HUMAN GROWTH

[Music] in this tribe the hair was cut in a special style when a boy reached ad lence almost finished with that report George soon he's reading about Indian boys adolesence like him oh why don't you grow up grow up listen to himie I'm just as grown up as you are even if you are older than I am say who Miss Baker she said at our age girls are more mature than boys I suppose if she said you were a genius you'd believe her yes I would now George I think Josie's right in believing Miss Baker she's a good teacher and a lovely person all the kids at school like her there's something for R for Dad what's that sge only the grown people have clothes on braid my hair tonight mommy please all right get the ribbons from the candy box says here that until they were 12 or 13 years old the children in the tribe usually wore no clothes at all the wearing of loin cloths and skirts was considered a sign of sexual maturity that's an interesting point George in fact it fits in very well for the film Josie told us about hey when are we going to see that film Josie tomorrow I have to tell a class what to look for daddy have you decided what you're going to say I'm going to tell him that the most important things to look for are the changes that take place in our bodies when we grow up grow up that is when we become young men and women and the film also shows how growth begin and the changes that take place even before we are born that's right Dorothy the film we're about to see shows the earliest phases of growth as well as the changes that occur during childhood and Adolescent now this motion picture was selected to give you an understanding of the way the cycle of human growth is repeated over and over from generation to generation has anyone else on the preview committee anything to add Warren I have a list of of points to look for the committee has worked out fine Warren will you read them to us please and Carolyn would you copy them down when does human growth begin how much does one grow before birth do boys and girls grow at the same rate what are the main growth changes that occur an adolescent boys and girls adolescent is a word we used before who can tell us what it means Jenny well it's boys and girls just beginning to mature it happens when they're about our age that's very good Jenny the picture will tell us more about it now I think we're all ready for the film remember to look for the answers to the questions on the board all set yes this Baker Nancy will you please turn off the light [Music] whenever we talk about growth we usually think of growing up but the long road of growth is not just up if it were it would mean that this little baby would someday look like this or that this man once looked like this now let's see how human beings really grow here are two average babies a little boy and a little girl in the course of a few years they will grow to maturity during the first three years growth is very rapid the boy and girl become twice as tall and three times as heavy as they were at Birth by the age of six more height and weight have been added notice that the boy is a little bigger than the girl at n n arms legs and trunk have become long and slender giving the body a slim appearance about this time the girl begins to grow faster than the boy by 12 or 13 the girl is taller and heavier than the boy and she looks more mature at 15 the girl's growth slows down while the boy keeps on growing at a rapid R for another year or two when they reach their late teens or early 20s they are fully mature people with the boy again being appreciably larger than the Girl by comparing the adult with the child we can see the growth changes more clearly notice that the adult face and head are less round and the arms legs and trunk relatively longer the boy's shoulders are broader and his body more muscular and the girl body is more curved and feminine thus we see that growth is more than just growing up the form of the body changes as well growth is controlled by tiny organs within our bodies called glands one of the most important of these is the pituitary gland located in the head it secretes chemicals into our blood the chemicals are called hormones and they regulate body growth the pituitary hormones also influence the secretions of other glands notably the testes and ovaries located in the pubic region of the body the testes secrete the male sex hormone and the ovaries the female sex hormone presence of the male hormone in the blood causes whiskers to appear on the face and hair to grow under the arms in the pubic region and Elsewhere on the body the vocal cords get larger and the voice deepens a little the female sex hormone also causes hair to grow under the arms and in the pubic region the breasts begin to develop and the girl's voice deepens a little too these physical changes usually make the boy feel more manly and the girl more womanly which are perfectly normal feelings in addition to hormones the testes and ovaries produce the male and female sex cells from which we all have our beginning the male cell or sperm cell is so small it can be seen only under a microscope when we magnify the sperm cell many times we see the head which contains the nucleus and the thread-like tail which Wiggles and causes the cell to move the female cell or oam while larger than the sperm is still no bigger than a pinpoint by enlarging the ovam many times we can see the cell wall and the dis- likee nucleus it is from the union of sperm and ovam from father and mother that growth Begins the nucleus of the sex cell carries the substance which enables a child to resemble his parents when a boy is between the age of 13 and 16 the testes begin to produce sperm cells at certain times the sperm cells pass from the testes through the tubes and out the penis this happens during mating and sometimes during sleep it is a normal function of the body in addition to the ovaries the sex orans of the girl consist of the tubes the uterus and the vagina when a girl is between the age of 12 and 15 the ovaries begin to produce OVA or egg cells about once every month an ovam ripens and leaves the ovary moving into the tube while the ovam moves slowly along the tube tube the uterus becomes richly supplied with blood to nourish the egg but if the ovam doesn't meet a sperm cell it fails to grow instead it disintegrates the uterus sheds its lining and a little blood passes from the body the bleeding decreases and in a few days stops completely this process is called menstruation the whole cycle begins again with another ovam ripening usually in the opposite ovary during early adolescence the menstrual cycle may be quite irregular it usually takes a year or two for a rhythm to become established these functions begin as we attain sexual maturity but all of us do not mature at the same age these boys and girls for example are all 13 years old yet among them we can see many differences in size and maturity by the time they reach their late teens or early 20s when they have completed their education have a steady job want to get married and are ready to accept the responsibility of having and raising children the differences in sexual maturity will have disappeared human growth can begin only when the sperm cells of the father during during mating pass from the penis into the vagina of the mother the sperm cells use their threadlike tails to move into the uterus and tubes if the sperm cells meet an ovam and one sperm succeeds in breaking through the cell wall fertilization occurs the nucleus of the sperm joins with the nucleus of the ovam and growth begins ends the fertilized ovam begins to divide into many cells while moving along the tube toward the uterus there it attaches itself to the inner lining drawing its nourishment from the blood of the mother it continues to grow and in a month looks like this at two months it is much bigger and is already beginning to look like a baby you you can see the cord which connects the baby to its mother and through which the baby receives its food one of the most wonderful things about nature is that the uterus which is normally not much bigger than a fist is muscular and elastic enough to expand to many times its normal size at 4 months you can already see why this expansion is necessary the baby now has AR arms and legs that move inside the mother by 6 months the baby has gradually turned and moved to this head down position in preparation for birth the baby is very active now it is not only the uterus that expands to accommodate the growing baby here you can see how the whole abdominal wall stretches this baby has developed for 9 months and is about to be born if the mother were lying down this would be the position of the baby just before birth you can see the mother's spine below the enlarged uterus the head settles to a lower position and the muscles of the uterus begin to force the baby out the muscle walls of the vagina expand to make room and the baby's head begins to move out of the mother the doctor lends a helping hand and the new baby meets the outside world since the baby no longer has to depend upon its mother's blood for food the doctor ties and cuts the cord the baby cannot feel the cutting any more than you can feel it when the barber Cuts your hair growth continues and this baby will become a full-grown boy or girl and eventually a father or mother thus continuing the cycle of human growth [Music] [Music] the principles of growth and development that we just seen in this film apply to all human beings perhaps we should start our discussion by answering the first of the questions on the board who can tell us when human growth begins Alan growth begins when a sperm cell enters an egg cell suppose the sperm cell doesn't enter the egg cell then the egg isn't fertilized and it dies in a few days Mor do you have a question question uh I guess it's kind of a silly question the only silly question is the one that isn't asked your questions help you to learn and they also help me to teach well I was wondering why there are so many sperm cells and only one egg cell that's a very good question Mor it's a point that wasn't very well covered in a film let's use a slide to explain it more fully dick it's slide 11 will you project it please let's pretend for a moment that there is only one sperm cell the ovam is produced here and moves into the tube the sperm cell has to travel all the way up here to find the OV most of the time the two sex cells wouldn't meet at all and very few babies would be born that's a reason for having more than one sperm in addition it takes many sperm cells striking against the ovam to weaken the cell walls so that one sperm can enter and Unite with the nucleus of the op so nature doesn't depend on just one sperm cell she provides millions of them any one of which might fertilize the ovam does that answer your question Mor yes it does Miss Baker are there any more questions Julie about menstration is it really normal for the body to bleed like there completely normal Julie simply because nature planned it that way remember in the animated film the lining of the uterus became filled with blood with which to nourish a fertilized OV yes Miss Baker well when the ovam is not fertilized there's no need for this nourishment so the uterus merely sheds its inner lining and naturally a little blood leaves the body at the same time now for the questions the rest of you have perhaps you should ask them in turn then we can organize our discussion around them as well as those on the board do boys have anything like ministration I heard mother tell a neighbor I was born cesarian what does that mean why don't all people have red hair what happens if more than one sperm cell enters an egg cell I've grown 4 Ines in the past year when will I stop growing how long will it take for my voice to change are girls always bigger than boys at 12 or 13 everybody says I look like aun Sarah why do I have to look like her when I don't like her all of those are excellent questions you students who've been watching this film you've heard the questions we're going to discuss you can discuss these same questions with your teacher and you can ask any other questions you have in mind mind