The digestive system
what part of the NS stimulates the sensation of "dry mouth"? What is the cause of this?
in fight or flight responses, the sympathetic NS will stimulate saliva produced by the salivary glands to increase in viscosity.
What is the difference between carbohydrate digestion/absorption and protein (polypeptide) digestion/absorption
in order for carbohydrates to be absorbed, they must be digested into monosaccharides. Proteins are able to be digested into di and even tri polypeptides, and are able at that point to be absorbed across the intestinal wall.
bile is produced in the ____ and stored in the _____ until stimulated for release. Bile will be stimulated to be released into the _____ via the ___ __ by the ____ hormone called ____ (which is secreted in response to _____).
bile is produced in the liver, stored in the gallbladder, until stimulated for release. Bile will be stimulated to be released into the duodenum via the bile duct by the peptide hormone CCK (cholecystokinin- which is secreted when chyle enters the duodenum).
when we feel lethargic/tired after eating a lot (food coma), this is due to the ____NS.
parasympathetic
Digestive Enzyme: Tryglycerols (lipid) (w/ exception!!) (2)
-lipase -bile (EXCEPTION! Not an enzyme but is involved in mechanical digestion of the fats)
what are the 3 accessory organs of digestion and where did they originate from during development?
-liver -pancreas -gallbladder outgrowths of endoderm from gut tube
What is the digestive tract? -in order explain (7 organs)
1. Oral cavity (mouth) 2. followed by the pharynx, which is shared pathway btwn food entering digestive system and the air entering respiratory system. From pharynx, food enters the 3. esophagus, which transports food to the 4. stomach, which moves the food to the 5. small intestine and then to the 6. large intestine, where finally, the food travel to the 7. Rectum, where feces are stored until an appropriate time for release.
Bile is produced in the ____ and travels down ___ ___ where it may be stored in the ____ or secreted into the ______.
bile is produced in the liver and travels down bile ducts, where it may be stored in the gallbladder or secreted in the duodenum.
bile salts are derived from ____ and serve an important role in (mechanical/chemical) digestion of ____ and will ultimately facilitate the mechanical/chemical digestion of ____ by Are bile salts considered enzymes? Why or why not
bile salts are derived from cholesterol and serve an important role in mechanical digestion of fats and will ultimately facilitate the chemical digestion of lipids by serving as a "bridge" between the aqueous environment of lipids and the aqueous environment of the duodenum. Not enzymes b/d don't break chemical bonds!
How does the oral cavity play a role in the chemical digestion, which is the _____? This process relies on enzymes in the _____ that is produced by (#) pairs of ____ ____. ____ also aids in mechanical digestion by ____ and _____ the food.
chemical digestion =breakdown of macromolecules that make up food into its simplest organic molecules The process relies on enzymes in the saliva that is produced by 3 pairs of salivary glands. Saliva also aids in mechanical digestion by lubricating and moistening the food.
the pharynx is the cavity that leads from the ____ and (anterior/posterior) ___ ____ to the _____. The pharynx can be divided into 3 parts: the _____ (location), the _____ (location) and the ____ (location) Food is prevented from entering the _____ during swallowing by the ______ which is a cartilaginous structure that folds down to cover the ____ _____. What can failure of this mechanism lead to?
pharynx is the cavity that leads from the mouth and the posterior (BACK) nasal cavity to the esophagus. The pharynx can be divided into 3 components: the nasopharynx (posterior of the nasal cavity), the oropharynx (back of the mouth) and the laryngopharynx (IN FRONT of the vocal chords). Food is prevented from entering the larynx during swallowing by the epiglottis, which is a cartilaginous structure that folds down to cover the the laryngeal inlet. Failure of this mechanism can lead to aspiration ("breathing in") food, causing choking.
Isomaltase State: site of production, site of function and the function itself
site of production: intestinal glands site of function: duodenum Function: hydrolyze isomaltose into two glucose molecules
enteropeptidease State: site of production, site of function and the function itself (3),
Site of production: intestinal glands Site of function: duodenum Functions: a) converts pepsinogen to active form b) converts carboxypeptidease A and B to active form C) converts tripsinogen to active form
why is vitamin B12 important? What if you are deficient in this?
Vitamin B12 is a nutrient that helps keep the body's nerve and blood cells healthy and helps make DNA, the genetic material in all cells. Vitamin B12 also helps prevent a type of anemia called megaloblastic anemia that makes people tired and weak
what is the difference between glycogenolysis (state what hormones control this process) and gluconeogenesis -state process -starting process -precursors
*glycogenolysis* - glycogen that is stored in liver will be converted into glucose. Two hormones that control this process are epinephrin (adrenal medulla) and glucagon (pancreas) *Gluconeogenesis*- is the process of synthesizing glucose from non-carbohydrate sources. The starting point of gluconeogenesis is pyruvic acid (procursors can be lactate, AA and glycerol
what is the alimentary canal? What else is it known as? What component of the alimentary canal allows for compartmentalization of function?
-GI tract -the whole passage along which food passes through the body from mouth to anus. -sphincters, allow for compartmentalization of different functions.
liver is located in the ____ of abd and contains two unique structures for communicating w/ digestive system: what are these structures?
-bile ducts -hepatic portal vein
disaccaridases digest _______ and produce _____. Examples of Disaccardidases are: (4) (state what they digest and what they produce)
-maltase: digest maltose into glucose (2 glucose units joined together at 1-4 glycosidic bond) -isomaltase: digests isomaltose (ISOMER OF MALTOSE) into glucose (2 glucose units joined together at 1-6 glycosidic bond) -lactase: digest lactose into monosaccharides galactose + glucose -sucrase: digests sucrose into monosaccharides glucose+fructose
What are the functions of the liver?
-storage of nutrients A) takes up excess sugar in blood to create GLYCOGEN (storage form of glucose) B) Stores fatty acids (fats) as triglycerides (storage form of fats) -synthesizing nutrients A) producing glucose for the rest of the body via glycogenolysis and gluconeogenesis B)mobilizing fats (breakdown of fats) via lipoproteins -produces urea -dexoxification of chemicals -produce bile -synthesis of albumin (plasma oncotic, serves as carrier for many drugs & hormones) and clotting factors
Digestive enzymes: Carbohydrates (6)
1)salivary amylase (ptyalin) 2)pancreatic amylase 3)maltase 4)isomaltase 5)sucrase 6)lactase
what is emulsification of fats? What does it do? Process? (4)
1. hydrophobic fats aggregate together in lumen to form fat globules, hydrophilic pancreatic lipase enzyme is only able to digest surface level ester bonds, but not the inner components b/c of the globule's hydrophobic nature 2. aliphatic bile salts and P.L from bile (secreted via the bile duct into duodenum), will fuse w/ the fat globule with the help of the aliphatic molecule colipase, will break down the globule into emulsion droplets, creating a larger surface area (increasing rate and efficiency of digestion) for the digestion of fat--> triglyceride--> fatty acids + glycerol to take place. 3. The pancreatic lipase + colipase on the will break down the emulsion droplets into the individual triglycerides molecules and then break those down into the fatty acids. 4. The fatty acids are hydrophobic, so the bile salts and the phospholipid molecules will form a micelle around EACH individual fatty acid ***the micelle is MUCH smaller than the emulsion droplet, allowing for absorption of the micelle (containing the f.a) into the enterocyte cell found in villi, which will transport the fatty acid into the lacteal through lymphatic system and ultimately release fatty acids into bloodstream**
how is salivation triggered? (2) what does it lead to
1. presence of good in the oral cavity triggers the increased parasympathetic stimulation of the salivary glands to produced saliva 2. salivation can also be triggered by seeing or smelling food that is nearby.
What is the pH of stomach
2 (very acidic)
what does triacylglycerol break up into after emulsification and packaging into micelles via bile and lipase? What occurs after?
2-monoacylglycerol and fatty acids -micelles form around fatty acids (long chain) and cholesterol (made from the P.L and bile salts) will diffuse via absorption into the mucosa cell -triacylglycerides will reform, will be packed (along with fat soluble vitamins, cholesterol and p/L) into chylomicrons (and diffuse out of cell
what are dimers and trimers
A chemical compound composed of two (dimer) or three (trimer) identical or similar (not necessarily identical) subunits or monomers
Digestive enzymes: Proteins (state both activated and inactivated zymogen form) (7)
A) pepsin (pepsinogen) B) tripsin (tripsinogen) C) Caboxypeptidase A and B (procarboxypeptidase A and B) D) enteropeptidase E) dipeptidase F) aminopeptidase G) Chemotrypsin (chemotrypsinogen)
How does the liver synthesize nutrients?
A) producing glucose for the rest of the body via glycogenolysis and gluconeogenesis B) mobilizing fats (breakdown of fats) via lipoproteins
How does the liver store nutrients? (2)
A) takes up *excess sugar in blood to create GLYCOGEN (storage form of glucose) B) Stores fatty acids (fats) as triglycerides (storage form of fats)
glycerol and proteins are broken down into
AA
What vitamins are fat soluble? Where do they go for absorption in the small intestine?
ADEK packaged into chylomicrons
what 2 hormones stimulate feelings of thirst in ingestion? Where are they secreted from
ADH (vasopressin) [secreted from posterior pituitary gland, stimulate water ONLY reabsorption in the kidneys Aldosterone [corticosteroid- secreted from adrenal cortex], stimulates water AND Na+ reabsorption, more water reabsorbed than kidneys This will increase fluid intake
what are some of the substances that are absorbed directly from the stomach? But mainly, stomach is an organ primarily of _____
Alcohol, Asa but mainly, stomach is an organ primarily of digestion.
What component of the NS heavily regulates peristalsis? Can it also work independently from the brain and spinal cord?
Autonomic NS (parasympathetic-- *stimulates digestion* and sympathetic *inhibits digestion*) can also work independently from brain and spinal cord.
How do undigested disaccharides cause diarrhea? What disorder does this relate to?
Because since the sugars are not being properly digested, the undigested disaccharides cause an osmotic effect, where water is being pulled into the stool and causes the diarrhea. Lactose intolerance; why sx include bloating flatulence (farting) and diarrhea, b/c their bodies do not have the lactase enzyme, so the disaccharide isn't digested normally and causes the above sx as a result.
What is the brush border? What is a brush border enzyme, where is it located
Brush border= the luminal surface of cells on the small intestine (surface of the small intestine),where there are finger like projections called microvilli (increase surface area available for chemical digestion and absorption). Brush border enzymes In order to absorb nutrients, molecules must cross border of lumen to the entercye (absorptive cell), and then cross through that into the bloodstream. BUT, *these macromolecules have to be digested first, which is partially the job of these brush border enzymes.* Must be embedded in plasma membrane of these microvilli
CCK (____) is secreted in response to the ___, specifically
CCK (cholecystokinin) is secreted in response to the entrance of chyle into the duodenum, specifically in response to presence of fats and AA.
____ hormone promotes the secretion of bile, as well as ___ ____ into the ___.
CCK hormone promotes the secretion of bile, as well as pancreatic juices into the duodenum.
What are the three functions of CCK, where is it secreted
CCK is secreted in the duodenum Functions -stimulates release of bile and pancreatic juices into the duodenum. -acts on brain to promote satiety (feeling of being full)
What is chyme and how does the stomach mix this material?
Chyme is a combination of partially digested food, hydrochloric acid (hcl) water and various digestive enzymes. Muscular contractions of the stomach walls that help to mix food and digestive substances together in forming chyme
T/F: the amount of chemical digestion that occurs in the oral cavity is a lot, why is this true or why is this false?
FALSE! amount of chemical digestion is minimal because the food does not stay in the mouth for long
DECREASED Parasympathetic activity will INCREASE water absorption in the colon, which causes diarrhea why?
LOWER MOTILITY In most cases, as food moves through your colon, the colon absorbs water while it makes stool. Muscle movements (contractions) push the stool toward your rectum (motility) because of the water. When the stool gets to the rectum, most of the water has been soaked up. The stool is now solid. If you have constipation, your colon's muscle movements are too slow. This makes the stool move through your colon too slowly. The colon absorbs too much water, and does not provide enough to push the stool toward your rectum, making the stool gets very hard and dry.
what is peristalsis, what causes peristalsis and what is it needed for
Peristalsis is the rhythmic contraction of the gut tube and is needed in order to move food through the digestive system. The enteric system is composed of neurons, which govern the peristalsis of the gut tube.
Salivary amylase (also known as ___) State: site of production, site of function and the function itself
Salivary amylase (also known as ptyalin) Produced in: salivary glands Site of Function: mouth Function: hydrolyzes starches into maltose and dextrins
Trypsin (tripsinogen) State: site of production, site of function and the function itself, what activates it
Site of production: acinar cells (pancreas) Site of function: duodenum Function: hydrolyze specific peptide bonds, activates other enzymes Activated by: enteropeptidase
Pancreatic amylase State: site of production, site of function and the function itself
Site of production: acinar cells in pancreas Site of function: duodenum Function: hydrolyze larger starch molecules into smaller disaccharides (starch to maltose and dextrins)
pepsin (pepsinogen) State: site of production, site of function and the function itself, what activates it
Site of production: chief cells (gastric glands) Site of function: stomach Function: hydrolyzes specific peptide bonds Activated by: HCl
Maltase State: site of production, site of function and the function itself
Site of production: intestinal glands Site of function: duodenum Function: hydrolyze maltose into two glucose molecules
Liver metabolizes alc and medication, T or F.
T
the _____ nervous system is a collection of 100 million _____ that govern the function of the ______ system. The _____ are present in the walls of the ______ and trigger _______ in order to ______
The enteric NS is a collection of 100 million neurons that govern the function of the GI system. The neurons are present in the walls of the digestive tract and trigger peristalsis in order to move materials through the digestive system
T/F: No chemical digestion occurs in the esophagus, besides the continued enzymatic activity in the mouth by the salivary enzymes
True
Upon release of ____ hormone, the _____ contracts and pushes bile out into the ___ ____. The bile __ system merges with the _____ duct, (before/after) emptying into the ______.
Upon release of CCK hormone, the gallbladder contracts and pushes bile bile out into the biliary tree. The bile duct system merges w/ the pancreatic duct, before emptying into the duodenum
what are the two water soluble vitamins, absorption?
Vitamin B complex and C, absorbed directly into the plasma.
what is the function of the colon? What does it do?
absorb salts and water from the undigested materials in the small intestine. Will concentrate the leftover water and salts to form decks.
absorption of nutrients occurs primarily in the ___ and ___ of small intestine, while absorption of _____ occurs in the large intestine
absorption of nutrients= jejunum and ilium of small intestine, while absorption of water occurs in the large intestine
bile salts absorption in blood
active transport directly into the plasma.
what hormones are involved in ingestion? (6)
aldosterone, ADH (vasopressin), glucagon, gherkin, leptin and cholecystokinin
all of the glands, except for the ____ glands are innervated (stimulated) by the ________ nervous system
all of the glands except for the sweat glands are innervated by the PARASYMPATHETIC NS
aminopeptidase is a ______ secreted by the ___ of the duodenum and its function is _____. dipeptidases are also ______ and function to _______.
aminodipeptidase is a peptidase secreted b y the glands of the duodenum and its function is to cleave an AA from the N-terminus of the polypeptide via hydrolysis Dipeptidases are also peptidases and function is to hydrolyze dipeptides into free AA.
what is a protease
an enzyme that breaks down proteins and peptides.
what are the different components of the rectum? (2)
anus- opening through which feces/wastes are eliminated internal and external sphincters
the colon is dividing into the (4)
ascending, descending, traverse and sigmoid colon
b/c pepsin is activated by the (acidic/basic) environment, it follows that pepsin is most active at a ____ ph. This is unique characteristic among human enzymes, as most enzymes are most active at ____ pH.
b/c pepsin is activated by the acidic environment (due to the parietal cells producing hydrochloric acid-HCl), it follows that pepsin is most active at a low pH. This is a unique characteristic among human enzymes, as most enzymes are most active at physiological pH.
why is the bicarbonate within the pancreatic juice important? (2)
because it provides an ideal working environment for the digestive enzymes, which are activated at around a pH of 8.5 -it also neutralizes the acidic chyme within the duodenum.
what does digestion involve?
breakdown of food into its constituent (most basic) organic molecules
bulk of the pancreas is made of (endocrine/exocrine) cells called _____ cells, which will secrete the ___ __. Like all (endocrine/exocrine) cells, the ___ cells will travel via a ___ system (in this case the (minor/major) pancreatic ___) which will travel to the _____, where the major/minor pancreatic ____ will empty the ___ ____ through the major and minor ____ ______
bulk of pancreas is made of exocrine cells called acinar cells, which will secrete the pancreatic juice. Like all exocrine cells, the acinar cells will will travel via a duct system (in this case the major pancreatic duct) which will travel to the duodenum of the small intestine, where the major pancreatic duct will empty the gastric juice (the product) through the major and minor duodenal papillae
In the middle of each villus of the small intestine, there is (2) (state function for each)
capillary bed- for absorption of water soluble nutrients lacteal-lymphatic channel that takes up fats for transport in the lymphatic system.
What are the 3 parts of the large intestine
cecum, colon, rectum.
chief cells produce ______, which is the ___ aka (active/inactive) form of the _____ enzyme called ______. The ____ ____ in the stomach, which are secreted by the parietal cells as _____ _____, will cleave _____ to ______, the activated version of .
chief cells produce pepsinogen, which is the zymogen, INACTIVE form of the proteolytic enzyme pepsin. The hydrogen ions in the stomach, which are secreted by the parietal cells as hydrochloric acid (HCL) will cleave the pepsinogen into pepsin, which is the activated version of pepsinogen
Gastric juice is a combination of the remaining 2 cells in the _____ glands. These two cells are: ___ and _____
chief cells+parietal cells = gastric juice
what 2 hormones stimulate feelings of satiety (suppression of hunger)? Where are they secreted from
cholecystokinin- secreted from enteroendocrine cells in the duodenum of the small intestine and leptin (fat cells in white adipose tissue)
gastrin (which is secreted by ___ cells in the ___gland) is a ___ hormone that induces the ____ cells in the stomach to secrete more ____, as well as also signaling the stomach to (relax/contract), mixing its constant. What is the product after mixture of these contents?
chyme: an acidic, semifluid mixture
How does pepsin digest proteins? What does this result in?
cleave peptide bonds near aromatic amino acids, resulting in short peptide fragments.
what is bile composed of (3)/what is it
complex fluid composed of bile salts, pigments, cholesterol
detoxification of endogenous compounds vs exogenous compounds
detoxification of compounds that were made in body= endogenous detox of compounds that were brought in from the outside environment= exogenous
Short-chain fatty acid absorption, what is this similar to. Why do they not require transporters?
diffuse directly into the intestinal capillaries do not require transporters because they are non-polar and can easily cross the cell membrane. carbohydrate and AA
digestion begins in the ____ ___ and continues in the _____ and the (#) part of the small intestine, known as the ______
digestion begins in the oral cavity and continues in the stomach and the 1st part of the small intestine, known as the duodenum.
the duodenum secretes _____ enzyme and (2) hormones (both ___ hormones).
duodenum secretes enteropeptidase enzyme (activates accessory digestion organ enzymes) as well as secreting secretin and CCK into the bloodstream (both peptide hormones
pancreas has both ____ and ___ functions.
endocrine and exocrine
is ammonia a endogenous or exogenous compound? What does it become?
endogenous. The toxic waste product of AA metabolism. Ammonia Is converted into urea and then transported to kidneys for excretion.
what is the exocrine function of the pancreas? Where does this occur, what does it produce
exocrine function is to secrete pancreatic juice. The pancreatic juice is a alkaline solution rich in HCO3-, as well as having digestive enzymes that work on all 3 classes of biomolecules (carbohydrates, lipids and proteins) within the juice.
what are the two sphincters that make up the rectum? what type of NS control is each?
external sphincter= somatic (voluntary control) internal sphincter= autonomic (involuntary control)
lipids (fats, oils, waxes) are broken down (digested) into
free fatty acids
The stomach can be divided into 4 anatomical divisions. The (2) contain mostly gastric glands and the (2) contains mostly pyloric glands.
fundus and body divisions of stomach are composed primarily of gastric glands pylorus and antrum divisions of stomach are composed primarily of pyloric glands
mucosa of the stomach consists of (2)
gastric and pyloric glands
gastric glands respond to signals from the ___ nerve in the _____ NS, which is activated by the brain in response to sight smell and taste of food. What are the three types of cells that the gastric glands have?
gastric glands respond to signals from the vagus nerve in the parasympathetic NS Gastic glands have these 3 cells: -mucous cells - chief cells -parietal cells
In addition to _____, parietal cells also secrete ___ ___. This is a ____ (type of protein) that is involved in the proper absorption of _____
in addition to secreting Hal, parietal cells also secrete intrinsic factor. This is a type of glycoprotein that is involved in the proper absorption of vitamin B12
In addition to the digestive tract itself (also called the GUT), the (4) help to provide the ____ and _____ necessary to aid in the digestion of food. These 4 organs are known as the _____ organs
in addition to the digestive tract itself, the salivary glands, pancreas, liver and gall bladder provide the lubrication and enzymes necessary to aid in the digestion of food. known as the accessory organs.
what does slowing of motility in digestive tract allow for?
increased time for digestive enzymes to act on the nutrients within the chyle, especially fats.
What are feces composed of?
indigestible material, water, bacteria (ex. e-coli), certain digestive secretions (such as enzymes and some bile)
intracellular digestion, as a part of _____, involves the (oxidation/reduction) of ____ and ____ _____ that is extracted from food we eat via ___ ____ digestion.
intracellular digestion, as a part of metabolism, involves the oxidation of fatty acids and glucose that is first extracted from food via extra-cellular digestion.
Lack of a particular disaccharidase causes ______, which in turn causes _____ in the intestines to hydrolyze the disaccharide (instead of the enzyme), producing _____ ___ as a biproduct ( commonly known as a ___).
lack of a particular disaccharidase causes an inability to diges/break down that disaccharide, which in turn causes the bacteria within the intestines to hydrolyze the disaccharide (instead of the enzyme) and producing methane gas as a byproduct (farts)
what is the final part of the GI tract
large intestine
The large intestine has a (larger/smaller) diameter than the small intestine and has a (shorter/longer length).
large intestine has larger diameter but shorter in length when compared to small intestine.
the colon is also known as the (2)
large intestine/large bowel
lipase, found in ___ catalyzes the hydrolysis of ____
lipase, found in saliva, catalyzes the hydrolysis of lipids into free fatty acids
what organ produces bile?
liver
what are the two subgroups of digestion?
mechanical and chemical digestion
starches and carbohydrates are broken down (digested) into
monosaccarides
mucous cells, which are a type of cell in the ____ gland (most of which are found in the ___ and ____ divisions of stomach) produces _____ that's function is to _____
mucous cells, which are a type of cell in the gastric glands (most of which are found in the fundus and body divisions of the stomach produces bicarbonate (NaH2CO3) rich mucus ("buffer") that protects the muscular walls from the harsh acidic (pH= 2) and from the proteolytic environment of the stomach. HCl + NaHCO3 → NaCl + H2CO3
extra-cellular digestion is the process by which
nutrients from the "outside world" (outside of the body) are obtained/extracted from food
Our muscular ___ forms the food into a ____, which is forced back to the ____ and swallowed.
our muscular tongue forms the food into a bolus, which is forced back to the pharynx and swallowed.
the cecum is an _____ ___ of the colon that's function is ______ ____ exiting the (organ) though the ______ _____ and is additionally the site of attachment of the ______.
out pocket of the colon that accepts fluid exiting the small intestine through the ileocecal valve and is additionally the site of attachment of the appendix.
the pancreas secretes _____ _____, which does what
pancreas secretes pancreatic lipase, which emulsifies fats into glycerol and free fatty acids.
pancreatic amylase is responsible for ____ digestion and will break down (small/large) _______ into smaller ______.
pancreatic amylase is responsible for carbohydrate digestion and will break down large polysaccharides into small disaccharides
what innervates saliva production of the salivary glands?
parasympathetic NS (just like all other glands in digestive tract!!!)
What is the endocrine function of the pancreas? Where does this only occur, what does it produce
peptide hormone function. Occurs ONLY within the cells of langerhans. Produces glucagon (alpha cells), insulin (beta cells) and somatostatin (gamma cells), all of which are necessary to regulate proper blood sugar levels.
peristalsis is the rhythmic contraction of ___ muscle that proceeds downward in digestive tract. Certain factors such as (4) can lead to REVERSAL of peristalsis can lead to what
peristalsis is the rhythmic contraction of SMOOTH muscle that proceeds downward in digestive tract certain factors such as -cognitive stimulation -chemical agents -infectious agents -stimulation to the POSTERIOR pharynx leads to reversal of peristalsis, leading to emesis.
the pyloric glands (found in the ___ and ____ divisions of the stomach) contain ___ cells that secrete ____, which is a ____ hormone.
pyloric glands (found in the pylorus and antrum divisions of the stomach contain G-cells that secrete gastrin, which is a peptide hormone.
How does the body maintain proper fluid levels in the body?
reabsorption by osmosis. As solutes are absorbed into the blood, water is drawn with them, eventually reaching the capillaries.
the internal lining of the stomach is thrown into folds called
rugae
saliva contains two enzymes: these are
salivary amylase (ptyalin) and lipase
salivary amylase, found in _____ (also known as ___) catalyzes the ______
salivary amylase, found in saliva (also known as ptyalin) catalyzes the hydrolysis of starches into simpler, smaller sugars (maltose and dextrins)
what are enteroendocrine cells
secrete hormones in GI tract that regulate digestion in reponse to various stimuli
secretin is a ___ hormone that causes ____ enzymes to be released into the ______. It's function is to regulate ____ by reducing ____ secretion in the parietal cells and increasing ____ secretion in the pancreatic cells. additionally, secretin is known as a ______, which is a hormone that (increases/slows) motility through the digestive tract
secretin is a peptide hormone that causes *pancreatic enzymes* to be released into the duodenum. Its function is to regulate pH by reducing HCl secretion in the parietal cells and increasing bicarbonate (HCO3-) secretion in the pancreatic cells. Additionally, secretin is known as a enterogastrone, which is a hormone that slows motility through the digestive tract
chymotrypsin (chymotrypsinogen) State: site of production, site of function and the function itself, what activates it
site of production: acinar cells (pancreas) Site of function: duodenum Function: hydrolyze specific peptide bonds Activated by: trypsin
(pro)Carboxypeptidase A and B State: site of production, site of function and the function itself, what activates it
site of production: acinar cells (pancreas) site of function: duodenum function: hydrolyze terminal AA at carboxy end, activated by: enteropeptidase
Lactase State: site of production, site of function and the function itself
site of production: intestinal glands site of function: duodenum function: hydrolyze lactose into glucose and fructose
dipeptidease State: site of production, site of function and the function itself,
site of production: intestinal glands site of function: duodenum function: hydrolyze pairs of AA
small intestine consists of (#) segments. These three are (in order)
small intestine= 3 segments duodenum jejunum ileum
what are sphincters
smooth muscles around the alimentary canal that contract, allowing for compartmentalization of function
what is the function of the retum?
storage site for feces
the gallbladder is located ____ and stores and concentrates what
stores and concentrates bile
What is the job of the digestive system?
take the complex foods (composed of polysaccharides, fats and proteins) and turn these *large macromolecules* into *smaller, simpler monosaccharides, fatty acids and AA* respectively
the ______ is a small finger like projection that was once thought to be vestigial (define), but now it is known that the _____ plays a role in warding off bacterial infections and repopulating the (organ) with normal ____ after episodes of _______.
the appendix is a small fingerlike projection that was once through to be vestigial (lost ancestral function, no use for it now) but now it is known to play a role in warding off bacterial infections and repopulating the large intestine after episodes of diarrhea.
Mechanical digestion is
the physical breakdown of food into smaller food particles, but does NOT INVOLVE the breaking (enzymatic cleavage) of chemical bonds
the small intestine is lined with _____, which are small fingerlike projections from the ____ lining of the small intestine. Each ____ has many ____, which increase the ___ ____ available for (digestion/absorption)
the small intestine is lined w/ villi, which are small fingerlike projections form the epithelial lining of the small intestine. Each villus has many microvilli, which increase the surface area available for absorption.
The stomach uses _____ and ____ to digest food, creating a fairly (mild/harsh) environment.
the stomach uses hydrochloric acid (HCl) and enzymes to digest food, creating a fairly harsh environment.
what is gut motility? what does it control? What is this also called?
the stretching and contractions of the muscles in the gastrointestinal (GI) tract, and it controls movement of food throughout the digestive tract. The synchronized contraction of these muscles is called peristalsis.
what does the stomach have in order to prevent autodigestion of its own tissue?
thick mucosa
How can water pass to reach blood?
transcellularly- across the cell membrane paracellularly- squeezing between cells.
where is the stomach located?
underneath the diaphragm in the LUQ of abd
how does the liver receive all the blood draining from the abdominal portion (GI tract, the abdominal digestive tract, as well as from the pancreas, gallbladder, and spleen) of the digestive tract?
via the hepatic portal vein.
what are the 5 components of the villus
villus -outer shell microvilli lacteal- transport chylomicrons (fats, cholesterol) to lymphatic system capillary beds- absorbs water soluble nutrients lymphatic vessel fat-soluble vitamins
Where does extracellular digestion occur?
within the lumen of the alimentary canal
the gallbladder is a common site of _____ or _____ _____ formation. This is a painful condition that causes _______ of the gallbladder. The ____ may also travel into the ___ ____ and get stuck in the ____ ____. In some cases the ____ can be caught just before entering the duodenum, resulting in blockage of not only the ____ ____, but also the ____ ____, causing _______.
gallbladder is a common site of cholesterol or bilirubin stone formation. This is a painful condition that causes inflammation of the gallbladder. The stone may also travel into the bile ducts and get stuck in the biliary tree. In some cases, the stone can be caught just before entering the duodenum, resulting in blockage of not only the biliary tree, but also the pancreatic duct, causing pancreatitis.
what 2 hormones stimulate feelings of hunger in ingestion? Where are they secreted from?
glucagon-pancreas and ghrelin-stomach
Chemical digestion is __. Ex?
the enzymatic cleavage of chemical bonds. Example: peptide bonds of proteins and glycosidic bonds of starches.
What are the two functions of enteropeptidase (formerly called enterokinase)
-activates trypsinogen (pancreatic protease) into its active form tripsin ( which)will initiate the an activation cascade) -activates procarbboxypeptidases A and B to their respective active forms.
what is liver cirrhosis? What is affected?
a chronic liver disease characterized by progressive destruction of liver cells, which are are replaced by fibrosis (scarring of the tissue). Bad when scared tissue builds up, causes backup of fluid within hepatic portal system, which in turn causes fluid buildup and swollen veins within digestive system (especially veins in esophagus). Which can rupture and cause fatal bleeding, resulting in hematemesis. -Cirrhosis can also cause bleeding disorders b/c production of clotting factors = disupted. -unable to properly process and dispose ammonia, leading to increased amounts of ammonia in blood, which affects brain functioning -hepatocellular carcinoma (ca of liver)
bile salts will emulsify ___ and ____ into micelles, which is apart of ____ digestion (emulsification). When the ___ enzyme actually hydrolyzes the ester bonds holding the lipid molecules together, is apart of ___ digestion.
bile salts emulsify cholesterol and fats, emulfification= mechanical digestion. when the pancreatic lipase enzyme actually hydrolyzes the ester bonds holding the lipid molecules together, this is chemical digestion.
How does the liver produce urea? Where is it then excreted?
by converting ammonia (toxic waste from AA metabolism) to create urea, which is then excreted by the kidneys
What can NSAIDs (asa and, ibuprofen)'s side effects do to the stomach?
disrupt the MUCUS (HCO3-) production within the stomach, causing it to become irritated b/c the mucosa of stomach is unprotected, leading to -gastritis--> inflammation of mucosa of stomach -gastric ulcers deep wounds in the lining of the stomach
What is absorption?
extract and transport the final products of digestion from the digestive tract into the circulatory system for distribution to the body's tissues and cells.
what are pancreatic juices, what stimulates the secretion of the juices into the duodenum?
pancreatic juice (release stimulated by CCK hormone) is a mixture of enzymes that digest carbohydrates, fats and proteins within a rich bicarbonate alkaline solution
proper digestion of fats depends on what (2)
pancreatic lipase and bile
Pancreatic peptidases (produced in ___ cells, secreted in the ____ and function in the ____) include (4) and are released in the ____ (____) form. When stimulated by ____ enzyme, the pancreatic peptidases will convert to their activated forms (3)
pancreatic peptidases (produced in acinar cells, secreted into the pancreas and function in the duodenum) include trypsinogen, procarboxypeptidase A and B and chymotrypsinogen. When stimulated by enteropeptidase, zymogens will converted to their active form. trypsinogen--> tripsin ( which will the go on activate other zymogens--activation cascade!) procarboxypeptidase A & B--> carboxypeptidease A and B
the parasympathetic division of the NS _____ digestive activities through (increase/deacrease) _____ ____ and promoting _____. the sympathetic NS is ____ of these activities. In periods of high sympathetic activity, blood flow is (increased/decreaased) to the digestive tract and ____ _____ speeds up/slows down significantly
parasympathetic NS activates digestive activities via increasing exocrine glands and promoting peristalsis the sympathetic NS is the opposite of these acuities. In periods of high sympathetic activity, blood flow is decreased to digestive tract and gut motility slows down significantly.
What does the hepatic portal vein do? What does it drain into
processes the nutrient rich, deoxygenated blood from the GI tract, pancreas, gallbladder and spleen. Hepatic portal vein will then drain into the interior vena cava and then go into the R atrium.
Sucrase State: site of production, site of function and the function itself
site of production: intestinal glands site of function: duodenum function: hydrolyze sucrose into glucose molecule and fructose molecule
The basic/acidic enviornment of the stomach and the basic/acidic environment of the duodenum point out an important correlation between pH and enzyme activity. Pepsin (inactive form= ____, produced by the __ cells in the ___ gland) is active in the ____ and works best at a pH of ____. Pancreatic enzymes are active in the ______ and work best at a pH of ____.
the acidic environment of the stomach and the basic environment of the duodenum point out an important correlation btwn pH and enzyme activity. Pepsin (inactive form= pepsinogen, produced by the *chief cells* within the gastric gland) is active in the duodenum and works best at a pH of 2 Pancreatic enzymes are active in the duodenum and work best at a pH of 8.5
What are the purposes of the low pH of stomach acid?
-kills most harmful bacteria -helps denature proteins and can break down some intramolecular bonds that hold food together
The stomach secretes 7 products. What are these products, what cells secrete these products? parts of the Stomach these are secreted in?
1. HCl -kills microbes -denatures proteins -converts pepsinogen into pepsin -gastic juice (stomach acid-- chief cells +parietal cells) 2. pepsinogen - cleaved in stomach via acidic conditions into active form pepsin, which will partially digest proteins 3. Mucus-protects mucosa 4. Bicarbonate (NaHCO3) (protects mucosa) HCl + NaHCO3 → NaCl + H2CO3 5. Water: dissolves and dilutes ingested material 6. Intrinsic Factor- insures proper absorption of vitamin B12-- parietal cells (1/2 cells that make up gastric/stomach acid) 7. Gastrin-- secreted from G-cells in the pyloric gland [antrum and pylorus division of stomach], induce stomach wall muscular contractions, as well as increase stimulation for pyloric cells to secrete HCl, creating chyle.
What is bilirubin come from? How does the liver process/excrete bilirubin? Where will it go?
Bilirubin is a byproduct of the breakdown of hb from RBC destruction (old/injured). Will travel thru the bloodstream (at this time unsoluble) but once in liver cell (hepatocyte) will be conjugated by a protein (turned water soluble) and secreted into bile for excretion thru the bile duct, where the bile will either be stored in gallbladder or secreted into duodenum.
What happens if liver is unable to process or excrete bilirubin? What can cause the liver to be unable to process or excrete bilirubin (3)?
Bilirubin will build up, causing elevated levels of bilirubin. This can cause jaundice. Caused by damage to liver, excessive RBC destruction, blockage of bile ducts)
Many meds have anticholinergic side effects, which block the activity of the parasympathetic neurons throughout the body. Older individuals can be on lots of these meds, increasing these side effects. Which of the following would NOT be expected in an individual taking meds with anticholinergic activity? A) dry mouth B) diarrhea C) slow gastric emptying D)decreased gastric acid production.
PARASYMPATHETIC= increasing motility and activity and functioning of the digestive system, eliminating C and D. A, Dry mouth WOULD occur b/c it is DECREASING PARASYMPATHETIC activity, meaning that it is DECREASING saliva production from salivary gland, causing dry mouth B is CORRECT because with DECREASED parasympathetic activity would SLOW DOWN motility through the colon, leading to INCREASED water reabsorption of the colon and NOT ENOUGH water to pass the waste thru the colon to the rectum, which leads to CONSTIPATION
Vitamins ADEK (____ soluble vitamins) will/will not drain into the liver before arriving at the R side of the heart. Vitamin B complex and VItiman C (___ soluble vitamins) will/will not drain into the liver before arriving at the R side of the heart.
Vitamins ADEK (FAT SOLUBLE) vitamins will NOT DRAIN into the liver before arriving at the R side of heart (b/c they enter the lymphatic system and *bypass the liver*. Vitamins B complex and C (WATER SOLUBLE vitamins) WILL drain into the liver before arriving at the R side of heart.
after the ___ cells (derived from the ___ gland) secrete ____ (___ hormone) and signals the _____ cells to secrete more _____ and induces ______ of the muscles in stomach, mixing the fluid, the semifluid acidic mixture is known as ____. The ____ will exit the stomach through the ______ _______, and will at this time enter the ______ (__ ____). The presence of ____ in the _____ stimulates the release of ___ _____ enzymes.
after the G cells (derived from the pyloric gland) secrete gastrin (peptide hormone) and signals parietal cells to secrete more HCl and induces contractions of the muscles of the stomach, mixing the fluid, the semifluid acidic mixture is known as chyle. The chyle will exit the stomach through the pyloric sphincter and will at this time enter the duodenum. The presence of chyle in the duodenum will stimulate the release of brush-boarder enzymes
bile ducts are located in the (organ) and function is to connect the ____ with both the ______ and the ___ ____. ____ is produced in (organ).
bile ducts are located in the liver and function is to connect the liver with both the gallbladder and small intestine
Bile, produced by the _____ is composed of pigments (most major pigment is _____ which is derived from ______), ____ ____ (emulsify fats, ____ molecule) and _____.
bile, produced by the liver, is composed of pigments (most major pigment is bilirubin, derived from breakdown of hb), bile salts (emulsify fats, amphipathic) and cholesterol.
that part of the large intestine is home to aerobic bacteria? What type of relationship does the presence of bacterial in the ____ represent? how? example?
colon. symbiotic bacteria are provided with a steady source of food, and the byproducts produced by the bacteria itself are beneficial to humans ex: bacteria in the gut produce vitamin K, which is essential for the production for clotting factors and biotin (vitamin b7) which is a coenzyme for many metabolic enzymes
How does the oral cavity play a role in the mechanical digestion of food? What its this process called and what does it enable (2)
plays a role in breaking down the food into smaller particles using the teeth, tongue and lips via mastication (chewing) mastication (chewing) enables 2 things: 1. increased surface area to volume ratio, creating more surface area for enzymatic digestion as the food passes through the tube 2. moderates size of food particles going through the *lumen* of the alimental canal, b/d particles that are too large can cause an obstruction in the tract
aminopeptidease State: site of production, site of function and the function itself,
site of production: intestinal glands site of function: duodenum function: hydrolyze terminal AA at amino end
bile State: site of production, site of function and the function itself,
site of production: liver (stored in gallbladder) site of function: duodenum function: emulsion of fats w/ help of lipase (mechanical digestion)
lipase State: site of production, site of function and the function itself,
site of production: pancreas (acinar cells) site of function: duodenum function: hydrolyze lipids into fatty acids and glycerol
small intestine is responsible for the majority of (mechanical/chemical) digestion, with some small involvement in absorption, but this occurs in the (2) parts of small intestine
small intestine= responsible for chemical digestion, w/ some involvement in absorption but this occurs in the jejunum and ileum of small intestine
Swallowing is initiated in the muscles of the _____, which constitute the (lower/upper) _____ ____. _______ will squeeze, push and propel the bolus toward the _____. As the bolus approaches the ____, a muscular ring known as the (upper/lower) ____ ___ (also known as ___ ____) contracts/relaxes, opening and allowing the passage of food into the ____.
swallowing is initiating in the muscles of the oropharynx, which constitute the upper esophageal sphincter. Peristalsis will squeeze, push and propel the bolus (down the esophagus) toward the stomach. As the bolus approaches the stomach, a muscular ring known as the lower esophageal sphincter (cardiac sphincter) RELAXES, opening and allowing the passage of food into the stomach.
what is ingestion?
taking food into the mouth in order t o supply body w/ nutrients
the chemical digestion of _____ occurs in both the ____ (___ ___) and the ____, with the two amylases targeting complementary ____. ____ _____ (active in the mouth) has a higher specificity for (less/more) soluble and (more/less) polar starches, while ____ _____ (active in the small intestine) has a higher specificity for (less/more) soluble and (more/less) polar starches.
the chemical digestion of amylases occurs both in the mouth (oral cavity) and the small intestine, with the two amylases each targeting complementary starches. salivary amylase (active in the mouth) has a higher specificity for the MORE (rapidly) soluble, MORE polar starches while pancreatic amylase (active in the small intestine) has a higher specificity for the LESS soluble less polar (more NONPOLAR) starches.
the combined mechanical and chemical digestive activities of the stomach result in significant (decrease/increase) ____ in the surface area of the now unrecognizable food particles. So, when the ___ passes through the ____ _____ and enters the ____ ____, what can be maximized?
the combined mechanical and chemical digestive activities result in significant increase in surface area of the now unrecognizable food particles So, when the chyle passes through the pyloric sphincter and enters the small intestine, absorption of nutrients from the chyme can be maximized
the esophagus is a muscular tube that connects the _____ to the ____. The top third (1/3) of the esophagus is composed of (smooth/skeletal/both) muscle, the bottom third (3/3) is composed of (smooth/skeletal/both) muscle and the middle portion of the esophagus (2/3) is composed of (smooth/skeletal/both) muscle. What does the type of muscle that the esophagus is made up of have to do with nervous control?
the esophagus is a muscular tube that connects the pharynx to the stomach. - top third (1/3) of esophagus= *skeletal muscle, meaning it is under VOLUNTARY (SOMATIC) CONTROL) -bottom third (3/3) of esophagus= *smooth muscle, meaning that is under INVOLUNTARY (AUTONOMIC) control -middle (2/3) of esophagus= mix
what are are the main categories of brush border enzymes in the ___ of the small intestine? What do they do?
to break down (digest) dimers and trimers of biomolecules into their respective absorbable monomer (absorbable= will eventually be put into circulation for nutrient delivery to tissues) -disaccharidases: enzyme will break down disaccharides into monosaccharides -peptidease: enzyme breaks down peptides (shorter chains of AA) into individual AA
to much or too little ____ ____ within the ____ of the large intestine can result in what
too much water absorbed back into the colon will result in CONSTIPATION (stool too hard, not enough water in stool to pass it thru the rectum and out the anus) too little water absorbed back into the colon will result in DIARRHEA (stool too watery)
what is a zymogen (also called ____)
zymogen, also called a PROENZYME (can be recognized by prefix pro-- or suffix --gen) Are cells that are the inactive precursor enzymes that can be be activated either another enzyme by their environment auto-catalytically (self-activation)
