Integrative Physiology and Ecology Week 6 Lecture Summary

Overview of Animal Nervous Systems

  • Nervous systems enable sensing, responding to the environment, coordinating movement, and regulating internal body functions.

  • Neurons are the basic functional units with dendrites (receive info) and axons (transmit info).

Neuron Types

  • Sensory neurons: detect stimuli.

  • Interneurons: process information.

  • Motor neurons: effect responses.

Membrane Potential

  • Resting potential: negative voltage across the membrane; maintained by the sodium-potassium pump.

  • Depolarization: membrane becomes less negative; action potentials generated if threshold potential is reached.

Action Potential Sequence

  1. Summed input depolarizes axon hillock.

  2. Voltage-gated Na+ channels open, allowing Na+ influx.

  3. K+ channels open later, reinstating negative potential through K+ efflux; results in refractory period.

Synaptic Transmission

  • Action potential reaches axon terminal, opening voltage-gated Ca2+ channels.

  • Neurotransmitters are released into the synaptic cleft and bind to postsynaptic receptors.

  • Summation of excitatory (EPSPs) and inhibitory (IPSPs) potentials determines if action potential occurs in postsynaptic neuron.

Nervous System Organization

  • Central Nervous System (CNS): Brain and spinal cord.

  • Peripheral Nervous System (PNS): Sensory and motor neurons, further divided into somatic (voluntary) and autonomic (involuntary) systems.

  • Reflex circuits enable rapid responses bypassing the brain.

Sensory Receptors

  • Chemoreceptors: detect chemical stimuli (smell/taste).

  • Mechanoreceptors: respond to pressure and touch.

  • Photoreceptors: convert light energy into electrical signals.

Brain Structure

  • Comprised of three regions: hindbrain, midbrain, and forebrain.

  • Grey Matter: cell bodies; White Matter: axons.

  • Areas for sensory processing are organized into specific lobes: frontal, parietal, occipital, and temporal.