Fertilization
[Figure 1] How far does a sperm have to swim? Sperm swimming to an egg. If fertilization occurs, the egg will have all the “instructions” to grow into a new organism. That one cell will become two, then four, then eight, then sixteen, and on and on and on. And after about 9 months, that one cell will have become […]
Menstrual Cycle
[Figure 1] What’s the most important part of the female menstrual cycle? A menstrual cycle calendar. A lot of things to keep track of. And for a few very important reasons, it is important to know when a woman is ovulating. But what’s the most important part of the female menstrual cycle? That depends on who you […]
Egg Cells
[Figure 1] What’s amazing about these cells? Many things. A human egg cell. Just add sperm and you have the necessary ingredients for a new baby. What’s amazing about these cells is that they are all produced before the girl is even born. Before the girl is even born, plans for the next generation have begun. And that is […]
Female Reproductive Development
What changes happen during puberty? A lot changes during this time, including changes to reproductive organs and other physical changes. Sexual Development in Females Female reproductive organs form before birth. However, as in males, the organs do not mature until puberty. Development Before Birth Unlike males, females are not influenced by the male sex hormone testosterone during embryonic development. This is because they […]
Female Reproductive Organs
[Figure 1] Think producing millions of sperm each day is complicated? If producing millions of sperm each day, as in the male reproductive system, is complicated, that is nothing compared to what must occur in the female reproductive system. This system is controlled by an intricate dance of hormones, cycles, and events. Female Reproductive Structures The female reproductive system consists […]
Sperm
[Figure 1] How many sperm does it take to fertilize an egg? 85 million sperm per day are produced…per testicle. That’s 170,000,000 every day. This means that a single male may produce more than a quadrillion (1,000,000,000,000) sperm cells in his lifetime! But it only takes one to fertilize an egg. Production and Delivery of Sperm A sexually […]
Male Reproductive Development
[Figure 1] What changes happen during puberty? A lot changes during this time. A boy has to start shaving, his voice deepens, he gets taller, as well as a few other changes. Sexual Development in Males The only obvious difference between boys and girls at birth is their reproductive organs. However, even the reproductive organs start […]
Male Reproductive Organs
[Figure 1] Would you believe the male reproductive structures are over 100 feet long? The male reproductive system has two goals: to produce and deliver sperm and to secrete testosterone. Might seem simple. But there are a number of complicated processes and structures – including over 100 feet of tubules – that go into these simple goals. The male reproductive […]
Bioterrorism
[Figure 1] “The world has definitely changed.” This statement is common at times. What might it refer to? Bioterrorism is a threat against civilized people worldwide. To be prepared, all levels of government have developed and conducted terrorism drills. These include protecting responders from harmful biological substances. Bioterrorism Bioterrorism is the intentional release or spread of […]
Air Pollution and Illness
[Figure 1] Is some air actually bad for you? This question shouldn’t even need an answer. Yes, some air can be harmful. Air Pollution and Illness Almost 5 million people die each year because of air pollution. In fact, polluted air causes more deaths than traffic accidents. Air pollution harms the respiratory and circulatory systems. Both […]
