Digestive System

Question 1

List the main functions of the digestive system.

Answer 1

Ingestion

Secretion

Mixing and propulsion

Digestion

Absorption

Defecation

Question 2

Describe the layers of the digestive tract.

Answer 2

The GI tract contains 4 layers:

1. Muscosa = Innermost layer
2. Submucosa = A secretory layer, a thick layer of loose connective tissue that surrounds the mucosa.
3. Muscular propria = smooth muscle layer
4. Adventitia = Outermost layer

Question 3

Identify the locations of the nine abdominal regions.

Answer 3

1 = Epigastric

2 = Umbilical

3 = Hypogastric

4 = Hypochondriac

5 = Lumbar

6 = Iliac (hypogastric)

Question 4

Describe the structure and function of the salivary glands.

Answer 4

Structure = branched ducts that open into the oral cavity

Function =
releases saliva in the mouth
moistens food
makes it easier to swallow
contains amylase to digest carbs

Question 5

Identify the voluntary and involuntary processes involved in swallowing (act of
deglutition).

Answer 5

Oral phase – voluntary, movement of the bolus from the oral cavity into the oropharynx.

Pharyngeal phase – involuntary, movement of the bolus from the oropharynx into the esophagus.

Esophageal phase – involuntary, movement of the bolus through the esophagus and into the stomach

Question 6

Describe the physiology of defecation.

Answer 6

the act of expelling faeces from the digestive tract via the anus.

Question 7

Define Ingestion

Answer 7

Taking food in the mouth, with mechanical and chemical digestion.

Question 8

Define Secretion

Answer 8

It is the release of water, acids, enzymes, buffers, and. salts. – By epithelium of the digestive tract.

Question 9

Define Mixing and propulsion

Answer 9

Mixing movements occur in the stomach as a result of smooth muscle contraction.

These repetitive contractions usually occur in small digestive tract segments and mix the food particles with enzymes and other fluids.

The movements that propel the food particles through the digestive tract are called peristalsis.

Question 10

Define Absorption

Answer 10

The simple molecules that result from chemical digestion pass through cell membranes of the small intestine’s lining into the blood or lymph capillaries. This process is called absorption.

Question 11

Define Elimination

Answer 11

Elimination

The food molecules that cannot be digested or absorbed must be eliminated from the body. The removal of indigestible wastes through the anus, in the form of faeces, is defecation or elimination.

Question 12

What is the function of the oesophagus?

Answer 12

To allow for the passage of material from the mouth and throat to the stomach.

Question 13

What is the function of the stomach?

Answer 13

Holds the food and mixes it with acid and enzymes that continue to break the food down into a liquid or paste.

Question 14

What is the function of the duodenum?

Answer 14

Food mixes with bile from the gallbladder and digestive juices from the pancreas. The absorption of vitamins, minerals, and other nutrients begins in the duodenum.

Question 15

What is the function of the jejunum?

Answer 15

to absorb sugars, amino acids, and fatty acids.

Question 16

What is the function of the ileum?

Answer 16

it absorbs any final nutrients

Question 17

What is the function of the large colon?

Answer 17

absorbing water and electrolytes,
producing and absorbing vitamins,
forming and propelling feces toward the rectum for elimination.

Question 18

What is the function of the rectum?

Answer 18

Excertion

Question 19

Describe the structure and function of the Pancreas.

Answer 19

located inside your abdomen, just behind your stomach.

During digestion, your pancreas makes pancreatic juices called enzymes. These enzymes break down sugars, fats, and starches.

Question 20

Describe the structure and function of the Liver.

Answer 20

Located beneath the rib cage in the right upper abdomen.

Removes toxins from the body’s blood supply, maintains healthy blood sugar levels, regulates blood clotting, and performs hundreds of other vital functions.

Question 21

Describe the structure and function of the Gall bladder.

Answer 21

It is a muscular organ that contracts when bile is needed, and forces the enzyme through the cystic duct.

Located underneath the right lobe of the liver.

Question 22

What are liver cells called?

Answer 22

hepatocytes

Question 23

What does the hepatic artery do

Answer 23

brings oxygenated blood from the heart (from the aorta) into the liver
supplies the O2 for aerobic respiration

Question 24

What does the hepatic portal vein do?

Answer 24

brings deoxygenated blood from the digestive system which is rich in the products of digestion.

Question 25

What does the liver do, and why is its role important?

Answer 25

The blood, returning from the digestive system, may contain toxic compounds that have been absorbed from the intestine - it’s important these substances don’t continue to circulate around the body before their concentrations have been adjusted

(The liver filters blood)

Question 26

Where does blood leave the liver?

Answer 26

through the hepatic vein - rejoins the vena cava

Question 27

What is bile?

Answer 27

Bile is a fluid secreted by the liver and stored in the gallbladder. Bile helps with digestion, breaking down fats into fatty acids in the small intestine so they can be absorbed.

Question 28

What does bile contain

Answer 28

some excretory products e.g. bile ligaments like bilirubin - leaves the body with faeces

Question 29

What is the biliary tree?

Answer 29

The biliary tree is a system of vessels that directs secretions from the liver, gallbladder and pancreas through a series of ducts into the duodenum.

Question 30

Where does the digestion of Disaccharides and Polysaccharides start?

Answer 30

Digestion of Disaccharides and Polysaccharides:
Mouth:
Salivary Amylase: Begins the breakdown of starches into smaller polysaccharides and maltose (a disaccharide).

Question 31

Where does the Digestion of Lipids occur?

Answer 31

Digestion of Lipids:
Small Intestine: Emulsification by Bile: Bile salts from the liver/gallbladder emulsify fats, breaking large fat globules into smaller droplets and aiding digestion.

Pancreatic Lipase: Released by the pancreas into the small intestine, breaks down triglycerides (fats) into fatty acids and glycerol.

Question 32

Where does the Digestion of Proteins start?

Answer 32

Digestion of Proteins:
Stomach:
Pepsin: Produced by stomach glands as pepsinogen and activated by stomach acid (HCl) into pepsin. It begins the breakdown of proteins into smaller peptide chains.

Question 33

9.2 Identify the three phases of gastric secretion.

Answer 33

The cephalic phase

The gastric phase

The intestinal phase

Question 34

What is the cephalic phase?

Answer 34

The cephalic phase of gastric secretion – The sense of thought, taste, smell, the sight of food, and swallowing activates the cephalic phase. It is mediated mostly by cholinergic/vagal mechanisms.

Question 35

What is the gastric phase?

Answer 35

The vagus nerve and the release of gastrin mediate the gastric secretion phase.

Question 36

What is the intestinal phase?

Answer 36

The intestinal phase of gastric secretion – involves complex stimulatory and inhibitory processes.

Question 37

Describe the roles of the hormone secretin in digestion.

Answer 37

Secretin has 3 main functions: regulation of gastric acid, regulation of pancreatic bicarbonate, and osmoregulation.

Question 37

Describe the role of the hormone cholecystokinin in digestion.

Answer 37

When fats and proteins enter your small intestine, cholecystokinin triggers your gallbladder and pancreas to contract. They deliver bile and enzymes to your duodenum to help break down the food for absorption.