Physiology Midterm Flashcards

MEMBRANE TRANSPORT Ions need to be regulated for normal neuron function. A state of relative constancy of the internal environment is known as homeostasis, maintained by negative feed- back loops

MEMBRANE TRANSPORT Body maintains a constant internal environment.

MEMBRANE TRANSPORT a solution that bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and transcellular fluid.

Active Transport and Cellular respiration: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP (energy). MEMBRANE TRANSPORT Ventilation and gas transport require energy to power a mechanical pump (the heart) and the muscles of respiration, mainly the diaphragm. In heavy breathing, energy is also required to power additional respiratory muscles such as the intercostal muscles.

Gain water

MEMBRANE TRANSPORT is the movement of a substance against its concentration gradient using energy.

MEMBRANE TRANSPORT Prevents the dissipation of the concentration gradient for Na+.  MEMBRANE TRANSPORT The Na+/K+ pump illustrates "active transport" since it moves Na+ and K+ against their concentration gradients.

MEMBRANE TRANSPORT Couples the movement of a substance up its concentration gradient to another ion that is moving down its electrochemical gradient which was established earlier using cellular energy (ATP).

MEMBRANE TRANSPORT For the voltage-gated sodium channel to open and allow sodium into the cell, the activation and inactivation gates must both be open.

Are short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a stereotyped trajectory. The opening of voltage-regulated channels produces an action potential. Stronger stimuli produce action potentials with greater frequency. One action potential serves as the depolarization stimulus for production of the next action potential in the axon. In unmyelinated axons, action potentials are produced fractions of a micrometer apart. In myelinated axons, action potentials are produced only at the nodes of Ranvier. This saltatory conduction is faster than conduction in an unmyelinated nerve fiber.

Depolarization to threshold or above > increased gNa+ (Na+ conductance) > Na+ influx > increased gK+ > K+ efflux

Nerve cells code the intensity of information by the frequency of action potentials. When the intensity of the stimulus is increased, the size of the action potential does not become larger. Rather, the frequency or the number of action potentials increases.

Calcium triggers neurotransmitter release from the presynaptic neuron. A chemical contained in synaptic vesicles in nerve endings that is released into the synaptic cleft, where it causes the production of either excitatory or inhibitory postsynaptic potentials.

ACh causes a hyperpolarization known as an inhibitory postsynaptic potential, or IPSP. The binding of ACh to its muscarinic receptors indirectly affects the permeability of K + channels. This can produce hyperpolarization in some organs (if the K+ channels are opened). Hyperpolarization, slowing rate of spontaneous depolarization, mechanism: ACh activates G-protein coupled receptor, opening channels for K+ Outward diffusion of K+ results, slowing the heart rate.

An acetic acid ester of choline—a substance that functions as a neurotransmitter chemical in somatic motor nerve and parasympathetic nerve fibers.