The Digestive System

Question 1

The Digestive System is comprised of 2 categories of organs. What are they called?

Answer 1

1. The GIT
2. Accessory digestive organs

Question 2

What organs comprise the GIT?

Answer 2

1. Oral Cavity
2. Pharynx
3. Oesophagus
4. Stomach
5. Small Intestines
6. Large Intestines
7. Anal Canal

Question 3

What organs comprise the Accessory Digestive Organs?

Answer 3

1. Teeth
2. Tongue
3. Salivary Glands
4. Liver
5. Gallbladder
6. Pancreas

Question 4

What are the 6 primary functions of the Digestive System?

Answer 4

1. Ingestion: introduction of food into oral cavity
2. Motility: muscular contractions for mixing and moving material through GIT
3. Secretion: manufacturing and releasing substances that facilitate digestion
4. Digestion: breakdown of ingested food into smaller structures for absorption
5. Absorption: membrane transport of digested molecules
6. Elimination: the expulsion of indigestible material

Question 5

What are the 4 layers that comprise the walls of the GIT from innermost to outermost?

Answer 5

1. Mucosa: lines the lumen
2. Submucosa: loose connective tissue with glands - controls secretion
3. Muscularis: smooth muscle - controls motility
4. Serosa

Question 6

What is the Peritoneum? And what are the 2 layers called?

Answer 6

Serous epithelial membrane that covers the wall of the abdominal cavity
1. Parietal Peritoneum: covers abdominal wall
2. Visceral Peritoneum: covers outer surface of abdominal organs

Note: anything pertaining to ‘Pylorus’, involves the stomach!
Go into depth about the Digestive System!

Question 7

What are the 3 main Macronutrients and their functions?

Answer 7

1. Carbohydrates: glucose is broken down to release energy
2. Lipids: form of energy storage
3. Proteins: provides energy

Question 8

Explain Protein Metabolism.

Answer 8

Involves breakdown of ingested protein in the small intestine to amino acids.
Amino acids can be used for:
1. Protein synthesis
2. Energy production (ATP)
3. Converted to fat for storage
4. Converted to glucose by gluconeogenesis

Question 9

What 5 cells play a role in producing the 3 litres of gastric secretions/day?

Answer 9

1. Surface mucous cells
2. Mucous neck cells
3. Parietal cells
4. Chief cells
5. G cells: secrete the gastrin hormone into the blood

Question 10

What are the 4 components of gastric juice?

Answer 10

1. Mucin
2. Intrinsic factor
3. Hydrochloric acid
4. Pepsin

Question 11

What are the 3 phases of Gastric Secretion/Motility?

Answer 11

1. Cephalic Phase
2. Gastric Phase
3. Intestinal Phase

Question 12

Explain the Cephalic Phase of Gastric Secretion/Motility.

Answer 12

1. Initiated by the sight, smell, taste and thought of food
2. Leads to parasympathetic activation and stimulation of gastric secretions and motility.

Question 13

Explain the Gastric Phase of Gastric Secretion/Motility.

Answer 13

1. Activated via stretch receptors and chemoreceptors in the stomach after the introduction of food
2. Results in increased peristalsis and increased release of gastrin which further increases force of contraction and release of secretions

Question 14

Explain the Intestinal Phase of Gastric Secretion/Motility.

Answer 14

1. Activated by the presence of acidic chyme in the duodenum
2. Enterogastric reflex and hormones enterogastrones decrease stomach secretions, motility and emptying

Question 15

What 2 glands does the Pancreas have?

Answer 15

1. Exocrine
2. Endocrine

Question 16

What organ stores bile?

Answer 16

The Gallbladder

Question 17

What are 5 of the many functions the Liver has?

Answer 17

1. Carb, Lipid and Protein metabolism
2. Processing of drugs, hormones and bilirubin
3. Synthesis of bile acids
4. Storage
5. Phagocytosis

Question 18

What are the 2 chemical reactions that happen during metabolism?

Answer 18

1. Catabolic: the breakdown of molecules/nutrients into smaller chemicals; energy can be released from molecules/nutrients
2. Anabolic: the use of simple molecules/nutrients and energy to form complex molecules

Question 19

Micronutrients are metabolised 2 different ways. What are they?

Answer 19

1. Via water (water-soluble)
2. Via fat (fat-soluble)

Question 20

Which micronutrients are water-soluble?

Answer 20

1. Vitamin B 1-3
2. Vitamin B 5-7
3. Vitamin 9
4. Vitamin 12
5. Vitamin C

Question 21

What micronutrients are fat-soluble?

Answer 21

1. Vitamin A
2. Vitamin D
3. Vitamin E
4. Vitamin K

Question 22

What are the 7 Major Minerals?

Answer 22

1. Calcium
2. Chloride
3. Magnesium
4. Phosphorus
5. Potassium
6. Sodium
7. Sulfur

Question 23

What are the 2 ways in which glucose is metabolised?

Answer 23

1. Glycolysis
2. Glucogenesis

Question 24

Explain Carbohydrate Metabolism.

Answer 24

Polysaccharides (long chains of sugars) are broken down into simple sugars and absorbed into the blood
The simple sugars (monosaccharides) journey through the blood to the liver and enter the hepatocytes where fructose and galactose are converted to glucose

Question 25

Explain Lipid Metabolism.

Answer 25

The breakdown or storage of triglycerides Triglycerides are transported first through the lymphatic capillaries of the small intestine and then released into the bloodstream where they travel to the hepatocytes The ingested triglycerides and the manufactured triglycerides are broken down to fatty acid chains and glycerol molecules and can either be: 1. Converted to very-low-density lipoprotein 2. Sent to cells for energy use 3. Stored in adipose tissue until required for energy at a later time

Question 26

Explain Protein Metabolism.

Answer 26

The breakdown of ingested protein in the small intestine to amino acids Amino acids are absorbed into the bloodstream and transported to the hepatocytes where they undergo deamination (removal of their amino group) Amino group is converted to ammonia and eventually excreted in the urine as urea The remaining components of the amino acids can then be either: 1. Used for new protein synthesis 2. Used for energy production (ATP) 3. Converted to fat for storage 4. Converted to glucose for gluconeogenesis

Question 27

Explain the Absorptive State of regulating nutrient blood levels.

Answer 27

Takes places for approximately four hours after a meal As the nutrients are being absorbed into the bloodstream it results in an overall increase in concentrations of glucose, triglycerides and amino acids Insulin is released from the beta cells of the pancreas

Question 28

Explain the Postabsorptive State of regulating nutrient blood levels.

Answer 28

Takes place between meals after the absorption of nutrients ceases Major controlling hormone is glucagon