digestion

Question 1

what are the 4 components of digestion?

Answer 1

1. ingestion
2. digestion
3. absorption
4. elimination

Question 2

what are 4 types of ingestion, what are examples of each

Answer 2

1. suspension/filter feeders -> whales
2. bulk feeders -> snakes, humans
3. fluid feeders -> mosquitoes
4. substrate feeders (eat where they live)

Question 3

why do animals have digestive compartments?

Answer 3

As a safety feature; don’t want digestive liquids to digest themselves

Question 4

what are the two types of digestion, how are they different from each other?

Answer 4

Intracellular and extracellular.

Intra is digestion that takes place inside of the cell, extra takes place outside of the cell.

Question 5

what is it called when cells engulf food particles?

Answer 5

Phagocytosis

Question 6

how does intracellular digestion work, is it chemical or mechanical digestion, and what is the organelle that accomplishes digestion?

Answer 6

chemical digestion

1. cell engulfs food particle -> phagocytosis
2. lysosome fuses with vacoule containing food particle
3. digestive enzymes in lysosome digest food particle

Question 7

What is the digestive enzyme found in lysosomes?

Answer 7

hydrolytic enzymes

Question 8

what is a digestive system?

Answer 8

an alimentary canal (digestive tract) + accessory glands

Question 9

what is peristalsis? how does it work in the digestive system?

Answer 9

• peristalsis is rhythmic muscle contractions
• in the digestive tract: food is pushed through the alimentary canal by peristalsis (contractions/relaxations of muscles found in the walls of the alimentary canal)

Question 10

what is a crop? What organisms are they found in?

Answer 10

a crop is a compartment for storage in the alimentary canal, found before digestion.
-found in earthworms, grasshoppers, ,and birds

Question 11

what is a gizzard? What organisms are they found in?

Answer 11

• a gizzard is a compartment for grinding up food in the alimentary canal.
• well defined muscles
• Found in organism that do not have teeth.
• often has rocks/debris in it to assist in grinding
• found in earthworms, and birds

Question 12

what is a typhlosole, what does it do, what organisms is it found in?

Answer 12

• internal fold of intestine, which helps to increase surface area.
• found in earthworms

Question 13

what are gastric caeca, what are their function, what organisms do we see this in?

Answer 13

• are stomach pouches that provide increased surface area

- found in grasshoppers

Question 14

why is increased surface area in the digestive system so important?

Answer 14

because it allows for more digestive enzyme secretion, and more nutrient absorption

Question 15

What are spiral valves in sharks for?

Answer 15

spiral valves push food to the outside of the small intestine, increasing the time food has contact with the wall of the small intestine, increasing absorption

Question 16

What are pyloric caeca, what is their function and what organisms are they found in?

Answer 16

• pouches between stomach and small intestine, allowing for more enzymes and absorption
• found in bony fish

Question 17

what is the function of the oral cavity?

Answer 17

• mechanical and chemical digestion

- break down of sugars, no protein, small amount of lipid breakdown

Question 18

what is the function of the esophagus?

Answer 18

• transport tube

- no digestion occurs here

Question 19

what is the function of the stomach?

Answer 19

• mechanical (3 muscles churning) and chemical (gastric juice) digestion
• protein digestion

Question 20

what is gastric juice?

Answer 20

hydrochloric acid + the enzyme pepsin

Question 21

what are the 3 types of cells involved in making gastric juice, what is their role?

Answer 21

1. Parietal cells
   - secrete hydrogen and chloride ions separately
2. Chief cells
   - secrete inactive pepsinogen
   - activated to pepsin when mixed with hydrochloric acid
3. Mucus cells
   - protects stomach lining from gastric juice

Question 22

what does pepsin do?

Answer 22

digests protein

Question 23

what does the pancreas do, how does this aid in digestion?

Answer 23

• pancreas secretes pancreatic juice into the small intestine
• this contains bicarbonate
• bicarbonate neutralizes stomach acid and adds digestive enzymes -> important because the small intestine doesn’t have mucus to protect it from the gastric juice

Question 24

what does the liver do, how does this aid in digestion?

Answer 24

• liver produces bile

- bile emulsifies fat, making it easier to digest

Question 25

what does the gallbladder do, ho does this aid in digestion?

Answer 25

- gallbladder stores bile from the liver - ensures that there is enough bile present when the organism eats; especially in bulk feeders that may eat a lot in one go

Question 26

what is a cecum, where is it found in the digestive system, what animals is it most prevalent in?

Answer 26

- cecum is a compartment that aids in the breakdown of plant material - found between small intestine and large intestine - most prevalent in herbivores.

Question 27

what are the parts of the large intestine, what is its main functions?

Answer 27

- colon and rectum - water reabsorption from chyme - storage until organism is ready to defecate

Question 28

what is chyme?

Answer 28

food after it leaves the stomach, before this it is bolus

Question 29

what is the main factor behind evolutionary adaptions of digestive systems in vertebrates?

Answer 29

diet

Question 30

what are the dental adaptations of herbivores vs carnivores vs omnivores?

Answer 30

``` Herbivores: -reduced/no canines -large flat pre-molars and molars for grinding their food Carnivores: -large canines for shredding/tearing food -molars are sharper Omnivores: -mixed teeth shapes/sizes -able to grind and tear ```

Question 31

what are stomach/intestinal adaptations of herbivores vs carnivores?

Answer 31

``` Herbivores: -have longer digestive tract -have large cecum Carnivores: -have short digestive tract -very small cecum -stretchy stomach ```

Question 32

What is coprophagy, which organisms do we see this in, why does this occur?

Answer 32

- poo eaters! - non-ruminant herbivores ie. rabbits - their cecum breaks down cellulose, but occurs after site for nutrient absorption ->after short intestine -> they have already absorbed all the nutrients they can before cecum can break down the rest - poop it out, eat it again, and now can absorb the rest of the nutrients

Question 33

what are ruminants?

Answer 33

ruminants are herbivores with a 4 chambered stomach that regurgitate their food and eat it again. ie. cows

Question 34

What are the 4 chambers in a ruminants stomach, what are their functions?

Answer 34

1. Rumen -> first chamber that bolus enters 2. Reticulum -> symbiotic microbes digest cellulose rich meal Reguritation and re chewing 3. Omasum -> swallowed cud goes to omasum for water removal 4. Abomasum -> digestion by cow's enzymes

Question 35

what is bolus?

Answer 35

food mass until it leaves the stomach

Question 36

what are villi? where are they found, what do they do?

Answer 36

- are small, finger-like projections that extend into the lumen of the small intestine - found in small intestine - increase the internal surface area of the intestinal walls making available a greater surface area for absorption