Week 10 CBIO
Week 10 CBIO CBIO 2200
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This 5 page Class Notes was uploaded by Bailey Dickinson on Friday October 14, 2016. The Class Notes belongs to CBIO 2200 at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months taught by in Fall 2016. Since its upload, it has received 10 views. For similar materials see Anatomy and Physiology I in Cellular biology at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months.
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Date Created: 10/14/16
Our patient’s blood was tested and found to contain high levels of anti- acetylcholine-receptor antibodies Her symptoms disappeared quickly when she was administered a drug that prevented the breakdown of acetylcholine (an acetyl cholinesterase inhibitor) What tells the muscle fiber to shorten? o Electrical impulse from a neuron (a nerve cell in the CNS) o The neuron communicates with the muscle fiber chemically, and the chemical signal is converted into an electrical signal o The signal in the muscle fiber causes Ca2+ release from the sarcoplasmic reticulum Electrical impulse or signal (at the NEURON)à Chemical signal (BETWEEN neuron and muscle fiber)à Electrical impulse or signal (at the MUSCLE) The Neuromuscluar junction o The point of communication between the CNS and the muscular system o Electrical signal to chemical signal to electrical signal When acetylcholine binds to the Ach receptors, it opens a sodium channel in the muscle cell. The sodium ions go in (facilitated diffusion) Electrical signal is generated in the motor neuron (action potential, nerve impulse) Acetylcholine is the chemical messenger that diffuses across the synaptic cleft, and when it binds, it generates an electrical signal (another action potential at the muscle cell itself) Starting with a Resting Cell: The Resting Membrane Potential o The transmembrane potential of a cell at rest o The separation of charges across a membrane in an excitable cell at rest Lots of sodium and chloride ions are outside of the cell (positive) Inside of the cell, we have negatively charged proteins, potassium, and phosphate ions Action Potential o Electrical signal produced by ion movements across the plasma membrane of excitable tissues o Nervous tissue and muscular tissue o OpenStax section 12.4; p.525 o -70 mv charge in cell//muscle cell is more like -95 mv Initially, the plasma membrane is polarized. Now, the separation of charges across the membrane begins to dissipate. The membrane potential becomes more positive. Depolarization is when the sodium gates open and sodium goes in. The membrane potential is now positively charged. This causes the sodium channels to close. The potassium channels open when we get to a particular charge across the plasma membrane. Potassium goes out of the cell (from where there’s more to less). The membrane voltage changes because we’re losing positively charges ions. This happens until we go back to the resting membrane potential. (repolarization) The nearby sodium channels will open. Our electrical signal starts on the left and moves all the way down the cell membrane. Eventually, the entire membrane is depolarized, and then we see a wave of repolarization. This is the nature of electrical tissues. The entire plasma membrane has been depolarized and there will now be a wave of repolarization Action potential- “an all or nothing phenomenon” If we don’t reach a particular threshold, then we don’t receive the signal PHRASES IN ORDER: (action potential in the motor neuron) 1. Voltage gated Na+ channels open 2. Na+ enters motor neuron 3. Motor neuron depolarizes; membrane potential ~ +30 mV 4. Voltage gated K+ channels open; Na+ channels close 5. K+ leaves motor neuron 6. Motor neuron repolarizes; membrane potential ~ -75mv 7. Voltage gated K+ channels close 8. ACh is released 9. ACh diffuses across synaptic cleft 10. And filaments slide PHRASES IN ORDER: (in the muscle) 1. Motor neuron depolarizes 2. Voltage gated K+ channels in the motor neuron open 3. Motor neuron repolarizes 4. ACh is released 5. Ligand gated Na+ channels are activated at the motor end plate 6. Muscle fiber is depolarized 7. Votage gated Ca++ channels in the SR open 8. Ca++ floods into sarcoplasm, binds to troponin 9. Tropomyosin changes shape; crossbridges are formed 10. And filaments slide