Basics of Digestion, Absorption, and Transport Flashcards
Process of breaking down food for absorption
digestion
two types of digestion
mechanical and chemical
where and how does mechanical digestion take place
food is broken up by teeth (digested by physical means)
how does chemical digestion work?
(processes and substances used)
enzymes and addition of water (hydrolysis) breaks down carbohydrates, proteins, and fats into simpler compounds)
products of carbohydrate digestion
fructose, galactose, and glucose
(monosaccharides)
product of protein digestion
amino acids
product of lipid digestion
glycerol and fatty acids
where does digestion begin
mouth
type of digestion in mouth
mechanical (teeth) and chemical (salivary amylase)
product of digested food in the mouth
bolus
how does the bolus move in the esophagus
by peristalsis and gravity
sphincter at the end of esophagus
cardiac sphincter or lower esophageal sphincter
how much food can stomach hold
4L
what are the gastric secretions/juices
- HCl
- Mucus
- Intrinsic Factor
- Enzymes
- Fluid
How much gastric seccretions are produced each day
2000-2500 mL
function of HCl in the stomach
- Digest protein by activating pepsinogen to pepsin
- prepares gastric area for enzyme action
purpose of mucus in stomach
protection from very low pH
what is intrinsic factor
(gastric secretion)
glycoprotein that aids in absorption of Vit. B12
what is Vit. B12 for?
for metabolism of all cells
especially of GIT, bone marrow and nervous tissue
what are the enzymes released in stomach
protease and gastric lipase
what enzyme is present in infants to break down breastmilk
renin
Sphincter at the end of stomach/before entering the small intestine
pyloric sphincter
hormones released in small intestine and what secretion do they trigger
secretin: release of sodium bicarbonate from pancreas
cholecystokinin: release bile from gallbladder
disease that causes the contents of the stomach to go up the esophagus
Gastroesophageal Reflux Disease
what do you call bolus after stomach digestion
chyme
Purpose of sodium bicarbonate released in small intestine
neutralize acidity of chyme
raw material for bile
cholesterol
contents of pancreatic juice
pancreatic protease, amylase and lipase
what do pancreatic proteases do
(also, what are the specific proteases)
trypsin, chymotrypsin, and carboxypeptidase, split proteins into smaller peptides and amino acids
how does the small intestine maximize its absorptive capacity
has villi which increases surface area of the small intestines
approx. how long is the small intestine
22 ft long
major site for absorption of nutrients
small intestine
purpose of villi in small intestine
increase surface area for maximum absorption
protective substance against low pH secreted in the large intestine
mucus
major tasks of large intestines
- absorb water
- synthesize some B vitamins and Vitamin K
- Collect food residue
why do the colon walls secrete mucus
to protect against acidic digestive juices in chyme
what is the arrangement of the different segments of the small intestine
- duodenum
- jejunum
- ileum
difference of rectum and anus
rectum: holds semisolid waste until defecation
anus: sphincter to allow passage of waste
last sphincter of the digestive system
anus
main function of saliva
moisten food to form bolus
protective function of saliva
due to presence of lysozyme and antibodies and allows food to be tasted
functions of different types of teeth
incisors: biting
canines: tearing
molars: grinding/mashing
other term for milk/baby teeth
deciduous teeth
how many baby teeth do we have
20
refers to chewed food at the time of swallowing
bolus
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