5187680
Descrição
FlashCards por Georgina Burchell, atualizado more than 1 year ago
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Criado por Georgina Burchell
mais de 8 anos atrás
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| Questão | Responda |
| Are Anions positively or negatively charged? | Negatively charged |
| Name three things that make a neuron special? | 1. Specialized membrane 2. Axons and dendrites 3. Communicate with eachother |
| What mV is resting potential? | -60mV compared to the outside of the cell |
| What are ion channels? | Proteins that span the membrane and allow ions to pass |
| The neuron shows selective permeability to... | K+ |
| What two forces drive ion movement? | Elecrostatic potential Diffusion |
| Why is the inside of the cell more negative? | Negatively charged proteins on the inside of the cell that cannot get past the membrane |
| How does the sodium potassium pump work? When is it activated? | 3 Na+ out 2 K+ in Uses a lot of ATP (energy) Activated during an action potential |
| Explain why some K+ ions move in and some move out during resting potential. | K+ ions move to negative interior of the the cell due to electrostatic pressure. k+ ions build up inside and they move out via diffusion. |
| When is equilibrium reached? | When the movement of K+ is balanced in and out |
| What is hyperpolarization? What does this do to the membrane potential? | Interior becomes even more negative. It increases the membrane potential |
| What is depolarization? What does it do to the membrane potential? | Decrease in membrane potential, interior becomes less negative |
| Expain two properties of a hyperpolarizing stimulus | Graded response. (Big stimulus=Big response) As the potential spreads across the membrane, it diminishes). |
| What is threshold potential? What does an action potential do to membrane potential? | An action potential occurs when a depolarizing stimulus reaches the threshold potential (-40Mv) Membrane potential reverses and the inside of the cell becomes positive |
| Where do action potentials originate? | Axon hillock |
| Name 3 properties of an action potential | All-or-nothing property Depolarizing stimulus Action potentials increase in frequency with increased stimulus strength (summation). |
| What ion produces an action potential? What is the Na+ equilibrium potential (in mV)? | Action potentials are produced by the movement of Na+ ions into the cell through channels in membrane. Membrane potential reaches the Na+ equilibrium potential of +40 mV. |
| How is resting potential restored? | Voltage gated K+ channels open to restore the resting potential and the sodium potassium pump restores the balance of Na+ and K+ |
| Absolute refractory phase | time when no action potentials are produced |
| Relative refractory phase | time when only strong stimulation can produce an action potential. |
| What does 'regenerated' refer to? | Action potentials are regenerated along the axon—each adjacent section is depolarized and a new action potential occurs. |
| Why can action potentials only go in one direction? | Refractory period |
| What do nodes of ranvier do? | Allow sultatory conduction to occur this is when potential travels inside the axon and jumps from node to node |
| What is the myelin sheath made of? | Schwann cells (PNS) Oligodendrocytes (CNS) |
| What is conduction velocity | The speed of propagation of action potentials—varies with diameter |
| What is a excitatory postsynaptic potential (EPSP) | A small local depolarization, pushing the cell closer to threshold. Caused by opening of Na+ channels on the post-synaptic membrane |
| Inhibitory postsynaptic potential (IPSP) | A small local hyperpolarization, pushing the cell further away from threshold Caused by chloride ions (Cl-) entering the post-synaptic membrane |
| How do neurons know if they should fire? | Neurons perform information processing to integrate synaptic inputs. A postsynaptic neuron will fire an action potential if a depolarization that exceeds threshold (-40mV) reaches its axon hillock |
| Two things that will effect whether an action potential occurs | Spatial Summation -Location of the synaptic inputs is significant Temporal Summation -Lots of action potentials in quick succession |
| What did Otto Loewi discover in 1936? | Acetylcholine |
| How does an action potential chemically pass over a synapse | |
| How does the neurotransmitter leave the synaptic cleft? | Transmitter is inactivated (by enzymatic degradation) or removed (by transporters for reuptake and recycling). |
| What are ligands? | Ligands fit receptors exactly and activate or block them |
| Two types of ligands | Endogenous ligands—neurotransmitters and hormones Exogenous ligands—drugs and toxins from outside the body |
| What are agonists? | Molecules that act like the transmitter at a receptor are called agonists of the receptor |
| What are antagonists? | Molecules that interfere with or prevent the action of a transmitter at its receptor |
| Describe a ionotropic receptor | also known as ligand-gated ion channel (fast) |
| Describe a metabotropic receptor | Activate G proteins G proteins, sometimes open channels or may activate another chemical to affect ion channels (slow) |
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