digestive sys 1

Question 1

What are the four general processes involved in assimilation?

Answer 1

Digestion, absorption, secretion, and motility.

Question 2

What is digestion?

Answer 2

The chemical breakdown of large nutrient molecules into smaller, absorbable units.

Question 3

How is absorption defined in digestive physiology?

Answer 3

The transport of small molecules from the GI tract into the blood.

Question 4

What is secretion in the context of the digestive system?

Answer 4

Transport of substances into the GI tract lumen to aid digestion and absorption.

Question 5

What does motility refer to in digestion?

Answer 5

Movement of contents through the GI tract, mainly via peristalsis.

Question 6

How do simple animals like sponges digest food?

Answer 6

By intracellular digestion using phagocytosis and vacuoles within choanocytes.

Question 7

What is the difference in digestion between cnidarians and sponges?

Answer 7

Cnidarians have both extracellular and intracellular digestion within a gastrovascular cavity.

Question 8

What is the benefit of compartmentalization in complex digestive systems?

Answer 8

Increases efficiency of digestion and nutrient absorption through specialization of gut regions.

Question 9

What are gastroliths and their function in birds?

Answer 9

Stones swallowed by birds to aid in mechanical breakdown of food in the gizzard.

Question 10

What is the purpose of the cecum in rabbits?

Answer 10

Hosts gut bacteria for fermentation; part of hindgut fermentation system.

Question 11

Why do rabbits eat their own feces (cecotropes)?

Answer 11

To re-digest and absorb nutrients more effectively from fermented food.

Question 12

How do ruminants like cows digest cellulose?

Answer 12

Through microbial fermentation in the rumen and reticulum, followed by regurgitation and re-chewing (cud).

Question 13

What role does the abomasum play in cow digestion?

Answer 13

Acts as the true stomach, secreting digestive enzymes for chemical digestion.

Question 14

What are the six integrated steps of digestion in mammals?

Answer 14

Ingestion, mechanical processing, digestion, secretion, absorption, and excretion.

Question 15

List the four layers of the GI tract.

Answer 15

Mucosa, submucosa, muscularis externa, and serosa.

Question 16

What cells line the GI tract and absorb nutrients?

Answer 16

Enterocytes (a type of epithelial cell) in the mucosa.

Question 17

What is the function of the enteric nervous system?

Answer 17

Coordinates GI function, including secretion and motility.

Question 18

Define peristalsis.

Answer 18

Wave-like contractions of smooth muscle in the GI tract that move contents along.

Question 19

What is the function of digestive enzymes?

Answer 19

To chemically break down macromolecules into absorbable monomers.

Question 20

What do amylases do?

Answer 20

Break down carbohydrates into simple sugars like glucose.

Question 21

What do proteases and peptidases do?

Answer 21

Break down proteins into peptides and amino acids.

Question 22

What do lipases do?

Answer 22

Break down fats into fatty acids and glycerol.

Question 23

What do nucleases do?

Answer 23

Break down nucleic acids into nucleotides.

Question 24

How are carbohydrates absorbed in the small intestine?

Answer 24

Monosaccharides are absorbed via active transport and facilitated diffusion by enterocytes.

Question 25

How are disaccharides like maltose and lactose broken down?

Answer 25

By enzymes like maltase, sucrase, and lactase in the small intestine.

Question 26

How are proteins absorbed after digestion?

Answer 26

Amino acids and small peptides are absorbed via Na+-linked cotransporters into enterocytes.

Question 27

Why is lipid digestion more complex than protein or carb digestion?

Answer 27

Because lipids are hydrophobic and require emulsification and specialized transport.

Question 28

How does bile assist in lipid digestion?

Answer 28

Emulsifies fats into micelles, increasing surface area for enzymatic breakdown.

Question 29

What are micelles?

Answer 29

Small lipid droplets formed by bile that help solubilize fats for digestion and absorption.

Question 30

How are long-chain triglycerides transported after absorption?

Answer 30

As chylomicrons via the lymphatic system.

Question 31

How are short-chain fatty acids transported?

Answer 31

They diffuse into the blood and are transported directly via circulation.

Question 32

Why do rabbits produce and re-ingest cecotropes?

Answer 32

To absorb nutrients produced during fermentation in the cecum, which would otherwise be lost.

Question 33

What would happen if bile secretion from the liver was blocked?

Answer 33

Fat digestion and absorption would be impaired due to reduced emulsification, leading to nutrient deficiencies.

Question 34

How does chewing (mechanical digestion) aid chemical digestion?

Answer 34

It increases surface area of food particles, making enzymatic action more efficient.

Question 35

What is the significance of the enteric nervous system in the digestive tract?

Answer 35

It regulates motility, secretion, and blood flow in the GI tract independently of the CNS.

Question 36

What would happen to carbohydrate absorption if sodium levels were depleted?

Answer 36

Absorption would decrease because monosaccharide transporters rely on Na+ gradients.

Question 37

If the mucosal layer of the small intestine was damaged, what symptoms might arise?

Answer 37

Malabsorption, diarrhea, nutrient deficiencies, and possible weight loss.

Question 38

Why is it important that peristalsis is a wave-like motion?

Answer 38

It ensures efficient and continuous movement of food through the GI tract.

Question 39

How does the structure of a ruminant stomach support cellulose digestion?

Answer 39

Multiple compartments with microbial fermentation allow breakdown of plant fibers.

Question 40

How does the physical state of lipids impact their digestion?

Answer 40

Their hydrophobic nature requires emulsification into micelles for effective enzymatic action.

Question 41

Why is the pancreas critical to digestion?

Answer 41

It produces digestive enzymes (amylase, protease, lipase) and bicarbonate to neutralize stomach acid.

Question 42

Why do lipids require both bile and enzyme activity for absorption?

Answer 42

Bile emulsifies fats into micelles; enzymes break them down, allowing absorption through enterocytes.

Question 43

How does the GI system coordinate digestion across its different regions?

Answer 43

Through compartmentalization and communication via neural (ENS) and hormonal signals.

Question 44

If a person lacked lactase enzyme, what condition would occur?

Answer 44

Lactose intolerance—causing bloating, gas, and diarrhea due to undigested lactose.

Question 45

What adaptive value does a one-way digestive tract offer compared to a gastrovascular cavity?

Answer 45

Allows continuous and efficient food intake and processing through specialized regions.

Question 46

Why do herbivores typically have longer intestines than carnivores?

Answer 46

To provide more surface area and time for digesting complex plant materials like cellulose.