Unit 3: Digestion Flashcards Preview

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Flashcards in Unit 3: Digestion Deck (42)
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1
Q

What are the digestive functions?

A

a. Ingestion
b. Digestion (both mechanically and chemically)
c. Propulsion
d. Absorption
e. Defecation

2
Q

What happens to food in the mouth?

A

a. It is ground by teeth. This is also called chewing and mastication.
b. It is mixed with saliva.
c. It is moved/propelled by the tongue.

3
Q

Where does saliva come from?

A

It is released by salivary glands. A signal is sent from the nervous system. It is an exo reaction; it releases something.

4
Q

What does the nervous system respond to?

A

a. mechanoreceptors (chewing)

b. chemoreceptors (food)

5
Q

What types of food especially stimulate the production if saliva?

A

Acidic and umami foods.

6
Q

What are the main constituents of saliva?

A

a. Water (97-99%)
b. salivary amylase
c. lysozyme

7
Q

What is the purpose of water in saliva?

A

It solubilizes food and is required for tasting.

8
Q

True or false: salivary amylase inhibits bacterial growth.

A

False. Lysozyme does this.

9
Q

What is the purpose of amylase?

A

To digest carbohydrates like starch into small glucose units such as maltose (2 glucose), maltotriose (3 glucose) and dextrins (5-10 glucose).

10
Q

How does the tongue move food around in the mouth?

A

It moves the food between the teeth, forms it into a round shape (bolus) and forces it back into the pharynx to initiate swallowing.

11
Q

What do enzymes require to function properly?

A

They can require a certain pH, concentration or temperature.

12
Q

The esophagus is made up of multiple layers, what are they?

A
  1. Lumen (whole/tube)
  2. Mucosa
  3. Submucosa
  4. Muscularis externa
  5. Adventitia (for esophagus)/ Serosa (other organs)
13
Q

What is the mucosa made of?

A

Epithelium, lamina propria and muscularis mucosa.

14
Q

What is the submucosa?

A

This is the connective tissue between the mucosa and muscularis externa. It is made of glands, blood vessels and nerves.

15
Q

What is the muscularis externa?

A

It is 2 to 3 layers of smooth muscle.

16
Q

What is the adventitia?

A

It is a connective tissue that supports and binds organs to others.

17
Q

How do the pharynx and esophagus work?

A

They use peristaltic contractions to move/propel bolus to the stomach.

18
Q

What does the esophagus require to function properly?

A

It requires two types of muscle: circular and longitudinal.

19
Q

What is the esophagus composed of and what makes it function?

A

It is made of smooth muscle and it is controlled by the nervous system.

20
Q

What does the stomach do?

A

It churns and mixes the bolus using peristaltic waves (mechanical breakdown and propulsion). This turns the bolus into chyme. The emulsification of fats to form liquid droplets also occur.

21
Q

What are other functions of the stomach?

A

The stomach secretes mucus, hydrochloric acid and absorbs substances that can pass through mucosa.

22
Q

What is the purpose of the mucus?

A

To protect stomach from acid and digestive enzymes and lubricates.

23
Q

What is the origin of hydrochloric acid in the body?

A

H+ and Cl- ions are secrete separately and originate from parietal.

24
Q

What does the hydrochloric acid do?

A

It solubilizes food, kills bacteria, denatures protein, breaks down cell walls in plant cells and breaks down connective tissue.

25
Q

True or false: The stomach also secretes pepsins.

A

True. Pepsin comes from chief cells. it digests proteins and breaks down proteins into polypeptides.

26
Q

True or false: Gastric lipase is secreted by the stomach in large amounts.

A

False. There is very little gastric lipase, which breaks down lipids into fatty acids and monoglycerides.

27
Q

True or false: Lipase only comes from the stomach.

A

False. Most lipase is produced in the pancreas. Only a very tiny produced by the stomach.

28
Q

What are the three substances that can pass through the mucosa?

A

Alcohol, aspirin and some drugs.

29
Q

What is the role of the small intestine?

A

To mix and propel chyme.

30
Q

What organs help the small intestine do its job?

A

The accessory organs: liver, gallbladder and pancreas.

31
Q

What does the small intestine use to help the digestion of food?

A

Digestive juices from the accessory organs such as bile.

32
Q

How does the segmentation of the small intestine help digestion?

A

Mechanical breakdown and propulsion mixes chyme with digestive juices.

33
Q

What are the three main points to know when it comes to the liver and gall bladder?

A

a. Liver makes the bile while the gallbladder concentrates and stores it.
b. Bile is released into the small intestine.
c. bile is a surfactant- helps emulsify fats.

34
Q

What juices does the pancreas release and what are their functions?

A

a. pancreatic amylase (breaks down carbohydrates into smaller glucose)
b. trypsin and chymotrypsin (break down polypeptides into smaller peptides)
c. pancreatic lipases (break down fats into free fatty acids)
d. Bicarbonate (neutralizes stomach acid)
e. water (keeps things moving)

35
Q

True or false: Bile makes it easier for lipase to attack.

A

True. Bile emulsifies fats, increasing their surface area which makes them more accessible to lipase.

36
Q

What does the small intestine release?

A

a. Peptidases
b. Dextrinase and other enzymes
c. Mucus
d. Water

37
Q

True or false: Peptidases breaks down carbohydrates into monosaccharides.

A

False: Dextrinase and other enzymes do this. Peptidases breakdown small peptides into amino acids, di-peptides or tri-peptides.

38
Q

What organ does most of the absorption in the body?

A

The small intestine.

39
Q

Why does the small intestine absorb so well?

A

High surface area amplifies absorptive surface. Circular folds have villi on them, and each villi has microvilli.

40
Q

What is absorbed in the small intestine?

A

a. monosaccharides (i.e. glucose, fructose, galactose)
b. amino acids, di-peptides and tri-peptides (di- and tri- peptides will be broken down into amino acids inside epithelial cells)
c. fatty acids an monoglycerides
d. nucleic acids
e. vitamins
f. electrolytes/ions
g. water

41
Q

What are the functions of the large intestine?

A

a. To churn and propel slowly (when food is present).
b. Digest residue by resident bacteria.
c. Absorption.
d. Defecation.

42
Q

What is absorbed in the large intestine?

A

Water, electrolytes, and vitamins produced by bacteria in the gut.