HUMAN DIGESTIONHUMAN DIGESTION

Fun FactsFun Facts

We eat about 500kg of food per year.We eat about 500kg of food per year. 1.7 liters of saliva is produced each day1.7 liters of saliva is produced each day You can swallow even if you are standing on your You can swallow even if you are standing on your

head.head. Every day 11.5 liters of digested food, liquids and Every day 11.5 liters of digested food, liquids and

digestive juices flow through the digestive system, digestive juices flow through the digestive system, but only 100mls is lost in feces. but only 100mls is lost in feces. 

Food stays in your stomach for 2-6 hours.Food stays in your stomach for 2-6 hours. Small intestine, 5-6 meters longSmall intestine, 5-6 meters long Esophagus is 25 cm longEsophagus is 25 cm long The food stays in the small intestine from 1-4 hoursThe food stays in the small intestine from 1-4 hours The food stays at the colon for 10 hours or for a The food stays at the colon for 10 hours or for a

several daysseveral days

Fart FactsFart Facts

Most of us pass somewhere between 200 and 2,000 ml of Most of us pass somewhere between 200 and 2,000 ml of gas per day (average, about 600 ml) in roughly 13-14 gas per day (average, about 600 ml) in roughly 13-14 passages.passages.

These emissions are composed of five gasses: nitrogen These emissions are composed of five gasses: nitrogen (N2), oxygen (O2), carbon dioxide (CO2), hydrogen (H2), (N2), oxygen (O2), carbon dioxide (CO2), hydrogen (H2), and methane (CH4). and methane (CH4).

produce more gas than meat-eaters because the intestinal produce more gas than meat-eaters because the intestinal enzymesenzymescan't digest the cellulose in vegetables' cell walls can't digest the cellulose in vegetables' cell walls

Does your poop float? If so, that means bacteria in your Does your poop float? If so, that means bacteria in your gut are producing methanegut are producing methane

The noise created by passing gas is not from the two The noise created by passing gas is not from the two buttocks vibrating together, as many believe. The noise buttocks vibrating together, as many believe. The noise created occurs as the gas passes through the anal created occurs as the gas passes through the anal sphincter. It's influenced by a combination of the volume of sphincter. It's influenced by a combination of the volume of gas, the force with which it's expelled and the tightness of gas, the force with which it's expelled and the tightness of the anal sphincter.the anal sphincter.

DigestionDigestion Digestion is the Digestion is the

breakdown of large, breakdown of large, complex organic complex organic molecules into molecules into smaller components smaller components that can be used by that can be used by the body.the body.

Molecules need to be Molecules need to be small enough to pass small enough to pass across the membrane across the membrane of your intestine to of your intestine to your blood streamyour blood stream

Digestion animationDigestion animation

IngestionIngestion Food enters the Food enters the

human digestive tract human digestive tract through the mouth through the mouth (aka oral cavity). (aka oral cavity).

Physical breakdown of Physical breakdown of food begins with the food begins with the teeth grinding the teeth grinding the food and increasing food and increasing its surface area. An its surface area. An increase surface area increase surface area allows for easier allows for easier chemical digestion chemical digestion

Alimentary CanalAlimentary Canal

The human digestive tract The human digestive tract is often referred to as the is often referred to as the alimentary canal.alimentary canal.

The alimentary canal of a The alimentary canal of a normal adult is normal adult is approximately 6.5 to 9 approximately 6.5 to 9 meters long.meters long.

It runs from mouth to anus!It runs from mouth to anus! What organs/structures What organs/structures

make up the alimentary make up the alimentary canal? Which contribute to canal? Which contribute to digestion? Which don’t?digestion? Which don’t?

Saliva Saliva Saliva is released from Saliva is released from

the salivary glands and the salivary glands and begins chemical begins chemical digestion of starches. digestion of starches. Saliva contains the Saliva contains the enzyme salivary enzyme salivary amylase which breaks amylase which breaks down starches into down starches into simpler carbohydrates.simpler carbohydrates.

Saliva also moistens Saliva also moistens and lubricates food, and lubricates food, making it easier to making it easier to swallow.swallow.

SwallowingSwallowing

EsophagusEsophagus

The The bolusbolus of food of food moves down the moves down the esophagus propelled esophagus propelled by wave-like by wave-like muscular muscular contractions known contractions known as as peristalsisperistalsis. .

Peristalsis moves Peristalsis moves food all the way food all the way through the through the gastrointestinal tract.gastrointestinal tract.

StomachStomach The stomach acts as a The stomach acts as a

temporary storage site temporary storage site for food. Food usually for food. Food usually spends about 4 hours spends about 4 hours in the stomach. It has in the stomach. It has ridges which allow it ridges which allow it to expand to store to expand to store about 1.5 litres of about 1.5 litres of food.food.

The stomach is also The stomach is also the site of initial the site of initial protein digestion.protein digestion.

EndoscopyEndoscopy

StomachStomach Movement of food into and Movement of food into and

out of the stomach is out of the stomach is controlled by circular controlled by circular muscles known as muscles known as sphincters.sphincters.

One at the top of the One at the top of the stomach allows food from stomach allows food from the esophagus to enter and the esophagus to enter and prevents food from going prevents food from going back up into the esophagus.back up into the esophagus.

Another located at the Another located at the bottom slowly releases bottom slowly releases partially digested food into partially digested food into the small intestine. The the small intestine. The partially digested food is partially digested food is called called chymechyme..

Stomach pylorisStomach pyloris

StomachStomach Millions of cells lining the stomach secrete Millions of cells lining the stomach secrete

various fluids known collectively as gastric various fluids known collectively as gastric fluids.fluids.

Gastric fluid consists of mucus, hydrochloric Gastric fluid consists of mucus, hydrochloric acid, pepsinogens (an enzyme) and other acid, pepsinogens (an enzyme) and other substances.substances.

MucusMucus coats and protects the lining of the coats and protects the lining of the stomach. stomach. Hydrochloric acidHydrochloric acid kills any harmful kills any harmful substances that have been ingested and it also substances that have been ingested and it also converts pepsinogen into converts pepsinogen into pepsinpepsin..

Pepsin is a protein digesting enzyme that Pepsin is a protein digesting enzyme that breaks large protein chains into smaller chains. breaks large protein chains into smaller chains.

Stomach pHStomach pH

The pH environment The pH environment of the stomach of the stomach normally ranges normally ranges between 2.0 and 3.0 between 2.0 and 3.0 on the pH scale.on the pH scale.

The high acidity The high acidity allows pepsin to allows pepsin to work and makes the work and makes the HCL effective at HCL effective at killing pathogenskilling pathogens

Small and Large IntestineSmall and Large Intestine The intestines are The intestines are

named for their named for their diameter, not diameter, not length.length.

The small intestine The small intestine is up to 7 m in is up to 7 m in length but only 2.5 length but only 2.5 cm in diameter.cm in diameter.

The large intestine The large intestine is only 1.5 m in is only 1.5 m in length but 7.6 cm in length but 7.6 cm in diameter.diameter.

Small IntestineSmall Intestine In mammals the length In mammals the length

of the small intestine is of the small intestine is directly related to their directly related to their diet. diet.

Due to the fact that Due to the fact that meats are easier to meats are easier to digest than plant digest than plant materials, carnivores materials, carnivores (lion) will have a shorter (lion) will have a shorter intestine than herbivores intestine than herbivores (rabbit). The length of (rabbit). The length of the digestive tract of the digestive tract of omnivores falls omnivores falls somewhere in the somewhere in the middle.middle.

Anatomy of the Small Anatomy of the Small IntestineIntestine

The majority of chemical The majority of chemical digestion occurs in the digestion occurs in the first of three sections of first of three sections of the small intestine the small intestine known as the known as the duodenumduodenum..

This section also This section also contains an opening contains an opening from the bile duct and from the bile duct and pancreatic duct through pancreatic duct through which bile and which bile and pancreatic enzymes pancreatic enzymes enter the small intestine.enter the small intestine.

Small IntestineSmall Intestine Food enters the small Food enters the small

intestine as a semi-intestine as a semi-solid mixture known solid mixture known as as chymechyme. The . The chyme is acidic due to chyme is acidic due to the HCl in the stomach the HCl in the stomach so it needs to be so it needs to be neutralized.neutralized.

PancreasPancreas The pancreas is an The pancreas is an

accessory organ of the accessory organ of the digestive system. It digestive system. It releases chemicals to releases chemicals to aid in digestion.aid in digestion.

Secretin will stimulate Secretin will stimulate the pancreas to release the pancreas to release a solution containing a solution containing bicarbonate ion into bicarbonate ion into the small intestine the small intestine where it will neutralize where it will neutralize the acidic chyme and the acidic chyme and raise the pH from 2.5 raise the pH from 2.5 to 9.0. This inactivates to 9.0. This inactivates the pepsin.the pepsin.

Pancreas and DigestionPancreas and Digestion

The pancreas also releases digestive The pancreas also releases digestive enzymes that break down the three enzymes that break down the three macromolecules: carbohydrates, lipids and macromolecules: carbohydrates, lipids and proteins.proteins.

LiverLiver

The liver is a large The liver is a large accessory organ of accessory organ of the digestive the digestive system that is system that is constantly constantly producing a fluid producing a fluid known as known as bile.bile.

Bile Bile is stored in the is stored in the gall bladder until it gall bladder until it is needed in the is needed in the small intestine.small intestine.

Liver and Gall BladderLiver and Gall Bladder The presence of lipids The presence of lipids

in the small intestine in the small intestine trigger the release of trigger the release of bile from the gall bile from the gall bladder.bladder.

Bile contains bile salts Bile contains bile salts that emulsifies fats that emulsifies fats which means it breaks which means it breaks them into smaller them into smaller droplets so they can droplets so they can be digested.be digested.

Absorption of MaterialsAbsorption of Materials

Now that nutrients Now that nutrients are small enough are small enough they need to be they need to be absorbed into the absorbed into the blood stream in the blood stream in the small intestine.small intestine.

Chemical digestion Chemical digestion of nutrients is of nutrients is completed by the completed by the time it reaches the time it reaches the large intestine.large intestine.

Large IntestineLarge Intestine The large intestine or The large intestine or

colon stores waste colon stores waste products long products long enough so that water enough so that water can be reabsorbed can be reabsorbed from the wastes.from the wastes.

Along with the water, Along with the water, some inorganic salts, some inorganic salts, minerals and minerals and vitamins are vitamins are absorbed.absorbed.

Large IntestineLarge Intestine

The large intestine The large intestine is home to several is home to several different types of different types of bacteria.bacteria.

These bacteria use These bacteria use waste materials to waste materials to make vitamins B make vitamins B and K. This is an and K. This is an example of a example of a symbiotic symbiotic relationship.relationship.

CelluloseCellulose Cellulose is more Cellulose is more

commonly known as fiber. commonly known as fiber. Fiber helps to remove Fiber helps to remove wastes and therefore wastes and therefore toxins from the body. toxins from the body.

Humans cannot digest Humans cannot digest cellulose however it cellulose however it provides bulk which provides bulk which promotes the movement promotes the movement of the waste products out of the waste products out of the colon.of the colon.

If you have a diet low in If you have a diet low in fiber you will have fewer fiber you will have fewer bowel movements which bowel movements which means toxins remain in means toxins remain in your body for longer your body for longer periods of time.periods of time.

It all comes down to poo…It all comes down to poo…