Repro Quiz -- Exam 4

The correct answer is that human eggs and sperm have the same number of chromosomes. This is because during fertilization, the egg and sperm combine to form a zygote, which contains the full set of chromosomes necessary for the development of a human being. Each egg and sperm cell contains 23 chromosomes, and when they combine, the resulting zygote will have a total of 46 chromosomes.

A low secretion of luteinizing hormone (LH) in the normal male adult would cause decreased testosterone secretion. LH stimulates the Leydig cells in the testes to produce testosterone. Testosterone is responsible for secondary sexual characteristics, such as facial hair growth, as well as regulating spermatogenesis. Therefore, a decrease in LH would result in a decrease in testosterone production, leading to a decrease in these functions.

The vagina does not serve as a passageway from the primary oocyte. The primary oocyte is released from the ovary during ovulation and travels through the fallopian tubes towards the uterus. The vagina is not directly involved in this process.

Estrogen is a hormone that plays a crucial role in the development of secondary sexual characteristics in females. During puberty, estrogen stimulates the growth of breast tissue, leading to the development of breasts. This is a normal part of female sexual development and is one of the primary effects of estrogen. The other options, such as increased oiliness of the skin, deepening of the voice, and growth of the larynx, are not directly associated with the effects of estrogen.

The structures that receive the ovulated oocyte, providing a site for fertilization, are called the fallopian tubes. These tubes serve as a pathway for the oocyte to travel from the ovary to the uterus. It is in the fallopian tubes where fertilization typically occurs, as the sperm can meet and fertilize the oocyte in this location.

The primary function of the uterus is to receive, retain, and nourish a fertilized ovum. After fertilization, the fertilized egg implants itself into the lining of the uterus, where it is protected and provided with nutrients for development. This process is essential for pregnancy and the continuation of the species. The uterus plays a crucial role in supporting the growth of the fetus until birth.

The basic difference between spermatogenesis and oogenesis is that in oogenesis, one mature ovum is produced, and in spermatogenesis four mature sperm are produced from the parent cell. This is because during spermatogenesis, one diploid parent cell undergoes two rounds of meiosis to produce four haploid sperm cells. On the other hand, during oogenesis, one diploid parent cell undergoes one round of meiosis to produce one haploid ovum and two polar bodies, which eventually degenerate. Additionally, the mature ovum is haploid (n), while the sperm is diploid (2n).

Fertilization generally occurs in the fallopian tubes. This is where the sperm and egg meet and the fertilized egg implants itself in the uterus for further development. The fallopian tubes provide the necessary environment for successful fertilization to take place by allowing the sperm to travel towards the egg and providing a suitable site for the egg to be fertilized. The uterus, vagina, and ovary do not typically serve as the site for fertilization, making the fallopian tubes the correct answer.

The blood-testis barrier is important because spermatozoa and developing cells produce surface antigens that are recognized as foreign by the immune system. Without this barrier, the immune system would attack and destroy the sperm cells, leading to infertility. The barrier prevents the entry of immune cells and antibodies into the testes, allowing for the development and maturation of sperm cells without interference from the immune system.

The statement "Rebuilding the endometrium is under the control of prolactin" is not true. Rebuilding the endometrium, which is the lining of the uterus, is actually under the control of estrogen and progesterone. Prolactin is a hormone that is primarily involved in milk production after childbirth.

GnRH (gonadotropin-releasing hormone) is responsible for controlling the release of anterior pituitary gonadotropins. It stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland. These hormones play a crucial role in regulating reproductive functions such as the development of ovarian follicles and the production of testosterone. Testosterone, on the other hand, is not involved in controlling the release of anterior pituitary gonadotropins.

The correct answer is meiosis. Meiosis is a type of cell division that occurs in sexually reproducing organisms. It involves two rounds of division, resulting in the production of four genetically unique daughter cells. During meiosis, the chromosomes are replicated once, followed by two rounds of division, resulting in the halving of the chromosome number. This ensures that the chromosome number remains constant from one cell generation to the next in sexually reproducing organisms. Cytokinesis is the process of cell division where the cytoplasm divides, DNA synthesis is the replication of DNA, and mitosis is a type of cell division that produces two genetically identical daughter cells.

Excessive body warmth can have a negative impact on the testes. In order to protect themselves from the high temperature, the testes move away from the pelvic cavity. This movement helps to maintain a cooler temperature for sperm production, as the testes need to be slightly cooler than the body's core temperature for optimal sperm production. This response is crucial for the overall health and functionality of the testes.

Peristaltic contractions refer to the rhythmic muscular contractions that occur in the walls of the ductus deferens. These contractions help propel the sperm cells forward, allowing them to move along the ductus deferens. Therefore, the ability of sperm cells to move along the ductus deferens is due to peristaltic contractions.

The mammary glands are modified sweat glands that are actually part of the integumentary system. This means that they are not specific to either males or females, as both sexes have mammary glands. They are responsible for producing and secreting milk during lactation. This statement is true because the mammary glands are indeed modified sweat glands and are considered part of the integumentary system, which includes the skin and its appendages.

If gametes were diploid like somatic cells, the zygote would contain twice the diploid number of chromosomes. This means that the chromosome number would double in each generation, leading to an abnormal increase in chromosome number. This abnormal chromosome number would prevent normal development from occurring.

The presence of Y chromosomes in approximately half the sperm is a characteristic of mature sperm. This is because sperm cells carry either an X or Y chromosome, which determines the sex of the offspring. If a sperm cell carries an X chromosome, it will result in a female offspring, while a sperm cell with a Y chromosome will result in a male offspring. Therefore, the presence of Y chromosomes in approximately half the sperm is a normal characteristic of mature sperm.

Inhibin is a hormone that is produced by the testes and acts to inhibit the secretion of follicle-stimulating hormone (FSH) from the pituitary gland. FSH is responsible for stimulating the production of sperm in males. Therefore, inhibin plays a crucial role in regulating the levels of FSH and ultimately the production of sperm. This makes inhibin the correct answer to the question.

The dartos and cremaster muscles are responsible for regulating the temperature of the testes. These muscles are located in the scrotum and help to control the position and tension of the testes. When it is cold, these muscles contract, bringing the testes closer to the body to keep them warm. Conversely, when it is warm, these muscles relax, allowing the testes to hang further away from the body to cool down. This temperature regulation is crucial for maintaining the proper environment for sperm production and overall reproductive function.

The sustentacular cells, also known as Sertoli cells, are responsible for constructing the blood-testis barrier. This barrier is essential for maintaining the unique microenvironment of the testes, protecting developing sperm cells from harmful substances, and allowing for proper sperm development. Sustentacular cells provide physical support, regulate the movement of substances between the blood and the seminiferous tubules, and also play a role in nourishing and nurturing developing sperm cells.

The most important risk for testicular cancer in young males is non descent of the testes. This refers to the condition where one or both testicles do not move down into the scrotum before birth. This condition increases the risk of testicular cancer because the undescended testicle(s) may be more prone to developing abnormal cells. It is important for parents and healthcare providers to monitor and address this condition early on to reduce the risk of testicular cancer in young males.

The seminal vesicles are responsible for 60% of the synthesis of semen. Seminal vesicles produce a fluid that makes up a significant portion of semen. This fluid contains various substances, including fructose, prostaglandins, and enzymes, which provide nourishment and energy for sperm. Therefore, the seminal vesicles play a crucial role in semen production and contribute to its overall composition.

Testosterone is a hormone primarily responsible for the development and maintenance of male reproductive tissues and secondary sexual characteristics. It stimulates protein synthesis, which is essential for muscle growth and repair. It also stimulates the male pattern of development, including the growth of facial and body hair, deepening of the voice, and enlargement of the penis and testes. Additionally, testosterone contributes to male sexual behavior and spermatogenesis, the production of sperm. However, it does not stimulate mammary gland development, which is a function of other hormones like estrogen and prolactin.

The duct system of the male reproductive system consists of the epididymis, ductus deferens, and urethra. The corpus spongiosum, on the other hand, is a spongy tissue that surrounds the urethra and helps maintain its shape during erection. It is not part of the duct system but plays a role in the physiology of the male reproductive system.

When cells separate at the two-cell stage following fertilization, it can lead to the production of identical twins. Identical twins occur when a single fertilized egg splits into two separate embryos, each with the same genetic makeup. This means that the twins will share the same sex and have very similar physical characteristics. Fraternal twins, on the other hand, occur when two separate eggs are fertilized by two different sperm, resulting in siblings with different genetic makeup and potentially different sexes. Therefore, the correct answer is "identical."

Sperm are not sluggish in an alkaline environment. In fact, they are adapted to survive and swim in the alkaline environment of the female reproductive tract. The alkaline environment helps to neutralize the acidity of the vaginal environment, allowing the sperm to reach the egg for fertilization.

The development of male reproductive structures depends on the secretion of male hormones prenatally and lasting into the first few months after birth. These hormones, such as testosterone, are responsible for the differentiation and growth of the male reproductive organs, including the testes, penis, and prostate gland. Without the proper secretion of these hormones during critical periods of development, the male reproductive structures may not develop properly, leading to various abnormalities or disorders.

The thalamus is not a part of the brain-testicular axis. The brain-testicular axis involves the hypothalamus, which releases gonadotropin-releasing hormone (GnRH) to stimulate the anterior pituitary gland. The anterior pituitary gland then releases luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which act on the testes to regulate testosterone production and sperm production. The thalamus, on the other hand, is involved in relaying sensory information to the cerebral cortex and is not directly involved in the regulation of the testes.

If the boy's anterior pituitary is injured and FSH is no longer released, it means that he will not be able to produce sperm. FSH is responsible for stimulating the production of sperm in the testes. Since LH is normal, it indicates that the boy's interstitial cells, which produce testosterone, are functioning properly. However, without FSH, the boy will not be able to produce mature sperm, leading to sterility. Therefore, the correct answer is that he would be sterile.

Undescended testes, also known as cryptorchidism, refers to a condition where one or both testes fail to descend into the scrotum. This can lead to inadequate or nonviable sperm production because the testes need to be in a cooler environment (scrotum) for proper sperm development. If the testes remain in the abdomen or inguinal canal, the higher temperature can impair sperm production. Therefore, the correct answer is that inadequate or nonviable sperm will be produced as a result of undescended testes.

Erection is the result of vascular spaces in the erectile tissues filling with blood. This means that during sexual arousal, the blood vessels in the erectile tissues of the penis dilate, allowing more blood to flow into these spaces. As a result, the penis becomes engorged and erect. This process is primarily regulated by the release of nitric oxide, which causes the smooth muscles in the blood vessel walls to relax and allow for increased blood flow.

Prostate cancer is sometimes a slow-growing cancer that may never represent a threat to the patient. This means that in some cases, prostate cancer develops at a slow rate and may not cause significant harm or pose a danger to the patient's health. It implies that not all cases of prostate cancer require aggressive treatment and that active surveillance or watchful waiting may be appropriate in certain situations.

GnRH from the hypothalamus causes FSH and LH release from the anterior pituitary. GnRH (gonadotropin-releasing hormone) is a hormone that is released by the hypothalamus and stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland. FSH and LH then act on the testes to stimulate the production of testosterone. This is an important mechanism in the control of testosterone levels in the body.

The bulbospongiosus muscles are responsible for the ability of a male to ejaculate. These muscles are located in the pelvic region and play a crucial role in the ejaculation process. When these muscles contract, they help propel semen out of the penis during ejaculation. Therefore, the action of the bulbospongiosus muscles is essential for the male reproductive system to function properly and for ejaculation to occur.

The cells that produce testosterone in the testis are called interstitial cells. These cells are located in the spaces between the seminiferous tubules in the testis. They are responsible for the production and secretion of testosterone, which is the primary male sex hormone. Testosterone plays a crucial role in the development and maintenance of male reproductive tissues, as well as secondary sexual characteristics such as muscle mass, bone density, and facial hair growth.

Normally, menstruation occurs when blood levels of estrogen and progesterone decrease. These hormones are responsible for maintaining the lining of the uterus during the menstrual cycle. When their levels drop, it signals the body to shed the uterine lining, resulting in menstruation. This is a natural process that happens in the absence of fertilization and pregnancy.

The correct answer states that the first polar body has also divided to produce two polar bodies. This means that one of the polar bodies formed from the unequal division of the ovum, while the other two polar bodies are produced from the division of the first polar body. This explanation provides a clear understanding of the origin of the three polar bodies found clinging to the mature ovum.

Syphilis is not caused by a virus, but by a bacterium called Treponema pallidum. If left untreated, syphilis can indeed lead to serious complications and even death.

The development of testes as opposed to ovaries is not considered a male secondary sex characteristic because it is a primary sex characteristic. Secondary sex characteristics are traits that develop during puberty and are not directly involved in reproduction, such as increasing mass of the skeleton, lowering of the voice, and development of body hair. Testes and ovaries are primary sex organs that determine an individual's biological sex.

During the uterine cycle, if fertilization occurs, the developing embryo secretes a hormone that maintains the corpus luteum. This is because the corpus luteum is responsible for producing progesterone, which is essential for maintaining the uterine lining and supporting pregnancy. The hormone secreted by the developing embryo ensures that the corpus luteum continues to produce progesterone, creating a suitable environment for implantation and pregnancy to continue.

LH (luteinizing hormone) is absolutely necessary for ovulation to occur. LH is produced by the pituitary gland and its surge triggers the release of a mature egg from the ovary. This surge usually occurs around the middle of the menstrual cycle, resulting in ovulation. Without the surge of LH, the egg would not be released, preventing ovulation from taking place.

The infundibulum is the funnel-shaped region near the ovary. This is a correct statement about uterine tubes. The infundibulum is the outermost part of the uterine tube and has finger-like projections called fimbriae that help to capture the released egg from the ovary during ovulation. It acts as a funnel to guide the egg into the uterine tube for fertilization.

Each spermatid forms two sperm is not true. During spermatogenesis, each spermatid undergoes a process called spermiogenesis, where it matures and develops into a single sperm cell with a head, midpiece, and tail. Therefore, each spermatid forms only one sperm, not two.

During the monthly reproductive cycle of the female, the regression of the corpus luteum and a decrease in ovarian progesterone secretion occur simultaneously. The corpus luteum is formed after ovulation and secretes progesterone to prepare the uterus for potential implantation of a fertilized egg. If fertilization does not occur, the corpus luteum regresses and its progesterone secretion decreases, leading to the shedding of the uterine lining, which is menstruation. Therefore, these two processes occur simultaneously in the female reproductive cycle.

The corpus luteum is not a part of the proliferative phase of the female menstrual cycle. The proliferative phase is characterized by the development of endometrial cells and the growth of vesicular follicles. During this phase, cervical mucus becomes thin and crystalline. The corpus luteum, on the other hand, is formed after ovulation and is responsible for the production of progesterone, which prepares the uterus for possible implantation of a fertilized egg.

The brain-testicular axis involves the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH are secreted by the anterior pituitary gland in response to gonadotropin-releasing hormone (GnRH) released by the hypothalamus. FSH stimulates the production of sperm cells in the testes, while LH stimulates the production of testosterone by the Leydig cells in the testes. This axis plays a crucial role in the regulation of testicular function and the maintenance of male reproductive health.

Spermiogenesis is the process by which spermatids, which are immature cells, undergo a series of changes to become mature, functional sperm. During this process, the excess cytoplasm is removed, leaving behind only the essential structures needed for fertilization. This stripping away of superfluous cytoplasm allows the sperm to become streamlined and more efficient in their movement. Therefore, the correct answer is "formation of a functional sperm by the stripping away of superfluous cytoplasm."

During the secretory phase of the menstrual cycle, progesterone levels are at their highest. This phase occurs after ovulation and is characterized by the thickening of the endometrium in preparation for possible implantation of a fertilized egg. Progesterone, which is primarily produced by the corpus luteum (the remnant of the ruptured follicle), helps to maintain the uterine lining and support a potential pregnancy. If fertilization does not occur, progesterone levels decrease, leading to the shedding of the endometrium during menstruation.

Erection of the penis results from a parasympathetic reflex. The parasympathetic nervous system is responsible for promoting relaxation and increased blood flow to the penis. When the parasympathetic nerves are activated, they cause the smooth muscles in the walls of the blood vessels in the penis to relax, allowing blood to flow into the erectile tissues and causing an erection. This reflex is triggered by sexual stimulation and is essential for the physiological process of achieving and maintaining an erection.

During ejaculation, the smooth muscle sphincter at the base of the urinary bladder closes. This closure prevents semen from entering the urinary bladder and ensures that it is expelled through the urethra instead. This mechanism helps to separate the reproductive system from the urinary system and allows for the proper functioning of both systems without interference.