Generation-and-Propagation-of-Nerve-Impulses-and-Synaptic-Transmission (2).pptx

Generation and propagation of Nerve impulses with description and illustration of diagrams

1. Generation and Propagation of Nerve Impulses and Synaptic Transmission Neurons are specialized cells that transmit electrical signals throughout the body. They have a unique structure with a cell body, dendrites, and an axon that allows them to generate and propagate nerve impulses, known as action potentials. PRESENTED BY MALAYKA AYYAZ (0684-MPHIL-Z-23)

2. Resting Membrane Potential 1 Electrical Charge Difference Neurons maintain a negative electrical charge inside the cell relative to the outside, creating a resting membrane potential. 2 Ion Concentration Gradients The unequal distribution of sodium, potassium, and other ions across the cell membrane generates this charge difference. 3 Importance for Signaling The resting potential is crucial for the generation and propagation of action potentials, the basis of neural communication.

3. Generation of Nerve Impulses 1 Depolarization Sufficient stimulus causes the membrane to depolarize, opening voltage-gated sodium channels. 2 Action Potential The influx of sodium ions generates a rapid, self-propagating action potential. 3 Repolarization Potassium channels open, allowing potassium to flow out, restoring the resting potential.

4. Refractory Period Absolute Refractory Period During this period, the neuron cannot generate a new action potential, no matter the stimulus strength. Relative Refractory Period Stronger stimuli are required to generate an action potential during this period. Importance The refractory period ensures proper timing and prevents tetanic contraction of muscles.

5. Propagation of Nerve Impulses Depolarization The action potential triggers the opening of voltage-gated sodium channels in the adjacent segment of the axon. Saltatory Conduction In myelinated neurons, the action potential "jumps" from one node of Ranvier to the next, increasing speed. Repolarization Potassium channels open, allowing potassium to flow out, restoring the resting potential in the wake of the action potential.

6. Synaptic Transmission Synaptic Structure Synapses are specialized junctions where the axon terminal of one neuron communicates with the dendrite or cell body of another. Presynaptic Terminal The axon terminal contains synaptic vesicles filled with neurotransmitters, ready for release into the synaptic cleft. Postsynaptic Membrane Neurotransmitter receptors on the receiving neuron's membrane bind to the released neurotransmitters, triggering a response.

7. Neurotransmitter Release Calcium Influx Arrival of the action potential causes calcium ion influx into the presynaptic terminal. Vesicle Fusion Calcium triggers the fusion of synaptic vesicles with the presynaptic membrane, releasing neurotransmitters. Receptor Binding Neurotransmitters bind to receptors on the postsynaptic membrane, initiating a response.

8. Factors Affecting Synaptic Transmission Neurotransmitter Type Determines the specific response in the postsynaptic neuron. Neurotransmitter Concentration Higher concentrations lead to stronger postsynaptic responses. Receptor Sensitivity Changes in receptor density or affinity can modulate synaptic strength. Presynaptic Regulation Factors like calcium levels and vesicle availability control neurotransmitter release.