1 / 14

Nervous System II

Nervous System II. SBI4U. Synaptic Transmission. Synaptic Transmission. 2 types of synapses: Chemical & Electrical Neurotransmitter-Receptor vs. Gap junctions. Electrical signals & electical synapse. Plasma membrane of presynaptic and postsynaptic cell are in direct contact.

hoshi
Download Presentation

Nervous System II

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nervous System II SBI4U

  2. Synaptic Transmission

  3. Synaptic Transmission • 2 types of synapses: Chemical & Electrical • Neurotransmitter-Receptor vs. Gap junctions

  4. Electrical signals & electical synapse • Plasma membrane of presynaptic and postsynaptic cell are in direct contact. • Current flows directly (unbroken transmission of electrical signal) • Faster neural transmission than chemical synapse

  5. Resting membrane potential Membrane potential: imbalance between charges outside and inside the membrane that causes an electrical (electrical difference between Na+ and K+) - 3 Na+ for every 2K+ ions pumped in(Na+/K+ active transport pump) - An unstimulated neuron has a resting membrane potential where the voltage difference in the nerve cell is – 70mV

  6. Action potential • Membrane potential changes during an electrical impulse. • All or nothing principle : frequency of AP not magnitude (a greater stimulus  faster AP not bigger)

  7. Action potential in Chemical synapse

  8. Activity-Questions • What is all-or-none response? • What is the difference between chemical and electrical synapse? • Which area of the graph indicates the opening of Na+ channels and their diffusion into nerve cells? And when does repolarisation occur ?explain

  9. Pg.529 Q1-3

  10. Answers • 1. A certain threshold stimulus is required to trigger an AP along a nerve. However, once the threshold has been reached further increase in stimulus will not increase nerve response. It is all-or-none response. A nerve or muscle fibre responds completely to a stimulus or it does not at all. • 2- Electrical transmission faster, diminish as it travels, and uses excitation energy to push elecrons. • Chemical: slower, impulse remain strong, uses cellular energy to generate current

  11. 3. During depolarization of the membrane . As it is depolarized the sodium ions rush into the cell causing the membrane potential to increase. Repolarisation occurs when K+ ions diffuses out of the axon. This diffusion lowers the membrane potential of the nerve cell.

More Related