lecture 20 - GI system basic structure

Question 1

What are the 4 fundamental functions of the GI system?

Answer 1

Motility, secretion, digestion, absorption

Question 2

What closes off the ends of the GI tracts?

Answer 2

Sphincters

Question 3

What lines the GI tract?

Answer 3

Epithelium

Question 4

What are the major organs of the GI system?

Answer 4

oral cavity/mouth, pharynx, oesophagus, stomach, small intestine, large intestine

Question 5

What are the accessory organs of the GI system?

Answer 5

Teeth, tongue, salivary glands, liver, gall bladder, pancreas

Question 6

In the GI tract, what is stratified squamous epithelium adapted for?

Answer 6

Protection from abrasion

Question 7

In the GI tract, what is simple columnar epithelium adapted for?

Answer 7

Secretion & absorption

Question 8

What type of epithelium lines the mouth/oral cavity and oesophagus?

Answer 8

Stratified squamous

Question 9

What type of epithelium lines the stomach, small intestine and large intestine?

Answer 9

Simple columnar

Question 10

What type of epithelium lines the anus?

Answer 10

Stratified squamous

Question 11

What cells make up the unicellular glands of the GI system?

Answer 11

goblet cells

Question 12

What is the shape of goblet cells?

Answer 12

Columnar, with a wide apical aspect

Question 13

How are multicellular glands formed in the GI tract?

Answer 13

When epithelium invaginates to form ducts

Question 14

What are the 2 types of multicellular glands?

Answer 14

Simple & compound

Question 15

What is a simple multicellular gland?

Answer 15

A gland with a single duct

Question 16

What is a compound multicellular gland?

Answer 16

A gland with 2 or more ducts

Question 17

What type of gland is a salivary gland?

Answer 17

Compound multicellular gland

Question 18

What are the 4 layers of the gut tube?

Answer 18

Mucosa, sub-mucosa, muscularis externa/proper, adventitia

Question 19

What are the layers (top to bottom) of the GI mucosa?

Answer 19

Epithelium, basement membrane, lamina propria (FCT), muscularis mucosa. Sometimes contains glands.

Question 20

What layer of the GI mucosa contains blood vessels and lymphatics?

Answer 20

Lamina Propria (FCT)

Question 21

What are the components of the GI submucosa?

Answer 21

Glands, blood vessels, the submucosal nerve plexus

Question 22

What layer of the gut tube contains the submucosal nerve plexus?

Answer 22

Submucosa

Question 23

What body system is the submucosal nerve plexus part of?

Answer 23

the Enteric Nervous system (ENS), the gut’s local nervous system

Question 24

What is the function of the enteric nervous system?

Answer 24

Allows local coordination of gut reflexes without significant contribution from the CNS

Question 25

What type of muscle is found in the muscularis externa/muscularis proper

Answer 25

Smooth muscle

Question 26

What are the 2 layers of smooth muscle in the muscularis proper?

Answer 26

Inner circular, outer longitudinal

Question 27

Is the circular smooth muscle of the gut tube the inner or outer layer of muscle?

Answer 27

Inner

Question 28

Is the longitudinal smooth muscle of the gut tube the inner or outer layer of muscle?

Answer 28

Outer

Question 29

What is the structure and function of the inner circular muscle of the muscularis?

Answer 29

Circumferential smooth muscle fibres that control gut tube diameter

Question 30

What is the structure and function of the outer longitudinal muscle of the muscularis?

Answer 30

Longitudinal/‘lengthways’ smooth muscle fibres that control gut tube length

Question 31

What feature of the muscularis in the GI tract regulates and stimulates motility?

Answer 31

The myenteric plexus

Question 32

What is the location of the myenteric plexus?

Answer 32

In the muscularis proper of the gut tube

Question 33

What is the function of the myenteric plexus?

Answer 33

Regulates gut tube motility, as part of the enteric nervous system

Question 34

What is the tissue type of the GI adventitia?

Answer 34

Fibrous connective tissue

Question 35

What is the additional outermost layer found on GI organs within the peritoneal cavity?

Answer 35

Serosa

Question 36

What type of membrane is the peritoneum?

Answer 36

Serous membrane

Question 37

What are the 2 layers of the peritoneum?

Answer 37

Parietal and Visceral

Question 38

What is the peritoneum?

Answer 38

A tissue/membrane that lines the abdominal wall and encloses most of the abdominal and GI organs

Question 39

What does the parietal layer of the peritoneum line?

Answer 39

The body wall

Question 40

What does the visceral layer of the peritoneum line?

Answer 40

The organs

Question 41

What sits between the parietal and visceral layers of the peritoneum?

Answer 41

Fluid filled space called the peritoneal cavity/space

Question 42

What is the term for abdominal organs that sit outside the peritoneum?

Answer 42

Retroperitoneal

Question 43

What is the most notable retroperitoneal GI organ?

Answer 43

The pancreas

Question 44

What is mysentery?

Answer 44

A double layer of visceral peritoneum that connects an organ to the body wall

Question 45

What is omenta?

Answer 45

Double layer of visceral peritoneum that connects an organ to another organ

Question 46

What are the similarities and differences between mesentery and omentum?

Answer 46

Both double layers of visceral peritoneum, but mysentery connects organ to body wall and omentum connects organ to organ

Question 47

What is the approximate volume of daily salivary secretions?

Answer 47

1L

Question 48

How many pairs of salivary ducts are connected to the oral cavity?

Answer 48

3 pairs - 6 in total

Question 49

How are salivary glands connected to the oral cavity?

Answer 49

Via ducts

Question 50

What are the 3 salivary glands?

Answer 50

parotid, sublingual, submandibular

Question 51

What do the parotid salivary glands secrete?

Answer 51

Serous fluid containing amylase

Question 52

What do the sublingual salivary glands secrete?

Answer 52

Mucous

Question 53

What do the submandibular salivary glands secrete?

Answer 53

Mixture of serous fluid with amylase and mucous

Question 54

What type of gland are salivary glands?

Answer 54

Compound secretory glands

Question 55

What are components of a compound gland?

Answer 55

Duct and acini

Question 56

What is an acinus?

Answer 56

A cluster of cells ( often within a compound duct)

Question 57

What does an acinus of a salivary duct secrete?

Answer 57

Enzymes, such as amylase

Question 58

What do the duct cells of salivary gland secrete?

Answer 58

bicarbonate for buffering

Question 59

What is the function of the bicarbonate secreted by the duct cells of salivary glands?

Answer 59

Buffering

Question 60

What is the approximate length of the esophagus?

Answer 60

~25cm

Question 61

What is the location of the oesophagus, in relation to the trachea?

Answer 61

Posterior to the trachea

Question 62

What feature ensures that food enters the oesophagus and not the trachea?

Answer 62

The epiglottis

Question 63

Why is the submucosa and mucosa of the oesophagus highly folded?

Answer 63

To give it the capacity to expand when a food bolus passes through

Question 64

What is the epithelium type in the esophagus?

Answer 64

Stratified squamous

Question 65

How does the muscle type in the muscularis externa change along the oesophagus?

Answer 65

1st third is skeletal muscle, 2nd third is mixture of skeletal and smooth muscle, 3rd third is smooth muscle

Question 66

Why does the oesophagus need mucus?

Answer 66

Protection and lubrication

Question 67

What secretes the mucus of the oesophagus?

Answer 67

Glands with ducts to the surface, rather than goblet cells