digestion quiz

filter feeders

aquatic animals that siphon water from surroundings and filters it to obtain small organisms to digest

substrate feeders

animals that live in or on their food source and eat their way through it (ex. caterpillar)

fluid feeders

animals that lick or suck nutrient-rich fluids from plants and animals. (ex. mosquitos and flies)

bulk feeders

animals that eat large pieces of food (ex. humans and vertebraes)

4 stages of food processing

1. Ingestion

2. Digestion

3. Absorption

4. Elimination

ingestion

taking in or eating food

digestion

breakdown of food into smaller molecules

absorption

transport of nutrients from digestive system into circulatory system

elimination

removal of undigested solid waste from the body

the digestive system consists of two components…

digestive tract and accessory organs

accessory organs

structures that aid digestion (liver, gallbladder, pancreas, salivary glands)

amylase

a carbohydrase enzyme found in saliva that breaks carbohydrates into sugars

lipase

type of enzyme that breaks down lipids into glycerol (alcohol) and fatty acids

pepsin

a protease enzyme found in the stomach that breaks down protein into amino acids

nuclease

a type of enzyme that breaks nucleic acid down into nucleotides

3 salivary glands in the mouth

sublingual, parotid, submandibular

epiglottis

a flap located above trachea which closes to ensure bolus does not travel down trachea

esophageal sphincter

connects esophagus to the stomach.

it is usually closed to prevent backflow of stomach acid/food.

but opens up to allow bolus into the stomach

peristalsis

involuntary muscle contractions (longitudinal & circular) that move food through the alimentary canal

gastric juice

found in stomach and contains hydrochloric acid (from parietal cells), salt, water, enzymes, and mucus

rugae

folds in the stomach that allow it to expand and contract to hold food

pyloric sphincter

connects the stomach and small intestine

chyme

digested food that is reduced to a thick liquid before leaving stomach

3 parts of the small intestine

1. duodenum

2. jejunum

3. ileum

duodenum

first region of small intestine, U-shaped, covered in villi and microvilli to break down carbs, fats and proteins

jejunenum

contains more folds, most absorption occurs here, breaks down remaining carbs and proteins to be absorbed

ileum

fewest villi, absorbs nutrients and pushes undigested material into the large intestine

lacteals

lymph vessels in the villi that allow for rapid absorption and transport of liquids

large intestine

smooth, doesn’t contain villi and reabsorbs water and electrolytes back into the blood

3 types of digestive enzymes created by the pancreas

amylase, lipase, and protease

bile

composed of bilirubin, cholesterol, and bile salts. its role is to emulsify fats

cofactors

metal ions found in the active site of an enzyme that allows it to lock onto the substrate

coenzymes

non-protein organic molecules found in the active site of an enzyme that allows it to lock onto the substrate

inhibitors

molecules that bind to an enzyme and prevent it from working

competitive inhibition

molecule that attaches to the active site of an enzyme and prevents it from binding to a substrate

allosteric activators

molecule that binds to allosteric site that keeps an enzyme active

what is released by the pancreas?

bicarbonate that neutralizes the acidic chyme, and 2 hormones; insulin and glucagon to control blood sugar levels

non-competitive inhibition

molecule attaches to an allosteric site, changes shape of the enzyme so it cannot bind to substrate