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![Membrane Potential
A resting neuron (non transmitting
neuron)has a voltage across its membrane
called the resting membrane potential, or
simply the resting potential.
The resting potential is determined by [ ]
gradients of ions across the membrane and
by membrane permeability to each type of
ion
Typical membrane potential: -70mV](https://image.slidesharecdn.com/neuron2022-250919072206-e11764c1/85/Chap-2-Neuron-2022-Presentation-AP-Biology-6-320.jpg)
![Setting up a membrane potential
LeakY channels
Permit ions to flow down [
] gradient
Passive
Na+ and K+
Membrane much more
permeable to K](https://image.slidesharecdn.com/neuron2022-250919072206-e11764c1/85/Chap-2-Neuron-2022-Presentation-AP-Biology-9-320.jpg)
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Chap 2 Neuron 2022 Presentation AP Biology
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- 5. •This stores energyand produces a measurable voltage across the membrane •Defined as the MEMBRANE POTENTIAL
- 6. Membrane Potential A restingneuron (non transmitting neuron)has a voltage across its membrane called the resting membrane potential, or simply the resting potential. The resting potential is determined by [ ] gradients of ions across the membrane and by membrane permeability to each type of ion Typical membrane potential: -70mV
- 9. Setting up amembrane potential LeakY channels Permit ions to flow down [ ] gradient Passive Na+ and K+ Membrane much more permeable to K
- 10. Na/K pump Setting upa membrane potential
- 11. Leak channels Sodiumpotassium pumps Both of these work together to keep the inside of a neuron at - 70 mV, or resting potential… and here is where it will stay until
- 13. • Changes inthe local environment of the neuron can affect the permeability of the plasma membrane to ions and alter the membrane potential.
- 14. • Any environmentalfactor that induces a change is called a STIMULUS! • Examples: Physical pressure, abrupt chemical change in extracellular environment, electric shock , change in temperature
- 15. Stimulus Increase voltage from theresting potential--- move from –70 mV towards zero! Decrease voltage from the resting potential--- move from –70 mV away from zero! Depolarized INCREASES chance an impulse will be triggered Hyperpolarized DECREASES chance an impulse will be triggered
- 17. Wait a minute...whatstarts this whole thing off in the first neuron? MEssage received Ligand gated
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- 19. Sending the messagedown the axon Voltage gated After the ligand gated channels open, Na+ rushes in. This makes the immediate area of the axon + That positive charge makes the voltage gates downstream open, letting in more NA+, leading to more +
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- 24. • Threshold isUSUALLY achieved at AXON HILLOCK • Strong stimuli do not change the STRENGTH of firing but result in GREATER FREQUENCY of action potentials. • The # of action potentials per second not the amplitude that codes for the stimulus intensity!!!!!
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- 26. Extreme athletes usesports drinks not only to hydrate but also to replenish the electrolytes (ions) in their body that are lost through sweat. Propose some reasons why this would be necessary to keep an athlete healthy and in top condition.
- 28. the electrical stimuluswill continue down the axon, opening voltage gated channels, causing depolarization downstream.
- 30. REPOLARIZATION Once the membranereaches +30mV, the voltage gated K+ ion channels will OPEN and the Na+ channels will close. K+ will be pumped out
- 33. hyperpolarization During repolarization theoverall charge will once again become negative inside the cell...sometimes TOO negative. If the charge is beyond -70mV we will refer to this as hyperpolarized. The neuron cannot fire during this time. It’s often referred to as the refractory period of a neuron.
- 36. Which of thesecorrectly describes the distribution of ions on either side of an axon when it is not conducting a nerve impulse? a. More Na+ outside and fewer K+ ions inside b. K+ outside and Na+ inside c. Charged proteins outside; Na+ and K+ inside d. Na+ and K+ outside, water on the inside
- 37. Repolarization of anaxon during an action potential is produced by a.Inward diffusion of Na+ b.Active extrusion of K+ c.Outward diffusion of K+ d.Inward active transport of Na+
- 38. EPSP (Excitatory PostSynaptic Potential): Excitatorymessages will open up ligand gated Na+ channels allows Na+ to flow in Cell become less negative IPSP (Inhibitory Postsynaptic Potential): Inhibitory will open up Cl channels, letting Cl- in Open K+ channels, letting them flow out of the cell Cell becomes more negative Message received
- 41. Lights, camera, actionpotential!
- 42. Messages can canceleach other out too
- 46. If the neuronreceives several EPSPs then….but...so...
- 47. Good Morning! Today: Wrapup Action Potential Get your brains warmed up… There are 4 major types of protein channels used in maintaining membrane potential or in an action potential. ---->Leak channel, Na/K pump, voltage gated pump and ligand gated pump. What do each type of these pumps mean?
Editor's Notes
- #2 Cell Body: contains the nucleus & other cell organelles Dendrites – typically short , slender extensions of the cell which RECEIVE stimuli AXON: typically a long, single, slender extension of the cell body that SENDS stimuli
- #7 http://www2.yvcc.edu/Biology/109Modules/Modules/RMP/RMP.htm *make sure you know concentration of Na, K, and Cl ions
- #16 Are there any other ions that could flow to impact voltage inside and outside of neuron? Would this impact whether or not an action potential would be sent?
- #18 Mechanically Gated Channels When a mechanical change occurs in the surrounding tissue, such as pressure or touch, the channel is physically opened. Thermoreceptors work on a similar principle. When the local tissue temperature changes, the protein reacts by physically opening the channel.
- #21 The actual impulse is generated when graded potentials that depolarize the membrane of a neuron are converted to an even larger depolarized state called the ACTION POTENTIAL! Action Potential RAPID, reversible depolarization near the point of stimulation that generates the nerve impulse Goes beyond depolarization: the inside actually becomes POSITIVELY charged Changed from –70mV to +35 mV Seen as a measurable spike a minimum depolarization that must occur before voltage sensitive Na gates open and action potential is achieved!
- #38 Exitatory Post synaptic Potential
- #41 The actual impulse is generated when graded potentials that depolarize the membrane of a neuron are converted to an even larger depolarized state called the ACTION POTENTIAL! Action Potential RAPID, reversible depolarization near the point of stimulation that generates the nerve impulse Goes beyond depolarization: the inside actually becomes POSITIVELY charged Changed from –70mV to +35 mV Seen as a measurable spike a minimum depolarization that must occur before voltage sensitive Na gates open and action potential is achieved!