Comparison of Snakecharmer and In the Snake Park :: comparison compare contrast essays

Comparison of Snakecharmer and In the Snake Park  Ã‚  Ã‚      There are many methods available for poets to utilize in creating a desired effect. They may take a number of different approaches to enhance an aspect of their poetry. Both Snakecharmer, by Sylvia Plath and In the Snake Park, by William Plomer show how the poets take advantage of different techniques to illustrate the world of the snake, and draw us into it. Plath using diction and Plomer using imagery, both describe the snake in order to establish a mood for their poems. They then proceed to show the relationships between man and the snake. Plomer applies characterization to achieve this effect, while Plath uses symbolism to do so in a more subtle manner.   Ã‚  Ã‚   Plath's use of diction to emphasize the movement of the snake produces a mood of anxiety by suggesting that something evil is stirring. Alliteration is used to make the sentences flow in the motion of a serpent. This effect is achieved by weaving the words together fluidly. It is especially effective when the snakecharmer 'pipes water green until green waters waver'. The 'sways', 'coilings' and 'writhings' which occur during the formation of his world create a feeling of restlessness. An image is conjured of a twisted mound of snakes that throbs and churns on a wave of 'green' putrid water. At the beginning of the poem, the piper 'begins a snaky sphere with moon-eye, mouth-pipe.' This is repeated at the end when he 'puts up his pipe, and lids his moony eye'. The poem is given a sense of closure. It reels as though a cycle has been completed. This makes the poem swell and flow to mimic the action of the snakes.   Ã‚  Ã‚   Plomer uses imagery to describe the snakes in his poem. This imagery shows a process of change in the snakes as they encounter humans. In the beginning of the poem 'lethargy' lies 'here and there in coils'. This portrays the snakes as languid, peaceful creatures. They are sleeping in the 'white-hot midday' sun. However, the Ringsnake is then said to be pouring 'slowly through an opening like smoke'. Using smoke as a simile is effective in changing the tone of the poem. Smoke moves very ominously, and the snakes are now waking from their peaceful sleep and emerging. Toward the end of the poem, the tone changes again.

Outline the Differences Between the Excitation

Outline the differences between the excitation-contraction coupling mechanism between skeletal and cardiac muscles. Excitation-contraction coupling is the combination of the electrical and mechanical events in the muscle fibres and is related by the release of calcium from the sarcoplasmic reticulum. (Silverthorn, 2007) In the skeletal muscle, action potential in the nerves is generated when the somatic motor neurons releases the neurotransmitter acetylcholine (ACh), at the neuromuscular junction. This initiates muscle action potential which is then transmitted to the t-tubules.Action potential in the t-tubules leads to the release of calcium in the sarcoplasmic reticulum triggering muscle contraction. In the cardiac muscles, the initial depolarisation in sino-atrial node initiates the action potential in the muscles. This is then transmitted to T-Tubule which leads to calcium influx from extracellular space. This leads to the sarcoplasmic reticulum releasing calcium which causes the muscle contraction. The skeletal muscles need ACh from the somatic motor neuron, in order for skeletal muscle action potential to initiate excitation- contraction coupling.In cardiac muscles, the action potential also initiates EC coupling, but it originates impulsively in the hearts pace maker cells and spreads via gap junctions. (Richard and Pocock, 2006) The skeletal muscles and cardiac muscles differ mainly in mechanisms by which the depolarisation in the membrane leads to the release of Ca2+. In the skeletal muscle, the T-tubule membrane is coupled closely to the sarcoplasmic reticulum via the L-type calcium channel and the ryanodine receptor.However, in the cardiac muscle the Ca2+ enters via voltage-gated calcium channels which initiate a regenerative release, through activation of the Ca2+ sensitive ryanodine receptor and this initial entry triggers further release from the sarcoplasmic reticulum. (Rang and Dale, 2003) The mechanism of excitation- contraction coupling in the skeletal muscle relies on the ryanodine receptor being activated to produce the Ca2+ from the sarcoplasmic reticulum that is responsible for allowing muscle contraction. This is evident of direct coupling between the calcium channels of the T-tubule and the ryanodine receptors of the sarcoplasmic reticulum.The cardiac muscles lack T-tubules and therefore, there is no direct coupling between the plasma membrane and the sarcoplasmic reticulum. In cardiac muscles, the mechanism relies on a calcium-induced calcium release, which includes the conduction of calcium ions into the cell, causing the further release of ions. (Rang and Dale, 2003) The duration of action potential also differs for the skeletal and cardiac muscles. In the skeletal muscles, the action potential short and ends as the related twitch contraction begins.The twitch contraction is short and ends as the sarcoplasmic reticulum recovers the Ca2+ that it released. In the cardiac muscle cells, the action potential is long- lasting, and Ca2+ carries on entering the cell throughout the plateau period. As a result, the muscle cell contraction continues until the plateau ends. Therefore, the cardiac muscle contractions are nearly 10 times as long as those of skeletal muscles fibres. (Silverthorn, 2007) The cardiac muscle tissue can contract without neural stimulation, via automaticity and the specialized cardiac muscle cells called pacemaker cells control the timing of contractions.However, the skeletal muscle requires ACh from the motor neurons for contractions. (Mader, 2006) Mader, S, S,. (2006) Human Biology (9th ed. ). New York: McGrawhill Pocock, G. , Richards, D. C. , (2006). Human Physiology – the basis of medicine (3rd ed. ). New York: Oxford University Press Rang, P, H,. Dale, M, M,. Ritter, M, J,. Flower, J, R,. (2007). Pharmacology (6th ed. ). New York: Churchill Livingstone Elsevier Silverthorn, D, U. , (2007) Human Physiology (4th Ed. ). San Francisco: Benjamin Cummings.

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