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Small intestine and food absorption | Physiology | Biology | FuseSchool

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can you believe your digestive system is

as long as a bus yep

it's about nine meters long all wrapped

up inside your body a lot of things go

on in your digestive system not just

digestion what else do you think happens

digestion goes hand-in-hand with

absorption which happens in your small

intestine which is what we're going to

look at in this video

digestion is the breakdown of food from

large insoluble molecules into small

molecules which can be used by your body

digestion involves many organs before it

reaches the small intestine for more

information on the roles of these organs

in the digestive system watch this video

enzymes and other chemicals such as bile

break down food for more on the role of

enzymes and bile in digestion watch

these videos as they move through the

digestive system carbohydrates are

broken down into sugars proteins are

broken down into amino acids and fats

are broken down into fatty acids and

glycerol but the job of the digestive

system doesn't stop a digestion for our

body to make use of these small soluble

molecules we need to absorb them into

our bloodstream this happens in a small

intestine the small intestine is made up

of lots of tiny finger-like projections

called villi the villi increased the

surface area of the small intestine the

larger the surface area the more

absorption that can take place each

villus has a tiny blood vessel called a

capillary and another vessel called a

lac till the food molecule is passed

from the villi of the small intestine

into either the blood capillary or the

lacteal once absorbed into the blood

vessel in the small intestine the

digestive food molecules can then be

transported around the body to where

they are needed so why did those large

molecules need to be broken down in the

first place the small intestine is kind

of like a sieve it has small holes in it

small molecules are able to pass through

those holes or large molecules cannot so

carbohydrates proteins and fats

all too large to pass through the holes

in the small intestine but sugars amino

acids fatty acids and glycerol are all

small enough to pass through sugars and

amino acids pass through the holes into

the blood capillary while fatty acids

and glycerol pass into the lacteal of

the villi these small molecules move by

diffusion moving from a high to a low

concentration for example the small

intestine has a high concentration of

sugar molecules whereas the blood

supplying the small intestine has a low

concentration of sugar so the sugar

moves down its concentration gradient

from a high concentration in the small

intestine through the holes in the villi

into the blood capillary where it's in

low concentration sugar amino acids

fatty acids and glycerol or use

diffusion to move into the blood within

the small intestine so after digestion

breaks down large molecules into small

molecules absorption of the small

molecules happens inside our small

intestine by diffusion into the blood

vessels what an amazing system if you

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if you have any questions why not check

out our first graph as well until next

time