MIS {excel project } Assignment Example | Topics and Well Written Essays - 500 words

MIS {excel project } - Assignment Example Additionally; the total quantity of stock is calculated. The sales sheet provides data on sales of the items in stock by the respective customers. The sales are recorded and the total sales are also calculated. The sheet also stores details of the respective customers. The look up function is used in the item column to march the item with its code in the products sheet: =LOOKUP (H4, Products!$A$3:$A$13,Products!$B$3:$B$13). The look up function is also used to determine the price of each item: =LOOKUP ([@[Item Code]],Table1[Code],Table1[Selling Price]). It is in this sheet that the total sales are also calculated and the data sorted according to item code in ascending order. A pivot table called sales summary is generated from the sales sheet. In this sheet, the summary of sales of each item is displayed. The total sales of each item and all the items are totalled. A graph is then generated showing the quantity of items sold. Capital financing analysis is done on the capital financing sheet. In this sheet, the total capital required to establish the business is estimated. A list of possible financing options is also provided together with the percentage of financing. Additionally, the interest rate and the amount to be repaid is

Structure of the Male Reproductive System

Structure of the Male Reproductive System New chapter 35 The Male Reproductive System INTRODUCTION The male reproductive system has three principal functions: The differentiation and maintenance of the primary and secondary sex characteristics under the influence of the hormone testos ­terone, made in the testes. Spermatogenesis—the creation of the male gametes inside the testes. The penile delivery of sperm from the testes into the female’s vagina in the act of procre ­ation. This includes penile erection and ejaculation. SYSTEM STRUCTURE The male reproductive system comprises not only the male genitals, but also the cranial structures that help regulate the performance of the male re ­productive system—namely, the hypothalamus and pituitary. At the hypothalamic and pituitary level, however, male and female anatomy and histology are more or less the same. For more details on the hy ­pothalamic and pituitary structures involved in hu ­man reproduction, see Chapter 36. In the section that follows, we will focus on the anatomy and histology of the testes, the penis, and the ductal connections between the testes and penis. The Testes The male gonads, or testes, are suspended from the perineum in an external contractile sac called the scrotum (Figure 37.1A). Each testis is about 4 cm long, and the testes are perfused by the spermatic arteries. The spermatic arteries are closely apposed with the spermatic venous plexus, and this close contact al ­lows countercurrent heat exchange between artery and vein, cooling the blood that flows to the testes. Countercurrent heat exchange helps keep the testic ­ular temperature cool enough for optimal spermato ­genesis (1 °C to 2 °C cooler than body temperature). The external location of the testes in the scrotum serves as a second important cooling mechanism. Because the testes develop within the abdomen, they descend into the scrotum during fetal life, reaching the deep inguinal rings around week 28 of gestation and inhab ­iting the scrotum by birth. In some instances (3% of the time in full-term male infants), the testes do not descend—a condition called c ryptorchidism. Cryp ­torchidism must be corrected if the male is to have properly functioning, fertile gonads. The testes are composed of coiled seminiferous tubules embedded in connective tissue (see Figure 37.1B). The connective tissue, which makes up about 20% of the testicular mass, contains Leydig cells, which make testosterone. The seminiferous tubules, constituting 80% of the testicular mass, generate the sperm. The tubules contain two main cell types: spermatogonia and Sertoli cells. Sper ­matogonia are the germ cells that undergo meiosis to give rise to spermatids, the immediate precursors to spermatozoa. The copious cytoplasm of the Sertoli cells completely envelops and protects the spermatids, sealing them off from any contact with the tubules’ outer basement membrane or blood supply. This Sertoli sheath hence forms a blood-testis barrier to protect the male gametes from any harmful bloodborne agents, and to prevent the immune system from attacking the unique sperm-specific proteins as though they were foreign anti ­gens. By virtue of their position between the blood and the spermatids, the Sertoli cells also transport nutrients, oxygen, and hormones, such as testos ­terone, to the spermatids. Figure 37.1 Anatomy of the male reproductive system. A. Overview. B. A closer look at the testis. C. The ducts of the reproductive system shown in isolation. The ducts arising from both testes are depicted, converging on the posterior urethra inside the prostate gland. The spermatogonia sit outside the blood-testis barrier near the basement membrane. Here, they continuously conduct mitosis. The products of mitosis are pushed toward the tubule lumen and undergo meiosis and differentiation into sperm cells. The Sertoli barrier is fluid and accommodates the passage of cells developing into spermatids. The testes make around 120 million sperm a day. As they differentiate, the sperm migrate into the tubule lu ­men for transport distally to the rete testis, a plexus of ducts that collects sperm from each of roughly 900 seminiferous tubules. The rete testis empties into the epididymis, a single coiled tubule running from the top of the testis down its posterior aspect. In the epididymis, sperm are stored and undergo maturation before continuing their voyage outside the testis. The Ducts and Penis Each epididymis leads to a long, straight tube called the vas deferens (see Figure 37.1C). The vas deferens from the epididymis of each testis rises in the scrotum, ranges laterally through the inguinal canals, runs along the pelvic wall toward the poste ­rior, and descends along the posterior aspect of the bladder. Here the two vas deferens tubes widen into ampullae, which are attached to glands called the seminal vesicles. (There are two seminal vesicles, one for each vas deferens.) The seminal vesicles se ­crete more than half the volume of the semen. The two ampullae each send an ejaculatory duct through the prostate gland, and the ejaculatory ducts join the urethra inside the tissue of the prostate gland. From this point onward, the male urethra serves as part of both the reproductive and urinary tracts, unlike female anatomy, in which the reproductive and urinary tracts are completely separate. Male physiol ­ogy ensures that micturition and ejaculation do not occur simult aneously. The urethra next passes through the muscle tissue of the urogenital diaphragm, a consciously controllable sphincter. Sitting just under the urogen ­ital diaphragm are the bulbourethral glands (also called Cowper’s glands), which lubricate the urethra with mucus. Finally, the urethra enters the penis. The cylindrical penis houses the urethra in erectile tissue, which helps effect the transition between the excretory and reproductive functions of the urethra (Figure 37.2). This erectile tissue contains cavernous sinuses that fill with blood under circumstances of increased penile blood flow, leading to erection of the penis. When erect, the penis may be inserted into the vagina so that sperm may be delivered to the fallop ­ian tubes. Figure 37.2 Cross-section of the penis. The erectile tissue is present in three cylinders inside the penis, each called a corpus cavernosum and together called the corpora cavernosa. Two of the corpora lie dorsally and are sheathed by the ischio ­cavernosus muscles. One lies ventrally and is sheathed by the bulbospongiosus muscle. The ventral corpus cavernosum is also called the corpus spongiosum, and it is special in that it contains the urethra and forms the glans penis, the spongy head of the penis. The corpora are each supplied by a cavernous artery that gives out helicine arteries. The penis averages 8.8 cm (3.5 in) in length when flaccid and 12.9 cm (5.1 in) when erect, indicating no correlation between flaccid and erect size. SYSTEM FUNCTION Just as the female reproductive system is coor ­dinated by the hypothalamus and pituitary, the activities of the male reproductive system are coor ­dinated by the HPG axis, in this case the hypothala ­mic-pituitary-testicular (HPT) axis (Figure 37.3). (The gonadal HPT axis is not to be confused with the hy ­pothalamic-pituitary-thyroid axis, also labeled HPT.) The male axis shares with the female the exact same hypothalamic hormone, gonadotropin- releasing hormone (GnRH), and the same pituitary go ­nadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). (The gonadotropins are named for their female reproductive functions, but they act in the male nonetheless.) The same array of gonadal steroid hormones that is produced by the ovary is also synthesized by the male reproductive system, but in different proportions. Because of differential expression of enzymes in the steroid synthesis pathway, the female gonad makes predom ­inantly progesterone and est rogen, while the male gonad predominantly makes the androgen steroid hormone testosterone. Testosterone inhibits the secretion of GnRH, LH, and FSH in a classic negative-feedback loop. Figure 37.3 Hypothalamic-pituitary-testicular axis. Plus signs represent stimulation; minus signs represent inhibition. The HPT Axis GnRH is the initial driver of testicular function. It is secreted in a pulsatile fashion (one pulse every 1 to 3 hours) and distributes to the pituitary gonadotrophs through the hypothalamic-pituitary portal circula- tion. There, the releasing hormone stimulates the LH- and FSH-secreting cells. Each GnRH pulse directly prompts an LH pulse from the gonadotrophs. More frequent or larger-amplitude GnRH pulses result in more frequent or larger-amplitude LH pulses. GnRH also increases FSH release, but the correlation between GnRH and FSH release is not as exact. LH acts on the Leydig cells. The LH signal is transduced by a seven- transmembrane receptor linked through a G protein to adenylyl cyclase, which produces cAMP. LH-dependent elevations in cAMP promote testosterone synthesis from cholesterol and promote the growth of Leydig cells. Testosterone synthesis is increased by the activation and increased expression of key proteins involved in steroidogenesis, such as the steroidogenic acute regu ­latory protein (StAR). StAR shuttles cholesterol into steroid-manufacturing cells. The Leydig cells of the testis are unique in their ability to make testosterone in large amounts (Figure 37.4). While the zona reticulata cells of the adrenal gland also make androgens, the adrenal pathway stops at androstenedione, the im ­mediate precursor to testosterone. (Some peripheral tissues can make testosterone from androstenedione in small amounts.) FSH, meanwhile, binds to receptors on the Sertoli cells, activating the production of proteins involved in spermatogenesis. FSH also stimulates glucose metabolism, thereby providing energy to the sperm precursors. (Spermatogenesis will be discussed in more detail below.) Finally, FSH upregu ­lates the expression of the androgen receptor in Sertoli cells, thereby potentiating the influence of testosterone upon spermatogenesis. Like all steroids, testosterone binds an intracel ­lular receptor, which binds DNA transcription factors and influences gene expression. The distribution of testosterone receptors in the body tissues deter ­mines the targets of testosterone action. In addition, target tissues express an enzyme that converts testos ­terone to its more active form, dihydrotestosterone (DHT). This enzyme is 5à ¯Ã‚ Ã‚ ¡-reductase. DHT binds more avidly to the androgen receptor than does testos ­terone itself. Testosterone from the Leydig cells passes through the Sertoli cells and into the seminif ­erous tubules, where, alongside FSH, it promotes spermatogenesis. The Sertoli cells make androgen-binding protein (ABP), which helps them to retain testosterone. Testosterone also acts systemically, promoting growth and sustaining gene expression in many peripheral tissues. Testosterone is transported in the blood by sex hormone-binding protein (SHBP), also called sex hormone-binding globulin, a liv er-produced carrier protein that is structurally similar to ABP. It is thought that testosterone and SHBP itself may act at cell membrane receptors, in addition to testosterone’s genomic effects. This is parallel to the genomic and nongenomic modes of signal transduc ­tion employed by thyroid hormone. Finally, testosterone inhibits GnRH and go ­nadotropin secretion. Thus, testosterone limits its own production and action. Inhibin from the Sertoli cells also inhibits the pituitary and hypothalamus. Inhibin is a TGF-à ¯Ã‚ Ã‚ ¢ glycoprotein hormone. Investiga ­tions suggest that additional feedback mechanisms link Sertoli cell behavior with Leydig cell behavior. Table 37.1 summarizes the actions of testosterone. Table 37.1 Testosterone Actions The Expression of Male Sex Characteristics The male reproductive system begins to function during embryonic life. As soon as the testes form and are capable of secreting testosterone, the androgen begins to act on the body tissues. At this stage, the hormone differentiates the fetus into a male with the appropriate primary sex characteristics—the male genitals. At puberty, testosterone causes sustained expression of the secondary sex characteristics, which are gender-based phenotypes other than the genitals, such as hair growth, muscle development, and a low voice. Fetal Life and Infancy (Primary Sex Characteristics) While the testes do act in utero, they cannot act before they have formed, and they do not form right away. In fact, before 6 weeks of gestation, the gonads of geno ­typically male or female embryos have not begun to differentiate into either ovaries or testes. The so-called â€Å"indifferent gonad† has an inner medullary (male) and an outer cortical (female) layer. In addition, the anatomic precursors of both males (the Wolffian ducts) and females (the Mà ¼llerian ducts) are present. Only at 6 to 8 weeks of gestation is male sexual devel ­opment initiated by the SRY gene, a gene on the short arm of the Y chromosome. SRY encodes a zinc finger DNA-binding protein called testis determining factor (TDF). Under the influence of TDF, the medullae of the indifferent gonads develop while the cortices regress. The previously indifferent gonads differentiate into testes: embryonic germ cells form spermatogonia, coelomic epitheli al cells form Sertoli cells (6 to 7 weeks of gestation), and mesenchymal stromal cells form Leydig cells (8 to 9 weeks of gestation). Now the testes can begin to act. The Sertoli cells secrete a Mà ¼llerian-inhibiting factor (MIF), which causes regression of the Mà ¼llerian ducts. Human chorionic gonadotropin (hCG)—which is structurally related to LH—stimulates the Leydig cells to prolifer ­ate and secrete testosterone. The testosterone is reduced to DHT in target tissues by 5à ¯Ã‚ Ã‚ ¡-reductase. As long as target tissues contain the androgen receptor and 5à ¯Ã‚ Ã‚ ¡-reductase, DHT induces those tissues to form the primary male sex characteristics, the male repro ­ductive organs. Under the influence of DHT, the Wolffian ducts differentiate into the epididymis, vas deferens, and seminal vesicles. The genital tubercle transforms into the glans penis, the urethral folds grow into the penile shaft, and the urogenital sinus becomes the prostate gland. Finally, DHT causes the genital swellings to fuse, forming the scrotum. At its peak, the fetal testosterone level reaches 400 ng/dL, but by birth it falls below 50 ng/dL. There is a brief spike in the male infant’s testosterone level between 4 and 8 weeks after birth, but its function is not well understood. Otherwise, the testosterone level remains low throughout childhood, until puberty. Puberty and Beyond (Secondary Sex Characteristics) Puberty is the process by which males and females achieve reproductive capacity, and it begins in both sexes with an increase in hypothalamic GnRH secre ­tion. It is possible that this increase is in response to decreasing hypothalamic sensitivity to testos ­terone’s negative-feedback effects. As the child ap ­proaches adolescence, the hypothalamus gradually escapes inhibition and GnRH secretion rises. LH and FSH secretion in turn rise, and testosterone secretion from the testes increases. Gradual maturation of hypothalamic neurons probably plays a role in this pubertal change in GnRH secretion. Increased testicular production of testosterone and other androgens at puberty has a host of effects. The earliest one is enlargement of the penis and testes. From the beginning to the end of puberty, the testicular volume more than quadruples. Spermato ­genesis commences (with testosterone effects per ­haps being most important on the spermatids), and the prostate gland is stimulated to grow. Growth oc ­curs in many tissues outside the reproductive system as well. Androgens are anabolic steroids; they promote the storage of energy in complex molecules. While an ­drogens promote protein synthesis, an anabolic hor ­mone like insulin has a greater effect on the formation of complex carbohydrates and fats. Increased protein synthesis is associated with the growth of skeletal muscle, bones, skin, and hair (pubic, axillary, facial, chest, arms, and legs) and the growth of the larynx (which deepens the voice and causes the thyroid car ­tilage, or Adam’s apple, to protrude). Men on average have around 50% more muscle mass than women; they have stronger, denser bone matrices and thicker skin. Muscle does not contain 5à ¯Ã‚ Ã‚ ¡-reductase, so it ap ­pears that testosterone, not DHT, promotes muscular protein anabolism. However, testosterone or DHT may promote muscular anabolism via extramuscular effects, such as the stimulation of growth hormone and insulin-like growth factor (IGF-1) production. Collectively, the development of the secondary sex characteristics is called virilization (after the Latin vir for man). It appears that while testosterone promotes all of these effects—genital growth and spermatogenesis, hair growth, behavioral changes, and anabolism in peripheral tissues—certain andro ­gen precursors, metabolic byproducts, and pharma ­ceutical androgen analogs preferentially serve peripheral anabolism. Many of these metabolites and drugs are abused by bodybuilders and athletes. (See Clinical Application Box The Use and Abuse of An ­abolic Steroids.) Testosterone, combined with a genetic predis ­position, also influences hair growth on the head. Male-pattern baldness typically begins with a de ­crease in hair growth on the top of the head and progresses to a complete lack of hair growth extend ­ing from the top of the head down. Both factors, the androgens and the genes, are necessary for baldness to occur; a man without the genetic predisposition will not become bald regardless of his testosterone level. A woman with the genetic predisposition will usually not become bald unless she suffers from excess androgen production. Similarly, a castrated male with low testosterone levels will not become bald even if he has a genetic predisposition. Once testosterone levels rise during puberty, they reach a plateau and remain elevated until a man reaches his seventies, when they begin to decline. This event, called the male climacteric, may create some symptoms resembling those of female menopause. However, hormone replacement therapy (HRT) is not commonly used to treat these symp ­toms. One reason is that men in this age group are at increased risk for prostate cancer. Because testos ­terone has proliferative effects on the prostate, HRT might further increase the risk of prostate cancer. While testosterone does promote spermatogenesis, this testicular function is remarkably well preserved in men even after the climacteric. The Haploid Life Cycle in the Male As mentioned above, spermatogenesis begins with puberty and continues into the eighth decade of life. Spermatogenesis has three phases: sperma ­tocytogenesis, during which the primordial sper ­matogonia divide by mitosis and differentiate into spermatocytes; meiosis, resulting in four haploid gametes called spermatids, each with a quarter of the cytoplasm of the original spermatogonium (see Chapter 36); and spermiogenesis, during which the spermatids are nourished and physically reshaped by the surrounding Sertoli cells. The product of spermiogenesis is spermatozoa, or sperm (Figure 37.5). After spermiogenesis, the epididymis and repro ­ductive tract glands help prepare the sperm for fertilization. Spermatocytogenesis and Meiosis The evolving group of cells spanning from spermatogonia to sper ­matozoa is sometimes called the spermatogenic series. Not all spermatogonia enter into the sper ­matogenic series. If they did, they would be con ­sumed—as happens to the oogonia in the ovary, eventually leading to menopause. Instead, the testis csontinually replenishes its own supply of spermato ­gonia. As they undergo mitosis, some of the new ones are committed to the spermatogenic series, while some remain undifferentiated. The undifferen- tiated stem cells are called type A spermatogonia, and the differentiated spermatogonia committed to becom ­ing spermatocytes are called type B spermatogonia. Once this allocation of mitotic products into one group or another occurs, spermatocytogenesis con ­tinues as follows. Type A spermatogonia remain on the outside of the blood-testis barrier, while type B spermatogonia cross it, becoming enveloped by the cytoplasmic processes of the Sertoli cells. These type B spermatogonia differentiate further and enlarge to become primary spermatocytes. The primary sperma ­tocytes then enter meiosis, a process that takes around 3.5 weeks to complete, almost all of which is spent in prophase (when the newly replicated chro ­mosomes condense). Each primary spermatocyte di ­vides into two secondary spermatocytes, which in turn divide again into a total of four haploid spermatids. Each spermatid contains either an X chromosome or a Y chromosome. The male’s gamete thus decides the sex of his offspring. Spermiogenesis Spermiogenesis begins once the spermatids are created and delivered into the em ­brace of the amoeboid Sertoli cells (Figure 37.6). The spermatid elongates and reorganizes its nuclear and cytoplasmic contents into a spermatozoon with a dis ­tinct head and tail. The head consists of a condensed nucleus surrounded by a thin layer of cytoplasm. The rest of the retained cytoplasm and cell membrane is shifted toward the opposite end of the sperm, the tail. A large amount of the spermatid’s cytoplasm is shed into the surrounding Sertoli cell during spermiogene ­sis. As the transformed sperm is extruded into the seminiferous tubule lumen, the discarded cytoplasm remains embedded in the cytoplasm of the Sertoli cell, where it is ultimately phagocytized. Figure 37.6 Spermiogenesis The structure of sperm cells enables them to swim up the female reproductive tract and fertilize oocytes. The tail of a sperm contains a flagellum for motility. Originating from one of the centrioles of the sperm cells, the flagellum consists of a central skele ­ton of microtubules called the axoneme. The axoneme is arranged in the ancient 9 + 2 pattern characteristic of eukaryotic cilia and flagella across all kingdoms and phyla of life: 9 pairs of microtubules surrounding 2 central tubules, linked via a complex array of protein bridges. The sperm cell’s mitochondria aggregate along the proximal end of the flagellum and supply energy for movement to the flagellum. The flagellum enables the sperm to swim. The anterior two thirds of the head of the sperm cell is surrounded by a thick capsule known as the acrosome, formed from the Golgi apparatus. The Golgi apparatus contains numerous hydrolytic and proteolytic enzymes, similar to those found in lysosomes, and ultimately facilitates the sperm’s penetration of the egg for fertilization. There is also evidence to suggest a role for the acrosomal enzymes in penetrating the mucus of the female cervix. Epididymal Sperm Maturation and Storage After spermiogenesis is complete, the sperm pass out of the testis (through the rete testis) and into the epi ­didymis, where growth and differentiation continue. After the first 24 hours in the epididymis, the sperm acquire the potential for motility. However, the epithelial cells of the epididymis secrete inhibitory proteins that suppress this potential. Thus, the 120 million sperm produced each day in the seminiferous tubules are stored in the epididymis, as well as in the vas deferens and ampulla. The sperm can remain in these excretory genital ducts in a deeply suppressed and inactive state for over a month without losing their potential fertility. The epididymis also secretes a special nutrient fluid that is ultimately ejaculated with the sperm and is thought to mature the sperm. This fluid contains hormones, enzymes (such as glycosyltransferases and glycosidases), and nutrients that are essential to achieving fertilization. The precise function of many of these factors is not known, but enzymes like gamma-glutamyl transpeptidase are thought to serve as antioxidants defending against mutations in the sperm. Potentiation in the Ejaculate The accessory genital glands—the seminal vesicles, prostate gland, and bulbourethral glands—also contribute to potentia ­tion. During ejaculation, their secretions dilute the epididymal inhibitory proteins, allowing the sperm’s motile potential to be realized. In addition, the glands make individual contributions to sperm preparation and support. The seminal vesicles secrete semen, a mucoid yellowish material containing nutrients and sperm-activating substances such as fructose, cit ­rate, inositol, prostaglandins, and fibrinogen. Carbo ­hydrates such as fructose provide a source of energy for the sperm mitochondria as they power the sperm’s flagellar movements. The prostaglandins are believed to aid the sperm by affecting the female gen ­ital tract—making the cervical mucus more receptive to the sperm, and dampening the peristaltic contrac ­tions of the uterus and fallopian tubes to prevent them from expellin g the sperm. The prostate gland secretes a thin, milky, and al ­kaline fluid during ejaculation that mixes with the contents of the vas deferens. The prostatic secretion contains calcium, zinc, and phosphate ions, citrate, acid phosphatase, and various clotting enzymes. The clotting enzymes react with the fibrinogen of the seminal fluid, forming a weak coagulum that glues the semen inside the vagina and facilitates the passage of sperm through the cervix in larger numbers. The al ­kalinity imparted to semen by the prostate counter ­acts vaginal acidity, which is a natural defense against microbial pathogens and which can kill sperm or impair sperm motility. By titrating the acid ­ity, the prostate ensures that the sperm can elude this antimicrobial defense. Capacitation in the Female Reproductive Tract Ejaculated sperm is not immediately capable of fertilizing the female oocyte. In the first few hours after ejaculation, the spermatozoa must undergo capacitation inside the female reproductive tract. This is the final step in preparation for fertilization. First, the fluids of the female reproductive tract wash away more of the inhibitory factors of the male geni ­tal fluid. The flagella of the sperm hence act more readily, producing the whiplash motion that is needed for the sperm to swim to the oocyte in the fallopian tube. Second, the cell membrane of the head of the sperm is modified in preparation for the ultimate acrosomal reaction and penetration of the oocyte. Capacitation is an incompletely understood phenomenon. Fertilization Once capacitated, the spermatozoa travel to the oocyte. There is an enormous rate of at ­trition among the hundreds of millions of ejaculated sperm, and at most a few hundred reach the oocyte. However, the female reproductive tract is simultane ­ously increasing receptivity to the male gametes (see Chapter 36). When the few hundred sperm reach the egg, they begin to try to penetrate the granulosa cells surrounding the secondary oocyte. The sperm’s acrosome contains hyaluronidase and proteolytic enzymes, which open this path. As the anterior mem ­brane of the acrosome reaches the zona pellucida (the glycoprotein coat surrounding the oocyte), it rapidly dissolves and releases the acrosomal enzymes. Within minutes, these enzymes open a pathway through the zona pellucida for the sperm cytoplasm to merge with the oocyte cytoplasm. From beginning to end, the process of fertilization takes about half an hour. Figure 37.7 Sexual response and changes in the penis. Penile Erection and Ejaculation The practice of internal fertilization, in which the male deposits gametes directly into the reproductive tract of the female, is at least 300 million years old. Early cartilaginous fishes probably were its innova ­tors. These elasmobranchs retained their concepti internally until the eggs could be waterproofed and thus protected from the osmotic stress of seawater. Eventually, almost all the higher vertebrates would practice internal fertilization for the sake of defending the next generation. For this reason, the male vertebrate possesses a special apparatus for penetrating the body of the female and delivering semen to an internal location. There are two physiologic events crucial to this in ­ternal delivery of semen: penile erection, which makes it possible for the penis to penetrate the vagina, bringing the urethral opening, or meatus, into close contact with the female cervix; and ejaculation, in which the semen is secreted into the male repro ­ductive ductal system, mixed with sperm, and then mechanically squirted out of the penis. Both of these events are initiated and controlled by the nervous system in connection with the subjective state of sexual arousal. Sexual Response in the Male William H. Masters and Virginia E. Johnson in 1966 described four phases of sexual response

Dunciad: Mock epic and parallels to Rape of the Lock (another satire) E

The Dunciad: A Mock Epic? Honors English   Ã‚  Ã‚  Ã‚  Ã‚  The fourth book of the Dunciad describes the fall and slow death of the English society that once taught him all the things he knew. He lashes out at his critics, accusers, and nay Sayers in his allegorical poem. It symbolizes a mock epic because of the elaborate use of words, calling on inspiration from a higher force, and using his work not so much to tell a story, but to point out the faults of a social order that can’t or chooses not to see what they’re really doing.   Ã‚  Ã‚  Ã‚  Ã‚  It opens with: â€Å"Yet, yet a moment, one dim ray of light Indulge, dread Chaos, and eternal Night!† [Line 1, A.P.] â€Å"Suspend a while your force inertly strong, Then take at once the Poet, and the song.† [Line 7, A.P.] In tradition of the epic, Alexander calls for the aide of an outside power. He doesn’t follow the rules completely, and replaces the muse with Chaos and Night, but does this only to enforce what he’s trying to do with his point and gives you a picture of where he’s going next. In epics, there’s always a battle or a scene that is brazenly described, adding drama, making it a little more important and draws the reader in. When Alexander Pope describes the room as the educators stand before the Goddess, and the scene where Dullness triumphs over everything that breathes life into human creativity, he makes it a point to describe each scene as a play-by-play battle in itself. An advocate of the empr...

“Cat in the Rain” by Ernest Hemingway Essay

The story under the title â€Å"Cat in the Rain† was written by Ernest Hemingway, one of the most favourite American novelists, short-story writer and essayist, whose deceptively simple prose style has influenced wide range of writers. So, the story begins with the description of the hotel where two Americans stopped. It was raining, that’s why the couple stayed in and just a cat in the rain attracted the young woman’s attention. She wanted to get the cat inside but failed and was brought another cat. The problem of the story lies very deeply and we are to uncover it. The story is written in one mood which constantly and directly increases. It starts from the beginning where it’s created by a persistent and repeated use of the â€Å"rain† with a number of phrases associating it, such as puddles, deserted square, glistening war monument. Repetition is one of the widely used and favourite stylistic devices of Hemingway. Here he applies it to reveal the relationship of the protagonist to the old hotel owner (she liked †¦ , she liked†¦ ). As the verb â€Å"to like† is not used to characterize relations of the wife to her husband, this contrast is full of the concealed but easily read meaning. Though the cases of repetition in the story may seem a bit obtrusive, their modifications enter into the core of the narration very organically. They carry emotional character, however penetrating the story the deep sorrow becomes evident gradually. We realize that little, as if meaningless, capricious wishes of a young woman reveal the drama of her fate, the absence of comfort in her life, comparable with the cat in the rain. The title of the story anticipates this confrontation and the fact that the cat’s image makes great play twice – just increases the total effect. In fact, the young woman pines for love, for home, for her family. And the purring cat she’d like to have and to stroke is a traditional symbol of home and comfort she lacks so much. She wants warmth, attention, care, joy, happiness; however she is brought the cat – a pitiful substitution of that, what she, a young, beautiful woman needs incredibly. This is the main problem of the novel we tried to uncover. Perhaps the hotel owner didn’t get the reason of her yearnings and took her wish for whim. But dignity, deference and respectfulness of the old man are confronted to egoism and carelessness of George not occasionally. The war monument is also mentioned deliberately. The world George and his wife belong to – is uncomfortable, homeless after-war world, where the fates of young people joined with such hardships and troubles. If to speak about the text itself, it is told in the 3rd person narrative. the description is interlaced with descriptive passages and dialogues of the personages. The author makes extensive use of repetitions to render the story more vivid, convincing, more real and emotional. The author’s style is remarkable for its powerful sweep, brilliant illustrations and deep psychological analysis. Everything he touches seems to reflect the feelings of the heroes. The story reveals the author’s great knowledge of man’s inner world. He penetrates into the subtlest windings of the human heart.

Philosophy Final Essay

Question One   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   In Plato’s work The Apology Socrates is on trial for three distinct things: Firstly, Socrates fell out of favor with the government (who were constantly berated for being ignorant by Socrates in a fashion) and so the sought to eradicate him by accusing him of not paying favors to the gods for whom the citizenry worshipped.   Secondly, Socrates was on trial for impiety.   Lastly, Socrates was on trial and sentenced to death for corruption of the young.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Socrates attempted to defend himself in front of the Senate by using his famous Socratic method as revealed in Plato’s pages of The Apology.   He bantered and lead the court officials around in a dialogue fashion, asking questions in order so that they would have to answer them themselves and thus prove Socrates’ point in a question answer dialogue.   The dialectic art of arriving at the was the system Socrates used.   In this regard he would arrive at the answer by questioning the belief of engaged speakers in a philosophic circle, or in this case, in a courtroom hearing. Although this idea of philosophy may come across as non-confrontational,             Socrates used this method to verbally jab at the speaker until they themselves found fault in their philosophy, and through a system of negative or positive responses came to recognize the truth: Thus, Socrates sought to find justice for himself by only asking questions, leaving the answers up to the officials.   This type of philosophy has been likened to a cross examination present in today’s court rooms, where the person under oath is asked a series of questions that are both destructive and humiliating, until they are forced to acknowledge the truth, much like the arguments around Socrates. The aim of such confrontational questioning was always about finding the ultimate truth, but in this court case it seems that Socrates failed because the case eventually lead to his demise. Socrates believed that this truth seeking was the main goal of philosophy, and philosophical discussions, and he believed that everyone involved with the account was in pursuit of this goal as well:   It was this optimism that lead to his downfall in a way. Socrates could be considered a martyr.   It was his stand against the government at the time which lead to the eventual destruction of the Thirty Tyrants, but when democracy came back into place, they then chastised Socrates because of his pull with the younger crowd.   The definition of a martyr is a person who dies for a cause.   Socrates’ cause was for truth and wisdom; that is what he taught the crowd which followed him about the city (and which attracted the disfavor of the democracy who felt Socrates had too much power and sway over the citizenry and feared an uprising) and in the end, those were the causes for which he died. In The Apology Plato writes of a scene where Crito offers Socrates the opportunity to escape from prison, but Socrates forbids it stating that it would go against democracy for which he stood and it would be a deceitful act which is the opposite of truth, for which he based his philosophy.   Thus, Socrates is offered with a form of escape which he denies, thereby choosing death willingly for his beliefs, the true definition of a martyr.  Ã‚  Ã‚   Socrates willingly or rather knowingly accepts his fate as governed by the ones whose democracy he upheld and it was through this act that Socrates was able to demonstrate philosophy in action. Question Two As to the existence of god, Descartes deems that this should be accounted for next to discovering what knowledge is. Descartes’ explanation of God and existence required an innate sense of the presence of God. He began by thinking that the cause of any idea is as real as the substance of said idea. Since his idea of a Supreme Being or god infinite, therefore the cause of this idea of infinity must also be never-ending and according to his belief, only the real god is boundless. Thus, the cause for the existence of god cannot be human beings because we are not infinite and we are mortal. There must be a cause of this Supreme Being’s existence which is outside the human race. Based on Meditation III, Descartes expressed â€Å"my idea of god cannot be either adventitious or factitious (since I could neither experience god directly nor discover the concept of perfection in myself), so it must be innately provided by god. Therefore, god exists.† It was Rene Descartes who delivered a â€Å"first systematic account of the mind/body relationship† (Descartes 1). Descartes’ dualism theory states that â€Å"mind is a nonphysical substance† (Descartes 1). Further, he differentiated mind from brain. He attributed consciousness and self-awareness to the mind while intelligence is contained in the brain. Descartes used his Meditations on First Philosophy to make certain what he is in doubt before regarding the existence of the mind and body. Because of this, he was able to take a hint that mind and body are two different things. He advocated that the â€Å"mind† is used for thinking, thus, it is immaterial and can exist even without the body. This immaterial and non-physical content of the mind then he called as the â€Å"soul.† And therefore, the mind is a substance distinct from the body, a substance whose essence is thought (Descartes 12). Based on this perspective, Cartesian dualism became a stronghold of future theories. It champions the idea of the â€Å"immaterial† mind and the â€Å"material† body. Even if these are two different entities, they interact to create actions and events reversibly involving mental and physical activities. Despite many non-European supporters of Cartesian dualism, this gave rise to the â€Å"problem of interactionism† wherein it averts the impossibility of interaction between an immaterial and material entity, the mind and body respectively. To defend these criticisms of Cartesian dualism, Descartes formulated an explanation through the pineal gland theory. This gland is located in the center of the brain between the left and right hemisphere, from which the â€Å"immaterial† mind and the â€Å"material† body purportedly interacts. However, this has remained a theory up to this time since Descartes failed to defend such idea of the causal interaction of the mind and body through the pineal gland. Question Three Kant’s deontology ethics involves the belief of actions being immoral despite the outcome.   Kant did not put faith in the consequences of people’s actions but the actions themselves; thus leaving the effect of a scenario out of the equation of morality.   This ethical stance was part of Kant’s philosophy and he believed that the absolutism of deontology was the correct course of action despite circumstances. For Mill on the other hand, his theory of utilitarianism was in stark contrast to Kant’s theory of deontology.   Utilitarianism speaks toward the action of a person directly results the outcome.   Thus, the truth is always the correct path in Kant’s philosophy while the outcome of a lie being the pathway to truth or justice is the course of Mill’s philosophy. In a situation where Kant and Mill were able to converse, there would be several issues on which they would agree, as well as many on which they would fervently argue. With Mill’s dedication to the understanding of natural sciences/economy, and his studies into the harm theory as it applies to humanity, he would be at odds with the strong religious conviction of Kant.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   For Kant, the existence of God was the principle motivating factor of his studies. His work dealt with the â€Å"constructing an adequate theoretical argument for the existence of God†. (Rossi) His early work was founded on, rather than the proof of God as a being to be worshipped, the idea that God was fundamentally provable through mathematics. Kant will argue that the concept of God properly functions only as a â€Å"regulative† — i.e., limiting —   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   principle in causal accounts of the spatio-temporal order of the world. Kant’s critical philosophy thus undercuts what rationalist metaphysics had offered as proofs for the   Ã‚  Ã‚  Ã‚  Ã‚   existence of God. On the other hand, the critical philosophy does more than simply dismantle the conceptual scaffolding on which previous philosophical accounts of the concept of God had been constructed. (Rossi) To this end, Kant spent his life in study of the pursuit of finding God in science and mathematics that man had developed.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   John Stuart Mill, on the other hand, felt that the harm principle was the ruling factors of world existence. John Stuart Mill’s argues in On Liberty that the use of the harm theory, or harm principle is that a state of government must ensure the quality of liberty just so long as the actions committed in the cause of liberty are not detrimental to the activists.   That is to say that the government may interfere in order to prevent harm.   The following paper will discuss Mill’s harm principle and its application to government in regards to restrictions and controls.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Mill argues for the doctrine of liberty.   Mill means to define the role of a person in society and as such the limited amount of coercion consistent in society that should affect that individual, â€Å"No society in which these liberties are not, on the whole, respected, is free, whatever may be its form of government; and none is completely free in which they do exist absolute and unqualified† (Mill).   Mill is stating that although these qualities are liberty come at a cost in no society would they be considered free because of the forms of government in which the world adheres. Question Four Nietzsche restricts the presence of God in his equation by saying that the concepts of good and evil have changed with the progression of history and that these two paradigms of human behavior and secular code will continue to evolve toward the demands of a changing society. Nietzsche, therefore, makes the argument that morals are constructs of the times in which we will and have evolved much as human beings have over the ages, but that this is not necessarily a good thing because it is meant as a manner of preventing others from having control over us. This is because people inherently wish to exercise power over others and morals are a way of leveling things off so that the strongest members of society do not dominate, as Nietzsche emphasizes, The pathos of nobility and distance, as mentioned, the lasting and domineering feeling, †¦something total and complete, of a higher ruling nature in relation to a lower nature, to an â€Å"beneath†Ã¢â‚¬â€that is the origin of the opposition between â€Å"good† and â€Å"bad.† (The right of the master to give names extends so far that we could permit ourselves to grasp the origin of language itself as an expression of the power of the rulers: they say â€Å"that is such and such,† seal every object and event with a sound and, in so doing, take possession of it.) (Nietzsche) In the Genealogy of Morals, Friedrich Nietzsche presents his idea about the morality of human beings and why it is flawed: Nietzsche begins by discounting many of society’s assumptions on how they function in life, as he believes that we tend to view things as having inherent meanings But all purposes, all uses, are only signs that a will to power has become master over something †¦with less power and has stamped on it its own meaning of some function, and the entire history of a â€Å"thing,† an organ, a practice can by this process be seen as a continuing chain of signs of constantly new interpretations and adjustments, whose causes need not be connected to each other—they rather follow and take over from each other under merely contingent circumstances. (Nietzsche) Nietzsche uses punishment as an example in this case, as human beings tend to believe that punishment is an action that happens to a person as a result of that person doing something that he or she deserves to be punished, although counter to this Nietzsche also states that suffering is meaningless and therefore, punishment may also with Nietzche’s own philosophy be meaningless. He would argue that punishment is completely separate from this, however, as punishment is very often used as a way of showing off one’s power or in some cases, as an act of cruelty. This suggests that the punishment does not always fit the crime, as the clichà © is written, so those two things should not necessarily be associated with each other. It cannot be understood how these two things are the same thing, so it is necessary to keep them separate. Nietzsche then continues this argument to show how morality has arrived at the point that it is at right now. Nietzsche argues that all of existence, especially in human beings, is a struggle between different wills for the feeling of power. This means that society wishes to have some sort of control over their own lives and also over the lives of others. This is why competition and the nature of this in man is so prevalent in society, Rather, that occurs for the first time with the collapse of aristocratic value judgments, when this entire contrast between â€Å"egoistic† and â€Å"unegoistic† pressed itself ever more strongly into human awareness—it is, to use my own words, the instinct of the herd which, through this contrast, finally gets its word (and its words). And even so, it took a long time until this instinct in the masses became ruler, with the result that moral evaluation got downright hung up and bogged down on this opposition (as is the case, for example, in modern Europe: today the prejudice that takes â€Å"moralistic,† â€Å"unegoistic,† â€Å"dà ©sintà ©ressà ©Ã¢â‚¬  [disinterested] as equally valuable ideas already governs, with the force of a â€Å"fixed idea† and a disease of the brain). (Nietzsche) It is all a competition to achieve this power, even if there is no physical reward for winning these competitions. Nietzsche shows the constant changing of the ideologies of good and bad by stating that in past generations, the concept of good was defined by the strongest people in society. In barbaric times, anything that the stronger members of society did was defined as good, while the weaker members of society were seen as bad. This is not something that we would agree upon today, but members of these past societies would not agree with the way we do things either. Therefore, Nietzsche believes that to give anything an absolute interpretation does not work because as the times change, so will this interpretation. It is wills which define this, so as wills change, so will the apparent truth. If it is truly desirable to have free will, therefore, a person must not believe in any absolutes, but rather view the world as a constantly changing place and let our wills define the things that are occurring around and in society. This includes looking at things from as many different perspectives as possible in order to decide contingently upon personal perspectives which viewpoint a person wishes to make. This can also be applied to morality as, since nothing is absolute, morals are constantly changing as well. Morality is not something that was passed down from God to human beings, but is rather something that has evolved and changed since the beginning of time and will continue to do so. The only thing that has not change in human beings is that they inherently have the desire to achieve more power over their fellow human beings, because of the existence of free wills. This means that the present morality that human beings possess has been born due to hatred for those things that are stronger in the presence of society. Nietzsche argues that a person will have fear of things that could possibly have power over them, so a person must have developed this moral code in order to protect themselves from the stronger members of society. Nietzsche believes that a person must embrace these animalistic instincts because a person is currently hurting themselves by repressing them. Work Cited Cooper, J.M.   Plato Complete Works.   Hackett Publishing Company.   1997. Descartes, Rene. n.d. â€Å"Meditations on First Philosophy.† 10 March 2008 Mill, John Stuart.   Utilitarianism.   Online.   10 March 2008:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   http://ethics.sandiego.edu/utilitarianism.html Nietzsche, F.   Genealogy of Morals.   Online.   10 March 2008.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   http://books.google.com/books?id=OwGPCsLiBlwC&dq=nietzsche+genealogy+of+mor  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   ls&pg=PP1&ots=rTBJrGtorH&sig=vLolmBFHWUdXa7z8_CxzfIlj18A&hl=en&prev=h  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   tp://www.google.com/search?hl=en&client=firefox-a&rls=org.mozilla:en  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   US:official&hs=ymY&pwst=1&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=Nietz  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   che+genealogy+of+morals&spell=1&oi=print&ct=title&cad=one-book-with-thumbnail Rossi, Phillip. â€Å"Kant’s Philosophy of religion†. Stanford Encyclopedia of Philosophy. June  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   2004. 10 March 2008. URL: http://plato.stanford.edu/entries/kant-religion/