eion)- When the electrical gradient opposes the concentration gradient - Calculated using the Nernst Equationo Eion= 62 mV (log [ion concentration outside] / [ion concentration inside])o EK+= -90 mVo ENa+= +60 mV- Depends on the concentration gradient IV. Resting Potential to Action Potential- Action Potential includes o Depolarization- what happens to the membrane potential with increased permeability to Na+o Hyperpolarization- what happens to the membrane potential with increased permeability to K+- How is an action potential generated in an axon?o Some voltage gated channels allowing sodium to pass through until threshold is reach, and then all of the channels are open.o Allows a rush of sodium to come into the cello Then after it reaches a threshold (graded potential), all of the sodium voltage-gated channels open.o Action potential occurs at the maximum of membrane potential Sodium channels begin to close and potassium channels being to


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