The Digestive System

CHAPTER 8

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 IN THROATSALIVARY GLANDS- UNDER EARS AND

UNDER THE TONGUEAMYLASE= 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= TO THE LUNGS) 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 2. PEPSIN- ENZYME THAT BREAKS DOWN

CONNECTIVE TISSUE THAT YOU EAT3. 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 when alive- it relaxes and gets longer after death

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 LONGCECUM- JUNCTION WITH S.I.APPENDIX- A SMALL POUCH-

PROBABLY PART OF THE IMMUNE SYSTEM

• REMOVES WATER FROM FECES• 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- PRESUMABLY DILUTES

BILE SALTS AND LOWERS RISK OF COLON CANCER

COLON TROUBLES

DIARRHEA- FECES MOVE THROUGH TOO FAST- INFECTION OR NERVES

CONSTIPATION- HOLDING FECES IN TOO LONG

• NOT ENOUGH WATER IN FECES

• CAN LEAD TO HEMORROIDS

OUT OF THE BODY…

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= A- FROM SEWAGE

B- SEXUAL- VACCINE TO PREVENT

C- BLOOD- CAN BE CHRONIC

CIRRHOSIS- DAMAGE AND LOTS OF SCAR TISSUE, more 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