The Digestive System Part 2 Flashcards
what does the PANCREAS + LIVER + GALLBLADDER all have in COMMON?
ACCESSORY ORGANS associated with the SMALL INTESTINE (DUODENUM)
describe the LIVER
- important for the DIGESTIVE FUNCTION IN TERMS OF PRODUCTION OF BILE
- in the URQ
- BILE: FAT EMULSIFIER
describe the GALLBLADDER
the CHIEF FUNCTION in terms of STORAGE OF BILE
describe the PANCREAS
- supplies most of the ENZYMES needed to DIGEST CHYME
- also supplies BICARBONATE to NEUTRALIZE STOMACH ACID
describe the CHARACTERISTICS OF THE LIVER
- REDDISH IN COLOR due to being BLOOD RICH
- the LARGEST GLAND IN THE BODY
- weighs around 3 POUNDS—WEDGE SHAPE
- the LESSER OMENTUM ANCHORS IT TO STOMACH
- right under the DIAPHRAGM
describe the DUCTS (BILARY TREE)
-
LEFT AND RIGHT HEPATIC DUCT
- drain the RIGHT AND LEFT SIDES OF LIVER
- coverage at COMMON HEPATIC DUCT:
- connects to GALLBLADDER (CYSTIC DUCT)
- union is known as COMMON BILE DUCT (BILIARY DUCT)
- empties into the SMALL INTESTINE
- connects to GALLBLADDER (CYSTIC DUCT)
what are the LOBES OF THE LIVER?
- consists of FOUR PRIMARY LOBES;
- RIGHT
- LEFT
- CAUDATE (inferior view)
- QUADRATE (inferior view)
what are the LIGAMENTS OF THE LIVER?
- FALCIFORM LIGAMENT:
- separates the LARGER RIGHT and SMALLER LEFT LOBES
- ROUND LIGAMENT (LIGAMENTUM TERES)
- remnant of the FETAL UMBILICAL VEIN
describe the HEPATIC ARTERIES
- BV that SUPPLIES OXYGENATED BLOOD to the LIVER
- supplies 25% of the ARTERIAL BLOOD TO THE LIVER/as well as HALF OF ITS OXYGEN SUPPLY
describe the HEPATIC PORTAL VEIN
- vessel located in the ABDOMINAL CAVITY—formed from UNION OF the SUPERIOR MESENTERIC & SPLENIC VEINS
- channels blood from the GI TRACT and SPLEEN to the CAPILLARY BEDS IN THE LIVER
- supplies of over 75% of the VENOUS BLOOD TO THE LIVER/as well as HALF OF ITS OXYGEN SUPPLY
describe the HEPATIC PORTAL SYSTEM
- connects the CAPILLARIES of the GI TRACT with the CAPILLARIES IN THE LIVER
-
NUTRIENT RICH BLOOD LEAVES the GI TRACT—first brought to the LIVER FOR PROCESSING before being sent to the HEART
- known as the FIRST PASS EFFECT
- all empty into the CENTRAL VEIN FIRST!!
what are some other FUNCTIONS of the LIVER other than creation of BILE?
- METABOLISM of CARBS, LIPIDS, and PROTEINS
- processing of DRUGS AND HORMONES
- creation of ANGIOTENSIONOGEN
- raises our BP
- renin-angiotensin aldosterone mechanism
- creation of INSULIN-LIKE GROWTH FACTOR; IGF-1 (polypeptide protein hormone—childhood growth)
describe the HISTOLOGY OF THE LIVER
composed of HEPATOCYTES + BILE CANALICULI + HEPATIC SINUSOIDS
describe the LIVER LOBULES
- has HEXAGONAL STRUCTURAL + FUNCTIONAL UNITS; made from HEPATOCYTES
- have rough and smooth ER
- lots of MITOCHONDRIA—just very active cells; to help produce BILE
- processing of BLOODBORNE NUTRIENTS
- filter and process NUTRIENT-RICH BLOOD
- move OUTWARD FROM CENTRAL VEIN
describe BILE SECRETION
secretion of BILE through TINY CANALS called BILE CANALCULI—runs between HEPATOCYTES to the BILE DUCT & branches in the PORTAL TRIADS
what is the PORTAL TRIAD?
- BRANCH OF HEPATIC ARTERY
- supplies OXYGEN CONTENT
- BRANCH OF HEPATIC PORTAL VEIN
- brings in NUTRIENT RICH BLOOD
- BILE DUCT
- receives BILE FROM THE BILIARY CANALICULI
function of STELLATE MACROPHAGES
- also known as HEPATIC MACROPHAGES/KUPFFER CELLS) within LIVER SINUSOIDS
- REMOVES DEBRIS OR OLD WBCs
what are the LIVER (HEPATIC) SINUSOIDS?
heavily FENESTRATED LEAKY CAPILLARIES between the HEPATIC PLATES
describe BILE and BILE SALTS
- composition and ENTEROHEPATIC CIRCULATION
-
YELLOW-GREEN + ALKALINE SOLUTION CONTAINING;
- BILE SALTS:
- cholesterol derivatives that FUNCTION IN FAT EMULSIFICATION & ABSORPTION
- recycled by through REABSORPTION through the ILEUM
- reused back into NEWLY-FORMED BILE 😄
- BILE SALTS:
what is BILIRUBIN?
- pigment formed from HEME
- broken down into STERCOBILIN—BROWN DISCOLORATION TO FECES
describe the CHARACTERISTICS OF THE GALLBLADDER and its FUNCTIONS
- GALLBLADDER:
- THIN-WALLED MUSCULAR SAC
- on the VENTRAL SURFACE OF THE LIVER
- around 3-4 inches in length
- FUNCTIONS:
- stores and concentrates BILE by absorbing WATER AND IONS
- contains HONEYCOMB FOLDS to allow for EXPANSION AS IT FILLS
what are GALLSTONES?
- PRODUCTION OF GALLSTONES:
- known as CHOLELITHIASIS
- see a HIGH CHOLESTEROL DIET and TOO LITTLE BILE SALT
- BLOCKAGE OF BILIARY TREE (asymptomatic until then)
- leads to a BACKUP OF BILE
- PAIN—in URQ
- gets worse when eating FATTY FOODS
describe the PANCREAS – and FUNCTION
- GLAND THAT LIES POSTERIOR TO THE STOMACH
FUNCTIONS:
- produces ENZYMES that begins to DIGEST CARBS, PROTEINS, FATS, and NUCLEIC ACIDS—ACINAR CELLS (99%)—EXOCRINE FUNCTION!!
- secretion of PANCREATIC JUICE
- produces SODIUM BICARBONATE which BUFFERS STOMACH ACID
- PRODUCTION OF INSULIN through ISLETS OF LANGERHANS (1%)—ENDOCRINE FUNCTION!!
describe the ACTIVATION OF PANCREATIC PROTEASES in the SMALL INTESTINE
- PANCREATIC JUICE COMPOSITION:
- BICARBONATE
-
PROTEASES (PROTEINS)
- only activated within the SI—don’t want AUTODIGESTION OF PANCREAS
TYPES:
- TYPES:
- TRYPIN
- CHYMOTYPSINOGEN
- PROCARBOXYPEPTIDASE
- all eventually BREAK DOWN PROTEINS
all first INACTIVE FORMS and then are ACTIVATED IN THE DUODENUM to PROTECT PANCREASE FROM DIGESTNG ITSELF
what is the SIGNIFICANCE OF ENTEROPEPTIDASE?
- has ENTEROPEPTIDASE (secreted from DUODENAL EPITHELIAL CELLS)
- ACTIVATES THE PROTEASES!!
what are the CORRESPONDING PROTEASES (INACTIVE AND ACTIVE FORMS) in the DUODENUM?
TRYSINOGEN (INACTIVE) > TRYPSIN
CHYMOTRYPSINOGEN > CHYMOTRYPSIN
PROCARBOXYPEPTIDASE (INACTIVE) > CARBOXYPEPTIDASE
why is the DUODENUM so IMPORTANT?
- where BILE DUCT & PANCREATIC DUCT unites in WALL
- FUSES TOGETHER as the HEPATOPANCREATIC AMPULLA
describe the FUNCTION OF THE AMPULLA and the HEPATOPANCREATIC SPHINCTER
- AMPULLA:
- opens into DUODENUM via the MAJOR DUODENAL PAPILLA
- HEPATOPANCREATIC SPHINCTER:
- controls ENTRY OF BILE and PANCREATIC JUICE into DUODENUM
How are the BILE AND PANCREATIC SECRETIONS REGULATED?
-
BILE & PANCREATIC JUICE SECRETIONS:
- both stimulated by NEUTRAL & HORMONAL CONTROLS
- HORMONAL CONTROLS;
- includes ENTEROGASTRONES; CHOLECYSTOKININ (CCK) & SECRETIN
describe the SMALL INTESTINE
- the MAJOR ORGAN OF DIGESTION & ABSORPTION
- around 2-4 m long (7-13 ft long)
- from the PYLORIC SPHINCTER to the ILEOCECAL VALVE (where it joins the LARGE INTESTINE)
- diameter; 2.5-4 cm (1.0-1.6 inches)—has a SMALLER LUMINAL SIZE VS. LARGE INTEST.
describe the SUBDIVISONS OF THE SMALL INTESTINE or what are they? (3)
- DUODENUM
[DUODENAL JEJUNAL JUNCTION] - JEJUNUM
- ILEUM
[ILEOCECAL JUNCTION—where SMALL INTESTINE and LARGE INTESTINE MEET]
describe the DUODENUM
- mostly retroperitoneal; around 25.0 cm (10 in)
- CURVES around the HEAD OF THE PANCREAS
- NUTRIENT IRON
describe the JEJUNUM
- around ~2.5 m (8 ft long); ATTACHES POSTERIORLY by the MESENTRY
- MAJORITY OF NUTRIENTS takes PLACE HERE (with exceptions of course)—ABSORPTION
describe the ILEUM
- around ~3.6 m (12 ft long); attaches POSTERIORLY by MESENTRY—joins the LARGE INTESTINE at the ILEOCECAL VALVE
- NUTRIENT VITAMIN B12—in TERMINAL ILEUM
- WATER & LIPIDS—SMALL INTESTINES
what is the BLOOD SUPPLY of the SMALL INTESTINE?
- SUPERIOR MESENTERIC ARTERY—BLOOD SUPPLY
-
VEINS (carries NUTRIENT-RICH BLOOD):
- drains into SUPERIOR MESENTERIC VEINS
-
goes into HEPATIC PORTAL VEINS
- then into LIVER
what is the NERVE SUPPLY OF THE SMALL INTESTINE?
- PARASYMPATHETIC INNERVATION—VAGUS NERVE
- SYMPATHETIC INNERVATION—THORACIC SPLANCHNIC NERVES
what are some MODIFICATIONS the SI has for ABSORPTION?
-
CIRCULAR FOLDS:
- increases the SA for DIGESTION & ABSORPTION in the SMALL INTESTINE
-
VILLI
- has LACTEAL IN BETWEEN—helps to ABSORB DIGESTED FOOD into the CAPILLARY AND LACTEAL
-
MICROVILLI
- contains ENZYMES (BRUSH BORDER)—continues DIGESTIVE PROCESS for CARBS and PROTEINS
function of ENTEROCYTES
- forms the BULK OF EPITHELIUM (SIMPLE COLUMNAR)
- ABSORBS NUTRIENTS and ELECTROLYTES in the BILII
- secretes INTESTINAL JUICE in the CRYPTS
function of PANETH CELLS
secretes DEFENSINS and LYSOZYMES + ANTIMICROBIAL AGENTS
describe INTESTINAL JUICE
provides a VEHICLE FOR ABSORPTION for SUBSTANCES from CHYME as they come in contact with VILLI
describe BRUSH BORDER ENZYMES
- found on the SURFACES OF THE MICROVILLI of ABSORPTIVE CELLS + BREAKS DOWN FOOD PRODUCTS
- MAJOR STIMULUS for PRODUCTION—HYPERTONIC or ACIDIC CHYME
describe the REGULATION OF CHYME ENTRY
- CHYME entering DUODENUM; typically HYPERTONIC (chyme delivery has to be SLOW)
- CHYME:
- must be mixed with BILE and PANCREATIC JUICE = continues DIGESTION
what controls the movement of food into the duodenum?
the enterogastric reflex
how does food MOVE in the SMALL INTESTINE?
- SEGMENTATION:
- the MOST COMMON MOTION of SMALL INTESTINE
- initiated by INTRINSIC PACEMAKER CELLS
- helps with MIXING and MOVING CONTENTS toward ILEOCECAL VALVE
- PERISTALSIS;
- has HORMONE MOTILIN—increases WAVES OF PERISTALSIS
describe the SUBDIVISIONS of the LARGE INTESTINE
- CECUM
- APPENDIX
-
COLON
- ascending
- transverse
- descending
- sigmoid
-
RECTUM
- 3 rectal valves
-
ANUS
- 2 sphincters
what are the THREE UNIQUE FEATURES of the LARGE INTESTINE?
- TENIAE COLI:
- THREE BANDS of LONGITUDINAL SMOOTH MUSCLE in the MUSCULARIS
- HAUSTRA:
- POCKETLIKE SACS caused by tone of TENIAE COLI
- EPIPLOIC APPENDAGES:
- fat-filled pouches of VISCERAL PERITONEUM
describe the HISTOLOGY OF THE LARGE INTESTINE
- HISTOLOGY:
- made up of SIMPLE COLUMNAR EPITHELIUM (except the ANAL CANAL)
- has NO CIRCULAR FOLDS, VILLI, and BRUSH BORDERS
-
MUCOSA:
- much more THICKER and CRYPTS —contains many GOBLET CELLS
describe C. DIFFICILE
- CLOSTRIDIUM DIFFICILE:
- an ANTIBIOTIC-ASSOCIATED DIARRHEA;
- accounts for 14,000 deaths per year
- type of an ANAEROBIC BACTERIUM that carries in INTESTINE
- when antibiotics kill other bacteria; BROAD SPECTRUM ANTIBIOTIC THERAPY
- begins to FLOURISH and CAUSE PSUEDOMEMBRANOUS COLITIS (the INFLAMMATION OF THE COLON)
- leads to BOWEL PERFORATION and SEPSIS
- begins to FLOURISH and CAUSE PSUEDOMEMBRANOUS COLITIS (the INFLAMMATION OF THE COLON)
- an ANTIBIOTIC-ASSOCIATED DIARRHEA;
describe the DIGESTIVE PROCESS
- DIGESTIVE PROCESS:
- residue remains in LARGE INTESTINE around 12-24 hours
- NO FOOD BREAKDOWN—except by ENTERIC BACTERIA
- VITAMINS (made by bacterial flora) + WATER + ELECTROLYTES (Na + Cl)
- FUNCTIONS:
- propulsion of FECES to ANNUS—DEFECATION
- colon not essential for life
defintiion of HAUSTRAL CONTRACTIONS
- has SLOW SEGMENTING MOVEMENTS
- sequentially CONTRACTS in RESPONSE TO DISTENSION
defintiion of GASTROCOLIC REFLEX
- GASTROCOLIC REFLEX:
- initiated by the PRESENCE OF FOOD in STOMACH
- activates THREE to FOUR SLOW POWERFUL PERISTALTIC WAVES per DAY IN COLON (MASS MOVEMENTS)
describe how the LOW FIBER DIET can influence the DIGESTIVE PROCESS
- an begin to NARROW THE COLON and cause STRONG CONTRACTIONS that INCREASES PRESSURE ON WALLS
- results in DIVERTICULA—HERNIATIONS OF MUCOSA
definition of IBS
- IBS:
- functional GI DISORDER
- recurring abdominal pain, stress, etc…
definition of IBD
-
CROHN’S + ULCERATIVE COLITIS
- ulceration of the GI TRACT (CONT.)
- have SKIP LESIONS—areas of inflammation and normal areas (CROHN’S)
definition of ABSORPTION
- ABSORPTION:
- process of MOVING SUBSTANCES from the LUMEN OF THE GUT into the BODY
- have TIGHT JUNCTIONS to let substances to PASS THROUGH
- ENTER THROUGH APICAL MEMBRANE
- EXIT THROUGH BASOLATERAL MEMBRANE
what are the SIMPLEST FORMS OF MONOSACCHARIDES?
- around 60% are DIGESTIBLE as STARCH
- all want them into their SIMPLEST FORMS!!
- SUCRASE > SUCROSE > GLUCOSE + FRUCTOSE
- LACTASE > LACTOSE > GLUCOSE + GALACTOSE
- MALTASE > MALTOSE > GLUCOSE
describe the PATHWAY OF DIGESTION OF CARBS
- all starts at the ORAL CAVITY with SALIVARY AMYLASE
- follows into PANCREAS with PANCREATIC AMYLASE
- follows into BRUSH BORDER within SI
- COTRANSPORTED across the APICAL MEMBRANE of ABSORPTIVE EPITHELIAL CELLS—mostly by SECONDARY ACTIVE TRANSPORT with Na+
- exit across the BASOLATERAL MEMBRANE by FACILITATED DIFFUSION
describe LACTOSE INTOLERANCE
- have DEFICIENT AMOUNTS of LACTASE and CAN NOT CONSUME LACTOSE
- remaining UNDIGESTED LACTOSE—the creation of an OSMOTIC GRADIENT in the INTESTINE
- prevents WATER FROM BEING ABSORBED; diarrhea
- can start pulling water from the INTERSTITIAL SPACE into the INTESTINAL LUMEN
- remaining UNDIGESTED LACTOSE—the creation of an OSMOTIC GRADIENT in the INTESTINE
what can LACTOSE INTOLERANCE CAUSE?
- BACTERIAL METABOLISM (undigested solutes):
- production of LARGE AMOUNTS OF GAS
- results of BLOATING + FLATULENCE + CRAMPING PAIN
describe PROTEIN DIGESTION
- PROTEIN DIGESTION:
- use of DIGESTIVE ENZYMES to BREAKDOWN
- broken down into LARGE POLYPEPTIDES > SMALL POLYPEPTIDES > PEPTIDES > AMINO ACIDS
- PROCESS:
- begins in STOMACH due to PEPSIN (inactive form—PEPSINOGEN)
- follows into PANCREAS—pancreatic enzymes
- follows into BRUSH BORDER ENZYMES
describe LIPID DIGESTION
- have to undergo EMULSIFICATION;
- large lipid globule is BROKEN DOWN INTO SMALLER ONES)
- TRIGS are now exposed with PRETREATMENT WITH BILE SALTS
- BILE:
- has the necessary BILE SALTS in order for the EMULSIFICATION PROCESS TO OCCUR
describe the LIPID DIGESTON PATHWAY
- DIGESTION:
- PANCREATIC LIPASES begin to HYDROLYZE TRIGLYCERIDES yielding MONOGLYCERIDES and FREE FATTY ACIDS
- MICELLE FORMATION:
- consists of FATTY ACIDS + MONOGLYCERIDES + BILE SALTS to move contents into EPITHELIAL CELLS
- have a BILIARY SALT—coated with LECITHIN
- DIFFUSION:
- FATTY ACIDS + MONOGLYCERIDES start to DIFFUSE from the MICELLEs into EPITHELIAL CELLS
- CHYLOMICRON FORMATION:
- FATTY ACIDS + MONOGLYCERIDES —are now RECOMBINED and PACKAGED with other FATTY SUBSTANCES + PROTEINS = CHYLOMICRONS
- CHYLOMICRON TRANSPORT:
- leaves EPITHELIAL CELLS via EXOCYTOSIS—enter LACTEALS and carried away from the INTESTINE IN LYMPH
describe NUCLEIC ACID DIGESTION
- can contain DNA AND RNA—all starts with PANCREATIC NUCLEASES
- also have BRUSH BORDER ENZYMES —breaks down nucleic acids even more
- products transported by the EPITHELIUM VILLI OF THE SI
describe ABSORPTION of MONOSACC in SMALL INTEST
- MONOSACCHARIDES:
- carbs are digested except with cellulose—use of FACILITATED DIFFUSION
-
SECONDARY ACTIVE TRANSPORT:
- with GLUCOSE and GALACTOSE
-
LEAVING CELL:
- use of FACILITATED DIFFUSION
describe ABSORPTION of AMINO ACIDS in SMALL INTEST
- AMINO ACIDS:
- ABSORBED through ACTIVE TRANSPORT or SECONDARY ACTIVE TRANSPORT (around 99% are ABSORBED)
- LEAVE THROUGH SIMPLE DIFFUSION
describe ABSORPTION OF LIPIDS in SMALL INTEST
- LIPIDS:
- ABSORBED THROUGH SIMPLE DIFFUSION (95%)
- LEAVE THROUGH SIMPLE DIFFUSION
where does the DIGESTIVE SYSTEM arise from?
the ENDODERM
