Human DigestionHuman Digestion

““Who has the Guts?”Who has the Guts?”

DigestionDigestion

There are 2 types of digestion:There are 2 types of digestion:

Mechanical Digestion – Mechanical Digestion – breaks food into breaks food into smaller pieces to increase surface area smaller pieces to increase surface area exposure to digestive enzymesexposure to digestive enzymes

Chemical Digestion – Chemical Digestion – breaks organic breaks organic compounds into their building blockscompounds into their building blocks

Mechanical DigestionMechanical Digestion

ChewingChewingSalivary glands release saliva which moistens Salivary glands release saliva which moistens the chewed food, now called a the chewed food, now called a Bolus.Bolus.The tongue pushes the bolus to the back of the The tongue pushes the bolus to the back of the throat, called the throat, called the Pharynx. Pharynx. A flap of skin called the A flap of skin called the Epiglottis Epiglottis flips down and flips down and covers the entrance to the covers the entrance to the Trachea Trachea during during swallowingswallowing

Peristalsis/Alimentary CanalPeristalsis/Alimentary Canal

The bolus passes through the The bolus passes through the esophagus esophagus by by peristalsisperistalsisPeristalsisFood continues to pass through the Food continues to pass through the Alimentary Alimentary CanalCanal (any part that food passes through) (any part that food passes through)Mouth-Pharynx-Esophagus-Stomach-Small Mouth-Pharynx-Esophagus-Stomach-Small Intestine-Large Intestine-AnusIntestine-Large Intestine-AnusAccessory organs Accessory organs play a role in digestion, but play a role in digestion, but food never enters themfood never enters themSalivary glands-Pancreas-Gall Bladder-LiverSalivary glands-Pancreas-Gall Bladder-Liver

Anatomy of DigestionAnatomy of Digestion

Do you know your guts?Do you know your guts?

Try the quiz.

Chemical DigestionChemical Digestion

Enzymes break down the organic compounds Enzymes break down the organic compounds (polymers) into their building blocks (polymers) into their building blocks (monomers) so they can be absorbed into the (monomers) so they can be absorbed into the blood stream and transported to all cellsblood stream and transported to all cellsCarbohydrates – Carbohydrates – Simple sugarsSimple sugarsProtein – Protein – Amino acidsAmino acidsLipids – Lipids – Glycerol and 3 Fatty acidsGlycerol and 3 Fatty acidsNucleic acids – Nucleic acids – NucleotidesNucleotidesDigestion

Digestion of CarbohydratesDigestion of Carbohydrates

Mouth – Mechanical digestion breaks the carbs Mouth – Mechanical digestion breaks the carbs into smaller pieces to increase the surface area into smaller pieces to increase the surface area exposure to enzymes.exposure to enzymes.

Saliva lubricates the bolusSaliva lubricates the bolus. . It contains the enzyme It contains the enzyme AmylaseAmylase whichwhich begins the Chemical digestion of begins the Chemical digestion of Carbs. Carbs.

Polysaccharides are broken into shorter chains.Polysaccharides are broken into shorter chains.

Swallowing pushes the bolus into the esophagusSwallowing pushes the bolus into the esophagus

Carbs in the StomachCarbs in the Stomach

Peristalsis moves the bolus to the stomach.Peristalsis moves the bolus to the stomach.Cardiac sphincter opens and bolus enters the Cardiac sphincter opens and bolus enters the stomachstomachBolus now mixes with the gastric juices of the Bolus now mixes with the gastric juices of the stomach. stomach. This acidic mixture is now called ChymeThis acidic mixture is now called ChymeMechanical digestion (churning) continuesMechanical digestion (churning) continuesNo chemical digestionNo chemical digestion of Carbs here because of of Carbs here because of the acidity of the chymethe acidity of the chymeProtein is digested hereProtein is digested here

Carbs in the DuodenumCarbs in the Duodenum

Pyloric sphincter opens and chyme moves Pyloric sphincter opens and chyme moves into the duodenum.into the duodenum.

Pancreas secretes:Pancreas secretes: Alkaline secretion that neutralizes the acidic Alkaline secretion that neutralizes the acidic

chymechyme Pancreatic Pancreatic amylaseamylase and and disaccharase disaccharase

continue the breakdown of carbs into simple continue the breakdown of carbs into simple sugarssugars

Absorption of Simple SugarsAbsorption of Simple Sugars

Small intestine is about 6 meters long!Small intestine is about 6 meters long!

The lumen of the small intestine is lined The lumen of the small intestine is lined with Villi.with Villi.

Absorption of CarbsAbsorption of Carbs

Each villi has microvilli on it’s surfaceEach villi has microvilli on it’s surface

The infolds increase surface area contact so the The infolds increase surface area contact so the simple sugars can pass into the blood by simple sugars can pass into the blood by diffusion.diffusion.

Small Intestine Small Intestine

Absorption is complete here.Absorption is complete here.

Peristalsis moves the digested food mass Peristalsis moves the digested food mass to the Large Intestine (Colon)to the Large Intestine (Colon)

Large IntestineLarge Intestine

Main function is to absorb water from the Main function is to absorb water from the unusable waste that remains.unusable waste that remains.

Too much water absorption – constipation!Too much water absorption – constipation!

Not enough water absorption – diarrhea!Not enough water absorption – diarrhea!

Bacteria in colon produce Vitamin KBacteria in colon produce Vitamin K

Feces passes from descending colon to Feces passes from descending colon to rectum and then is excreted through the rectum and then is excreted through the anus (anal sphincter) anus (anal sphincter)

Accessory organs and their Accessory organs and their Functions Functions

Salivary glands – Salivary glands – AmylaseAmylase

Pancreas – Pancreas – AmylaseAmylase

- Protease- Protease

- Lipase- Lipase

Liver – produces bile which is stored in the Liver – produces bile which is stored in the Gall Bladder and secreted into the Gall Bladder and secreted into the duodenum through the Common Bile Ductduodenum through the Common Bile Duct

- Bile emulsifies fats- Bile emulsifies fats

DigestionDigestion

Human DigestionHuman Digestion

Have another lookHave another look

Digestion AnimationDigestion Animation

Digestive ProblemsDigestive Problems

Heart burn – acidic gastric juice enters the Heart burn – acidic gastric juice enters the esophagusesophagus

Gastric ulcer – mucus lining of the Gastric ulcer – mucus lining of the stomach deteriorates and the gastric juice stomach deteriorates and the gastric juice of the stomach begins to digest the of the stomach begins to digest the stomach wallstomach wall

Pig DissectionPig Dissection