Digestive system

Question 1

The digestive tract begins and ends where?

Answer 1

begins - oral cavity - mouth

ends - anus

Question 2

what are the six functions of the digestive system?

Answer 2

1. Ingestion – takes place when food enters the mouth (oral cavity).
2. Mechanical processing (or mechanical digestion) – involves crushing and shearing food and then propelling the food along the digestive tract.
3. Digestion (or chemical digestion) – chemical breakdown of food into small molecules that are suitable for absorption.
4. Secretion – release of water, acids, enzymes, buffers, and salts by the epithelium of the digestive tract, glandular organs, and the gallbladder.
5. Absorption – movement of substances across the digestive epithelium that lines the small intestine. Substances move from the lumen to the interstitial fluid.
6. Excretion (or defecation) – removal of waste products from body.

Question 3

What are the Major organs of the digestive system?

Answer 3

oral cavity 
small intestine 
large intestine 
stomach 
pharynx 
esophagus

Question 4

What are the accessory organs of the digestive system?

Answer 4

teeth 
salivary glands 
gallbladder 
pancreas 
tongue 
liver

Question 5

The digestive tract contains four layers of tissue. What is the name of each layer of tissue and where is each layer located relative to the lumen?

Answer 5

1. mucosa - closest to the lumen
2. submucosa - 2nd closest to lumen
3. muscularis externa (or muscular layer) - 3rd closest to lumen
4. serosa - furthest from lumen

Question 6

Which layer of the digestive tract wall contains epithelial cells?

Answer 6

Mucosa

Question 7

What type of epithelial cells are found in the stomach and intestines and what is the function of these epithelial cells?

Answer 7

simple columnar epithelial cells; absorption and/or secretion

Question 8

What types of specialised epithelial cells are found in the epithelial lining of the stomach and intestines?

Answer 8

stem cells

enteroendocrine cells

goblet cells

Paneth’s cells

Question 9

What is the function of the muscularis externa (or muscular layer) of the digestive tract?

Answer 9

involved in the mechanical processing of food and movement of materials along the digestive tract

Question 10

Name the two types of motility (movement) in the digestive tract.

Answer 10

segmentation

peristalsis

Question 11

Describe peristalsis

Answer 11

peristalsis - a propulsion process involving waves of smooth muscle contraction that move compacted ingested materials (e.g. bolus) along the digestive tract.

Question 12

Describe segmentation

Answer 12

cycles of smooth muscle contraction and relaxation that churns and fragments the bolus to mix the contents of the bolus with secretions (e.g. enzymes).

Question 13

The oral cavity (mouth) is the first part of the digestive tract that is exposed to food. What are the functions of the oral cavity (mouth)?

Answer 13

ingestion of food

sensory analysis of ingested material

mechanical processing of ingested material

limited chemical digestion

lubrication

Question 14

what are the functions of saliva?

Answer 14

lubrication of the mouth and pharynx

• cleanse the mouth and teeth
• moistening of food
• limited chemical digestion (i.e. break down starch (carbohydrate) and lipids)

Question 15

Which glands produce saliva?

Answer 15

Sublingual glands
Submandibular glands
parotid glands

Question 16

After leaving the oral cavity (mouth), which structures does food pass through on the way to the stomach?

Answer 16

Food passes from the oral cavity (mouth) to the pharynx, esophagus, and then the stomach.

Question 17

The stomach performs mechanical processing (or mechanical digestion) of materials that enter the digestive tract. Which of the following terms describes the partially-digested food/fluid in the stomach?

Answer 17

Chyme

Question 18

Function of the Stomach

Answer 18

Carbohydrates digestion
Protein Digestion
Storage and mixing chamber
triglyceride digestion

Question 19

What type of muscular tissue is found in the walls of the stomach?

Answer 19

Smooth muscle only

Question 20

The mucosa of the stomach contains four types of secretory cells. What is the name of each type of secretory cell and what substance does each type secrete?

Answer 20

Mucous cells - mucus
Parietal cells - hydrogen chloride (HCl)
Chief cells - pepsinogen
G cells - gastrin

Question 21

The regulation of gastric activity involves three overlapping phases. What are these phases called?

Answer 21

cephalic, gastric, and intestinal phases

Question 22

The sight, smell, taste, or thought of food is the beginning of which phase of regulation of gastric activity?

Answer 22

cephalic

Question 23

Cephalic phase, the sight, smell, taste, or thought of food leads to increased secretion of which substances into the stomach?

Answer 23

gastrin, mucous, hydrogen chloride (HCl), and pepsinogen

Question 24

What is the function of the cephalic phase of regulation of gastric activity?

Answer 24

prepares stomach for arrival of food

Question 25

What marks the beginning of the gastric phase of regulation of gastric activity and what is the function/purpose of this phase?

Answer 25

beginning: arrival of food into the stomach | function/purpose: increases gastric motility

Question 26

The gastric phase of regulation of gastric activity involves increased secretion of which substance/s?

Answer 26

gastrin mucous hydrogen chloride (HCl) pepsinogen

Question 27

What is the beginning of the intestinal phase of regulation of gastric activity?

Answer 27

chyme entering the duodenum

Question 28

In the intestinal phase of regulation of gastric activity, chyme entering the duodenum stimulates increased secretion of

Answer 28

secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP)

Question 29

What is the function of the intestinal phase of regulation of gastric activity?

Answer 29

control rate of gastric emptying (from stomach to duodenum)

Question 30

What are the three regions of the small intestine?

Answer 30

ileum duodenum jejunum

Question 31

What does the Ileum do?

Answer 31

nurtrients absorption only | no chemical digestion

Question 32

Function of the Duodenum

Answer 32

receives chyme from the stomach which mixes with digestive enzymes and buffers from the pancreas

Question 33

Function of the Jejunum

Answer 33

chemical digestion occurs here and the majority of nutrient absorption

Question 34

List 3 features of the small intestine that increase the surface area, and therefore increase the amount of absorption that can occur.

Answer 34

Length (approx 6 m) Circular folds (also known as plicae circulares) Villi (finger-like projections of mucosa) Microvilli (extensions of the plasma membrane of absorptive cells; form a brush border)

Question 35

What type of epithelial cells cover the villi in the small intestine?

Answer 35

Simple columnar

Question 36

Name the four layers of tissue that make up the wall of the small intestine and state where each layer is located relative to the lumen?

Answer 36

1. mucosa - closest to the lumen 2. submucosa - 2nd closest to lumen 3. muscularis externa (or muscular layer) - 3rd closest to lumen 4. serosa - furthest from lumen

Question 37

Movement of food/material along the small intestine (i.e. motility) occurs via peristalsis and segmentation. Both peristalsis and segmentation involve contraction of smooth muscle located in the walls of the small intestine. What are the characteristics of these two types of motility?

Answer 37

``` Peristalsis - Propels bolus forward Segmentation - mix bolus with intestinal secretions - mixing/churning of bolus - breakup/fragment of bolus - non-directional movement of bolus ```

Question 38

What are the two parts of the pancreas called?

Answer 38

endocrine pancreas and exocrine pancrea

Question 39

Which part of the pancreas is involved in digestion?

Answer 39

Exocrine pancreas

Question 40

How do pancreatic secretions drain into the digestive tract and where does this occur?

Answer 40

Pancreatic secretions (i.e. pancreatic juice and digestive enzymes and buffers) drain into the duodenum via the pancreatic duct.

Question 41

Exocrine characteristics/functions

Answer 41

``` secrete digestive enzymes and buffers into duodenum controlled by secretin duodenal hormone function: aid digestion controlled by CCK duodenal hormone secrete pancreatic juice into duodenal contains acing glands ```

Question 42

endocrine characteristics/functions

Answer 42

function: blood glucose homeostasis secrete glucagon and insulin into blood contain pancreatic islets

Question 43

what is the name of the two functions of the liver

Answer 43

metabolic and haematological

Question 44

metabolic functions

Answer 44

``` process drugs protein metabolism lipid metabolism carbohydrates metabolism store minerals and vitamins ```

Question 45

Haematological functions

Answer 45

make plasma proteins remove hormones remove old blood cells remove toxins from blood

Question 46

What type of cells are found in the liver?

Answer 46

hepatocytes and Kupffer cells

Question 47

What substance is produced in, and secreted by, the liver and stored in the gall bladder?

Answer 47

bile

Question 48

What is the function the substance that is produced in, and secreted by, the liver and stored in the gall bladder?

Answer 48

Bile is involved in digestion of lipids. Bile salts break down large droplets of lipids (emulsification) to aid lipid absorption in the small intestine.

Question 49

Where does bile enter the small intestine and how does this occur?

Answer 49

The gall bladder releases bile into the duodenum via the common bile duct.

Question 50

what structures and functions of the small and large intestine do they have in common

Answer 50

- peristalsis - segmentation - serosa - mucosa - musculares externa (muscular layer)

Question 51

Which of the following is NOT a function of the large intestine

Answer 51

The digestion and absorption of lipids occurs in the small intestine.

Question 52

What carries out chemical digestion in the large intestine?

Answer 52

bacteria (or gut biome)