Transcript The Digestive System

The Digestive System
CHAPTER 8
FUNCTION
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INGEST FOOD
BREAK IT DOWN
ABSORB THE NUTRIENTS
ELIMINATE INDIGESTIBLE
MATERIAL
Digestive system
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
Mouth and teeth
TEETH
• BABY- 20
• ADULT- 32
• BREAK UP FOOD
CROWN- ENAMEL, DENTIN (BONE),
PULP (NERVES AND BLOOD VESSELS)
Tooth structure
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
Swallowing
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
Peristalsis
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
Small intestine
VILLI
CONTAIN SMALLER EXTERNAL CELLSMICROVILLI
• THESE PROVIDE MORE SURFACE
AREA FOR ABSORBING NUTRIENTS
• AMINO ACIDS AND SUGARSABSORBED 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 POUCHPROBABLY PART OF THE IMMUNE
SYSTEM
• REMOVES WATER FROM FECES
• CONTAINS LOTS OF GOOD BACTERIA
Junction of small and large intestine
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
Defecation reflex
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
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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