【正文】 hich it has bound. This will only happen if the concentration of acetylcholine in the synaptic cleft is very low. Low synaptic concentrations of acetylcholine can be maintained via a hydrolysis reaction catalyzed by the enzyme acetylcholinesterase. This enzyme hydrolyzes acetylcholine into acetic acid and choline. If acetylcholinesterase activity is inhibited, the synaptic concentration of acetylcholine will remain higher than normal. If this inhibition is irreversible, as in the 10 case of exposure to many nerve gases and some pesticides, sweating, bronchial constriction, convulsions, paralysis, and possibly death can occur. Although irreversible inhibition is dangerous, beneficial effects may be derived from transient (reversible) inhibition. Drugs that inhibit acetylcholinesterase in a reversible manner have been shown to improve memory in some people with Alzheimer39。 in response to activation of this nerve supply, smooth muscle contracts (notably in the gut), the frequency of heart beat is slowed, and glands secrete. Acetylcholine is also an important transmitter at many sites in the brain at nervetonerve synapses. To understand how acetylcholine brings about a variety of effects in different cells it is necessary to understand membrane receptors. In postsynaptic membranes (those of the cells on which the nerve fibres terminate) there are many different sorts of receptors and some are receptors for acetylcholine. These are protein molecules that react specifically with acetylcholine in a reversible fashion. It is the plex of receptor bined with acetylcholine which brings about a biophysical reaction, resulting in the response from the receptive cell. Two major types of acetylcholine receptors exist in the membranes of cells. The type in skeletal muscle is known as ?nicotinic‘。 9 請您刪除一下內(nèi)容， O(∩ _∩ )O 謝謝?。?！ 2021 年中央電大期末復(fù)習(xí)考試小抄大全，電大期末考試必備小抄，電大考試必過小抄Acetylcholine is a neurotransmitter released from nerve endings (terminals) in both the peripheral and the central nervous systems. It is synthesized within the nerve terminal from choline, taken up from the tissue fluid into the nerve ending by a specialized transport mechanism. The enzyme necessary for this synthesis is formed in the nerve cell body and passes down the axon to its end, carried in the axoplasmic flow, the slow movement of intracellular substance (cytoplasm). Acetylcholine is stored in the nerve terminal, sequestered in small vesicles awaiting release. When a nerve action potential reaches and invades the nerve terminal, a shower of acetylcholine vesicles is released into the junction (synapse) between the nerve terminal and the ?effector‘ cell which the nerve activates. This may be another nerve cell or a muscle or gland cell. Thus electrical signals are converted to chemical signals, allowing messages to be passed between nerve cells or between nerve cells and nonnerve cells. This process is termed ?chemical neurotransmission‘ and was first demonstrated, for nerves to the heart, by the German pharmacologist Loewi in 1921. Chemical transmission involving acetylcholine is known as ?cholinergic‘. Acetylcholine acts as a transmitter between motor nerves and the fibres of skeletal muscle at all neuromuscular junctions. At this type of synapse, the nerve terminal is closely apposed to the cell membrane of a muscle fibre at the socalled motor end plate. On release, acetylcholine acts almost instantly, to cause a sequence of chemical and physical events (starting with depolarization of the motor endplate) which cause contraction of the muscle fibre. This is exactly what is required for voluntary muscles in which a rapid response to a mand is required. The action of acetylcholine is terminated rapidly, in around 10 milliseconds。（ 2）比例賠償方式 （ 3）保險人應(yīng)該支付的保險賠款是 186萬元。在救火搶險過程中發(fā)生施救費用 1萬元。但保險金應(yīng)作為被保險人的遺產(chǎn)，由被保險人的繼承人申領(lǐng)。在《保險法》中受益人均是指定的，不存在法定受益人的概念，因此，應(yīng)認定被保險人把受益人填寫為“法定”是無效的，等同于未指定。受益人故意造成被保險人死亡或者傷殘的，或者故意殺害被保險人未遂的，喪失受益權(quán)。保險人不承擔(dān)給付保險金的責(zé)任。本案中，對被保險人來說，完全是一種外來的、突然的、不能預(yù)料的客觀事件，符合意外傷害的定義和特征，屬于保險公司承擔(dān)保險責(zé)任的范圍。 第二種意見是正確的。第二種意見認為，被保險人被其妻故意殺害，是違法行為，但對于被保險人來說屬于意外傷害，應(yīng)承擔(dān)賠償責(zé)任。保險公司經(jīng)審查，形成了兩種截然不同的意見：第一種意見認為，被保險人是被其妻故意殺害，是違法犯罪行為，不屬于意外傷害。在受益人的項目內(nèi)，王某填寫的受益人為“法定”。請分析該案例，并回答下列問題 : （ 1）根據(jù)建筑工程一切險條款規(guī)定，地基下陷應(yīng)屬于意外事故還是自然災(zāi)害？ （ 2）該建筑工程保險的被保險人可以為誰？ （ 3）在工程保險中，保險人賠償被保險人的方式有哪些？ （ 4）若按專家在查勘后得出的結(jié)論，地陷原因為該地區(qū)地質(zhì)構(gòu)造形成巖溶坍塌所致。 2 某建筑公司在承建某工業(yè)局主管的工廠進行技術(shù)改造時，對擴建的四車間投保建筑工程一切險，保險金額 560 萬 7 元，按工程概算總造價投保金額應(yīng)為 800萬元。 2 某汽車投保了第三者責(zé) 任保險，保險期間為一年，責(zé)任限額為 15萬元，在保險期間先后發(fā)生兩次保險事故，被保險人應(yīng)承擔(dān)的賠償責(zé)任分別為 9萬元、 23萬元。保險事故在此期限內(nèi)發(fā)生，保險人負給付保險金的義務(wù)；反之，則不負義務(wù)。因為保險合同成立的時間與保險責(zé)任開始的時間并不是一回事，保險責(zé)任的開始時間應(yīng)根據(jù)保險合同約定的保險期限而定。投保后兩 天即 5月 3