Question

5. Describe the body structures that a sperm cell and a secondary oocyte will encounter prior to their encounter and merging to form a zygote. Your response should include a thorough review of the structures connecting the epididymis to the external urethral orifice, and how the structures (and secretions from those structures, to be discussed in detail) support and assist the sperm cell in its trip out of the body. Also, the response should thoroughly describe the structures and obstacles that the sperm cell will encounter within the female body, from the v@gina to the oviduct. For the secondary oocyte, describe the structures it encounters and passes through before meeting up with the sperm cell in the oviduct.

6. The body has an interesting way of using deriving uses from waste material prior to its disposal. For example, carbon dioxide is a waste product of cellular respiration, and is disposed of through the lungs. However, prior to its removal, it is the source of one of the most important buffer systems in the body—the carbonic acid/bicarbonate buffer system. Identify and describe two other waste products in the body that have a critical role in body function. And no, removal of toxins from the body—or any related function—does not count; the waste product in question (or what it can turn into) must have some actual positive effect on the body prior to its disposal.

Answer 1

The mammalian sperm cell can be divided in 2 parts: head: contains the nucleus with densely coiled chromatin fibers, surrounded anteriorly by a thin, flattened sac called the acrosome, which contains enzymes used for penetrating the female egg. It also contains vacuoles.

Sperm are smaller than most cells in the body; in fact, the volume of a sperm cell is 85,000 times less than that of the female gamete. Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month as is true for most cells in the body, the structure of sperm cells speaks to their function. Sperm have a distinctive head, mid-piece, and tail region. The head of the sperm contains the extremely compact haploid nucleus with very little cytoplasm. These qualities contribute to the overall small size of the sperm (the head is only 5 μm long). A structure called the acrosome covers most of the head of the sperm cell as a “cap” that is filled with lysosomal enzymes important for preparing sperm to participate in fertilization. Tightly packed mitochondria fill the mid-piece of the sperm. ATP produced by these mitochondria will power the flagellum, which extends from the neck and the mid-piece through the tail of the sperm, enabling it to move the entire sperm cell. The central strand of the flagellum, the axial filament, is formed from one centriole inside the maturing sperm cell during the final stages of

Fertilization is a numbers game. During ejaculation, hundreds of millions of sperm (spermatozoa) are released into the vagina. Almost immediately, millions of these sperm are overcome by the acidity of the va-gina (approximately pH 3.8), and millions more may be blocked from entering the uterus by thick cervical mucus. Of those that do enter, thousands are destroyed by phagocytic uterine leukocytes. Thus, the race into the uterine tubes, which is the most typical site for sperm to encounter the oocyte, is reduced to a few thousand contenders. During the journey, fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation, or priming. The fluids improve the motility of the spermatozoa. They also deplete cholesterol molecules embedded in the membrane of the head of the sperm, thinning the membrane in such a way that will help facilitate the release of the lysosomal (digestive) enzymes needed for the sperm to penetrate the oocyte’s exterior once contact is made. Sperm must undergo the process of capacitation in order to have the “capacity” to fertilize an oocyte. If they reach the oocyte before capacitation is complete, they will be unable to penetrate the oocyte’s thick outer layer of cells.journey—thought to be facilitated by uterine contractions—usually takes from 30 minutes to 2 hours. If the sperm do not encounter an oocyte immediately, they can survive in the uterine tubes for another 3–5 days. Thus, fertilization can still occur if intercourse takes place a few days before ovulation. In comparison, an oocyte can survive independently for only approximately 24 hours following ovulation. Intercourse more than a day after ovulation will therefore usually not result in fertilization.

Urea

Urea, also known as carbamide, is an organic compound with chemical formula CO(NH2)2. This amide has two –NH2 groups joined by a carbonyl (C=O) functional group.

Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. It is a colorless, odorless solid, highly soluble in water, and practically non-toxic.

HCL

Hydrochloric acid constitutes the majority of gastric acid, the human digestive fluid. In a complex process and at a large energetic burden, it is secreted by parietal cells (also known as oxyntic cells). These cells contain an extensive secretory network (called canaliculi) from which the HCl is secreted into the lumen of the stomach. They are part of the epithelial fundic glands (also known as oxyntic glands) in the stomach. The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl).