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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 THROAT
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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 THROAT 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= 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 SECRETIONS 1. HCl= HYDROCLORIC ACID- ACTIVATES PEPSIN 2. PEPSIN- ENZYME THAT BREAKS DOWN CONNECTIVE TISSUE THAT YOU EAT 3. 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 LONG CECUM- 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