Lecture 8 & 9 Flashcards

Question

Synaptic Cleft

Answer 1

the space b/t the pre- & postsynaptic cells

Answer 2

neurotransmitters are packaged into synaptic vesicles. When an action potential opens presynaptic voltage-gated Ca2+ channels, the neurotransmitters are released by Ca2+-triggered synaptic vesicle exocytosis into the synaptic cleft, where they activate postsynaptic receptors. ?

Answer 3

the cell that receives the signal

Answer 4

small secretory vesicles that release neurotransmitter into the synapse

Answer 5

an extension of a neuron that carries signals to the target cell

Answer 6

a nonmyelinating Schwann cell - trophic factors - a type of glia in PNS

Answer 7

cell that forms myelin around a peripheral neuron axon - AKA myelinate axons - a type of glia in PNS

Answer 8

CNS glial cell that forms myelin around several axons | - myelinate axons

Answer 9

glial cells in the CNS that contact both neurons & blood vessels - blood brain barrier, trophic factors, take up excess water & K+, neural stem cells, pass lactate to neurons

Answer 10

CNS glial cell that are specialized cells that create selectively permeable epithelial layer, the ependyma, that separates the fluid compartments of the CNS - line "ventricles", make neural stem cells

Answer 11

macrophages in the CNS | - "immune cells" of CNS

Answer 12

- may be specific for one ion or may allow ions of similar size & charge to pass - other ion channels are Ca2+ channels & Cl- channels * - neurons contain a high density of ion channels many types of ion channels, classified according to - ions they carry - where on the cell they are located - gating mechanisms

Answer 13

1. Voltage gated ion channel 2. Receptor channels 3. Phosphorylation gated 4. Stretch gated 5. Temperature gated

Answer 14

electrical signals??

Answer 15

(=ligand gated ion channel) - gate when they bind a ligand (releases neurotransmitter, cGMP...from a presynaptic cell) - an ion channel that is gonna open/close when it binds to a ligand

Answer 16

- changes in membrane potential open the channel - "threshold" - opened & closed by changes in MP

Answer 17

- undergoes a small conformational change that can allow some of those channels to open/close

Answer 18

- opens & closes when the cell membrane is deformed

Answer 19

- cell membrane will open & close depending on changes in specific temps

Answer 20

Graded Potentials: 1. Signals communicated from one neuron to the next are graded potentials: POSTSYNAPTIC POTENTIALS 2. Small, "SUBTHRESHOLD" changes in membrane potential 3. Can be DEpolarizing or HYPERpolarizing 4. PASSIVE (do NOT regenerate) 5. Gradually DISSIPATE as they travel through a cell 6. Proportional to the SIZE of the stimulus 7. Caused by the FLOW OF IONS through a few ion channels 8. Can be SUMMED 9. Can be LONG-LASTING Action Potentials: 1. Wave of depolarization that ACTIVELY PROPAGATES across neuronal membrane (=REGENERATIVE, NOT PASSIVE) 2. ALL or NONE 3. FAST! Lasts only a few milliseconds 4. Often called a SPIKE, or abbreviated AP 5. LARGE AMPLITUDE, about 100 mV (from RMP to peak) 6. ALWAYS DEpolarizing 7. Requires the membrane be depolarized PAST a THRESHOLD 8. There is a REFRACTORY PERIOD 9. CANNOT be summed 10. In neurons, SITE of AP generation is the AXON HILLOCK

Answer 21

- when one neuron stimulates something to happen in a postsynaptic neuron or cell, but the change in MP is gonna be a postsynaptic potential - a temporary change in the electric polarization of the membrane of a nerve cell (neuron). The result of chemical transmission of a nerve impulse at the synapse (neuronal junction), the postsynaptic potential can lead to the firing of a new impulse. ?

Answer 22

Degradation usually refers to reduction in quality of an analog or digital signal. When a signal is being transmitted or received, it undergoes changes which are undesirable. These changes are called degradation. ?

Answer 23

action potentials are uniform, all-or-none depolarizations that can travel undiminished over long distances - they either occur as a maximal depolarization (if the stimulus reaches threshold) or do not occur at all (if the stimulus is below threshold)

Answer 24

is the process of adding things up. In the case of nervous system, it is about adding up the effect of multiple stimuli, that are all individually subthreshold, so that together they are suprathreshold and are able to generate an action potential (a response) ?

Answer 25

Molecules must collide with sufficient energy, known as the activation energy, so that chemical bonds can break. Molecules must collide with the proper orientation. A collision that meets these two criteria, and that results in a chemical reaction, is known as a successful collision or an effective collision. ?

Answer 26

channels are closed??

Answer 27

channels are open??

Answer 28

Closed and inactivated states are ion impermeable. Before an action potential occurs, the axonal membrane is at its normal resting potential, about −70 mV in most human neurons, and Na+ channels are in their deactivated state, blocked on the extracellular side by their activation gates. ?

Answer 29

this delay, called the ABSOLUTE refractory period, represents the time required for the Na+ channel gates to reset to their resting position - b/c of the absolute refractory period, a 2nd action potential CANNOT occur before the 1st has finished - consequently, action potentials moving from trigger zone to axon terminal cannot overlap & cannot travel backwards a RELATIVE refractory period follows the absolute refractory period - during the relative refractory period, some but not all Na+ channel gates have reset to their original positions - in addition, during the relative refractory period, K+ channels are still open

Answer 30

the rising phase is due to a sudden temporary increase in the cell's permeability to Na+ - an action potential begins when a graded potential reaching the trigger zone depolarizes the membrane to threshold (-55mV) - as the cell depolarizes, voltage-gated Na+ channels open, making the membrane much more permeable to Na+ - Na+ ions then flow into the cell, down their concentration gradient & attracted by the negative membrane potential inside the cell - the strength of the electrochemical gradient is called the driving force for Na+ movement

Answer 31

the falling phase corresponds to increase in K+ permeability - voltage-gated K+ channels, like Na+ channels, open in response to depolarization - the K+ channel gates are much slower to open, however, & peak K+ permeability occurs later than peak Na+ permeability - by the time the K+ channels finally open, the membrane potential of the cell has reached +30 mV b/c of Na+ influx through faster-opening Na+ channels

Answer 32

This phase is the repolarization phase, whose purpose is to restore the resting membrane potential. Repolarization always leads first to hyperpolarization, a state in which the membrane potential is more negative than the default membrane potential. ?

Answer 33

fugu poison, or tetrodotoxin (TTX) comes from pufferfish & several other species of animals fugu is a very specific antagonist of voltage gated Na+ channels - high affinity, high specificity - high efficacy, high potency prevents entry of Na+ into cells prevents action potentials in neurons & muscle lidocaine, benzocaine & other anesthetics also block VG Na+ channels

Answer 34

competing ligands that bind & block receptor activity are called antagonists of the primary ligand

Answer 35

a competing ligand that binds & elicits a response is known as an agonist of the primary ligand

Answer 36

making the ion channels local???

Answer 37

occurs when myelin, which is the protective coating of nerve cells, experiences damage. When this happens, neurological problems can occur. It can result from various medical conditions, including multiple sclerosis (MS). (demyelination of CNS axons for MS)?

Answer 38

happens when the body's natural defense system can't tell the difference between your own cells and foreign cells, causing the body to mistakenly attack normal cells. - ex: multiple sclerosis

Answer 39

Modern genetics study defines environment as every influence other than genetic—such as air, water, diet, radiation, and exposure to infection—and it subscribes to the overarching assumption that every trait of every organism is the product of some set of interactions between genes and the environment. ?

Answer 40

Acute conditions are severe and sudden in onset. This could describe anything from a broken bone to an asthma attack. A chronic condition, by contrast is a long-developing syndrome, such as osteoporosis or asthma. ?

Answer 41

is the very large axon that controls part of the water jet propulsion system in squid. ?

Answer 42

is how individuals perceive, analyze, manipulate, use, and remember information. ?

Answer 43

an increase in blood K+ concentration shifts the RMP of a neuron closer to threshold & causes the cells to fire action potentials in response to smaller graded potentials

Answer 44

if blood K+ concentration falls too low - the RMP of the cells hyperpolarizes, moving father from threshold

Answer 45

the apparent leap-frogging of the action potential down myelinated axons

Answer 46

have no apparent axon, but have numerous branched dendrites

Lecture 8 & 9 Flashcards

(70 cards)