Inside the Living Body Page #5

with our lover, another hormone comes into play

our brain floods with dopamine

The feel-good hormone

As potent as cocaine, it induces euphoria and its addictive. it leaves us on thing more

eventually, after a time together, we start thinking about the final stage of love

commitment, marriage and even kids

Love, both chemical and emotional, wins the ????

It's a relationship we hope a last lifetime

and the process of long-term bonding is chemical too

Sex isn't just about procreation or recreation

It also strengthens the bond between lovers

During orgasm, both partner's pituitary glands flood the bodies with oxytocin

the bonding hormone

It's the very same hormone

that binds us to our mother as new born baby

The more sex we have, the more oxytocin we produce

the stronger the bond between us

Some anthropologists believe oxytocin

could be evolution's way of creating a bond

the strong enough ,to keep parents together

through the trials of parenthood

And the time for parenthood is now

An egg - the largest cell in the human body - ripens

and bursts from the ovary

it begins the same monthly journey , hundreds of others made before it

While ?????? were lost in menstruation

this one's destined to become a baby

the smallest cells in the body

enter the vagina during ejaculation

They have a tough journey front of them

First they must survive the hostile environment of the vagina

it's secretions ??????? to prevent bacterial infection

but they also kill sperm

Most of sperm are killed before they reach the cervix

the Surviving sperms swim on into the uterus and fallopian tubes

Muscular contractions in the walls of the fallopian tube

helps the sperm towards the egg

Only a few hundred make it this far

And only one will succeed in fertilizing the egg

This truely is survival of the fittest

only the most viable sperm with the best DNA

will survive to pass on its genes

so far, there is no sign of what is happened

We're totally unaware that we're about to embark a new chapter in our life

over the next 40 weeks

a single cell will develop into baby

Often the first symptom is morning sickness

No one knows for sure what causes the nausea

but one theory is that it protects the fetus from toxins in food

these could harm its tiny organs during this critical phase of development

Another theory is that nausea is side effect of the mother's immune system

as it weakens to avoid attacking the developing embryo

The fetus is effectively a parasite

It ???? the mother's energies as it draws what it needs from her body

it has its own life support system - the placenta

Here the mother's blood passes nutrients across a membrane

into the fetal blood

Thanks to this constant nourishment

The baby grows over 850 grams in 10 weeks

and the uterus expands up to a 1000 times its normal size, just to hold it

The story of human life continues

form the peak years of early adulthood to the joy of becoming a parent

As our children grow older, so do we

Our body is about to face the next challenge

by this time of life, our body has already peaked

We have been aging for many years

but it is only now, in our 40s, we really notice out changing appearance

Our body is changing and begining to show its age

The cumulative effect of years in the sun causes the first symptom

Our skin is getting wrinkled

since birth, we have been replacing our skin at astonishing rate

We can make up to 40,000 new skin cells every minute

these replace the dead cells with constantly sheding

by 45 , we've created more than 180 kg of dust from old skin cells

Our skin cells are never more than a ?????, even at middle age

wrinkles are not caused by damage to the cells

The problem is the stuff that binds some together - collagen

Ultraviolet radiation in sunlight triggers a molecular chain reaction

which degrades collagen

the fibers get thiner and break

our middle age skin loses its elasticity

become saggy and wrinkly

as we enter our 50s

our body's metabolism may be slowing down

but our lifestyle isn't

We have a growing family

and a demanding career

And this can create another killer

stress

We all recognize the outward signs of stress

sweaty palms,a shortness breath, a dizzy feeling

but the real damage takes place inside our body

When we've stressed

the body instinctively shifts into the fight or flight mood

hormones, adrenaline and cortisol flood from the adrenal glands into the bloodstream

This makes muscles contract

arteries constricts, and heart pump faster , increasing blood pressure

We evolved the fight or flight reflects

to respond to attacks from predators

But we cann't escape our predator

The ????? pressure of being a working parent

and our body has no release

It's the constant triggering of fight or flight

that can be damaging to our body

Stress make cause irreparable harm to our cardiovascular network

speeding up the aging process in blood vessels

the High blood pressure damages cells in the artery walls

they Become stiff and thick

Especially here in the biggest artery - the aorta

arteries with stiff walls

restrict blood flow around the body

our Blood pressure rises, so our heart must work harder

It's a vicious circle

The more stress we exprience

the more we damage our blood vessels

And more damaged of our blood vessels ,

the less able we are to deal with the effects of stress

If stress gets out of control

the heart can become enlarged

as it struggles to force blood

through our narrowing , lessy elastic blood vessel

High blood pressure can also rupture blood vessels in the brain

causing stroke

Most of us learn to manage stress

but for women at 50s

another factor compounds the problem

menopause

During menopause

the ovaries run out of eggs

they Also stop producing the sex hormones

estrogen and progesterone

It's signals the end of women's reproductive life

As the supply of hormones winds down

it upsets the balance in regions of the brain

responsible for mood, sleep and temperature control

when the hypothalamus is turned off course

hot flushes occur, moment when the body can't ????????

it's Not just the brain that affected

bones and muscles tissues also weaken

a woman's bodies spend its whole life getting accustomed to these hormones

no they're gone

and the aging process accelerates

as children leave home

and we retire from work

our body enters a new phase of life

old age has arrived

in 70 years we have grown from a tiny baby to an adult

from child, to parent

to grandparent

the Aging process began several decades ago

Now we are on the ????? of old age

It's the final chapter in the journey of life

When we retire from work, our life style begins to slow

Our body's slowing down too

The outward signs of aging are only part of the story

our senses are affected

We have been losing the sensory hairs we used to hear from our cochlea ,

since birth

Now most of higher-frequency hairs are gone

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