Male Reproductive System - Assignment Example

Textbook7 Q1 How could you redesign the male reproductive system so that the path of urine and sperm are separate? Both sperm and urine leave the male body through the urethra. The two routes for these meet at the opening to the bladder, close to the ejaculatory duct which carries the sperm from the testes. In a redesign of this system the ejaculatory duct would require a new opening whereby sperm could still leave the body. This could be from the end of the penis, but from a parallel tube, so that there would be two tubes, very close to each other. The penis would still need to be inserted into the vagina in order that fertilization could take place. Q2 What advantage does a penis serve for humans, who reproduce on land? The penis has what disadvantage? Sperm would quickly dry out if ejaculated on land, as fish do in the sea, outside their partner’s body. The penis provides a moist means of transferring the sperm, as well as ensuring that the sperm has the highest possible chance of fertilizing an egg, because it enters deeply into the vagina. Because the penis lies outside the main torso these is some small risk that this increases its chances of being damaged or injured. This could then mean that the individual never has an opportunity to reproduce and pass on his particular genes. The penis is only efficient at doing this if it is properly formed, and if it is capable of stiffening in order to enter the female vagina, and to maintain this stiffness until ejaculation has taken place. This is not always the case. Ejaculation takes energy, so is harder if the person is ill or undernourished. Q3 How could you redesign the female reproductive system so that the vagina is not both the organ of copulation and the birth canal? In order to redesign the female reproductive system to separate the birth canal from the means of copulation a second canal would be required, probably immediately above or below the present vagina. Both tubes would need to be flexile, so that they can increase in their internal size as required to take either a baby or tumescent penis. The tubes would need to meet below the cervix so that sperm could enter the cervical opening in order to reach the egg to be fertilized. It might however be confusing for a man to find the correct opening , especially in the dark and under cover, which is where much copulation takes place. Q4 Following menopause, females stop producing eggs and cannot get pregnant. Males produce sperm their entire lives. Relate this discrepancy to differences in the reproductive function and expected behaviour of the sexes. In earlier times many women would often die in childbirth, and lots of children died young and so a man might have several partners or wives during his lifetime. He would perhaps need to carry on having children, in order to pass on his genes for more than one generation. Also it is much more exhausting in the long term for a woman to go through pregnancy and then care for a child, than it could ever be for a man to simply have an ejaculation of sperm, so he is capable of doing so for much longer. As she has more children to care for she has less energy to spare to sustain a pregnancy. Also women are born with a fixed number of eggs, and these might deteriorate over time, and so she becomes infertile or unable to maintain a pregnancy . Male sperm on the other hand are created fresh throughout his lifetime Textbook8 Answer: 1. Why wouldn't penicillin, an antibiotic that cures syphilis, be effective against AIDS? And why wouldn't a physician prescribe AZT, an AIDS treatment, for syphilis? Syphilis is caused by a bacteria, whereas AIDS is the result of a viral infection, so what will help with syphilis will not work in the case of AIDS. Antibiotics work by acting upon the metabolic processes within bacterial cells, but do not have such an effect upon viruses. AZT is a specifically anti-viral agent which inhibits the action of the HIV enzyme and so prevents the virus from reproducing itself. It does not have this effect upon syphilis bacterium. 2. Relate the symptoms of AIDS, genital herpes, genital warts, gonorrhea, chlamydia, and syphilis to the activities of the causative agent. Aids is the result of an attack upon the body’s immune system. The symptoms experienced, which include huge weight loss, night sweats and high fevers, are a result of the failing immune system , rather than being caused directly by the virus. These symptoms do not occur until long after the original infection and so the virus is spread through sexual contact by someone who may not know he is infected. Genital herpes, also a viral infection, is also spread by sexual contacts. In this case the infection brings with it quite obvious and blisters form in the genital area. Touching these obviously infected areas will spread the disease both to others and to different parts of the body. However the disease can spread even if blisters have not formed, and the person is unaware that they are infected. Genital warts are caused by the human papillaloma virus (HPV) caused by HPV. It can be seen as flat warts in the genital region. Again sexual contact spreads this virus. Infection in this way is known to be a cause of cervical cancer. Gonorrhea is the result of infection by the bacterium Neisseria gonorrhoeae. In men infection can be quite obvious, as it results in pain when urine is passed and will be accompanied by a white , or even pus filled, discharge from the penile opening of the urethra. In women such discharges can be absent and they remain asymptomatic until the condition has a good hold and they find themselves with a painful inflammation of the pelvic region (PID). Women with gonorrhea are therefore likely to be unknowing agents of transmission for this condition.Treatment consist of a single dose of antibiotics, However the condition is often accompanied with chlamydia infection and this requires treatment too. Chlamydia infection is often asymptomatic,at least at first. It is the result of infection by the bacterium Chlamydia trachomatis. After a latent period of about three weeks, the infected person develops, symptoms such as pain on urination, discharge from the vagina , and, if these are not dealt with an inflammatory pelvic disease will develop. The condition can be treated with antibiotics. Syphilis is the result of infection by the Treponema pallidum bacterium. The symptoms are quite obvious. A painless ulcer or chancre develops at the site of the infection. This has hard defined edges. The person also develops a non-itchy rash and may suffer from a loss of hair. If untreated. If untreated syphilis results in damage to the nervous system. In late stage syphilis this is totally debilitating and was known historically as general paralysis of the insane. The person’s cardiovascular system will also be affected and the condition can be fatal.The antibiotic penicillin can be used to treat the condition. 3. Both HIV and Treponema pallidum lead to illness throughout the body. Discuss similarities and differences between the two infections. HIV is the result of infection by a virus, Treponema pallidum is a bacterium which causes syphilis. There are obvious early symptoms in the case of syphilis, whereas HIV may not bring on symptoms for a long period. HIV can be treated, but there is no easy cure available, whereas syphilis can be halted if treated at an early stage. Both of these conditions are passed on by sexual contact; both are progressive conditions; and both can be fatal. Textbook 9 – answers Q1 The Masters and Johnson model of human sexual response has how many phases? What are they? Humans respond to the possibility of sexual encounter, according to this model in four stages, these being excitement; a plateau of varied length; climax and then resolution Q4 How do men and women differ with regard to sexual arousal? There are many similarities, but it is timing which is one of the main differences, in that men tend to reach orgasms more speedily than their female partners. Also women may subjectively experience orgasm in a variety of ways. Women are likely to flush during the primary excitement phase, whereas for men this comes most often in the second phase. After orgasm a woman can repeat the experience quite quickly, whereas men cannot. This could be linked to the fact that women are only fertile for a few days a month, so, if they wish to be fertilized, they need to make the most of every opportunity available. Men on the other hand are equally fertile at any time of the month. In their minds men can tend to see the sex act in a more detached way than women are perhaps more likely to romanticize the sexual event. Q6 Discuss three controversies about female sexual response. Orgasms –Women may experience these in different ways. As many as seven types have been reported, but most researchers would say that they are related to stimulation of the vagina and of the clitoris. This would involve more than one neurological pathways The G spot this term came into general use in the 1980s, but is named for a biologist, Grafenbug, who suggested it much earlier. The G spot is on the inner front face of the vagina, and when stimulated this area increases in size, and so results in an orgasm. Ejaculation – Grafenberg also proposed that some women produce a fluid similar to semen, and many women report that this does occur on occasions during orgasm. According to Berkely Wellness ( 2013) this fluid comes from Skene’s gland, sometimes described as the female prostate and located on the anterior vaginal wall. The moisture makes intercourse more comfortable and may also be antimicrobial, so preventing infection. Q2 Women are more apt to see sexual desire as a means to love, emotional intimacy, or physical closeness. Is this goal consistent with the female's role of bearing children? Why? A human child takes a very long time to reach maturity and so a woman has to invest a huge amount of time into rearing her off spring. She therefore seeks long term support in the form of a partner who will stay around and who will care what happens to her. Men in general do not spend so much effort in child care, and so can see the rearing of children in a somewhat different way. Textbook 11 answers 1. Describe the sequence of events that begins when a pollen grain lands on the surface of a compatible stigma and ends in double fertilization. i. The plant pollen grain is germinated on the stigma; ii. The male reproductive cells and tube nucleus are then transferred down the style within the pollen tube tip; iii. As the tube grows through the style, the cytoplasm becomes sealed off from the remainder of the pollen tube by callose plugs iv. The male reproductive cell divides by mitosis in order to develop into a pair of haploid sperm cells; v. One of these haploid sperm then joins with the egg in the ovule to produce the diploid zygote (2n). vi. The second sperm joins with both the polar nuclei and so produces a triploid (3n) cell; vii. As the zygote (2n) changes into an embryo, the triploid cell, at the same time, becomes the endosperm, a food source for the fertilized cell. 2. Why is the cereal grain really a fruit? Grains are the result of the fertilization of flowering plants, and are the mature ovaries of plants such as oats and barley. They are therefore a type of fruit, even if not usually named as such. 3. A) describe apomixis b) What would be an evolutionary advantage to a plant having this mode of reproduction?
a. Apomixis is the name given to the process by which plants reproduce parthenogenetically, that is where fertilized eggs become seeds. b. The plants produced are identical. This would be an advantage if an individual plant is successful in their environment, as they could then multiply to produce many plants which also suit the environment. References Berkeley Wellness, (2013), A female prostate? Retrieved from http://www.berkeleywellness.com/self-care/sexual-health/article/female-prostate Read More