【正文】 and there are some of each type in the brain. These terms are used because nicotine mimics the action of acetylcholine at nicotinic receptors, whereas muscarine, an alkaloid from the mushroom Amanita muscaria, mimics the action of acetylcholine at the muscarinic receptors. Acetylcholine is the neurotransmitter produced by neurons referred to as cholinergic neurons. In the peripheral nervous system acetylcholine plays a role in skeletal muscle movement, as well as in the regulation of smooth muscle and cardiac muscle. In the central nervous system acetylcholine is believed to be involved in learning, memory, and mood. Acetylcholine is synthesized from choline and acetyl coenzyme A through the action of the enzyme choline acetyltransferase and bees packaged into membranebound vesicles . After the arrival of a nerve signal at the termination of an axon, the vesicles fuse with the cell membrane, causing the release of acetylcholine into the synaptic cleft . For the nerve signal to continue, acetylcholine must diffuse to another nearby neuron or muscle cell, where it will bind and activate a receptor protein. There are two main types of cholinergic receptors, nicotinic and muscarinic. Nicotinic receptors are located at synapses between two neurons and at synapses between neurons and skeletal muscle cells. Upon activation a nicotinic receptor acts as a channel for the movement of ions into and out of the neuron, directly resulting in depolarization of the neuron. Muscarinic receptors, located at the synapses of nerves with smooth or cardia。 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’。（ √ ） .（ √ ） 25 請(qǐng)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(guò)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。（ √ ） 。（ √ ） ，不必考虞經(jīng)營(yíng)租憑對(duì)長(zhǎng)期償債能力的影響（ ） 。（√ ） ,表明該企業(yè)支付現(xiàn)金股利的能力越強(qiáng)。（ √ ） ,在其他因素不變的情況下 ,提高權(quán)益乘數(shù) ,將提高凈資產(chǎn)收益率 . （ √ ） ..（ √ ） 。（ √ ） .（ √ ） . 。（ ） .（ ） ,說(shuō)明部分長(zhǎng)期資產(chǎn)是以流動(dòng)負(fù)債作為資金來(lái)源的 .（ √ ） ,有利于不同企業(yè)之間的比較 。（） 49．一般來(lái)說(shuō)服務(wù)業(yè)的資產(chǎn)周轉(zhuǎn)率比制造業(yè)的資產(chǎn)周轉(zhuǎn)率慢。（） 24 47．一般情況下，長(zhǎng)期資產(chǎn)是償還長(zhǎng)期債務(wù)的資產(chǎn)保障。（ ） 45．企業(yè)放寬信用政策，就會(huì)使應(yīng)收賬款增加，從而增大了發(fā)生壞賬損失的可能。（） 43．固定資產(chǎn)折舊是一種付現(xiàn)成本，在計(jì)算現(xiàn)金流量時(shí)不應(yīng)加以扣除。（ ） 41．一般情況下，經(jīng)營(yíng)租賃中的利息費(fèi)用約占到整個(gè)租賃費(fèi)用的 1/2。（√ ） 39．如果已知負(fù)債與所有者權(quán)益的比率為 40％，則資產(chǎn)負(fù)債率為 60％。（ ） 37．如果流動(dòng)負(fù)債為 60萬(wàn)元，流動(dòng)比率為 ,速動(dòng)比率為 ，則年末存貨價(jià)值為 84萬(wàn)元。（√ ） 35．存貨發(fā)出計(jì)價(jià)采用后進(jìn)先出法時(shí)，在通貨膨脹情況下會(huì)導(dǎo)致高估本期利潤(rùn)。（√ ） 33．現(xiàn)金比率可以反映企業(yè)隨時(shí)還債的能力。（ ） 31．酸性測(cè)試比率也可以被稱為現(xiàn)金比率。（） 29．銀行本票存款是屬于具有特殊用途的 現(xiàn)金，在確定流動(dòng)資產(chǎn)時(shí)應(yīng)將其扣除。（√） 27．債務(wù)保障率是經(jīng)營(yíng)活動(dòng)產(chǎn)生的現(xiàn)金凈流量與流動(dòng)負(fù)的比值。（） 25．現(xiàn)金流量表中的現(xiàn)金包括庫(kù)存縣金，可以隨時(shí)支付的銀行存款和其他貨幣資金。（√ ） 23．特殊的經(jīng)濟(jì)增加值是公司經(jīng)濟(jì)利潤(rùn)最正確和最準(zhǔn)確地度量指標(biāo)。（） 21．如果企業(yè)因認(rèn)股證持有者行使認(rèn)股權(quán)利，增發(fā)的股票超過(guò)現(xiàn)有流通在外普通股的 3%時(shí)，則該企業(yè)屬于復(fù)雜資本結(jié)構(gòu)。（√ ） ，息稅前利潤(rùn)越大，財(cái)務(wù)杠桿系數(shù)越大。（√ ） 17．在資本總額，息稅前利潤(rùn)相同情況下，負(fù)債比例越大，財(cái)務(wù)杠桿系越大。（） 15．營(yíng)業(yè)周期越短，資產(chǎn)流動(dòng)性越強(qiáng)，資產(chǎn)周相對(duì) 越快。（√ ） 13．應(yīng)收賬款周轉(zhuǎn)率用賒銷額取代銷售收入，反映資產(chǎn)有效性。（√ ） 11．當(dāng)流動(dòng)資產(chǎn)小于流動(dòng)負(fù)債時(shí)，說(shuō)明部分長(zhǎng)期資產(chǎn)是以流動(dòng)負(fù)債作為資金來(lái)源的。（ ） 9．分析企業(yè)的流動(dòng)比率，可以判斷企業(yè)的營(yíng)運(yùn)能力。（ ） 7．分析企業(yè)的流動(dòng)比率，可以判斷企業(yè)的營(yíng)運(yùn)能力。（ ） 5．壞賬是否發(fā)生以及壞賬準(zhǔn)備提取的數(shù)額屬于會(huì)計(jì)政策。（ ） 3．比較分析有三個(gè)標(biāo)準(zhǔn)：歷史標(biāo)準(zhǔn)，同業(yè)標(biāo)準(zhǔn)，預(yù)算標(biāo)準(zhǔn)。（ ） 23 1．企業(yè)的基本活動(dòng)主要是供應(yīng)，生產(chǎn)，銷售活動(dòng)。（ ） 49．一般來(lái)說(shuō)服務(wù)業(yè)的資產(chǎn)周轉(zhuǎn)率比制造業(yè)的資產(chǎn)周轉(zhuǎn)率慢。（ ） 47．一般情況下，長(zhǎng)期資產(chǎn)是償還長(zhǎng)期債務(wù)的資產(chǎn)保障。（ ） 45．企業(yè)放寬信用政策，就會(huì)使應(yīng)收賬款增加，從而增大了發(fā)生壞賬損失的可能。（ ） 43．固定資 產(chǎn)折舊是一種付現(xiàn)成本，在計(jì)算現(xiàn)金流量時(shí)不應(yīng)加以扣除。（ ） 41．一般情況下