The Food Machine | Part 6 | Discovery Channel Body Atlas

Summary

The video explores the intricate process of human digestion, revealing how our body functions like a complex machine. It delves into how food fuels vital processes, starting from chewing, swallowing, and stomach breakdown, to nutrient absorption in the intestines. The video highlights the roles of enzymes, bile, and digestive juices in transforming food into energy. It also covers the body’s water management, nutrient absorption, and waste elimination, emphasizing the remarkable coordination of organs like the liver, kidneys, and intestines in keeping us alive and healthy.

Takeaways

• 🍽️ The human body is a complex machine that consumes about 30 tons of food over a lifetime, which fuels essential processes.
• 💤 Even during sleep, the digestive system continues to work, using about 10% of daily energy for digestion while 70% is used to maintain vital body functions.
• 🍳 Over a lifetime, the average person consumes large quantities of food including 8,000 eggs, 6000 loaves of bread, 24 pigs, and a ton of fruit.
• 👅 The digestive process begins in the mouth, where saliva and enzymes help break down starches into sugars, preparing food for further digestion.
• 🦷 The stomach, a muscular bag, uses strong acids and enzymes to break down food, turning it into a thick paste called chyme, which stays in the stomach for 2 to 6 hours.
• 🌀 The small intestine, with its villi, absorbs nutrients into the bloodstream, while the liver and pancreas assist by producing bile and alkaline liquids to neutralize acids.
• 🥦 The body requires 40 essential nutrients from various food sources, and a balanced diet is key to maintaining a healthy body.
• 💧 The large intestine reclaims water from digested food, filtering about 10 pints of water daily, with bacteria in the intestine aiding in the digestion process.
• 🏃 The liver manages the body’s energy supply, storing sugar and releasing it when needed, especially during physical activities.
• 🚽 The kidneys and bladder regulate water balance, filtering 400 gallons of blood a day and producing urine, which is stored in the bladder until excretion.

Q & A

What role does digestion play in our body's energy usage?

Digesting food uses 10% of our daily energy requirements, while 70% is spent on keeping the body's basic functions running, and 20% is left for activities.

How does swallowing prevent food from entering the wrong passages?

When swallowing, a reflex raises the soft palate to stop food from backing into the nose, and the epiglottis bends backwards to close off the larynx, preventing food from entering the air passage to the lungs.

What is peristalsis, and how does it help in digestion?

Peristalsis is the wave-like contraction of muscles in the esophagus that pushes food down the digestive tract, allowing food and drink to travel through the body, even if you’re upside down.

What happens to food when it reaches the stomach?

In the stomach, food is broken down by strong acids and enzymes like pepsin, turning it into a paste called chyme. The stomach also acts as a reservoir, holding food between meals.

How does the body protect the stomach from being damaged by its own acid?

The stomach lining secretes a sticky mucus that coats its walls, protecting it from the corrosive effects of the hydrochloric acid produced to break down food.

What role does the liver play in digestion?

The liver produces bile, which helps break down fats, and processes nutrients absorbed from the small intestine, recombining them into complex proteins and fats the body needs.

What happens to the food once it enters the small intestine?

In the small intestine, nutrients are absorbed through tiny projections called villi, which increase the surface area and allow glucose, amino acids, and fats to enter the bloodstream and lymphatic system.

Why is cooking important for digestion?

Cooking breaks down the complex fibers in foods like potatoes and soybeans, making them digestible. It also helps kill harmful bacteria and enhances flavors, which stimulate saliva and gastric juice production.

How does the body reclaim water from digested food?

As food passes through the large intestine, water is reabsorbed through the intestinal walls. Blood vessels surrounding the intestine then return the water to circulation, ensuring the body maintains proper hydration.

What is the function of the kidneys in maintaining the body’s water balance?

The kidneys filter blood, removing waste and excess water to form urine. They also return 99% of clean water back into the bloodstream, helping maintain the body's water balance.

Outlines

00:00

🔍 The Human Body as a Food Machine

The human body is likened to a complex machine that functions as a power station, chemical factory, and waste disposal unit, all of which are fueled by the food we eat. Over a lifetime, we consume approximately 30 tons of food, which is essential for our body's daily energy requirements. Digestion begins with the act of swallowing, which is a coordinated effort involving the soft palate and epiglottis to prevent choking. The esophagus uses peristaltic contractions to move food towards the stomach. Saliva, produced by three pairs of glands, aids in the lubrication and breakdown of food. The journey of food through the digestive system is a 36-foot long process involving both physical and chemical changes to break down food into basic nutrients.

05:00

🍲 The Stomach: Food Processor and Reservoir

The mouth initiates the digestion process with 32 teeth designed for milling, cutting, and tearing food. Enzymes in saliva begin the chemical breakdown of food, particularly starch into sugar. The stomach acts as a muscular bag that further processes food into a paste called chyme through churning and blending actions. It also serves as a reservoir, holding food between meals. The stomach lining is protected from its own corrosive gastric juices by a layer of mucus. Cooking aids digestion by altering the chemical structure of food, making nutrients more accessible and destroying harmful bacteria. The importance of a balanced diet is emphasized, as different foods provide various nutrients necessary for a healthy body.

10:02

🌀 The Small Intestine: Nutrient Absorption

The small intestine continues the process of digestion through peristaltic movements that push chyme through the duodenum. The inner lining of the small intestine is covered with villi, which increase the surface area for nutrient absorption. Nutrients such as glucose and amino acids are absorbed into the bloodstream through a network of blood vessels within the villi. The small intestine is also responsible for absorbing fat and some vitamins, with the help of bile produced by the liver and stored in the gallbladder. The importance of a balanced diet is reiterated, highlighting the need for essential nutrients from various food sources.

15:03

💧 The Large Intestine: Water Reclamation and Waste Formation

The large intestine marks the final stage of digestion, where the remaining food is processed into solid waste. It is home to bacteria that aid in the production of certain vitamins. The primary function of the large intestine is to reclaim water from the waste products, as the body is constantly working to maintain proper hydration levels. The lining of the large intestine changes to filter out water, which is then absorbed back into the bloodstream. The remaining solid waste, composed mostly of bacteria and undigested food, is eventually excreted from the body.

20:04

💦 Water Balance and Excretion

The body's water balance is crucial for maintaining overall health, and the kidneys play a central role in this process. They filter blood, removing waste and excess water to form urine. The urine is transported through the ureters to the bladder, which stores it until it is excreted. The body loses water through various means, including sweating and breathing, necessitating the constant replenishment of fluids. The digestive system operates primarily on automatic, but the final stage of excretion is under conscious control, completing the cycle of digestion and waste removal that keeps us alive and healthy.

Keywords

💡digestion

Digestion refers to the process by which the body breaks down food into simpler molecules that can be absorbed and utilized for energy, growth, and repair. In the video, digestion is the central theme, showing how food travels through the body and is processed by various systems. The script highlights the complexity of digestion, detailing the roles of the mouth, stomach, small intestine, and other organs in breaking down food into usable nutrients.

💡peristalsis

Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. It begins as soon as food enters the esophagus and continues throughout the intestines. In the video, peristalsis is described as the force behind the food's journey through the digestive system, ensuring that food moves from one organ to the next, including from the esophagus to the stomach and through the intestines.

💡saliva

Saliva is a fluid produced by three pairs of salivary glands in the mouth. It plays a crucial role in the digestion process by moistening food, making it easier to swallow, and containing enzymes that start breaking down starches into sugars. The video illustrates how saliva not only aids in digestion but also protects the mouth and tongue by maintaining moisture, and how it is produced in response to the thought or presence of food.

💡gastric juice

Gastric juice is the acidic liquid secreted by the stomach lining, composed primarily of hydrochloric acid and digestive enzymes like pepsin. This juice helps break down proteins into amino acids and prepares food for absorption in the intestines. In the video, gastric juice is shown as an essential part of digestion, helping to liquefy food into chyme and contributing to the destruction of harmful bacteria.

💡villi

Villi are tiny, finger-like projections found in the lining of the small intestine. They increase the surface area available for nutrient absorption. The video emphasizes the importance of villi in absorbing glucose, amino acids, and other nutrients, enabling them to enter the bloodstream and lymphatic system. The villi play a vital role in extracting nutrients from the digested food and facilitating their transfer into the body’s circulation.

💡bile

Bile is a green liquid produced by the liver and stored in the gallbladder. It plays an essential role in the digestion of fats by breaking them into smaller droplets, making it easier for enzymes to digest them. The video explains how bile is released into the duodenum to assist in fat digestion and absorption, demonstrating the coordinated actions of digestive organs.

💡pancreatic juice

Pancreatic juice is an alkaline fluid produced by the pancreas. It neutralizes the acidic chyme from the stomach and contains enzymes that further break down carbohydrates, proteins, and fats. The video highlights how pancreatic juice is crucial for continuing the digestive process in the small intestine, ensuring that nutrients are fully broken down and ready for absorption.

💡nutrients

Nutrients are substances that the body needs for energy, growth, and maintenance, including carbohydrates, proteins, fats, vitamins, and minerals. The video underscores that food provides essential nutrients that our bodies need to stay healthy. The digestive system's primary function is to extract these nutrients from the food we eat and deliver them to the bloodstream for use throughout the body.

💡water absorption

Water absorption refers to the process by which the body reclaims water from the food and waste products passing through the digestive system, particularly in the large intestine. The video explains how the large intestine absorbs most of the water from the chyme, preventing dehydration and maintaining hydration. This critical function ensures that the body retains enough water for its daily needs.

💡excretion

Excretion is the process of removing waste products from the body. After nutrients have been absorbed, the leftover waste travels through the large intestine, where water is reabsorbed, and solid waste is formed. The video concludes with a focus on how the digestive system disposes of what the body cannot use, such as indigestible fibers and waste, ultimately through the rectum and anus.

Highlights

The human body functions like a complex machine, including roles as a power station, chemical factory, and waste disposal unit.

Throughout a lifetime, humans consume approximately 30 tons of food to fuel their bodies.

Digesting food takes up 10% of our daily energy, while 70% is used for basic life functions, and 20% powers our daily activities.

Swallowing triggers reflex actions that prevent food from entering the nose and lungs, ensuring safe passage to the esophagus.

Peristalsis, wave-like contractions, moves food down the esophagus and throughout the digestive system.

Saliva, produced by three pairs of salivary glands, begins the breakdown of starch into sugar while lubricating food for easier swallowing.

The stomach functions as both a food processor and reservoir, breaking down food with powerful acids while protecting itself with mucus.

Bile produced by the liver and pancreatic enzymes play a crucial role in digesting fats and neutralizing stomach acid.

The small intestine, lined with villi, absorbs nutrients into the bloodstream, covering an area 10 times greater than the surface of the skin.

Nutrients absorbed in the small intestine pass into the blood and lymphatic systems, distributing essential elements like glucose and amino acids throughout the body.

Bacteria in the large intestine help break down remaining food, producing vitamins and aiding in the formation of solid waste.

Water is continuously reclaimed by the body from digested food, as 60% of the human body is water, requiring constant replenishment.

The kidneys filter blood, removing waste and excess water, with all blood in the body passing through the kidneys every five minutes.

The bladder expands to store urine, produced by the kidneys, until it is excreted, completing the digestion and waste process.

The entire digestive process—from ingestion to excretion—operates automatically, sustaining life through continuous and unseen effort.

Transcripts

inside your body is a complex machine a

power station a chemical factory and a

waste disposal unit all in one to

operate it all you need to do is eat

over a lifetime we consume 30 tons of

food discover the ins and outs of

digestion next on body atlas

[Music]

[Applause]

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to sleep perchance to digest

although Gary's mind is switched off his

digestive system is never off duty it's

still busy working on last night's

dinner food is the starting point for

everything that happens in our bodies

just digesting this food takes 10% of

our daily energy requirements 70% is

expended in keeping the body idling

running the processes that keep us alive

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that leaves only 20% of our energy

output for all our activities during the

day food is the fuel that we burn when

our muscles work it provides essential

nutrients that keep us healthy food also

supplies the contents of our internal

first-aid kit which repairs damage to

the body and gets us back on our feet

Gary's ready for breakfast the meal that

breaks the overnight fast from table to

tile 'it the food will make a 24 hour

journey through his body the raw

material comes in many shapes sizes and

tastes in a lifetime the average person

consumes 8,000 eggs half a ton of cheese

6000 loaves of bread 1,000 gallons of

milk 24 pigs and a ton of fruit

swallowing starts the food machine as we

swallow a reflex action stops us from

breathing the soft palate is raised to

prevent food from backing up into the

nose an elastic flap behind the root of

the tongue called the epiglottis bends

backwards to close off the larynx the

air passage to the lungs the mouthful is

steered safely into the esophagus a

muscular tube with a lining very like

skin waves of contractions pass along

its walls propelling the contents with

such force that you could drink standing

on your head these contractions called

peristalsis are the start of an

ever-rolling conveyor belt that carries

food and drink through the entire

process of digestion just the thought of

food is enough to make your mouth water

three pairs of salivary glands produce 2

pints of saliva every day it pours

through miniature fountains from under

the tongue to lubricate the food and

make it easier to swallow it also keeps

the mouth and tongue moist saliva really

starts gushing when there's food in the

mouth or even when you think of

something tasty

from here the food has a twisting 36

foot journey through the digestive

system it will be subjected to physical

and chemical attack as the body

systematically dismantles the complex

ingredients of food into the basic

nutrients it can utilize chewing starts

the assault the mouth is loaded with 32

teeth designed to mill cut and tear the

white surface of the teeth enamel is the

hardest substance in the body as hard as

glass yet it's a living tissue and can

repair minor damage to its surface as

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the teeth demolish the physical

structure of solid food saliva mounts a

second attack it contains two enzymes

chemicals that help pull apart the foods

complex chemical structure one of these

enzymes breaks down starch molecules

into sugar to test this choose something

starchy for a minute or two and you can

taste the result of this chemical

reaction a sugary sweetness in your

mouth the mouthful of food or bolus is

squeezed down the esophagus

a journey of only three seconds this is

the gateway to the stomach a valve at

the bottom of the esophagus

beyond is the inside of a muscular bag

about the size and shape of a boxing

glove the stomach is a food processor it

pulverizes what we eat diluting or

concentrating it preparing it for the

next stages of digestion it's also a

reservoir for holding food between meals

[Music]

this cavern is the stomach at full

stretch at its maximum capacity of 3

pints strong acid pours in attacking and

breaking down food mysteriously it

remains safe from its own corrosive

contents the secret lies in its

convoluted walls they are covered with

deep pits each lined with microscopic

cells in a bizarre balance some of the

cells release hydrochloric acid while

their neighbours secrete a sticky mucus

this coats the stomach walls and

protects it from self destruction the

stomach lining pours out almost a gallon

of gastric juice a day like saliva these

glands can start to water at even the

thought of food the corrosive gastric

juice also contains an enzyme called

pepsin it dismantles proteins into their

basic molecules amino acids little

absorption of nutrients happens here but

food stays for 2 to 6 hours

waves of muscular contractions in the

stomach churn squeeze and blend the food

into a thick paste called chyme this

helps the digestive juices to get to

work our versatile food machine can cope

with everything we throw into it some

foods have structures that we simply

can't digest unless we give nature a

helping hand our digestive system can

only absorb the nutrients from potatoes

and soybeans after we change their

chemical structure by cooking fire has

been the cook's allies since prehistoric

times heat loosens the fibers holding

proteins and carbohydrates together

cooking also destroys many of the

harmful bacteria which find homes on our

food appetizing aromas and flavors also

play an important role they stimulate

our glands to produce saliva and gastric

juice they also bring a special pleasure

to cooking well some do this slice of

bread burns up in just a few seconds if

it released its energy as quickly in the

body we'd also go up in a puff of smoke

the body has more subtle ways of

extracting energy from food but no

matter how the energy is released the

same foods will always release the same

amount of energy this experiment reveals

the amount of energy in ordinary white

sugar exactly half a gram of pure

carbohydrate energy is measured in

calories in the bomb calorimeter the

sugar burns in a flash it produces two

calories a teaspoon full of sugar will

give 20 calories all carbohydrates

produce about the same amount of energy

other foods may be more or less

efficient energy stores fat contains

over twice as many calories as

carbohydrate while the sugar in our diet

gives us instant energy fatty foods

provide us with a more concentrated form

of fuel it's almost three hours since

Gary had breakfast most of it has now

left his stomach and is starting its

twenty-foot journey through the small

intestine if our digestive tract were a

straight cube like a worm we would have

to be thirty feet tall instead our

intestines are neatly looped in two

coils to fit inside a convenient sized

body

peristalsis continues its conveyor belt

role moving the chyme out of the stomach

through this tiny non-return valve each

contraction forces less than a

teaspoonful of time on into the top of

the small intestine the duodenum here

the inner surface of the gut changes to

a moist velvety lining it's specially

designed to absorb the broken down

constituents of food these tiny finger

like projections called villi increase

the area for absorbing nutrients they

give the lining of the small intestine

an area 10 times greater than the

surface of your skin enough to carpet a

living room

[Music]

this is where nutrients pass from the

intestine into the bloodstream each of

the tiny villi contains a network of

blood vessels which absorb glucose and

amino acids the building blocks of

carbohydrates and proteins that flows

into tiny tubes in the villi these

bodies plumbing systems the lymphatic

vessels which eventually empty into the

blood circulation this dense network of

microscopic tubes is wrapped around the

small intestine to carry away the

components of food after we've eaten a

heavy meal blood floods to these

capillaries from other parts of the body

leaving our muscles weak and our brains

foggy we are what we eat and a healthy

body needs a balanced diet the science

of nutrition has pinned down the

essential ingredients from thousands of

different foods our bodies need only 40

different nutrients there's no such

thing as a perfect diet what is meat to

some is poison to others but somehow we

have to take in the essential nutrients

we need to stay alive

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fruits are rich in sugars minerals and

vitamins this is a crystal of pure

vitamin C found in citrus fruits like

oranges it's responsible for the health

of our bones gums and teeth

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vegetables are an excellent source of

carbohydrate they also supply vitamins

and minerals keeping us

bright-eyed

vish provides vitamin e meat and dairy

products contain protein fats and

calcium for healthy nails skin and hair

beans are an excellent source of

nutrients but many raw beans are toxic

until they've sprouted cereals contain

indigestible material called roughage

its bulk helps to keep food moving

through the intestine in contrast we

need only tiny amounts of some vitamins

just a teaspoon full in a lifetime to

digest all these different substances

three organs packed around the stomach

produce a cocktail of digestive juices

the liver the gallbladder and the

pancreas discharge their chemicals into

a single duct which runs along inside

the duodenum before emptying through a

tiny valve called the sphincter of Oddi

[Music]

every day

the liver produces two pints of green

liquid called bile as chyme flows into

the intestine bile helps to break up

globules of fat and some vitamins so

they can be absorbed waves of

peristalsis propel this time loaded with

acid deeper into the small intestine and

dangering its delicate lining so nerves

in the intestine walls trigger the

pancreas to manufacture an alkaline

liquid which neutralizes the acid this

pancreatic juice also contains powerful

enzymes they finish the process of

breaking down the ingredients of time

into simpler molecules this is where the

body begins to reassemble those building

blocks the liver is the largest organ in

the body with over 500 different

functions

it's a busy chemical factory made of

75,000 identical groups of cells it

filters out nutrients carried by blood

vessels directly from the small

intestine

here they are recombined into the highly

complex protein and fat molecules that

the body requires it's also a store of

sugar which provides energy on demand

the body's energy supply is controlled

by the liver we've already seen it's

easy to measure the amount of energy

foods like sugar can release quickly and

violently this laboratory experiment

measures how the human body releases

energy more slowly it doesn't detect

energy directly it analyzes the air that

Sarah breathes as her body burns sugar

it uses up oxygen by measuring the

difference in the amount of oxygen

between the inhaled and exhaled breath

the computer can calculate her

production of energy the flat line on

the graph shows her body is just idling

she's at rest

[Music]

pick your sound let's start doing the

exercise now

[Music]

when Sarah starts exercising immediately

her oxygen consumption Rises her muscles

need fuel so the liver kicks in with

extra supplies from its energy stores

provided by earlier digestion six hours

after breakfast the food stripped of its

nutrients starts the final stage of its

journey a slow trek of five feet through

the large intestine this is the setting

for the third stage of digestion huge

numbers of bacteria reside in the large

intestine living on the remains of our

digested food these bacteria are quite

harmless in the digestive tract in fact

they help us out by making small amounts

of some vitamins bacteria not the

remains of food make up most of our

solid waste the last component is water

a substance so important that the body

is constantly reclaiming it from our

waste products water makes up 60% of the

human body ten gallons in all even so we

are in constant danger of drying out to

play its part in our water control the

lining of the digestive tract changes as

we enter the large

testin from cells that absorb nutrients

to cells designed to filter out water

[Music]

our digestive juices have turned the

original food into a slush and the body

needs that water back two-thirds of the

water in chyme is extracted by the large

intestine filtered out by a microscopic

sieve of cells thousands of blood

vessels in the intestine wall soak up 10

pints of water every day a dense network

of capillaries carries the reclaim water

and absorb nutrients away from the

intestines and back into circulation the

muscular walls of the large intestine

force its contents onward to the rectum

the end of the 30 foot journey through

the digestive tract

[Music]

water drained from the large intestine

may end up in the skin sweat glands

secrete water to cool us when exercising

hard or on a hot day we can easily sweat

a couple of pints without even noticing

as we breathe out an additional pint of

water is lost in the warm moist breath

even without strenuous exercise we need

to replace as much as five pints of

water every day the organs in charge of

our water balance are the two kidneys

they filter the blood excreting any

waste through long tubes shown here in

red wide arteries and veins ensure a

plentiful flow of blood through the

kidneys all of the blood in the body

passes through them every five minutes

that's 400 gallons a day 10 million

gallons in a lifetime each kidney

contains over a million filter units

blood flows through a knot of

capillaries water and waste is filtered

out then collected by intertwined

tubes 99% of the clean water is then

returned to the blood

the remaining liquid urine flows into

collecting ducts and then down long

tubes called ureters just a few pints of

urine flow through these tubes everyday

the amount depends on how much we drink

and how much we sweat urine is produced

slowly during sleep and quicker during

activity the 12 inch journey ends in the

bladder urine pulses from the end of the

ureters

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it's muscular elastic walls expand as it

fills when empty the bladder is the size

of a walnut it can grow to the size of a

fist before it needs to be emptied the

food machine runs mainly on automatic

but the final stage excretion is under

our conscious control just like the

first part of the digestive process

eating digesting and excreting is an

endless cycle even the most exotic foods

have but one purpose to keep us alive

and healthy

thanks to the unseen work day and night

of our uncomplaining food machine

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