The Digestive System

CHAPTER 5

FUNCTION

• INGEST FOOD

• BREAK IT DOWN

• ABSORB THE NUTRIENTS

• ELIMINATE INDIGESTIBLE MATERIAL

MOUTH

• HARD PALATE- BEHIND UPPER FRONT TEETH

• SOFT PALATE- MUSCLES BEHIND HARD PALATE

• UVULA- HANGS DOWN• SALIVARY GLANDS- UNDER EARS AND

UNDER THE TONGUE• AMYLASE= AN ENZYME THAT BREAKS

DOWN STARCH, IN SALIVA

TEETH

• BABY- 20

• ADULT- 32

• BREAK UP FOOD

CROWN- ENAMEL, DENTIN (BONE), PULP (NERVES AND BLOOD VESSELS)

PHARYNX

• BACK OF THE THROAT

• EPIGLOTTIS- TISSUE THAT COVERS THE GLOTTIS (LARYNX OPENING) WHEN YOU SWALLOW

• PREVENTS YOU FROM CHOKING WHILE EATING AND DRINKING

ESOPHAGUS

• CARRIES FOOD FROM PHARYNX TO THE STOMACH

• PERISTALSIS- MUSCLE CONTRACTIONS THAT MOVE FOOD TO THE STOMACH

• HEARTBURN- ACID MOVING UP INTO THE ESOPHAGUS AND IRRITATING IT

• SPHINCTERS- MUSCULAR VALVES ON EITHER SIDE OF THE STOMACH

STOMACH

• MUSCULAR• GASTRIC GLANDS- PRODUCE SECRETIONS1. HCl= HYDROCLORIC ACID- ACTIVATES

PEPSIN, BREAKS DOWN CONNECTIVE TISSUE THAT YOU EAT

2. PEPSIN3. MUCUS• EMPTIES IN 2-6 HOURS• CHYME- ACIDIC LIQUIFIED “FOOD”

SMALL INTESTINE (S.I.)

FIRST SEGMENT OF S.I. =DUODENUM

BILE FROM LIVER (EMULSIFIES FATS) AND ALKALINE PANCREATIC ENZYMES ARE RELEASED INTO THE DUODENUM

• VILLI- FINGELIKE TISSUES THAT INCREASE SURFACE AREA FOR ABSORPTION

Total length of S.I. is 9 FEET LONG

VILLI

• CONTAIN SMALLER EXTERNAL CELLS- MICROVILLI

• THESE PROVIDE MORE SURFACE AREA FOR ABSORBING NUTRIENTS

• AMINO ACIDS AND SUGARS- ABSORBED BY BLOOD VESSELS

• FATS- ABSORBED BY LACTEAL= LYMPH VESSEL

LARGE INTESTINE

• AKA COLON• 4.5 FEET LONG• CECUM- JUNCTION WITH S.I.• APPENDIX- A SMALL POUCH-

PROBABLY PART OF THE IMMUNE SYSTEM

• REMOVES WATER FROM REMAINS• CONTAINS LOTS OF GOOD BACTERIA

POLYPS

• PRECANCEROUS OUTGROWTHS OF THE COLON

• BILE SALTS GET CONVERTED INTO CARCINOGENS BY BACTERIA

• LESS FAT IN DIET= FEWER BILE SALTS• FIBER IN DIET- DILUTES BILE SALTS AND

LOWERS RISK OF COLON CANCER

COLON TROUBLES

DIARRHEA- MOVES THROUGH TOO FAST- INFECTION OR NERVES

CONSTIPATION- HOLDING IT IN

• NOT ENOUGH WATER IN FECES

• CAN CAUSE HEMORROIDS

HAPPY TRAILS

• ANUS- OPENING TO THE OUTSIDE

• RECTUM- LAST SEGMENT OF L.I.

• DEFICATION REFLEX- WHEN MATERIAL ENTERS THE RECTUM YOU GET THE URGE TO GO TO THE BATHROOM

PANCREAS

• Endocrine function- RELEASES INSULIN AND GLUCAGON INTO THE BLOODSREAM TO REGULATE BLOOD GLUCOSE levels

• Exocrine function- RELEASES DIGESTIVE SECRETIONS- SODIUM BICARBONATE, TRYPSIN (WORKS ON PROTEIN), AMYLASE (WORKS ON STARCH), LIPASE (WORKS ON FATS)

LIVER

• LARGEST ORGAN IN THE BODY• SEVERAL LOBES• STORES GLUCOSE AS GLYCOGEN• CONVERTS AMMONIA TO UREA• DETOXIFIES BLOOD• STORES IRON AND SOME VITAMINS• REMOVES BILIRUBIN (which comes from dead

red blood cells)

BILE

• CONTAINS BILE SALTS WHICH EMULSIFY FATS

• CONTAINS BILIRUBIN WHICH WAS REMOVED FROM THE BLOOD (YELLOWISH GREEN COLOR)

LIVER DISORDERS

JAUNDICE- Yellow skin/eyes caused by too much bilirubin- possibly a blocked bile duct

HEPATITIS- cause= virus, can lead to cancer• TYPES OF HEP.= A-SEWAGE WATER B-

SEXUAL- VACCINE TO PREVENT C- BLOOD- CAN BE CHRONIC

CIRRHOSIS- DAMAGE and LOTS OF SCAR TISSUE, Common among ALCOHOLICS

GALLBLADDER

• STORES BILE AND RELEASES IT WHEN NEEDED (FATTY MEAL)

• CHOLESTEROL CRYSTALS - GALLSTONES - CAN BLOCK BILE DUCT and lead to jaundice

OTHER ENZYMES

PANCREAS- also makes NUCLEASE- breaks down DNA AND RNA

SMALL INTESTINE makes:• NUCLEOSIDASE- breaks down NUCLEOTIDES

INTO SUGAR, PHOSPHATE AND BASE• PEPTIDASE- breaks down PROTEINS INTO

AA’S• MALTASE- Breaks down STARCH INTO

GLUCOSE