A+P II Lab: Ex. 5: Digestive System
the digestive system is composted of two separate groups of organs:
1. alimentary canal or gastrointestinal tract - organs that are tubular in shape and connected sequentially together 2. accessory digestive organs - connected through various ducts or are attached to the alimentary canal. these aid in mechanical and chemical digestion through the alimentary canal
enzymes found within the brush border include:
1. alpha dextrinase - carbohydrase 2. maltase - carbohydrase 3. sucrase - carbohydrase 4. lactase - carbohydrase 5. aminopeptidase - protease 6. dipeptidase - protease 7. nucleosidases - nuclease 8. phosphatases - nuclease
major components of saliva include:
1. immunoglobulin A - important in preventing attachment of microbes, preventing penetration into the epithelium 2. bacteriolytic lysozyme - kills bacteria 3. salivary amylase - carbonhydrase 4. lingual lipase - lipase 5. bicarbonate - buffers acidic foods
gastric glands are found at the base of the gastric pits and consist of 4 types of cells:
1. mucous cells 2. parietal cells 3. chief cells 4. G cells
components of gastric juices include:
1. water 2. hydrochloric acid (HCI) - denatures proteins, making it easier for protease enzymes to target peptide bonds. also has an antimicrobial function 3. pepsinogen - activated into pepsin (protease) by HCI within the stomach lumen 4. gastric lipase - lipase 5. intrinsic factor - aids in vitamin B12 absorption within the ileum
pancreatic acini produce...
a mixture of enzymes, water, and bicarbonate, named pancreatic juice
chymotrypsinogen
activated into chymotrypsin (Protease) by trypsin
procarboxypeptidase
activated into chymotrypsin (Protease) by trypsin
Proelastase
activated into elastase (Protease) by trypsin
trypsinogen (pancreatic juice)
activated into trypsin (Protease) by enterokinase within the duodenum
amino acids are absorbed by...
active transport or secondary active transport, using Na+ symporters
bile aids in lipid digestion by serving as...
an emulsifier
salivary secretions serve as an immune function by containing...
bacteriolytic lysozymes
produced by the liver, then concentrated, stored and released by the gall bladder aids lipid digestion by serving as an emulsifier aids in lipid absorption by making fatty acid chains more water soluble contains bicarbonate to aid in the neutralization of the acidic chyme coming from the stomach
bile
fatty acids and lipid-soluble vitamins are absorbed with the assistance of...
bile salts via simple diffusion
once the brush border enzymes have generated monomers, the majority of nutrients with the exception of some lipids will be absorbed into...
blood capillaries
chemical digestion occurs both within the lumen of the small intestine through bile and pancreatic enzymes as well as along the mucosal border in a region referred to as the ________ ___________
brush border
pancreatic amylase
carbohydrase
as ________ sits in the stomach, a small amount of absorption occurs as water, ions, short chain fatty acids, as well as some drugs and alcohol are absorbed. most absorption is prevented as the mucosal cells are relatively impermeable to most materials.
chyme
gastric contortions mix the bolus of food with gastric juices, forming a liquid mixture of enzymes and food called...
chyme
feces are eventually eliminated when the ____________ _________ is initiated when fecal matter enters into the rectum
defecation reflex
as the bolus enters the oropharynx, receptors initiate the...
deglutination reflex (this first involves lifting the uvula to block off the nasopharynx, followed by closing the epiglottis to block the trachea
regulation of digestion is accomplished by interactions of the...
diencephalon, cerebrum, enteric nervous system, autonomic nervous system, and endocrine system
ribonuclease and deoxyribonuclease
digest RNA and DNA respectively
the stomach serves as a site of continued mechanical and chemical digestion, as well as a holding area for food as only small amounts can be moved into the ___________ of the small intestine at one time
duodenum
the small intestine is divided into three regions:
duodenum, jejunum, ileum
the sympathetic nervous system does the opposite of the parasympathetic nervous system. it inhibits the activities of the __________________
enteric nervous system
the stomach receives the semisolid bolus of food from the...
esophagus
which portion of the pancreas produces pancreatic juices containing a mixture of water, bicarbonate, ions and enzymes
exocrine portion of the pancreas
pancreatic lipase breaks down...
fat
absorption in the large intestine is restricted to finishing water and electrolyte absorption along with some vitamins. as chyme moves through the large intestine and more water is absorbed, solid or semi-solid _________ __________ are generated
fecal boli
hepatic portal triads
found among the borders of the lobule contain a hepatic artery, portal vein, and bile duct
once the food has entered the stomach, the lower ________ ______________ contracts, preventing the contents within the stomach from regurgitating back into the esophagus
gastoesophageal sphincter
chemical digestion occurs through secretions of...
gastric glands found within the mucosa of the stomach
the gastric mucosa is lined with an epithelium, which folds, creating...
gastric pits
mechanical digestion in the large intestine is responsible for the formation of feces through ___________ ____________
haustral churning
bile coats lipid aggregates in a way that produces a _____________ core and a _______________ cover
hydrophobic core and hydrophilic cover
The majority of absorption occurs in the _______
ileum
components of the liver and pancreatic juices include:
in liver - 1. bile pancreatic juices - 1. bicarbonate 2. trypsinogen 3. chymotrypsinogen 4. procarboxypeptidase 5. proelastase 6. pancreatic amylase 7. pancreatic lipase 8. ribonuclease 9. deoxyribonuclease
where are gastric juices found
in the mucosa of the stomach
as the stomach transitions to the duodenum, the gastric pits transition to the long and slender ____________ _______
intestinal villi seen in the duodenum
no human produced enzymes are found in the...
large intestine
pancreatic lipase
lipase
lipids are absorbed by the lymphatic system where they are transported to the ________ and metabolized
liver
materials from the blood are processed in the _______, where they can be stored or converted into other organic compounds
liver
which accessory digestive organs secrete digestive aids into the duodenum?
liver and pancreas
peristalsis serves to mix chyme with secretions from the ________________ ___________ and __________
liver, pancreas, and small intestines
the liver is organized into several ______________, each with a central vein surrounded by rows of ______________
lobules hepatocytes
the mucous that is generated from mucin works as a __________, and makes swallowing the ball of food (bolus) easier
lubricant
the process of breaking down food is accomplished by two digestive mechanisms:
mechanical digestion and chemical digestion
chyme
mixture of enzymes and partially-digested food
lacteals
modified lymphatic capillaries found in intestinal villi
general functions of saliva include:
moistening food to make it easier to swallow, dissolving food for tasting, buffering acidic foods with the help of bicarbonate ions, and protecting the mouth from infection with its rinsing action
when the bolus reaches the esophagus, stretch receptors in the myentric plexus trigger the muscularis to commence peristalisis...
moving the bolus into the stomach
secretions from the liver and pancreas enter the duodenum through ducts piercing the _________
mucosa
mechanical digestion occurs as gastric contortions initiated by the ________________________ mix the bolus of food with secretions from gastric glands
muscularis of the stomach
bicarbonate (pancreatic juice)
neutralizes acidic chyme from the stomach
deoxyribonuclease
nuclease
ribonuclease
nuclease
Three main salivary glands
parotid, submandibular, sublingual
mechanical digestion within the small intestine occurs through _______________
peristalsis
ions found in saliva that serve as a buffer for acidic food entering the mouth
phosphate & bicarbonate
deglutination
process of swallowing
mucous acini
produce mucin, a glycoprotein
the parasympathetic nervous system stimulates the enteric system as well as...
promotes salivation, secretion of gastric fluids, and defecation
within pyloric region of the mucosal, gastric glands are now referred to as __________ ___________, but secrete the same substances
pyloric glands
the duodenum receives chyme from the stomach through the ________________
pyloric sphincter
the large intestine consists of several regions ending in the _________ and __________
rectum and anus
serous acini
release a water and electrolyte solution laced with salivary amylase of lingual lipase.
hormones regulating digestion: secretin
released by enteroendocrine cells of the duodenum in response to a drop in duodenal pH. responsible for stimulating the secretion of bile and pancreatic juices rich in bicarbonate. INHIBITS secretion of gastric juices
hormones regulating digestion: cholecystokinin (CKK)
released by enteroendocrine cells of the duodenum in response to chyme rich in proteins and lipids. responsible for increasing the secretion of pancreatic juices rich in digestive enzymes and the ejection of bile from the gall bladder. INHIBITS gastric emptying
hormones regulating digestion: gastrin
released by the stomach in response to stomach distension and an increase in gastric pH. stimulates digestion by secreting additional gastric juices and increasing gastric motility
glucose is absorbed by...
secondary active transport employing Na+ symporters
parietal cells
secret hydrochloric acid, which denatures proteins and intrisic factor, which is needed for vitamin B12 absorption within the ilieum
Brunner's glands
secrete alkaline mucus (to help neutralize the acidic chyme coming from the stomach)
G cells
secrete gastrin
chief cells
secrete pepsinogen, which is activated by HCI into pepsin in the stomach lumen and targets peptide bonds and gastric lipase, which targets triglycerides
primary function of the liver
secretion of bile
the endocrine system regulates...
secretion of gastric fluids, intestinal, pancreatic, and hepatic fluids, as well as the motility of several digestive organs
bolus
semisolid mass of chewed food mixed with saliva
the rows of hepatocytes in the liver are separated by ___________ ___________ that connect to the central vein
sinusoid capillaries
mechanical and chemical digestion occur throughout the ______________ ______________
small intestines
pancreatic amylase furthers the digestion of...
starch
gastric emptying and intestinal motility are controlled by both the...
sympathetic and parasympathetic nervous systems
mechanical digestion within the oral cavity primarily occurs through the actions of...
teeth
chemical digestion
the breakdown of the larger food materials at the chemical level, separating individual organic monomers from their larger polymers. ____________ targets chemical bonds with the assistance of enzymes and other chemical agents. the process begins with the dissolution of food materials in saliva and continues with various digestive secretions, enzymatic activity, and the action of pH shifts in the stomach and small intestines
mechanical digestion
the physical degradation of larger food materials into smaller pieces. this process increases the surface area of the food, which will increase the efficiency of the enzymatic chemical digestion that follows. types of mechanical digestion include mastication, gastric churning, segmented peristalsis, and haustral churning
mastication
the process of chewing with teeth - incisors are able to slice, canines can puncture, and premolars and molars are use to grind food
the enteric nervous system independently regulates digestion through the activity of two plexuses:
the submucosal plexus & the myenteric plexus
chemical digestion within the oral cavity occurs through secretions from ____ main salivary glands, each of which produces saliva of different composition
three
The pancreas has both an endocrine and an exocrine function (t/f)
true
each salivary gland produces saliva of a different composition. they have the same basic components but their concentrations differ depending on the gland (t/f)
true
pancreatic juice consists of precursors to the proteases _________, ____________, ____________,
trypsin chymotrypsin pancreatic amylase pancreatic lipase ribonuclease deoxyribonuclease
chemical digestion in the large intestine is associated with several bacterial enzymes that are responsible for producing _______________
vitamins B and K
once surrounded by bile salts, fatty acids become temporarily ____________ and are absorbed by lacteals
water-soluble
mucous cells
within the neck of the gland secrete mucus for lubrication and protection of the gastric mucosa
