Digestive System

Question 1

What are the four accessory organs to the GI system?

Answer 1

• Salivary glands
• Gallbladder
• Liver
• Pancreas

Question 2

How many teeth do kids and adults have?

Answer 2

Kids: 20 deciduous teeth

Adults: 32 permanent teeth

Question 3

What are the types of teeth (from front to back)

Answer 3

• Two incisors (cutting)
• One cuspid/canine (tearing)
• Two bicuspids/premolars (crushing)
• three molars (grinding)

Question 4

What are the salivary glands and what do they secrete?

Answer 4

• Parotid
• Sublingual
• Submaxillary

Secretes mucous and salivary amylase

Question 5

What does salivary amylase do?

Answer 5

Splits starch and glycogen into disaccharide subunits

Question 6

What is the scientific term for swallowing?

Answer 6

Deglutition

Question 7

What are the two layers of muscle in the esophagus?

Answer 7

• Inner circular layer
• Outer longitudinal layer

These produce peristalsis, which is modulated by the ANS

Question 8

Which division of the ANS stimulates the GI system?

Answer 8

The parasympathetic nervous system

Question 9

Which cells in the protect the lumen of the stomach from gastric juices?

Answer 9

Mucous secreting goblet cells

Question 10

What can increase the production of gastric juice? (2)

Answer 10

• Gastrin (stomach hormone)

- Parasympathetic impulses

Question 11

What are the two important components of gastric juice?

Answer 11

• HCl to keep pH at 2, kills microorganisms and aids in hydrolysis
• Pepsinogen (inactive enzyme: zymogen) is converted to pepsin in presence of low pH. Pepsin digests proteins

Question 12

Chyme is squirted through a sphincter (called what) into what?

Answer 12

The pylorus, into the duodenum.

Question 13

Give some functions of the liver (8)

Answer 13

• Conversion of glucose to glycogen (glycogenesis)
• Synthesis of glucose from non-carbohydrates (gluconeogenesis)
• Production of plasma proteins
• Destruction of erythrocytes
• Deamination of amino acids and formation of urea
• Storage of iron and certain vitamins
• Alteration of toxic substances (detoxification)
• Exocrine role (eg. production of bile by hepatocytes)

Question 14

What is bile?

Answer 14

Produced by hepatocytes (liver cells), bile is mainly composed of water, cholesterol, pigments (from destruction of erythrocytes) and salts.

The bile salts have a digestive function (emulsification of fat into micelles). Emulsification also helps in the absorption of fat soluble vitamins A, D, E and K

It is stored in the gallbladder (a small muscular sac) and secreted into the duodenum via the common bile duct

Question 15

What are the 4 fat soluble vitamins?

Answer 15

• Vitamin A (retinal, carotenoids)
• Vitamin D (cholecalciferol, ergocalciferol)
• Vitamin E (tocopherols, tocotrienols)
• Vitamin K (phylloquinone, menaquinones)

Question 16

What do the hormones secretin and CCK do when they are released by the duodenum in response to the presence of chyme?

Answer 16

Cholecystokinin makes the pancreas secrete alkaline bicarbonate ions (to neutralize acidic chyme)

Secretin makes the pancreas secrete digestive enzymes

Question 17

True or false? The pancreas has endocrine and exocrine functions?

Answer 17

True

Endocrine: islets of Langerhan, insulin and glucagon
Exocrine: Bicarbonate ions and digestive enzymes

Question 18

What are the digestive enzymes secreted by the pancreas? (6)

Answer 18

• Pancreatic amylase
• Pancreatic lipase
• Nucleases
• Trypsin
• Chymotrypsin
• Carboxypeptidase

PLANT can be used to remember most of these (not including chymotrypsin and trypsin)

Question 19

What are the three divisions of the small intestine (in order)?

Answer 19

• Duodenum
• Jejunum
• Ileum

Peristalsis is primary mode of transport in all these.

Question 20

What absorbs fat in the small intestine?

Answer 20

Lacteals in villi absorb most fat into the lymphatic system

Question 21

Nutrients (other than fats) get absorbed how in the small intestine?

Answer 21

Absorbed in blood capillaries in the villi bordering the lumen. These are taken directly to liver via the hepatic portal vein.

Question 22

What are three major features of epithelium in the lumen of the small intestine?

Answer 22

• Villi
• Microvilli (brush border)
• Goblet cells (excess mucous lubricates and protects against acids, enzymes etc.)

Question 23

What are the divisions of the large intestine?

Answer 23

• Cecum (connects to the ileum and projects closed end tube/appendix)
• Colon (ascending, traverse, descending and sigmoid portions; the rectum and the anal canal)

Question 24

What is feces?

Answer 24

• Water
• Undigested material
• Gut flora (60% dry weight!)
• mucous
• Bile pigments (responsible for poo colour)

Question 25

What are some mutualistic symbiotic functions of gut flora (bacteria)? (5)

Answer 25

- Fermenting unused energy substrates - Training the immune system - Preventing harmful species growth - Producing vitamins for host (eg. vitamin K) - Producing bile pigments

Question 26

What are the intestinal folds called?

Answer 26

Plicae circulares

Question 27

How do kidneys respond to a decrease in glomerular blood pressure (usually a result of decreased blood pressure)?

Answer 27

By activating the renin-angiotensin system of hormones. This increases the amount of sodium and water that is reabsorbed by the kidneys, therefore increasing blood volume and pressure.

Question 28

What is the source, target, triggers and effects of gastrin?

Answer 28

It is from gastric mucosa and acts on the stomach. It is triggered by food in the stomach and psychic factors. It results in increased HCl secretion and gastric emptying

Question 29

What is the source, target, triggers and effects of CCK?

Answer 29

It is from the duodenal mucosa and acts on the gallbladder and pancreas. It is triggered by amino acids, peptides and fatty acids in the duodenum. It causes contractions of gallbladder and secretion of pancreatic juice.

Question 30

What is the source, target, triggers and effects of secretin?

Answer 30

It is secreted from gastric mucosa and acts on the pancreas. It is triggered by acid in the duodenum and causes increased bicarbonate secretion.

Question 31

What is the source, target, triggers and effects of enterogastrone?

Answer 31

Also known as gastric inhibitory peptides, enterogastrone is secreted by duodenal mucosa and acts on the stomach. It is triggered by fat digestion products in the duodenum. It causes decreased gastric emptying.