Digestive System (Lecture) Flashcards
Primary function of the digestive system:
break down food mechanically and by the use of enzymes so that it can be used by the body for energy and cell growth and repair
Catabolism of organic molecules:
polymer to monomer
Alimentary Canal:
mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus
Accessory organs:
tongue, teeth, salivary glands, liver, pancreas, gall bladder
Accessory organs have to be stimulated by:
nerve impulses or hormones
Digestive system processes/functions:
ingestion, mechanical digestion and chemical digestion, propulsion/movement, absorption, elimination
Term for the physical breakdown of food:
mechanical digestion (chewing, grinding, etc.)
Term for the use of enzymes to break down food:
chemical digestion
What process increases the surface area of food?
mechanical digestion
During chemical digestion, what breaks down the food into monomers?
enzymes
Three main types of digestive enzymes:
amylase, protease, lipase
What enzyme breaks starch down into glucose?
amylase
What enzyme breaks protein down into amino acids?
protease
What enzyme breaks fats down into fatty acids and glycerol?
lipase
Basic monomers of carbohydrates/polysaccharides:
glucose, fructose, galactose
One of the most common lipids in our diet:
triglycerides
Four layers of the Alimentary canal (begin with layer closest to the lumen):
mucosa, submucosa, muscularis, serosa
Layer of the alimentary canal that contains nerves and glands:
submucosa
Layer of the alimentary canal that has at least two layers of smooth muscle:
muscularis
Smooth muscle layers of the muscularis:
longitudinal muscle and circular muscle layer
Where is the myenteric nerve plexus located that controls the contraction and movement process?
smooth muscle of the alimentary canal
Movement/contractile process that is carried out to get food through the alimentary canal:
peristalsis
Network of connective tissues and epithelial tissues of the alimentary canal:
serosa
Specialized serous membrane that holds the organs in place:
peritoneum
Peritoneal membrane coming from the lower part of the stomach to the pelvic cavity:
greater omentum (contains a lot of fat for insulation)
Part of the peritoneum attached to the small intestine:
mesentery
Part of the peritoneum attached to the large intestine:
mesocolon
Saliva is secreted by what three major pairs of salivary glands?
parotid (by ear), sublingual (under tongue), submandibular (under the jaw)
Fluid formed by the three major salivary glands:
saliva
Functions of saliva:
lubrication, solvent, antibacterial property from lysozyme, digestion of complex carbs, neutralization of acid (contains bicarbonate)
Saliva contains:
enzymes
Two enzymes found in saliva:
amylase, lipase
What enzyme begins the chemical breakdown of carbohydrates?
amylase
____ are large polymers of carbohydrates.
starches
What enzyme works to break down lipids?
lipase
A triglyceride contains:
glycerol compound and three fatty acids
Primary lipid in the body:
triglyceride
Teeth and tongue are in charge of what kind of digestion?
mechanical digestion
deglutition means:
swallowing
Three steps of deglutition:
voluntary phase (occurs when food is in the mouth), pharyngeal phase (involuntary), esophageal phase
Deglutition center in the brain controls:
constriction muscles for the pharyngeal phase of deglutition to prevent choking
Serves as a passageway for air and food and where peristalsis begins:
pharynx
Sphincter where esophagus is connected to the stomach and closes off the entrance to the stomach to prevent HCl from splashes up to the lower part of the esophagus:
lower esophageal sphincter
Condition where lower esophageal sphincter remains open:
GERD
Highest section of the stomach:
fundus
Narrowed area of the stomach that approaches the small intestine:
antrum
The antrum attaches to the small intestine at the ____.
pyloric canal
Sphincter between stomach and small intestine (duodenum):
pyloric sphincter
Term for food in the area of the duodenum characterized as a semi-solid, soapy mixture:
chyme
The secretions from the stomach come from which layer?
mucosa
The mucosa contains ____glands:
gastric
What are the cells that form the gastric glands?
surface mucous cell (secrete thick mucous), parietal cells, chief cells, G cells
What kind of cell produces a thick mucous that protects the lining of the stomach from acid?
surface mucous cell
What cells are important for digestion and produce HCl and intrinsic factor?
parietal cell
What chemical is needed for protein digestion?
HCl
What chemical is important for B12 absorption?
intrinsic factor
What cell secretes the two enzymes pepsinogen and gastric lipase?
chief cells
What are the enzyme producing cells?
chief cells
What cell secretes the hormone gastrin?
G cell
B12 is necessary for ____ synthesis.
DNA
The lining of the stomach is a _____ membrane.
mucous
What chemical produced by the stomach helps kill bacteria and denatures protein?
HCl
What is the inactive form of pepsin?
pepsinogen
What stimulates acid secretion by the stomach?
Gastrin
The parietal cell has receptors for ___, ____, ____, which stimulate the production of HCl:
acetylcholine, histamine, gastrin
Three phases of regulation of stomach secretion:
cephalic phase, gastric phase, gastrointestinal phase
cephalic phase is:
stimulatory (initiated by sight, smell, taste, or thought of food)
gastric phase is:
stimulatory
gastrointestinal phase is:
inhibitory
Which phase of stomach secretion “gets the stomach ready” by activation of the parasympathetic nervous system which activates the vagus nerve?
cephalic phase
Which phase activates the production of pepsin, HCl, histamine, gastrin?
cephalic phase
Once food enters the stomach, what phase of stomach regulation is it in?
gastric phase
During the gastric phase the G cells produce more:
gastrin…and all other cells enhance/increase production and secretion as well as churning
Eventually the ____ opens up and the food enters the first part of the small intestine.
pyloric sphincter
The first part of the small intestine is called the ____.
duodenum
Once food leaves the stomach, what phase is it in?
gastrointestinal phase
Which phase inhibits stomach activity?
gastrointestinal phase
The intestinal phase relies on an _____ response to inhibit stomach activity.
endocrine
What kind of cell in the intestinal phase secretes CCK, GIP, Secretin?
enterogastric cell
CCK shuts off:
stomach secretions
Secretin shuts off:
peristalsis
GIP shuts off:
secretions and contraction within the stomach
What three accessory organs does the small intestine rely on?
pancreas, liver, gallbladder
The accessory organs are attached to the alimentary canal by ____.
ducts
The liver, pancreas, and gallbladder are stimulated by _____ signaled from the duodenum.
hormones
The common bile duct and the pancreatic duct form the:
hepatopancreatic ampulla/duct
Secretions from the liver and the pancreas enter the duodenum by way of the:
hepatopancreatic ampulla
Endocrine function of the pancreas produces:
insulin, glucagon
Enzymes produced by the pancreas break down:
proteins, carbohydrates, nucleic acids, lipids
Pancreatic enzyme that breaks down proteins:
protease
Pancreatic enzyme that breaks down carbohydrates:
amylase
Pancreatic enzyme that breaks down nucleic acids:
nuclease
Pancreatic enzyme that breaks down dietary fat:
lipase
Two hormones involved in the intestinal phase and have an effect on the pancreas:
CCK and secretin
What hormone triggers the pancreas to release its digestive enzymes?
CCK (Cholecystokinin) : triggers amylase, lipase, nuclease, protease
What hormone triggers the pancreas to release bicarbonate ions?
secretin
The fluid released by the pancreas contains:
H2O, bicarbonate, and digestive enzymes
The bicarbonate released by the pancreas helps neutralize the:
HCl
What neutralizes the acidic chyme entering the duodenum:
bicarbonate ions from the pancreas
Secretin triggers the liver to produce:
bile (alkaline pH to further neutralize the acids entering the small intestine from the stomach)
CCK gets its name from its action in the:
gallbladder
Functions of bile:
dilutes contents from the stomach, creates optimum pH for pancreatic enzymes, contains bile salts which emulsify fats
What product from the gallbladder helps emulsify the fats?
bile salts
What process increases the surfaces are of fat which makes chemical digestion and absorption easier in the small intestine?
emulsification
Fats are digested in what two stages:
emulsification and then the digestive enzyme lipase
What hormone shuts down the digestive process?
somatostatin
Three sections to the small intestine:
duodenum, jejunum, ileum
What is the terminal section of the small intestine?
ileum (attaches to the large intestine)
Function of the small intestine:
chemical digestion (major organ of digestion and absorption) and absorption so the nutrients of the food enters the bloodstream
The small intestine has a surface area of:
300m^2
What extends from the mucosa of the small intestine and increase the surface area of the small intestine?
villi
What kind of cells make up the villi?
absorptive cells
absorptive cells on the villi increase surface area with:
microvilli (increase the surface area of each villus)
Name the structural components that increase the surface area of small intestine:
circular folds, villi, microvilli
Functional unit of the small intestine:
villi
The core of the villus has a specialized set of:
blood capillaries and lacteals (lymphatic capillaries)
First place food is metabolized after it is absorbed by the blood capillaries and lacteals:
liver
Most liver functions take place post absorption and is called:
first pass effect
Transformation of one organic compound into something else (detoxification process):
biotransformation
Biotransformation is performed by the:
liver
All fat soluble vitamins are stored in the:
liver
The liver stores:
fat soluble vitamins, glycogen, lipids
The liver synthesizes:
albumin, growth factors, urea
Liver functions:
breaks down RBCs, protein metabolism, synthesis of plasma proteins, enzyme synthesis, conversion of ammonia to urea, carbohydrate metabolism (storage of glucose), fat metabolism, detoxification
The ileum attaches to the ____ of the large intestine.
cecum
Sections of the large intestine:
cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anus
Term for the “pockets” in the colon:
haustra
Primary component absorbed by the large intestine:
water and some medications given by suppository
The bacteria in the large intestine produce:
vitamin K