Digestive System

Mrs. Stein

Nutrients Supply the body with materials for energy, growth,

and maintenance Carbohydrates - major energy source

Simple (fruit, sugar) and complex (starch, grain) Fats (lipids) - found in cell membranes

Fatty acids and glycerol Proteins play a variety of roles; growth, repair

Amino acids Meat, beans, dairy

Vitamins help regulate processes Minerals are inorganic compounds needed in small

amounts Calcium in bones, iron in hemoglobin

Digestive System

Pharynx

SalivaryGlands

Stomach

Esophagus

Mouth

Large Intestine

Gallbladder (behind the liver)

LiverPancreas

(behind stomach)

Rectum

Small Intestine

Digestion Break down large

molecules into smaller molecules which can be used by cells

Physical and chemical Alimentary Canal – one

way tube which food passes through the body

Accessory structures do not carry food, but aid in digestion

PharynxSalivaryGlands

Stomach

Esophagus

Mouth

Large Intestine

Gallbladder (behind the liver)

LiverPancreas

(behind stomach)

RectumSmall

Intestine

Accessory Structures Liver produces bile which emulsifies fat Gallbladder stores bile Pancreas produces enzymes

Mouth Mechanical digestion

Teeth crush food Saliva moistens food and

contains salivary amylase Starch into simpler sugar Chemical digestion

Esophagus Muscular tube connects

pharynx & stomach Peristalsis

Waves of muscle contractions Bolus enters the stomach

thru a sphincter Acid may back up into the

esophagus Heartburn, reflux

Stomach

Chemical digestion HCl kills bacteria, lowers pH to activate pepsin Proteins break down

Peptic ulcer – hole in stomach wall Caused by bacteria

Muscular sac lined with mucus Protection, lubrication

Mechanical digestion Smooth muscles churn

food

Small Intestine Duodenum - 1st part of the small intestine

Enzymes & fluids enter here Carbohydrates, lipids, and proteins

digested here Nutrients absorbed

PharynxSalivaryGlands

Stomach

Esophagus

Mouth

Large IntestineGallbladder

(behind the liver)

Liver Pancreas (behind stomach)

Rectum

Small Intestine

Small Intestine Lined with finger-like projections called villi

Increase surface area for absorption Carbs and proteins

enter capillaries Fats enter the

lymph vessels Water, cellulose,

and indigestibles remain

Large Intestine Absorbs water from

undigested material Bacteria synthesize

vitamin K Feces is stored in the

rectum, excreted by the anus

Enzymes Stomach

Pepsin – proteins smaller peptide chains Rennin – curdles milk proteins

Pancreas produces 3 enzymes which are secreted into the duodenum Pancreatic amylase – starch maltose Trypsin – proteins amino acids Lipase – fats fatty acids and glycerol

Enzymes of the Small Intestine Enzymes break disaccharides into

monosaccharides Maltase: maltose 2 glucose molecules Lactase: lactose glucose and galactose Sucrase: sucrose glucose and fructose

Peptidase – breaks down small polypeptides into amino acids

Enzyme or Digestive

Fluid

Where it is manufactur

edWhere it

actsWhat

molecule it acts on

What results from

its actionSalivary Amylase

  Mouth   Maltose

Gastric Glands Stomach Proteins  

Bile   Duodenum    

  Pancreas Duodenum Starch  

Trypsin   Duodenum    

  Pancreas Duodenum Lipids  

Maltase   Duodenum Maltose  

  Duodenum Duodenum   Glucose and Fructose

Lactase Duodenum Duodenum    

  Duodenum Duodenum   Amino Acid

Pepsin

Salivary Gland

Liver

Polypeptides

Starch

Smaller Lipids

Pancreatic Amylase

Lipids

Pancreas Smaller PeptidesPolypeptides

Maltose

Lipase

Sucrase

Duodenum

Fatty Acids & Glycerol

Sucrose

Glucose

Glucose & GalactoseLactose

PeptidesPeptidase

Accessory Structures