Biology 101 - Reproductive System and Development Part 2
This deck covers key concepts related to the human reproductive system, focusing on puberty, menstrual cycles, and hormonal changes. It includes definitions, physiological processes, and the roles of various structures and hormones.
Define: puberty
Key Terms
On the diagram below, label the ovaries, Fallopian tubes, uterus, and vagina.
What is another term used for the Fallopian tubes?
oviducts Each Fallopian tube connects a single ovary to the uterus.
What are follicles, and in which female reproductive structure are they located?
These are multicellular structures located within the ovaries. Each follicle surrounds and nourishes a single oocyte. During ovulation, the follicl...
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| Term | Definition |
|---|---|
Define: puberty | The period of the human lifespan during which the reproductive system becomes mature. In females, this process is marked by menarche, or the first menstrual period. In males, spermatogenesis begins at puberty. |
In females, which process involves a decrease in sex hormones and the halting of ovulation? | menopause Specifically, menopause is the period when menstrual cycles stop occurring and a female can no longer become pregnant. |
On the diagram below, label the ovaries, Fallopian tubes, uterus, and vagina. | |
What is another term used for the Fallopian tubes? | oviducts Each Fallopian tube connects a single ovary to the uterus. |
What are follicles, and in which female reproductive structure are they located? | These are multicellular structures located within the ovaries. Each follicle surrounds and nourishes a single oocyte. During ovulation, the follicle bursts and develops into the corpus luteum. |
Once every 28 days, one follicle ruptures inside the ovary, releasing an oocyte into the Fallopian tube. What term is used to refer to this process? | ovulation |
In which structure of the female reproductive system does the fertilized zygote implant? | The endometrium (lining) of the uterus. Immediately after ovulation, this lining begins to thicken to provide a favorable environment for the potential zygote. |
How many sperm cells typically fertilize a single ovum? | One sperm fertilizes each ovum, assuming fertilization occurs at all. Ova use specific mechanisms to avoid polyspermy, or fertilization by multiple sperm. It is important to know that polyspermy inevitably causes the death of the zygote. |
What is the length of an average menstrual cycle? | 28 days |
Name the two simultaneous cyclical processes involved in the menstrual cycle. | ovarian cycle uterine cycle In general, the ovarian cycle relates to the development of the follicle within the ovary. The uterine cycle describes the buildup and degradation of the endometrial lining. |
What are the phases of the ovarian cycle? | follicular ovulation luteal The follicular phase roughly corresponds to the first half of the menstrual cycle, with the luteal phase comprising the other half. Ovulation occurs between these two phases. |
What physiological changes occur during the follicular phase? | Both LH and FSH are released at fairly high levels, stimulating the development of the follicle. The follicle itself starts to secrete estrogen. Remember, both LH (luteinizing hormone) and FSH (follicle-stimulating hormone) are peptides released from the anterior pituitary. |
Describe the conditions that trigger ovulation. | Estrogen levels increase due to its release from the follicle. At this time only, estrogen exerts a positive feedback effect on LH secretion, causing a spike known as the LH surge. The follicle then ruptures, releasing the oocyte. |
Prior to ovulation, what type(s) of feedback is/are exhibited by estrogen? | Estrogen exhibits positive feedback, triggering the LH surge. At other times, however, estrogen negatively feeds back on LH and FSH production. Estrogen's activity prior to ovulation is one of the few examples of positive feedback. Less common examples include thrombin's role in blood clotting and the effect of oxytocin during labor. |
The active ingredients of many birth control medications include synthetic estrogen and progesterone. What effect would such medications have on ovulation? | Ovulation would be inhibited. The presence of both estrogen and progesterone mimics the condition of pregnancy, in which FSH and LH are inhibited. Without these hormones, no LH surge can be initiated and ovulation cannot occur. In pregnancy, this effect is important to prevent multiple pregnancies from simultaneously occurring. |
What physiological changes occur during the luteal phase? | The follicle, now called the corpus luteum, begins to secrete progesterone. LH and FSH fall to very low levels. If fertilization occurs, implantation of the zygote would occur during this phase. Menstrual cycles, then, would temporarily cease due to pregnancy. |
What are the three phases of the uterine cycle, and what major events do they contain? | Menstruation is marked by the degeneration of the endometrial lining. Proliferative phase is involve in regrowth of the endometrium, promoted by estrogen. Secretory phase is affected by progesterone from the corpus luteum. This causes the uterine lining to release nutrients. |
How do the phases of the uterine cycle match up with the ovarian cycle? | The follicular phase encompasses both menstruation and the proliferative phase, while the luteal phase aligns perfectly with the secretory phase. |
Define: corpus luteum | The structure that arises from the burst follicle after ovulation. If the ovum is not fertilized, it is degraded; otherwise, it persists during early pregnancy. Since the corpus luteum secretes progesterone, it technically functions as an endocrine gland. |
Which hormone, commonly detected in pregnancy tests, prevents the corpus luteum from degrading after implantation? | Human chorionic gonadotropin, a classic sign of pregnancy; it maintains the corpus luteum. | (hCG) Note that hCG is a peptide hormone. |