Lecture 8: Digestion

Question 1

Animals are chemoheterotrophs which means?

Answer 1

they get their energy and carbon from breaking down organic compounds(example: eating)

Question 2

What are the 4 steps in food processing?

Answer 2

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?

Question 3

What is ingestion and what are the 4 types?

Answer 3

ingestion is how the animal eats/feeds
the 4 types are: suspension and filter feeders, substrate feeders, fluid feeders, and bulk feeders

Question 4

Describe the ingestion method suspension and filter feeders.

Answer 4

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

Question 5

Describe the ingestion method substrate feeders.

Answer 5

substrate feeders live in or on their food source
- example: many insects live on their host plan or decomposing organisms

Question 6

Describe the ingestion method fluid feeders.

Answer 6

fluid feeders suck fluid with nutrients from a living host
- example: hummingbird, mosquitos

Question 7

Describe the ingestion method bulk feeders.

Answer 7

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

Question 8

What is digestion?

Answer 8

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

Question 9

What are the two steps in digestion?

Answer 9

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

Question 10

What are enzymes?

Answer 10

• 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

Question 11

What do hydrolase enzymes do?

Answer 11

uses water to break a big molecule into two smaller molecules
ex: disaccharide gets cut into two monosaccharides via an amylase enzyme

Question 12

What is absorption?

Answer 12

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

Question 13

What is elimination?

Answer 13

undigested material passes out of the digestive system and removed from the body

Question 14

Food is digested within specialized compartments that can be?

Answer 14

intracellular and extracellular

Question 15

What is intracellular digestion?

Answer 15

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

Question 16

What is the only animal that uses only intracellular digestion?

Answer 16

porifera aka sponges

Question 17

What is extracellular digestion?

Answer 17

breakdown of food outside of cells within digestive organs or systems

Question 18

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?

Answer 18

• food can be refined before the cell engulfs it
• more diverse options
• faster metabolism because the food is broken down before entering the cell

Question 19

Digestion in gastrovascular cavity(one hole)?

Answer 19

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

Question 20

Digestion in alimentary canals?

Answer 20

• 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

Question 21

What does the oral cavity include?

Answer 21

mouth including tongue, teeth, salivary glands

Question 22

What does the tongue do?

Answer 22

move food around

Question 23

What do teeth do?

Answer 23

for mechanical digestion to cut and grind food: food forms a bolus that has increased surface area

Question 24

What do salivary glands do?

Answer 24

saliva has salivary amylase enzymes for chemical digestion: hydrolyzes starch and glycogen into smaller molecules like maltose

Question 25

What is the esophagus?

Answer 25

the passage between mouth and stomach
- muscle contractions move food down the esophagus

Question 26

What is the epiglottis?

Answer 26

flap that prevents food and water from entering the windpipe

Question 27

What is the esophageal splinter?

Answer 27

a muscle that prevents food from going back up, one is located in throat and one is in top of stomach

Question 28

What does the stomach do?

Answer 28

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

Question 29

What is hydrochloric acid/hcl for?

Answer 29

very acidic, breaks apart cells and can denature proteins to increase peptide bond exposure

Question 30

What is pepsin for?

Answer 30

protease that hydrolyzes proteins into smaller molecules

Question 31

What is chyme?

Answer 31

combo of food and gastric juice, stomach contractions churn food which helps in mechanical digestion

Question 32

What are the parts of the small intestine?

Answer 32

duodenum, jejunum, and ileum

Question 33

What is the function of the duodenum?

Answer 33

chyme from the stomach mixes with digestive juices from pancreas, liver, and gall bladder; most digestion occurs here

Question 34

What is the function of the jejunum and ileum?

Answer 34

absorption of nutrients and water

Question 35

What are the 3 digestive system accessory organs?

Answer 35

pancreas, liver, and gallbladder

Question 36

What does the pancreas do?

Answer 36

secretes pancreatic juice into duodenum, it neutralizes acidic chyme
- the juices also help digest carbohydrates, proteins, and nucleic acids

Question 37

What does the liver do?

Answer 37

produces bile that aids in digestion and absorption of lipids

Question 38

What does the gallbladder do?

Answer 38

stores and concentrates bile

Question 39

What are some additions to the small intestine?

Answer 39

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

Question 40

What is the function of the large intestine/colon?

Answer 40

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

Question 41

What is the function of rectum?

Answer 41

feces is stored there until elimination from anus

Question 42

Animal nutrition for herbivore, carnivore, and omnivore?

Answer 42

herbivore: mostly eats plants and digest a lot of cellulose: cows
carnivore: mostly eat meat: shark
omnivore: eat both plants and meat: humans

Question 43

Dentition for carnivores and herbivores?

Answer 43

carnivores have large canines and incisors to kill prey and rip pieces away whereas herbivores generally lack canines

Question 44

Stomach and intestine for carnivores and herbivores?

Answer 44

carnivores have large expandable stomachs to eat large meals and herbivores have a longer alimentary canal because plant material more difficult to digest