Digestive System
describe the three stages of metabolism
(1) digestion, transport absorbed nutrients to tissue cells via blood (2) anabolic pathways within the cells cytoplasm, where nutrients are built into cellular molecules-or- catabolic pathways, where nutrients are broken down to simpler form (3) catabolic pathway within the mitochondria of cells, which completes the breakdown of newly digested or stored foods. this produces CO2 and water and harvests large amounts of ATP.
A mucosal barrier of the stomach is created by what four factors?
(1) thick coating of mucus on stomach wall (2) epithelial cells of mucosa are joined together by tight junctions that prevent gastric juices from leaking into tissue (3) where protective mucus is absent, plasma membrane is impermeable to HCl (4) stomach surface epithelium is completely renewed every 3-6 days
the syloric region of the stomach acts as a "dynamic filter" allowing only liquids and small particles to pass through the barely open pyloric valve. only (?) of chyme goes through the sphincter at a time. the rest of the chyme is propelled back into the stomach for further mixing to break up solids. the more food in the stomach, the more vigorous the stomach mixing and emptying
3 ml
How many ATP molecules are formed during aerobic respiration?
36-38
the substrate level phosphorylation is the conversion of (?) to (?). this occurs after one step of glycolysis and after one turn of the Krebs cycle.
ADP to ATP
most foods are used as metabolic fuels. they are oxidized and transformed into (?)
ATP
nutrients absorbed by active transport are driven by (?), through the villi and into the capillary blood.
ATP
the (?) are located in the duodenum only. these glands produce alkaline (bicarbonate rich) mucus. it neutralizes the acidic chyme moving in from the stomach
Brunner's glands
the large intestine contains (?) which breaks down cellulose, synthesizes vitamin K, B12, Thiamine and Riboflavin
E. coli bacteria
the (?) cycle breaks down acetyl CoA. its carbon atoms are liberated to CO2 and its hydrogen atom is removed and delivered to the electron transport chain
Krebs cycle
the oxidative phosphorylation is the (?) which releases ATP
Krebs cycle
the (?) are aggregates of lymph nodules that increase in abundance toward an end of the small intestine. this is due to the high bacteria content of the chyme as it comes to the end of the ileum. each lymph nodule is a clot of macrophages.
Peyer's patches
only small quantities of water, glucose, salts, alcohol and lipid soluble drugs are (?) within the stomach.
absorbed
(?) is the passage of digested end products (plus vitamin, minerals and water) from the GI tract into the blood or lymph. this occurs by products entering mucosal cells by active or passive transport processes.
absorption
proteins, broken down to amino acids, are absorbed by (?).
active transport
carbohydrates (simple sugars) are absorbed by (?) or (?).
active transport and facilitated diffusion
(?) is when food fuels (glucose) are broken down within the cells and some the energy released is captured to form ATP.
aerobic repiration
another name for the digestive tract is the (?) canal. it is approx a 30 ft long tube.
alimentary canal
The pancreas secretes a broad spectrum of hormones and digestive enzymes capable of digesting (?).
all food groups
the (?) rule of protein is that "all amino acids needed to make a particular protein must be present in a cell at the same time and in sufficient amounts." If not, proteins cannot be stored and are therefore used for energy or converted into carbs or fats.
all-or-none
during primary metabolism, nutrients are incorporated into cellular molecules by a process called (?). or nutrients may be broken down via glycolysis by the process called (?)
anabolic/ catabolic
the pancreas also secretes (?) which neutralizes stomach acid.
biarbonate
the duodenum recieves (?) from the liver and (?) from the pancreas at the hepatopancreatic ampulla
bile/ pancreatic juices
chemical digestion of (?) first occurs in the mouth, with salivary amylase breaking down starch and glycogen. the small intestine continues the chemical digestion process by use of pancreatic amylase and secreting intestinal enzymes.
carbohydrates
Pancreatic amylase breaks down (?), pancreatic lipase breaks down (?) trypsin, chymotrypsin and carboxypeptides each break down a specific type of (?)
carbohydrates/ fats/ protein
each villi of the small intestine contains 2 blood capillaries, a venous and artery and a lymph capillary. the venous capillary absorb the breakdown of (?) and (?), whereas the lymph capillary (lacteal) absorbs (?)
carbohydrates; protein; fat
the (?) sphincter controls the chyme from re-entering the esophagus
cardiac
when gastric juices are secreted in response to the parasympathetic reflexes triggered by sight, taste, smell and thought, the (?) phase is occurring
cephalic phase
name the three phases of gastric secretion
cephalic phase, gastric phase, intestinal phase
when complex food molecules are broken down to their monomers (chemical building blocks) by the enzymes secreted by various glands, (?) digestion is occurring.
chemical
bile is releases when the gall bladder us stimulates by the hormone (?), secrete by the small intestine
cholecystokinin
in the stomach, food transported by the esophagus is mixed with gastric juices and converted to a creamy paste called (?)
chyme
the (?) duct combines secretions from the lover, gall bladder and pancreas and delivers them to the duodenum
common bile duct
the (?) glands secrete intestinal juice t/o the entire small intestine. this secretion is a watery mixture containing mucus that serves as a carrier fluid for absorption of nutrients and chyme
crypts of Lieberkuhm (intestinal glands)
the small intestine completes (?) and is the most important absorbong organ. very little absorbable material reaches its distal end
digestion
when stimulates, receptors initiate reflexes to activate or inhibit glands that secrete (?) juices into lumen, or mix lumen contents and move them along the length of tract by stimulating (?) of GI tract walls.
digestive juices/ smooth muscle
the stomach usually empties completely within 4 hours after a meal. however, the rate of gastric emptying depends on the contents of the (?)
duodenum
in what two regions does most of the absorption occur within the GI tract?
duodenum and jejunum
the small intestine is divided into what three secretions?
duodenum,jejunum,ileum
(?) cells release the hormones gastrin, intestinal gastrin, enterogastrones, secretin and cholecystokinin. These hormones diffuse into the blood capillaries and influence several digestive system target organs.
enteroendocrine cells
when there is a high fat content in the intestine, the hormone (?) is released which causes a decrease in gastric juice secretion, which inhibits peristalsis. this process gives the small intestine more time to break down the fat.
enterogastrone
bile breaks up (?) into tiny particles so they are more accessible to digestive enzymes. It also creates a salty environment, which enzymes prefer.
fat
carbs moves thru the duodenum rapidly, however (?) are digested more slowly and can remain in the stomach for six or more hours
fats
fats are broken down into (?) and (?) by pancreatic enzymes. they enter the epithelial cell, where the E.R. uses the fatty acids to synthesize triglycerides. Fatty globules combine with protein to form chylomicrons.
fatty acids and glycerol
The (?) is a storage organ for bile between meals to concentrate it.
gall bladder
bile is a major vehicle for cholesterol excretion from the body. bile slats keep the cholesterol dissolved within the bile. too much cholesterol or too few bile salts can lead to crystallization of cholesterol, forming (?) which obstruct the flow of bile from the gall bladder.
gall stones
(?) is formed from the combination of pepsinogen. HCl, pepsin< mucus, intrinsic factor and gastric lipase, and is secreted into the lumen of the stomach via gastric glands and pits
gastric juice
when the food within the stomach stimulates release of more gastrin into the blood, which in turn stimulates secretion of gastric juices, the (?) phase is occurring.
gastric phase
persistent damage to underlying tissues can cause erosions of the stomach wall called (?)
gastric ulcers
ATP is formed from what three processes within aerobic respiration?
glcolysis, Krebs cycle, electron transport chain
when the stored glucose has diminished and the blood glucose levels have declined, (?) occurs, which is the process of forming new sugar from noncarbohydrate molecule. (ex. glycerol and amino acids are converted to glucose.)
gluconeogenesis
During carbohydrate metabolism, when there are already high ATP level, (?) occurs, which is the conversion of glucose into glygogen for storage or for liver and skeletal muscle
glycogenesis
during carbohydrate metabolism, when blood glucose drops, (?) occurs, which is the break down of glycogen to release glucose.
glycogenolysis
the pits of the colon are heavily covered with (?) which secrete mucus to protect it's lining and to hold the fecal material together.
goblet cells
parietal cells release (?)
hydrochloric acid and intrinsic factor (glycoprotein required for absorption of B12 in the small intestine)
by the time the chyme reaches the (?) its major absorptive role is reclaiming bile salts to be recycled back to the liver for further secretion.
ileum
describe the six activities of the digestion process
ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation
when the duodenum is filled with chyme, the internal pressure increases which stimulates wall receptors and triggers enterogastric reflexes, which inhibits (?)
inhibits the parasympathetic NS from acting on stomach, which inhibits peristalsis, which causes the stomach to move slower, which causes the intestines to fill less rapidly
as food enters the small intestine, cells in the intestinal mucosa release intestinal gastrin, which promotes secretion of gastric juices within the stomach, this phase is called (?)
intestinal phase
blockage of bile ducts prevents bile salts and bile pigments from entering the intestine. the result f this is (?) due to yellow bile pigment accumulating in the blood and eventually depositing into the skin.
jaundice
chylomicrons are absorbed by the (?). the smooth muscle contractions cause the lymph capillary to transport chylomoicrons into the blood stream, which then goes to adipose tissue.
lacteal
the chemical breakdown of lipids begins in the small intestine where pancreas secretes fat digesting enzymes called (?). Large fat globules are formed and broken up in the duodenum by the use of bile salts. the globules form fatty droplets.
lipase
The (?) produces bile for export to the duodenum.
liver
chewing, mixing food with saliva using the tongue, churning food within the stomach, segmentation (rhythmic local constrictions) of the intestines are all examples of (?) digestion.
mechanical digestion
once inside the cell, nutrients become involved in biochemical reactions to maintain the homeostasis of life. This process is called (?)
metabolism
the (?) also called "Brush Border", amplifies the absorptive surface and contains enzymes which complete the final stages of digestion of carbs and proteins in the small intestines
microvilli
name the six regions of the true digestive tract
mouth, pharynx, esophagus, stomach, small intestines, large intestine
when the pancreas secretes (?) it is breaking down nucleic acid which becomes sugar, phosphate, and nucleotide (base, which mostly goes to uric acid)
nucleases
chemical digestion of proteins begins in the stomach with the digestive enzyme (?). The small intestine secretes pancreatic enzymes and then intestinal enzymes reduce proteins down to their amino acids.
pepsin
chief cells secrete (?)
pepsinogen (protein digesting enzyme)
swallowing is an example of propulsion within the pharynx (process of moving food through the alimentary canal) What is the form of propulsion that occurs within the remainder of the digestive tract?
peristalsis
the (?) of the small intestine, force the chyme to spiral through the lumen to continually mix with the intestinal juices and to slow its movement. this allows for full nutrient absorption
plica circularis
the digestion process of the pharynx and esophagus is (?), accomplished by the act of swallowing and serving as conduits to pass food from mouth to stomach. food is rolled into a mass called the bolus.
propulsion
(?) digestion is initiated in the stomach and is the only type of enzymatic digestion that occurs in the stomach.
protein
the (?) sphincter performs as a valve which controls stomach emptying.
pyloric sphincter
glycolysis breaks glucose down to (?) and (?)
pyruvic acid and acetyl CoA
Name the four functions of the digestive system
receiving, transporting, digesting, and absorbing food
the salivary glands contains the first digestive enzyme, (?) which breaks down carbohydrates into sugars (starch into glucose)
salivary amlase
the hormone (?) is secreted from the duodenal walls which causes the pancreas to secrete bicarbonate ion to neutralize acid entering the intestine
secretin
the stretching of the organ wall by food products, osmolarity (solute concentration) pH of the food contents and presence of substrates and end products of digestion are all(?) which alert sensors located in the walls of GI tract organs to initiate reflexes.
stimuli
the (?) is a temporary "storage tank" for food, where the chemical breakdown of proteins begins.
stomach
the chemical breakdown of nucleic acids is to break down the acid into nucleotides and the nucleotides are then broken up by intestinal brush border enzymes. these enzymes release the (?), (?) and (?) from the nucleotide.
sugar, phosphate, base
name the three functions of the tongue
taste, initiate swallow reflex, chewing
name the six accessory digestive organs
tongue, teeth, salivary glands, liver, gull bladder, pancreas
gastric secretion is regulated by neural control from the (?), of which it's impulse stimulates hormonal control by release of the hormone (?) into the blood
vagus nerve of the parasympathetic NS/ gastrin
the (?) contains the absorpative columnar cells. it also contains the lactgeal and a line of smooth muscle which allows it to lengthen and shorten, increasing the amount of contact with the nutrients.
villi
(?) is the most abundant substance in chyme. 80-95% of it is absorbed in the small intestine by osmosis.
water
the main function of the large intestine is to absorb (?) electrolytes. it eliminates all that can't be absorbed by the small intestine
water, electrolytes
at the end of the ilieum, all that remains is (?), (?) and (?). these remaining items are then transferred to the large intestines.
water, indigestible food materials (cellulose) and bacteria