Digestion Flashcards
Mechanical digestion
Cutting/tearing food into smaller pieces
Chemical digestion
Breakdown of food using enzymes
Overveiw of digestive system (4 main steps)
Ingestion, Digestion, Absorption of nutrients, Egestion
What types of digestion does the mouth do?
mechanical and chemical
Where is saliva secreted?
3 pairs of saliva glands
What are the 3 main components of saliva?
Water, mucus (lubricates food), and salivary amylase
How is starch digested in the mouth, and what disaccharide does it become
By the enzyme salivary amylase, into maltose
Enzyme for fat digestion in mouth
lingual lipase
What is food called once it leaves the mouth
bolus
Where is the pharnx
Connects the mouth to esophagus
Uvula (dangly thing at back of throat) function
prevents food from going up the nose
Epiglottis (flat at top of larynx) function
prevents food from going down the larynx and trachea
How does food reach the stomach
Through the esophagus, through the process of peristalsis
Longitudinal muscles function
Contract in front of the bolus to shorten the distance it needs to travel
Circular muscle function
Contracts behind bolus and reduces its diameter, preventing it from going backwards
What types of digestion happen in the stomach?
Mechanical (churning) and chemical digestion
How much food can the stomach hold
Up to 1.5L
What regulates the opening and closing of the stomach
Sphincters
Contents of gastric juices of stomach (4)
water, mucus, HCl, and pepsinogen
Function of the mucus
Protects stomach lining from acidic conditions
How is pepsinogen activated
when it comes into contact with HCl of stomach, and it becomes pepsin (digestive enzyme)
Ulcers
Tears in stomach lining due to acidic HCl
What are the 3 portions of the small intestine?
Duodenum, jejenum. and ileum
Length and fucntion of duodenum
8 inches, connects stomach to jejenum
Length of jejenum
8ft
Length of ileum
12ft
What is bolus called once it leaves the stomach
chyme
Function of peristalsis in small intestine
Forces chyme to mix with enzymes
Function of maltase and lactase and where is it produced
Digests matose and lactose, produced and functions in the small intestine
Peptidase/Protease
Any enzyme that digests proteins
Where is Erepsin produced, and what does it do?
Secreted by intestinal glands and pancreas, breaks peptides into amino acids
Exopeptidase function
breaks amino acids from ends of chains
Dipeptidase function
cleaves dipeptides
nucleodase
breaks down nucleotides (DNA and RNA) into bases, sugars, and phosphates
Nuclease function
Breaks down nucleotides into smaller nucleotides
What is a dextrin
Components of amylopectin and glycogen that consist of 1-6 glycosidic bonds
Dextrinase function
Breaks down dextrins (1-6 glycosidic bonds) that amylase can’t break
How is absorption in the small intestine maximized?
villi and microvilli increase SA:V ratio
Length of villi
Around 0.5-1.5mm, 40/mm^2
What does the villi absorb?
vitamins, minerals, and monomers
Lacteal of the villi function
absorbs fatty acids and monoglycerides
Capillary of villi function
Absorbs nucleotides, amino acids, and monosaccharides
Serosa
Outer coat of small intestine
Muscle layers
longitudinal and circular muscles for slow peristalsis
sub-mucosa contents
contains blood and nymph vesssels
mucosa
lining of small intestine that project into villi
Functions of the large intestine (3)
Absorption of water, storage of fecal matter, synthesis of vitamin K from cellulose
How long is the large intestine
5ft in length
Accessory organs definition
Contributes to digestive system by providing fluids, but food doesn’t directly go through them
Accessory organs of digestive system
Pancreas, Liver, Gallbladder
Function of the liver in digestion
Produces bile
Function of bile
emulsifies fats, which allows enzymes to act on it
How does bile reach the duodenum
Bile is stored in the gallbladder, which is later secreted into the duodenum
Contents of pancreatic juice (3)
Sodium bicarbonate, water, enzymes
Function of sodium bicarbonate
neutralizes acidic chyme in stomach to pH of 7.5-8
Pacreatic amylase function
Digests remaining starch into maltose
Where is trypsinogen produced
pancrease
How is trypsinogen activated into trypsin?
Enzyme enterokinase
Function of trypsin
Digests proteins into peptides
Function of erepsin
Digests peptides into amino acids
phospholipase function
Digests phospholipids into fatty acids, glycerol, and phosphates
lipase function
digests fats into fatty acids and monoglycerides
Hormone definition
Proteins that are secreted into the blood stream and carry messages to target organs
Gastrin function
Signals stomach to release HCl
Where and when is gastrin secreted
From the stomach in the presence of food
Where and when is enterogastrone secreted
Small intestine in the presence of fat
Enterogastrone function
Slows peristalsis in small intestines to allow more time for digestion/absorption
when and where is secretin secreted
small intestines in the presence of acidic chyme
Secretin function
singals pancreas to release sodium bicarbonate to neutralize pH to 7.5-8
where and when is cholecystokinin secreted
Small intestines in response to fat
cholecystokinin function
signals gallbladder to release bile into small intestines
What is the difference between pepsin and peptidase?
Pepsin digests proteins into peptides, peptidase digests proteins into amino acids
What is the difference between nuclease and nucleosidase?
Nuclease digests RNA & DNA into nucleotides, nucleosidase digests nucleotides into base, sugar, and phosphates
