Why does body temperature increase when ovulation?
After the release of an ovum, the remaining cells of the Graafian follicle, the corpus luteum, will produce the hormone progesterone, which you know inhibits FSH production (thereby preventing other follicles from maturing) and maintains the uterine lining. Progesterone is also responsible for the raise in body temperature.
Does the blastocyst stage come after the embryo or before?
The blastocyst (see picture below) is actually a stage of embryonic development! Blastocyst formation begins around day 5 after fertilization in humans.
Once the zygote undergoes its first cell division, it is called an embryo. In humans, it is considered an embryo until about 8 weeks after fertilization, and thereafter it is instead called a foetus.
What happens when menopause occurs? Does it mean that the woman has run out of eggs?
Menopause occurs due to a complex series of hormonal changes.When menopause occurs, menstruation stops and ovulation ceases, and the female can no longer become pregnant. But it is not triggered by an absence of ova.
A female is born with all the eggs she needs, which averages 1.5 million.When menstruation begins, one ovum is released every 28 days. Occasionally, 2 or 3 may be released (resulting in fraternal twins/triplets if fertilised). So, if menstruation commences at age 15 and continued up to age 55, around 522 eggs would have been released. 522 is a far cry from a million!
However, by the time a female reaches menopause age, most of the ova may become no longer viable due to two reasons:
1. The number of eggs in the ovaries decreases with age. When the female reaches puberty, there are only about 400,000 eggs available for fertilization. Each month several follicles are stimulated to mature [recall video in class], but only 1 will release an ovum.
2. Ova have to be healthy (e.g. correct shape, physiology, DNA) in order for an embryo to develop to a healthy baby. need to have the right shape, health, and chromosomes in order to be able to develop into an embryo and, eventually, a baby. But with age, quality of the ova decreases, due a process called atresia (the degeneration and subsequent resorption of immature ovarian follicles - fluid filled cysts that contain the eggs).
1. The number of eggs in the ovaries decreases with age. When the female reaches puberty, there are only about 400,000 eggs available for fertilization. Each month several follicles are stimulated to mature [recall video in class], but only 1 will release an ovum.
2. Ova have to be healthy (e.g. correct shape, physiology, DNA) in order for an embryo to develop to a healthy baby. need to have the right shape, health, and chromosomes in order to be able to develop into an embryo and, eventually, a baby. But with age, quality of the ova decreases, due a process called atresia (the degeneration and subsequent resorption of immature ovarian follicles - fluid filled cysts that contain the eggs).
What does the pubic bone do in humans?
Also known as the baculum, the penis bone is a bone found in the penis of most mammals. However, it is absent in humans! In humans, the rigidity of the penis erection is provided entirely by blood pressure, as blood fills up the erectile tissue within the penis.
Richard Dawkins proposed that the loss of the pubic bone is a result of sexual selection by females looking for signs of good health in prospective mates. For the penis to solely rely on blood pressure to achieve a rigid state makes it particularly vulnerable to blood pressure variation. Hence, poor erectile function reveals physical states such as diabetes and neurological disorders, and mental states such as stress and depression. [Relate this to the inability to engage in sexual intercourse if the male has erectile dysfunction, resulting in the inability for sperm to be deposited in the female via sexual intercourse.]
Richard Dawkins proposed that the loss of the pubic bone is a result of sexual selection by females looking for signs of good health in prospective mates. For the penis to solely rely on blood pressure to achieve a rigid state makes it particularly vulnerable to blood pressure variation. Hence, poor erectile function reveals physical states such as diabetes and neurological disorders, and mental states such as stress and depression. [Relate this to the inability to engage in sexual intercourse if the male has erectile dysfunction, resulting in the inability for sperm to be deposited in the female via sexual intercourse.]
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