Inside the Living Body Page #3

learning to speak

Most of us learn to talk by our first birthday

but by 2 years old, we're learning 10 new words a day

This is the Broca's area,

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With it you can create sentences

and communicate complex thoughts

Language is what separates us from other animals

By talking, we can exchange thoughts and ideas

We can teach our children not just by showing, but by telling

As our brain develops, we gain other uniquely human qualities

We're aware of our own identity and individuality

we learn to think for ourselves

We become concsious of ourselves as individual

and We're forming memories that will last a lifetime

human childhood is unique

Few other mammals spend such a huge potion of their lifes preparing for adulthood

to do so would be a costly waste of time

by the equivalent age in their life span, most mamal, like dogs

would already be reproducing

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a timeline set by our DNA clock

puts a delay on our sexual development

to give us enough time for one thing

learning

it takes well over a decade to learn complex skill we need

to become adult

and evetually parents ourselves.

through our childhood, we're prime to learn

Our brain is a mass of 100 billion nerve cells, called neurons

Between them,they generate enough electricity to keep a light bulb burning for a day

the Neurons communicate using electric impulses

Each impulse is a tiny fraction of a thought and memory

When we hear a new word,

our ears convert the sound into electrical impulses in our brain

The brain can learn,

because the connections between the brain cell,the neurons

aren't permanent

The brain revise itselfs

the Neurons send out tentacles, constantly forming new connections

where they meet is a synapse

Chemicals, called neuro transmitters,

bridge the gap. to allow the impulse to continue the chain

The new connections form a pattern - a new memory

We learn by making new connections between brain cells

and then reinforced them through repetition

The stronger the reinforcement, the more likely the memory'll stick

And when later, someone asks us to recall that memory

the same pattern of brain cells ?????

and we remember the answer

Because the brain grows quickly in childhood

millions of new connections'll be made all the time

making this the prefect time to learn

Learning takes many forms

Not only in class room but also in the world at large

We learn by experience, and sometimes these experiences are unpleasant

because we're programmed to try out new things when we're young

we take risk with our body

Fortunately, ???????

capable of repairing itself when injure

A cut knee, is part of childhood

As soon as skin is broken,

the body's repair mechanisms swing into action

blood capillaries can constrict

to reduce bleeding????????

next, platelets, a type of blood cell,

make the blood in the cut become viscous and clot

Eventually, the clot forms a plug that stops blood leaking out

Our cells multiply at profilic rate

not only to increase their numbers of cells in the body

but also to replace worn out tissue with newer , stronger. bigger versions

It's the same process of cell growth that heals wounds

In fact we're so good at healing in our youth, even the scar disappears

Childhood is also the time when our horizons expand

we Interact with more and more people

But this increased sociabiliy exposes us to an incresed risk of infection

Fortunately, our body has a arsenal of defenses against germs

Eyebrows, eyelashes, ear hairs and nasal hairs catch airborne bacteria

Sweat, tears , mucus wash them off

And skin constantly sheds its top layer of cells

taking bacteria with it

The mouth is especially vulnerable

recent discoveries have shown that pathogens found here are so potent

that if they ended up in vital organ like heart

they can even prove fatal

Fortunately, the body has a secret weapon

saliva contains lysozyme, an enzyme specially develop to destroy bacteria

though tiny, saliva glands create nearly 1.5 liters of saliva

every day

When a pathogen like chicken pox

does break through these external defenses

our immune system must react to prevent serious infection

Thousands of tiny viruses travel through the blood

The virus hijacks a cell

????????????

Then the infected cell ruptures

spreading yet more vireses around the body

The outward signs of chickenpox are rash and high temperature

The fever that comes with the infection is a sign that the body is fighting back

The heat slows down the spread of the disease

viruses don't reproduce so well when it's hot

The immune system kicks into action

White blood cells latched onto the infected cells

and pumping poisonous proteins

it kills the cell, but it kills the viruses too

The crusty skin pustules

they're remnants of the battle between the immune system and the chicken pox

Each one contains cell debrid and thousands of dead viruses

It may be unpleasant

but getting diseases like this when we're young

is vital for our developing immune system

Our body creates "memory molecules" against the viruses antibodies

we use to rely on antibody form our mother's milk

now we make our own

If we catch the same disease when we're older

the antibodies enable our body to recognize the virus instantly

white blood cells wipe it out before it ever takes hold

this makes childhood the ideal time for vaccination

Vaccines are harmless doses of certain types of virus

like rubella, mumps or polio

they prompt the body to create antibodies

just As it would if infected

by the age of 11, childhood is nearly over

and We're about to change like never before

We're on the brink of adulthood

But first,the hormone surge of puberty

Puberty doesn't stick to a schedule

it begins at any time, depending our DNA clock, our lifestyles , even our diet

whether female or male, for all of us , it begins in brain

At the base, the hypothalamus

the same region that controls our body temperature

Puberty starts when the hypothalamus releases the protein

Kisspeptin into the brain.

the Kisspeptin triggers the release of other hormones throughout the body

This stimulates the sex organs to mature

In girls, that means ovulation

For the first time on television

a high definition view of the ovaries

these off white organs

This unique footage from Gold Coast IV fertility Centre

shows some thing incredible

An egg, inside a protective blister of liquid

At ovulation,the blister ruptures

the egg inside will travel down the fallopian tube

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or lost in menstruation

From the onset of puberty, ovulation occurs once a month

But the ovaries begin another equally important role

they start release in hormones into the bloodstream

including estrogens

they Have dramatic and lasting effects

on both emotional and physical develoment

Both boys and girls experience a growth spread

and each day when we look in the mirror,

we see a new face looking back

And the entire body changes beyond recognition

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