Cellular Ion Exchange

The function of the Patellar-tendon stretch reflex is to obtain a mechanistic understanding of a simple reflex behavior. It is a monosynaptic reflex. The model system for this reflex is the Knee-jerk reflex.

The components of the nervous system include the central nervous system (CNS) and the peripheral nervous system (PNS). The neuronal structure consists of membrane structure, pumps, channels, and resting membrane potential.

An action potential is generated by the depolarization of the neuron's membrane, which leads to the opening of voltage-gated sodium channels. The action potential is then transmitted along the neuron's axon through the process of depolarization and repolarization.

<p>The signal travels from the neuron to the muscle through the release of neurotransmitters, such as acetylcholine, at the neuromuscular junction. This triggers an action potential in the muscle fiber, leading to muscle contraction.</p> Signup and view all the answers

<p>The learning objectives include being able to identify the different components of the CNS and PNS, the different cell types of the CNS, and describing their function. Additionally, understanding how the signal travels from neuron to muscle and how the electrical signal is converted into a mechanical movement (muscle contraction) is important.</p> Signup and view all the answers

<p>The goal is to obtain a mechanistic understanding of simple reflex behaviors, including how information is produced, transmitted, and processed along nervous system pathways. These reflexes serve as model systems for studying neural processing and behavior.</p> Signup and view all the answers

<p>Sodium and potassium ions play a key role in maintaining the resting membrane potential by contributing to the ionic gradients through the Na+/K+ pump, and by their movement across the membrane driven by chemical and electrical gradients.</p> Signup and view all the answers

<p>The resting membrane potential is determined by the balance of forces acting on each ion, including the influence of the Na+/K+ ATPase and selective leak channels.</p> Signup and view all the answers

<p>Leak channels, which are always open, allow passive flow of ions into and out of the neuron, contributing to the resting membrane potential.</p> Signup and view all the answers

<p>The equilibrium potentials for potassium and sodium are approximately -90mV and +60mV, respectively.</p> Signup and view all the answers

<p>The resting membrane potential is influenced by the activity of the Na+/K+ ATPase and selective leak channels, which help maintain the ionic gradients and passive ionic fluxes.</p> Signup and view all the answers

<p>The objectives covered in the text include understanding the action potential, electrotonic conduction, saltatory conduction, and the stretch reflex and its mechanistic understanding.</p> Signup and view all the answers

<p>Glia cells support and isolate neurons, produce myelin, guide migrating neurons, and form the blood-brain barrier.</p> Signup and view all the answers

<p>Neurons have distinct structures and polarities, with components such as dendrites, cell body, axon hillock, axon, and synaptic terminals determining the flow of information.</p> Signup and view all the answers

<p>The spinal cord houses three types of neurons: dorsal roots (sensory), ventral roots (motor), and interneurons. They are involved in reflexes and information processing.</p> Signup and view all the answers

<p>The resting membrane potential (Em) is approximately -70mV and is primarily maintained by the movement of ions through specific channels and pumps, such as the Na+/K+ pump.</p> Signup and view all the answers

<p>The reflex loop involves afferent fibers, dorsal horn, white matter, gray matter, efferent fibers, and ventral horn, which collectively generate a reflex response.</p> Signup and view all the answers

<p>Different types of neurons, including bipolar, pseudo-unipolar, and multipolar cells, have specific functions and structures, contributing to sensory processing and information transmission.</p> Signup and view all the answers

<p>Voltage-gated Na+ channels open during depolarization, allowing Na+ to flow into the cell and causing the rapid depolarization phase of the action potential. Voltage-gated K+ channels open during repolarization, allowing K+ to flow out of the cell and restoring the resting membrane potential.</p> Signup and view all the answers

<p>Muscle stretch or other stretch receptor sensory stimuli lead to increased opening of specialized Na+ receptors and depolarization of afferent neurons, which results in the opening of voltage-gated Na+ channels and the generation of an action potential.</p> Signup and view all the answers

<p>The resting membrane potential is determined by the relative permeability of the membrane to Na+ and K+ ions.</p> Signup and view all the answers

<p>The refractory period prevents the reopening of voltage-gated Na+ channels and ensures that the action potential can only propagate in one direction along the axon.</p> Signup and view all the answers

<p>The patellar-tendon stretch reflex involves interneurons in a monosynaptic reflex arc, which helps relay sensory information from the stretch receptors to the motor neurons, leading to the muscle contraction.</p> Signup and view all the answers

<p>Specific stimuli disrupt the steady state and cause ion-selective channels in the membrane to open, leading to changes in membrane potential and the generation of an action potential.</p> Signup and view all the answers

<p>Myelination increases the speed of electrotonic conduction by forming a sheath around the axon, which allows for saltatory conduction and regeneration of action potentials at the nodes of Ranvier, thus increasing conduction speed without requiring AP regeneration at every part of the axonal membrane.</p> Signup and view all the answers

<p>Electrical synapses allow for bidirectional communication between cells and are important for rapid and synchronized signaling, particularly in networks requiring coordinated activity.</p> Signup and view all the answers

<p>Afferent neurons carry information from the periphery to the spinal cord, transmitting sensory information to the central nervous system.</p> Signup and view all the answers

<p>Myelination contributes to the refractory period by enabling the spread of action potentials in a unidirectional manner, due to the regeneration of action potentials at the nodes of Ranvier.</p> Signup and view all the answers

<p>Chemical synapses are larger in gap, directly-gated, and involve the transmission of signals between pre and post-synaptic cells.</p> Signup and view all the answers

<p>Afferent fiber types are classified based on their diameter and conduction speed, with larger diameter fibers having faster conduction speeds compared to smaller diameter fibers.</p> Signup and view all the answers