02 The Growing Body – Youthealth

The Growing Body

Systems Check

The different systems in your body are there to give you energy and to help you grow and develop.

Digestive System

Your digestive system takes the food and drink you swallow and turns it into energy to help your body to work and grow. It breaks the food you eat into nutrients called protein, carbohydrate and fat. These nutrients are sent into the blood stream to supply the rest of the body with all the fuel needed to give you energy (carbohydrates and fat) or help you grow (protein and fat).

Respiratory System

The Respiratory System is the pathway your body uses to get oxygen from the air around you into your bloodstream to give you energy. Air is breathed into your lungs where oxygen is separated from all the other gases. You breathe out the other gases (mainly carbon dioxide) while the oxygen crosses from your lungs to your bloodstream. From here the oxygen mixes with your red blood cells, travelling throughout your body and providing fuel for different organs.

Immune System

Your Immune System is your body’s main defence against microscopic invaders like bacteria, giving your body the best conditions to grow and develop. Your skin, respiratory system and digestive system are all designed to be barriers to stop bacteria getting into your body. Your body also creates micro weapons called antibodies and T lymphocytes, which attack and destroy any bacteria that break through this defence.

Endocrine System

How your body grows is monitored and controlled by your Endocrine System. Different parts of your Endocrine System produce hormones that are sent throughout your body affecting things like calcium levels, blood sugar levels, reactions to stress, growth and sex organs. Growth, thyroid and sex hormones are the ones that make you grow.

Growth Hormone

Growth Hormone makes you grow (what a surprise!). It increases your height during childhood and adolescence by stimulating the growth plates in your long bones. GH also puts your blood sugar levels up. You mostly produce it at night (so it’s true when your mother says that you grow in your sleep)! Not producing enough GH makes you very short. Luckily we can produce synthetic GH these days which can fix the problem.

Thyroid Hormone

The thyroid gland sits just under the larynx (Adam's apple) and makes thyroid hormone under instructions from the pituitary gland. Thyroid hormone is essential for growth, for keeping your metabolism and circulation going and for keeping your skin and hair healthy. The salt iodine is needed to make thyroid hormone, so it’s important to get enough iodine in our diet.

Sex Hormone

The testicles in boys produce testosterone (male sex hormone) and the ovaries in girls produce oestrogen and progesterone (female sex hormones). These hormones are needed for some of the growth and emotional changes that occur in puberty.

Stages Of Development

Growth is about getting taller, heavier and older. It’s about the most important thing that happens to your body during childhood and adolescence. Growing properly is incredibly important to your health for all of your life.

Unborn Lenny

We take 40 weeks (9 months) to grow from a single cell to a baby ready to be born. This growth happens by cells splitting (cell division) and multiplying millions on millions of times. The fuel and energy needed to grow Baby Lenny is transferred through the umbilical cord from the mother's placenta.

Baby Lenny

The incredibly fast growth we see in the womb continues during the first year. Most babies are born weighing around 2.5 to 3.5kg (six to eight pounds). But in the first year of life, we triple our weight and almost double our height, which is the fastest period of growth in our life! Growth at this time is driven by how much you eat which is why very well fed babies grow quickly.

Lenny As A Small Child

Most babies are around the same size, but by the time you get to two or three years, some children are much bigger or smaller than others. Growth from this time onwards is not just driven by how much you eat, but is driven by a chemical messenger in the blood called ‘Growth Hormone’ which makes your bones grow longer. If you don't have enough growth hormone, you end up very short.

Growth Hormone

Growth Hormone makes you grow (what a surprise!). It increases your height during childhood and adolescence by stimulating the growth plates in our long bones. GH also puts your blood sugar levels up. You mostly produce it at night (so it’s true when your mother says that you grow in your sleep)! Not producing enough GH makes you very short. Luckily we can produce synthetic GH these days, which can fix the problem.

Lenny at around 10

Just before puberty sets in, growth at the end of childhood often slows right down as if the body is pausing before jumping in for the next big stage of growth. Growth hormone is still important here but its effects are wearing off as the body waits for the puberty growth spurt.

Lenny at Puberty

Puberty is when you get your growth spurt. This is your fastest period of growth after the first year of life. Most people grow about 25cm (around 11 inches) during the growth spurt, which usually happens around 11 years in girls and 14 years in boys. The male and female puberty hormones (testosterone & oestrogen) work together with growth hormone to produce the sudden growth spurt.

Sex Hormone

Adult Lenny

Growth stops around 16 years in girls and around 18 years in boys, although you can still grow a tiny bit until you are around 20 or so. Growth stops because the growth plate turns completely into bone and no more growth can occur. This is caused by the sex hormones, which are testosterone in boys and oestrogen in girls.

What’s A Bone Age?

Your bones can mature at a different rate to the rest of your body and it is your ‘bone age’ that really matters for your growth. Your doctor can find out your bone age by X-rays of your hands like here, but this should only be done if you are too tall or too short. If someone's bone age is ahead of their real age, this can be a problem as it means their bones will stop growing early and they may end up short.

Puberty

Puberty is when your body and mind changes from childhood to adulthood. It is the biggest period of change in your life after your first year.

Puberty is one of the main parts of Adolescence, which is the process of becoming an adult. During adolescence, many other things about you will change, including relationships with your family and friends, and where and how you live.

What Is Puberty?

During puberty your body changes to give you the abilities you need as an adult, like strength, height, maturity and the ability to reproduce. However, puberty isn’t just about physical changes. You develop new ways of thinking that are more adult, and these body and thinking changes may affect the way you feel about family, friends and classmates too. You may want to change the way you act and look and even who you want to be around.

Hormones

Puberty starts when your body reaches a certain age and the pituitary gland in your brain starts to produce hormones (chemical messengers) called gonadotrophins. The Gonadotrophins (LH & FSH) turn on the testicles in boys and the ovaries in girls. LH tells the testes to produce more testosterone (male hormone) and the ovaries to produce oestrogen (female hormone). FSH tells the gonads to produce eggs in girls and sperm in boys. The male and female hormone levels get higher as you go through puberty, making the rest of your body grow and change. At the end of puberty, your body is fully grown and developed and you have adult hormone levels.

Changes In Boys And Girls

Puberty is all about change: some physical and some emotional. The start of puberty is different for everyone, so some people start or finish early and some people start or finish late.

Girls begin puberty between 9 and 14 years and finish between 12 and 16 years
Boys begin puberty between 10 and 15 years and finish between 13 and 17 years.

Physical Changes

Whether you are a boy or a girl, you can expect your body to:

Grow taller
Develop body hair and body odour (BO)
Gain weight and get stronger
Develop a male or female body shape and external genitalia
Develop your internal genitalia and the ability to reproduce
Develop a deeper, stronger voice
Possibly get pimples (acne)

Emotional Changes

The emotional changes of puberty are just as important as the physical ones. They can include:

· Moodiness and mood swings

· Reacting more emotionally to things than before

· Feelings of awkwardness

· Concern about your changing body

· Concern about what other people think about you

· Crushes and Sexual Curiosity

· Sexual feelings that get you easily aroused (and sometimes confused)

· A need to be seen as a person that is different and independent from your parents

The feelings occur due to a combination of hormonal changes and trying to adjust to suit those changes. Sometimes it’s hard for your mind and body to keep up with each other!

At times when you have confusing feelings, especially sexual ones, it’s important to make responsible choices. While it may be embarrassing, it’s often a good idea to talk about things with your parents or a responsible adult you trust, such as a doctor, school counsellor, teacher or friend. Remember, all adults had to go through many of the same things that you are, so they may be able to help.

Changes In Boys

Changes during puberty for a boy include:

· Changes in the sex organs – In boys the external genitals (penis and scrotum) hardly change between birth and just before puberty. During puberty, the penis gets longer and wider, the scrotum grows and becomes more wrinkled, and coarse curly pubic hair starts to cover the base of the penis and scrotum.

· Becoming taller and gaining weight - The growth spurt occurs for boys at around 14, usually three years after girls of the same age. Boys often keep growing until they are 18-20 years of age.

· Becoming more muscular – Testosterone makes a boy’s body more muscular around the shoulders and chest, as well as becoming taller and heavier set than girls.

· Body hair - Boys develop pubic hair (under arms and in the groin) at the beginning of puberty. This is followed later on by hair on the face, chest, back, arms and legs. The amount of hair that grows is different from person to person; some boys are shaving by 13, while others don’t shave till they are 18 or older.

· Voice Deepens – Testosterone makes a boy’s vocal cords become longer and thicker during puberty which makes the voice deepen. This can happen in stages over time, which is why the voice ‘cracks’ (usually about age 13-14) and seems to sound like a child and an adult at the same time. It can be embarrassing but it will pass.

· Erections - Erections are when the penis becomes erect or stiff because it fills with blood. This starts in boys as babies, but happens much more frequently after puberty starts. Because the puberty hormones are mainly produced at night, boys have most erections when they wake in the morning, however, erections can occur any time of day and often for no reason at all. While this can be embarrassing, it’s also quite normal and happens to everyone going through this stage.

· Ejaculation and Wet Dreams – Ejaculation means the sudden release of sperm from the penis, which usually happens during an orgasm. Boys usually start to ejaculate from the middle of puberty, generally around 12-14 years. When enough sperm builds up, boys will ejaculate when they are sleeping – called a ‘wet dream’. This is a normal part of puberty although it can be embarrassing.

Changes in the sexual organs in boys

In boys the external genitals (penis and scrotum) hardly change between birth and just before puberty. During puberty, the penis gets longer and wider, the scrotum grows and becomes more wrinkled, and coarse curly pubic hair starts to cover the base of the penis and scrotum. This happens in 5 stages (called puberty stages).

Internal genitalia: The internal male genitalia (testicles, prostate and seminal vesicles) develop around the same time as the outside genitals grow. The testicles begin to produce sperm from early on in puberty but ejaculations usually start in mid puberty.

External genitalia: Testosterone makes the penis and scrotums (ball sac) begin to grow right at the beginning of puberty and keep growing till puberty is over. The time of growth and size of the penis is different from person to person and there is no ’normal’ size.

Changes In Girls

Changes during puberty for a girl include:

· Becoming taller and gaining weight - The growth spurt usually starts in girls at around 10-11, about two to three years before boys of the same age. Girls stop growing very soon after their periods start.

· Body hair - Girls develop pubic hair (underarm and in the groin) early in puberty, followed by a little hair on the arms and legs. The amount of hair that grows is quite different from person to person, but is a lot less when compared with boys.

· Body shape - Due to the rise in oestrogen levels, a girl’s body becomes fuller and more rounded, especially around the hips and thighs (and breasts).

· Periods - Menstrual periods are the time in the month when women lose blood from their vagina as part of the normal female cycle. Beginning periods is a sign that puberty is almost over for a girl.

Changes In The Sexual Organs In Girls

In girls, the breasts and internal sex organs hardly change between birth and just before puberty. At puberty, rising oestrogen levels start breast and pubic hair development usually around 11 years of age. The breasts and pubic hair continue to develop slowly over the next 2-4 years in around five stages as shown here.

Internal sex organs: Oestrogen makes the internal genitals (the uterus or womb, ovaries, fallopian tubes, cervix and vagina) increase in size gradually during puberty. When they are almost fully developed and ready for reproduction, periods will begin.

Breasts: Breasts usually begin to develop at around 11 years, but of course this varies from person to person. Breast development continues throughout puberty with breasts becoming fuller and rounder by adulthood. It’s important to know that sometimes this development is uneven and one breast can be larger than the other. If this happens, don’t worry as both breasts even out with time.

Periods

Menstrual periods are the time in the month when young women lose blood from their vagina as part of the normal female cycle. Periods begin at puberty and while they can be a hassle, they are a sign that your body is working properly. Most young women get their period once a month, however, anywhere between every three weeks and every six weeks is quite normal. It usually lasts from three to seven days and often starts with heavier bleeding that gradually becomes lighter.

What Causes Periods?

Periods depend on changes in female hormone, which are chemical messengers that circulate in your blood. The two main female hormones are oestrogen and progesterone, which every month makes the lining of your uterus (womb) thicker and ready for if you were to have a baby.

If the woman doesn’t get pregnant, the hormone levels drop and the lining of the womb is not needed anymore. It forms into reddish material like blood and leaves the body through the vagina as a ’period’.

When Do Periods Start?

Starting periods is called menarche, and for most girls, it happens at about 12 or 13 years of age. However, it is not unusual to be having periods when you are 10 or even younger! When periods start, they are often irregular for up to two years. This is because the hormones that make them happen are still practicing and don't always reach high enough levels to make you bleed. If you have not started your periods by 15 years old, it may be because late periods run in the family or it may be because something is stopping them. A doctor will be able to help you work out why.

Tips On Tampons & Pads

Pads are worn inside your underwear and absorb the blood as it comes out of the vagina. Sometimes pads can be inconvenient, for instance you can't go swimming in a pad. Tampons were invented to absorb the blood from within the vagina and stop the blood leaking out. Tampons should be changed regularly - every 3 to 4 hours. Because of this it is best to use a pad when going to bed. Never wear a tampon for more than eight hours!

A very serious (although rare) infection known as Toxic Shock Syndrome or TSS has been linked to tampons so it’s very important to wash your hands before you insert a tampon and to change them regularly. Inside packs of tampons are information pamphlets - so have a read through before you use them.

PMT

PMT, short for pre-menstrual tension, is the effect hormones can have on how you feel. Hormones make many women feel a bit different for the week before their period. Your breasts may swell and sometimes your tummy too. It's perfectly normal and goes away when your period starts.

Some women feel more emotional before a period, and may cry or feel cross more than usual. It doesn’t mean you are crazy, although boys find it difficult to understand because it doesn't happen to them. It doesn’t have to be horrid - some women feel braver when they are like this!

The pain that sometimes comes with periods is the muscle stretching as your body tries to release the blood. There are lots of medicines designed to help, which are usually painkillers or muscle relaxants, or both.

Everyone's periods are different, so the best thing to do is to get to know your own. Then you will notice if they change or when something feels wrong. If you do have heavy periods where you lose a lot of blood, it’s a good idea to see a doctor. Even if there is nothing wrong, losing a lot of blood can make you anaemic (low blood count). You will notice this by feeling more tired than usual.

What Makes Periods Stop?

Periods are regular when your body is at a healthy weight. If you are too thin or overweight, your periods can become irregular or stop. The most common reason that women’s periods stop is because they are pregnant! Modern pregnancy tests can show results less than a week after someone misses a period.

Puberty: Ways To Survive

Puberty can be a pretty rough time to go through for some people. It can be difficult to deal with the changes in your body, changes in the way people treat you and the changes in your feelings. Here are some suggestions on how to survive:

· Talk to people - Every adult has gone through puberty. If you are unsure or you’re feeling down about something, talk to an adult you can trust, such as your parents (though this can be hard for some people), doctor, teacher, coach, school counsellor or adult friend. Even if they don’t have the answers you need, they may be able to help you find them. You don’t have to go through it alone!

· Find out the facts - There are many books and sites available on the topic of puberty. Go to a bookstore, library, trusted website or medical centre and read up!

· Look after yourself - During puberty, when your body is a mass of conflicting hormonal and chemical changes, the last thing you should do is add more chemicals to the mix! Avoid drugs such as tobacco, alcohol and other ‘hard’ drugs that will harm your body. Eat a well-balanced diet (if you MUST be on a diet don’t cut out foods, just eat more nutritious foods) and get plenty of exercise.

· Accept the changes - If reading all of this tells you anything, it’s that there is going to be a LOT of changes on the way to becoming an adult physically and emotionally. Being happy with who you are and how you look is the key. People may develop earlier or later than you, but eventually it all evens out so DON’T WORRY.

Being Short Or Tall

Because young people start puberty growth at different ages, young people of the same age can be really tall or short compared to their classmates. This is usually very normal, but it can sometimes be a source of worry. Medical conditions can also make you very tall or very short.

What Is Too Short?

Only around 2 in 100 young people (2%) are very short. So most kids who worry about being too short are completely normal and most of them will end up a normal height when they grow up. However, some young people are very short which is a problem because the world is built for people of normal size.

What Causes It?

Having short parents is why most young people are short. Most people end up as adults within 10cm (four inches) of the average of their parents' heights. Race is also important, for example people of Asian origin are often shorter than white or black people. In the teenage years, going into puberty late can make you shorter than other kids your age, although you will catch up later.

If you are really very short, you may have growth hormone or thyroid hormone deficiency, a gene problem like Turners syndrome (the most common cause of extreme shortness in girls), bone problems, poor nutrition or some other disease.

Can You Treat It?

If you are very short compared to what you would expect from your parents, your doctor can test you for a growth hormone deficiency or other causes of being short. Growth hormone injections can help short children grow into the normal height range but it won't make you much taller if you are short just because you have short parents. If you are a short teenager, male hormone (testosterone) or female hormone (oestrogen) can also help you grow and go through puberty.

Feeling Bad About Being Short

Boys in particular worry a lot about being short and can become very unhappy about being smaller and weaker than other boys their age. This is especially true in the teenage years if they enter into puberty late. In general, young people who are short are pretty well adjusted. But if you are worried about being short, do something about it. See your doctor, get measured properly and ask about your growth predictions.

What Is Too Tall?

Only around two young people in a hundred (2%) are very tall. So most young people who worry about being too tall are completely normal. The most common reason for being very tall is that they began to develop in puberty earlier than other young people. This means that the others will catch up when they start to grow as well.

When Being Too Tall Becomes A Problem

Girls who develop in puberty early, quickly, become the tallest in their class, because the boys don’t start their growth spurt for a few years after the girls. This can be upsetting, but the boys and other girls quickly catch up. In fact, young people who develop in puberty early usually end up a very average height. Late developers often end up taller. Very rarely, young people do become extremely tall. This can be treated with hormone injections which make the bones fuse and stop growing.

How Tall Will You Be?

You inherit genes for your height from both your parents. So you will be around as tall as they are. You can calculate how tall you will be as an adult using the following equation.

Boys: You = Dad’s height + (Mum’s height + 13 cm)

Girls: You = Mum’s height + (Dad’s height - 13 cm)

If you are worried that you are too tall or too short, your doctor can measure you accurately and then compare your height to charts of normal heights for your age. The doctor may also order an X-ray of your wrist to tell how developed your bones are, which gives a clue to how much growing you have left to do.

Brain Development And The Way You Think

The way you think changes gradually as you get older because your brain grows and develops. School work gets harder every year because your brain is able to handle more complex thinking problems as you get older. Your brain is not fully developed until around 14 years of age, when young people can handle very complex thoughts.

Baby

Your brain grows to its full size by about 2 years of age. After this age you don’t grow any more nerve cells.

Child

You become smarter as you get older because you grow more connections between your brain cells (neurones) and develop a covering of myelin that insulates the brain cells to make the brains electrical impulses travel faster. As childrens’ brains are not fully mature, they have difficulty thinking about the future and tend to live in the ‘here and now’.

Adolescent

By the time you are almost a teenager, your brain development is complete, meaning that teenagers can think and reason about what might happen in the future and work out what might be the consequences of doing things in different ways. This is called ‘abstract thinking’.

Adult

By the time you are an adult, your brain is fully developed. Adults however, through years of experience, can help you with problems, as they have a good understanding of people and how the world works.