Essays --

The term â€Å"Manifest Destiny† was, in part, an expression of a genuine ideal on the part of Americans. Yet it was also a justification to a push and to assume territory. The idea of Manifest Destiny was sparked by revolutionary American writings that encouraged appropriation of Canada. These writings rationalized that the Louisiana Purchase and the Untied States’ annexation of Texas ordained American complete domination of the North American continent. More broadly stated, Manifest destiny was a conviction that God intended North America to be under the control Americans. It’s an assertion of Anglo-Saxon supremacy. Imbedded in the notion of Manifest Destiny is an American hypocrisy of the 1st Order. While its founding documents espoused freedom and independence, the United States adopted a philosophy of dominance by shear brute force, or whatever means necessary to achieve hegemony over its continent. This conviction of Manifest Destiny was a product of American propaganda and publicity. While America represented liberty, it poised itself for expansion. The Mexicans, warily acknowledge...

A Study Of Anatomy And Psychology Essay

The procedure in lifting the leg to climb a stair is a complex one which involves a huge amount of technology inter-transfer between the brain and the eventual skeletal muscle. There is initiation of the movement at the brain which is transmitted via specialized white fibre tracts to the hip flexors via the intermediate spinal cord, involving a very complex mechanism at the cellular level   The initiation of the   process is at the motor cortex (Ms I) of the brain. The primary motor area is located at the precentral gyrus of the frontal lobe. The area controlling the motion of the lower limbs lies towards the superior surface of the brain. Within this area lies the cell body of the primary neuron. These neurons are known as upper motor neurons (UMN). These UMNs receive modulating impulse from the inputs from the cerebellum and the basal ganglia via the extrapyramidal pathways. These tracts modulate the gross movement initiated at the frontal cortex. In turn these areas are modulated by afferent signals from ascending spino cerebellar, and spino-thalamic pathways. The complex the signal initiated at the nucleus of the cell body is transmitted electronically via the axon of the myelinated neuron via the mode of salutatory conduction. The myelin sheath which surrounds the axon of nerves that involve fast transport, breaks at intermediate regions known as Nodes of Ranvier. The electrical impulse moves in   a jumping manner at these nodes nerve transmission as a neural impulse, generated by the formation of a nerve action potential. Like all excitable tissue, nerves maintain a resting membrane potential that is the difference of voltage across the membrane of the neuron. In neurons this value is   – 70 mV. This voltage difference is maintained by the Na/K pump on the membranes. This impulse generated at the axon hillock is transmitted via the depolarizing phase which allows sodium ions ingress into cells via opening of the Na channels. This entry of Na in one portion allows activation of other Na channels, causing depolarization of the adjacent region of the neuron. Subsequently repolarization occurs via the opening of K channels, which restores the membrane potential. Thus this process continues which allows the transmission of impulse. Many such nerves together descend as the descending cortico spinal tract in the pyramidal system, which travels through the midbrain into the spinal cord, decussating at the level of midbrain( 90% of the fibres decussating and forming the lateral spinothalamic tract) and again at the level of spinal cord ( the other 10%, forming the anterior spinothalamic tract) . It is the former which is responsible for the lower limb movements. The cortico-spinal tract travels in the anterior horn cell of the spinal cord till the lumbar level where they synapse with the spinal ventral root neuron (lower motor neuron). A single post-synaptic neuron receives signals from many neurons. At the axon terminal, the propagation of impulses leads to release of neurotransmitters, which are stored in specialized vesicles. The released Ach diffuses into the synaptic cleft and binds with receptors on the post synaptic membrane to produce excitatory post synaptic potentials. This leads to generation and propagation of impulse in nerves which are destined to innervate the neuro-muscular junction. At the neuro-muscular junction, Ach is released, which diffuses into the synovial cleft and binds to receptors in the motor end plate, and triggers a muscle action potential. The released Ach is destroyed by the acetylcholinestrase. At the level of the sarcolemma of the muscles, the muscle AP travels along T-tubules, opening Ca release channels in the sarcoplasmic reticulum. Ca binds to troponin-tropomysin complex, which releases the myosin heads, these then bind to the actin thin filaments, and draws them closer to the M line. Meanwhile bringing the Z disc closer. This leads to muscle fibre contraction. This is a self propagating sequence eventually leading to the contraction of ilio-psoas muscle, which causes the flexion of thigh on the pelvis. Each nerve fibre innervates many musle fibres ( about 150). This is   the motor unit. The greater the number of motor units recruited by the nerve action potential, the greater the force of contraction of the muscles. In the spinal cord, nerve impulse travels along the lumbar plexus (L1-L5) to innervate the iliopsoas ( hip flexion- ilio-inguinal nerve), biceps femors, semitendinosus and semimembranosus ( knee flexion – sciatic nerve), ankle flexors ( EHl, EDL, TA – tibial nerve), leading to the person climbing the step. This excitatory impulse is also associated with the production of inhibitory action potential ( hyperpolarizing impulse) in the antagonists (eg the glutei, which must relax to allow flexors to act. In the event of raising of the upper limb above the head, to lift a book, the impulse travels along the cortico spinal tract till the level of the cervical cord to synapse with the lower motor neurons of the brachial plexus ( C3-T1). From here the nerve impulses travel to shoulder elevators ( supraspinatus, deltoid, trapezius, and latissimus dorsi)- posterior cord ), elbow extensor ( triceps and anconeus – radial nerve) wrist extensor ( ECRL, ECRB – radial nerve), finger flexors ( FDS, FDP – median nerve and the ulnar nerve)   and the intrinsics – ulnar nerve and the median nerve)

Analysis Of On Keeping A Notebook By Joan Didion

ON KEEPING A NOTEBOOK RHETORICAL ANALYSIS The point of keeping a notebook has never been, nor is it now to have an accurate factual record of what I have been doing or thinking. Author, Joan Didion, in her essay, â€Å"On Keeping a Notebook† explains how to keep a notebook and why. Didion’s purpose is to inform us on how she keeps a notebook and why notebooks are useful in helping us to remember events that happened in the past. She adopts a sentimental tone in order to emphasize how many memories are kept alive by keeping a notebook. Didion uses ethos, pathos, and different rhetorical devices in her essay to explain her point. Didion uses ethos appeals. She explains in the first paragraph all of her accomplishments. She is the author of novels, short stories, screen plays, and essays. She began as a staff writer for Vogue Magazine in New York in 1956. Run River was her first novel published in 1963. Her collection of essays includes â€Å"On Keeping a Notebook†, Slouching Towards Bethlehem, published in 1968, The White Album, Salvador, Miami, After Henry, Political Fictions, Fixed Ideas: America Since 9.11, and Where I Was From, were all written and published within the next twenty four years (paragraph 1). In the essay â€Å"On Keeping a Notebook†, Didion uses pathos appeals to reveal emotions. In the second paragraph Didion states â€Å"I write entirely to find out what’s on my mind, what I’m thinking, what I’m looking at, what I’m seeing, and what it means, what I want and what I’m afraidShow MoreRelatedEssay on On Keepin a Notebook783 Words   |  4 PagesAnalysis on On Keeping a Notebook Joan Didions tone in her essay On Keeping a Notebook, is explanatory and a little sarcastic. She wasnt so much explaining how to keep a notebook as she was explaining why she kept hers the way she did; which made the reader interested in reading it. Didions sarcasm comes from her explanation. Joan Didions diction in her essay was informal and abstract. Since the note is in my notebook, it presumably has some meaning to me, (pg. 79) In fact I haveRead MoreThe Effects Of Imperialism In George Orwells Shooting An Elephant1633 Words   |  7 Pageslast their families a lifetime, or perhaps even longer.    Process Analysis: Joan Didion, On Keeping a Notebook   Ã‚  Ã‚   In the selection On Keeping a Notebook, Joan Didion uses her experiences in day to day life as a writer in order to demonstrate the importance/methods of keeping a daily notebook. Didion appeals to her audience by displaying her expertise in the subject at hand, especially by stating, â€Å"So the point of keeping a notebook has never been, nor is it now, to have an accurate factual record