BIOD 121 EXAM REVISION SUMMARY
function of food
growth, energy, immune system support
What is digestion?
Food turns into basic nutrients that can be absorbed by
the body
Before food enters the mouth
1. thoughts about food start flow of saliva (cognition)
2. sound- popcorn popping
3. odor- stimulates a hunger response
4. appearance- color and texture
5. taste
where does digestion begin
in the mouth
how is food broken down (mouth and GI)
1. chemical process- enzymes, acids, bile, mucus
2. mechanical process- chewing and churning (peristalsis)
Function of enzymes
act as a catalyst for digestion by speeding up the chemical
reactions.
Absorption
nutrients move from digestive system into the
bloodstream.
Absorption involves these processes
passive diffusion, facilitated diffusion, active transport.
passive diffusion
,no energy required, flows from high concentration to low
concentration.
facilitated diffusion
no energy required, but uses protein carriers. (high to low)
protein carriers funtion
help move substances in and out of cells.
active transport
1. energy is required, low concentration to high
concentration (against the gradient).
2. Some types require protein carrier/trans. molecule
3. endocytosis
Endocytosis
large molecules go into a cell, cell membrane folds around
the molecule.
passive transport
1. no energy or ATP
2. Low to high (down concentration gradient)
3. FD requires protein carrier
4. osmosis and simple diffusion (no protein carrier)
parts of the GI tract
mouth, esophagus, stomach, small intestine, large
intestine, rectum
Accessories of digestion
salivary glands
liver
pancreas
gallbladder
NOT PART OF GI TRACT****
mouth
1. chemical + mechanical digestion occur
2. saliva- watery substance containing mucus and
, enzymes
3. mucus- lubricant
4. enzymes
5. tongue - sweet, salty, bitter, sour, umami
enzymes in the mouth
1. salivary amylase- break down starches
2. lingual lipase- break down fats
esophagus
1. tube connecting the mouth to the stomach
2. epiglottis- flap that closes over trachea, prevents
choking
3. peristalsis occurs here
4. sphincter muscles- esophageal sphincter controls food
going from esophagus to stomach.
stomach
1. chemical and mechanical digestion- (mix, store,
dissolve)
2. pepsin (enzyme) -protein digestion
3. gastric lipase (enzyme) - fat dig. can be triggered by
cognition.
4. gastrin (hormone)- controls acid production
5. chyme- end product
chyme
food particles mixed with enzymes to produce watery
substance.
**IF gastrin is produced, mucus production must increase
to prevent high acid levels and protect the stomach from
burns and ulcers
majority of digestion and absorption occur here
small intestine (about 20 feet long)
small intestine parts
function of food
growth, energy, immune system support
What is digestion?
Food turns into basic nutrients that can be absorbed by
the body
Before food enters the mouth
1. thoughts about food start flow of saliva (cognition)
2. sound- popcorn popping
3. odor- stimulates a hunger response
4. appearance- color and texture
5. taste
where does digestion begin
in the mouth
how is food broken down (mouth and GI)
1. chemical process- enzymes, acids, bile, mucus
2. mechanical process- chewing and churning (peristalsis)
Function of enzymes
act as a catalyst for digestion by speeding up the chemical
reactions.
Absorption
nutrients move from digestive system into the
bloodstream.
Absorption involves these processes
passive diffusion, facilitated diffusion, active transport.
passive diffusion
,no energy required, flows from high concentration to low
concentration.
facilitated diffusion
no energy required, but uses protein carriers. (high to low)
protein carriers funtion
help move substances in and out of cells.
active transport
1. energy is required, low concentration to high
concentration (against the gradient).
2. Some types require protein carrier/trans. molecule
3. endocytosis
Endocytosis
large molecules go into a cell, cell membrane folds around
the molecule.
passive transport
1. no energy or ATP
2. Low to high (down concentration gradient)
3. FD requires protein carrier
4. osmosis and simple diffusion (no protein carrier)
parts of the GI tract
mouth, esophagus, stomach, small intestine, large
intestine, rectum
Accessories of digestion
salivary glands
liver
pancreas
gallbladder
NOT PART OF GI TRACT****
mouth
1. chemical + mechanical digestion occur
2. saliva- watery substance containing mucus and
, enzymes
3. mucus- lubricant
4. enzymes
5. tongue - sweet, salty, bitter, sour, umami
enzymes in the mouth
1. salivary amylase- break down starches
2. lingual lipase- break down fats
esophagus
1. tube connecting the mouth to the stomach
2. epiglottis- flap that closes over trachea, prevents
choking
3. peristalsis occurs here
4. sphincter muscles- esophageal sphincter controls food
going from esophagus to stomach.
stomach
1. chemical and mechanical digestion- (mix, store,
dissolve)
2. pepsin (enzyme) -protein digestion
3. gastric lipase (enzyme) - fat dig. can be triggered by
cognition.
4. gastrin (hormone)- controls acid production
5. chyme- end product
chyme
food particles mixed with enzymes to produce watery
substance.
**IF gastrin is produced, mucus production must increase
to prevent high acid levels and protect the stomach from
burns and ulcers
majority of digestion and absorption occur here
small intestine (about 20 feet long)
small intestine parts
