Lecture 8: Digestion Flashcards
Animals are chemoheterotrophs which means?
they get their energy and carbon from breaking down organic compounds(example: eating)
What are the 4 steps in food processing?
1) ingestion: how does the animal eat?
2) digestion: how is ingested food broken down into nutrients?
3) absorption: how do nutrients get into the cells?
4) elimination: how do the waste materials leave the body?
What is ingestion and what are the 4 types?
ingestion is how the animal eats/feeds
the 4 types are: suspension and filter feeders, substrate feeders, fluid feeders, and bulk feeders
Describe the ingestion method suspension and filter feeders.
aquatic animals that sift particles and small organisms out of the water.
- suspension feeders eat food particles suspended in water
- filter feeders are a type of suspension feeder that move water through a filteration system that catches the food particles
- only aquatic animals do this and some examples include: clams, sponges, whales
Describe the ingestion method substrate feeders.
substrate feeders live in or on their food source
- example: many insects live on their host plan or decomposing organisms
Describe the ingestion method fluid feeders.
fluid feeders suck fluid with nutrients from a living host
- example: hummingbird, mosquitos
Describe the ingestion method bulk feeders.
bulk feeders eat large chunks of food
- they have adaptations like tentacles, claws, fangs, and jaws to aid in killing prey or ripping off pieces of food
- pythons have elastic jaws
What is digestion?
Digestion is the process of breaking down food into smaller molecules we can use.
Food is made up of large macromolecules like proteins, nucleic acids, lipids, and carbohydrates and animals need to break these into smaller components
What are the two steps in digestion?
1) mechanical digestion: breaking down the food into smaller pieces : increases surface area available for chemical digestion
ex: chewing, churning in the stomach
2) chemical digestion: chemical breakdown of large molecules into smaller molecules via hydrolase enzymes
What are enzymes?
- a type of protein
the job of an enzyme is to make chemical reactions occur faster
enzymes do not get destroyed during the reaction so they can be used over and over
What do hydrolase enzymes do?
uses water to break a big molecule into two smaller molecules
ex: disaccharide gets cut into two monosaccharides via an amylase enzyme
What is absorption?
the cells absorb the small molecule nutrients
- ex: the amino acids from larger proteins or simple sugars from carbohydrates
- glucose goes up to the mitochondria
What is elimination?
undigested material passes out of the digestive system and removed from the body
Food is digested within specialized compartments that can be?
intracellular and extracellular
What is intracellular digestion?
breakdown of food INSIDE CELLS
- usually within food vacuoles
- food ingested into the cell via phagocytosis
- food vacuole fuses with lysosomes that use enzymes to break down food particles
What is the only animal that uses only intracellular digestion?
porifera aka sponges
What is extracellular digestion?
breakdown of food outside of cells within digestive organs or systems
Now, there is a trend in animal evolution toward increasing dependance on extracellular digestion, what major advantages do you think extracellular digestion has over intracellular digestion?
- food can be refined before the cell engulfs it
- more diverse options
- faster metabolism because the food is broken down before entering the cell
Digestion in gastrovascular cavity(one hole)?
cnidaria have a gastrovascular cavity where food enters and exits via one opening
- tenticles move food into the opening
- nutrients passed from cell to cell via diffusion
- extracellular digestion first within gastrovascular cavity and then intracellular digestion follows
Digestion in alimentary canals?
- food moves in one direction through different specialized compartments
- crop=food ingested via mouth is stored here
- glizzard= mechanically breaks down food with 2 sacs for mechanical chewing
- intestine= chemically breaks down large molecules so small molecules can be absorbed by the cells in the intestine lining : those nutrients are then transported to the rest of the body via circulatory system
What does the oral cavity include?
mouth including tongue, teeth, salivary glands
What does the tongue do?
move food around
What do teeth do?
for mechanical digestion to cut and grind food: food forms a bolus that has increased surface area
What do salivary glands do?
saliva has salivary amylase enzymes for chemical digestion: hydrolyzes starch and glycogen into smaller molecules like maltose
What is the esophagus?
the passage between mouth and stomach
- muscle contractions move food down the esophagus
What is the epiglottis?
flap that prevents food and water from entering the windpipe
What is the esophageal splinter?
a muscle that prevents food from going back up, one is located in throat and one is in top of stomach
What does the stomach do?
food storage and digestion(mechanical and chemical)
- elastic and can stretch to fit more food/liquid
- secretes gastric juice: mix of pepsin and hydrochloric acid
What is hydrochloric acid/hcl for?
very acidic, breaks apart cells and can denature proteins to increase peptide bond exposure
What is pepsin for?
protease that hydrolyzes proteins into smaller molecules
What is chyme?
combo of food and gastric juice, stomach contractions churn food which helps in mechanical digestion
What are the parts of the small intestine?
duodenum, jejunum, and ileum
What is the function of the duodenum?
chyme from the stomach mixes with digestive juices from pancreas, liver, and gall bladder; most digestion occurs here
What is the function of the jejunum and ileum?
absorption of nutrients and water
What are the 3 digestive system accessory organs?
pancreas, liver, and gallbladder
What does the pancreas do?
secretes pancreatic juice into duodenum, it neutralizes acidic chyme
- the juices also help digest carbohydrates, proteins, and nucleic acids
What does the liver do?
produces bile that aids in digestion and absorption of lipids
What does the gallbladder do?
stores and concentrates bile
What are some additions to the small intestine?
the wall is folded with finger like projections called villi ad those have microvilli
- together the folds maximize the SA to increase rate of nutrient absorption= nutrients go into circulatory system to be carried to the rest of the cells in the body
What is the function of the large intestine/colon?
absorb more salts and water preparing waste to be eliminated: the cecum connects the small intestine to the colon
- feces become more solid as it passes through ascending, transverse, and descending colon
What is the function of rectum?
feces is stored there until elimination from anus
Animal nutrition for herbivore, carnivore, and omnivore?
herbivore: mostly eats plants and digest a lot of cellulose: cows
carnivore: mostly eat meat: shark
omnivore: eat both plants and meat: humans
Dentition for carnivores and herbivores?
carnivores have large canines and incisors to kill prey and rip pieces away whereas herbivores generally lack canines
Stomach and intestine for carnivores and herbivores?
carnivores have large expandable stomachs to eat large meals and herbivores have a longer alimentary canal because plant material more difficult to digest
