Lektion 4 - Digestive system

Question 1

Why do we need a digestive system?

Answer 1

“Harvest nutriens molecules to maintain homeostasis

• energy production for cell survival
• molecules for cellular components
• Intake of essential nutriens
• intake of water
• fermentation plant derived fibers (microbiota)

Question 2

What prevents autodigestion?

Answer 2

Compartmentalization, the separation of potentially competeing processes.

Question 3

How is hydrolysis used in the body?

Answer 3

It breaks down macromolecules (carbs, protein and fats) into smaller parts

Question 4

What is endogenous digestion?

Answer 4

Feeding through pores.

Question 5

Explain: Exogenous digestion, one-way and two way-traffic.

Answer 5

One-way: mouth and anus. Has the advantage of eating and digesting at the same time

Two-way: only mouth OR anus, cannot digest and eat at the same time due to traffic jam. This limits the size of the organism.

Question 6

What are the the parts of a general digestive system in order?

Answer 6

1) mouth
2) esophagous
3) stomach
4) small intestine
5) large intestine

Question 7

How is the digestive function regulated?

Answer 7

Extrinsic nerves:
- information about food from other senses (sight smell)
- Emotional control
- Flight or fight vs rest and digest mood

Intrinsic nerves:
- peristalsis
- secretion into lumen

Hormones:
timing and efficiency of the digestion

Question 8

What role does the mouth have in the DS?

Answer 8

• tear food into smaller pieces
• The mouth form is diet-dependent (adaptation)
• mixes food with salavia (amylase breaks down food)

Question 9

What is the function of the esophagus in the DS?

Answer 9

• It carries food and liqiud from the mouth to the stomach
• Opens when you want to swallow

Question 10

What is the function of the stomach in the DS?

Answer 10

• Churn (muscular wall) mechanical digestion
• Protein hydrolysis with pepsin (chemical digestion)

Question 11

How does the chemical digestion in the stomach work?

Answer 11

HCl is needed for the activation of pepsinogen to pepsin.

pepsin cleaves proteins (only digestion of proteins in stomach)

there is gastrin that regulates the secretiono of HCl and pepsinogen

Question 12

What is the function of the small intestine in the DS?

Answer 12

• full digestion and absorbtion
• recive bile from liver and gall bladder
• recive digestive enzymes and NaHCO3 from pancreas

Question 13

What is the function of the pancreas (bukspottskörtel) and the liver in the DS?

Answer 13

To deliver effectors that carry out digestion

Question 14

What does the Pancreas do?

Answer 14

Exocrine:
Secreation of digestive enzymes and buffering solution

Endocrine:
Regulation of blood glucose levels

Question 15

What is the liver function?

Answer 15

Metabolism
- Protein synthesis (plasma protein)
- Degradation of “old” proteins (haemoglobin)

Storage
- glucose and fat
- Bile production
- Detoxification (drugs and alcohol)

Question 16

What is bile and what does it do?

Answer 16

• Synthesised in the liver
• Stored in gallbladder
• emulsification of lipids

Question 17

What is the function of the large intestine in the DS?

Answer 17

• Fermentation
• Absorbtion of water and inorganic ions
• temporary storage for excreta

Question 18

Animals cannot digest fibers, how is this problem solved?

Answer 18

By Microbiota:
Fermentation, microbial anaerobic metabolism of glucose to produce short fatty acids which are then converted to glucose by the feeder

Question 19

What is the physical difference in herbivores and carnivores?

Answer 19

herbivores have longer intestine due to low digestion speed of cell wall component
they also hae a larger cecum for the need of fermentation

Question 20

How do we know that we are not hungry?

Answer 20

• high glucose levels (insulin)
• high lipid levels in apipose tissue (leptin)
• Full stomach (distension)

Question 21

How do we know that we are hungry?

Answer 21

• low blood glucose levels
• Low lipid levels in adipose tissue
• empty stomach (growl)