nervous system ii
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/1.jpg)
NERVOUS SYSTEM II
SBI4U
![Page 2: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/2.jpg)
SYNAPTIC TRANSMISSION
![Page 3: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/3.jpg)
![Page 4: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/4.jpg)
SYNAPTIC TRANSMISSION
2 types of synapses: Chemical & Electrical
Neurotransmitter-Receptor vs. Gap junctions
![Page 5: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/5.jpg)
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
![Page 6: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/6.jpg)
![Page 7: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/7.jpg)
RESTING MEMBRANE POTENTIALMembrane 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
![Page 8: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/8.jpg)
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)
![Page 9: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/9.jpg)
ACTION POTENTIAL IN CHEMICAL SYNAPSE
![Page 10: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/10.jpg)
![Page 11: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/11.jpg)
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
![Page 12: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/12.jpg)
Pg.529 Q1-3
![Page 13: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/13.jpg)
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
![Page 14: Nervous System II](https://reader035.vdocument.in/reader035/viewer/2022081603/56813d61550346895da7344c/html5/thumbnails/14.jpg)
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.