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what are the 3 things food is used for?
- fuel to make (ATP)
- provide raw materials (for biosynthesis)
- provides essential nutrients (molecule that can't be made in the body by itself)
what does energy budgets describe?
describe energy allocations to different uses
what do homeostatic mechanisms regulate?
regulate food use and intake
what 3 things are glucose used for?
what happens in undernourishment?
undernourishment uses up body reserves
what happens in overnourishment?
overnourishment leads to obesity
what happens in malnourishment?
lacking essential nutrients
what are the 4 main essential nutrients?
- amino acids
- fatty acids
how many of the amino acids can we make? How many are essential?
- we can make about 10-12 of the 20
- about 8 are essential
what is the most common human malnourishment?
in amino acids
what are 2 characteristics about fatty acids?
- animals can make most fatty acids
- essential ones usually common in diet
what are vitamins? (2) what are the 2 kinds of vitamins?
- organic molecules
- needed in small amounts, many are coenzymes
- fat soluble and water soluble
what are minerals? how much are needed for your body?
- are inorganic
- needed in small amounts
what is the difference between ingestion and digestion?
- ingestion: eating
- digestion: breaking into small molecules (monomers, dimers)
what are the 2 ways food can be broken down in digestion?
- mechanical digestion: teeth, gizzard
- chemical digestion: hydrolytic enzymes
what are the 4 processes of food processing?
ingestion--> digestion--> absorption--> elimination
List the 2 modes of digestion.
what is intracellular digestion? what is an example of organism that uses the intracellular mode and what is a disadvantage?
- via phagocytosis
- ex. sponges
- disadvantage: can't be anything big
describe extracellular digestion.
within compartments that are really "outside" the body
describe the 2 types of extracellular digestion.
- gastrovascular cavity: food and enzymes meet in a dead-sac ex. cnidarian
- Alimentary Canal (digestive tract): one way tube; from mouth to anus
- allows for specialized regions (digestion, then absorption(
what kind of digestive system do mammalian's have?
= alimentary canals + accessory glands
describe what is included in the alimentary canal and accessory glands in mammalian digestive systems?
- alimentary canals: wall 4 layers thick
- includes smooth muscle
accessory glands: salivary glands, gastric cells, pancreas, intestinal cells, liver, gall bladder
how is food moved in the digestive tract?
by peristalsis (muscles squishing it through)
what is the pathway that food goes through from mouth to anus? (7)
- oral cavity
- small intestine
- large intestine
what does the oral cavity include? (6)
tonsil, tongue, teeth, uvula, soft palate, hard palate
what are the 3 types of teeth in the mouth?
what is the function of salivary glands? what is saliva?
- to produce saliva to help breakdown food
- saliva: lubricant to keep mouth dry, buffer, antibiotics, contains enzymes
what are the 2 enzymes found in saliva?
what is the pharynx (throat)? (2)
- shared by digestive and respiratory tracts
- epiglottis blocks food from entering trachea when swallowing
what is the function of the esophagus?
carries bolus of food to stomach
what is the function of the stomach? (3) what is the entrance and the exit of the stomach called?
- for storage, mixing, digestion
- entrance= cardiac sphincter
- exit= pyloric sphincter
internal folds in the stomach which allows stretching
what is the gastric pits in the stomach lined with?
gastric pits lined by cells that secrete mucus, HCl, enzymes
what happens to pepsinogen in the gastric pits?
pepsinogen converted by low pH and pepsin to make more pepsin
what is the function of pepsin?
helps break down proteins into amino acids
what is chyme?
food and gastric juice
how much gastric juice does your body produce in a day?
about 3 L
what are 2 characteristics of the small intestine and what is its function?
- about 6 meters long in humans
- longest part if digestive tract; small in terms of diameter
- main site for digestion and absorption
what are the 3 sections of the small intestine?
duodenum, jejunum, and ileum
where does most of the digestion take place and how is this done?
- most digestion in duodenum
- via enzymes from stomach (activated in intestine); cells lining intestinal walls and
describe what the pancreas contains.
pancreatic juice: collection of digestive enzymes such as lipases, proteinases, carbohydrases, nucleases, and bicarbonate
what neutralizes the chyme?
what is the function of the liver?
liver adds bile salts (stored in the gall bladder) which emulsify lipids
how is the surface area for absorption increases in the small intestine? (3)
increased by folds, villi, and microvilli
what does each villus in the small intestine contain? how does the molecule enter?
- each villus contains capillaries and a lymph vessel
- molecules enter by diffusion and active transport
how to the capillaries take the molecules from the small intestine to the liver? what happens in the liver?
- capillaries converged into hepatic portal vein which leads to the liver
- molecules stored, used and converted
what is the main function of the large intestine? what is the function of bacteria in the large intestine?
- site of water absorption
- bacteria digest molecules; produce vitamin K
where is the feces stored?
feces stored in rectum
what are the 4 digestive adaptations vertebrates?
- expandable stomachs
- long digestive tract, big cecum
what kind of dentition do herbivores have?
- nipping incisors and canines
- grinding pre-molars
- wide molars, with sharp ridges of the surface
what kind of dentition do carnivores have?
- teeth for stabbing, tearing and slicing
- molar sharp and go past each other
what kinds of dentition do omnivores have?
teeth for biting off; grinding (no ridges, some bumps)
what kind of vertebrates have expandable stomachs?
some carnivores like snakes
what kind of organisms have a long distance tract, big cecum?