Intro to GI tract

Question 1

What are the functions of the GI tract

Describe each one

Answer 1

Digestion-The processes by which foodstuffs are degraded to produce smaller molecules that can be absorbed
Finishes at small intestine

Absorption- The processes by which nutrient molecules are absorbed by cells that line the GI tract and enter the bloodstream Starts at small intestine
Protection- The processes by which the lining of the GI tract is protected from damage during digestion of foodstuffs

Question 2

Describe the gastrointestinal tract proximal to distal

Answer 2

Mouth- Pharynx- Oesophagus- Stomach - Duodenum- Jejunum- Ileum- Colon- Rectum- Anus

Question 3

What are the associated organs of the GI tract and what do they associate with

Answer 3

Salivary glands - mouth

Liver, Gallbladder, Pancreas- Small intestine

Question 4

What is the exocrine pancreas

Answer 4

part of the pancreas that produces enzymes

Question 5

What is the common structure layers of the GI tract starting proximal to the lumen

Answer 5

Mucosa
Submucosa
Muscularis externa
Serosa- closest to abdomen

Question 6

What is the regional specialisation of the stomach

Answer 6

Gastric pits

Gastric glands- responsible for acid secretion

Question 7

What is the regional specialisation of the large intestine

Answer 7

Flat surface

Crypts coming of surface- mucus secreting cells

Question 8

Where are crypts found

Answer 8

Small and large intestine

Question 9

What are the three layers of the mucosa?

Answer 9

Epithelium- Single layer
Lamina propria- Most of the mucosa
Muscularis mucosae- Muscular layer

Question 10

What is lamina propria

Answer 10

Loose connective tissue made up a fibroblast predominantly

made of muscle nerve blood cells

Question 11

What is the function of the muscularis mucosae

Answer 11

Local movement E.g squeezing glands

Question 12

What is the submucosa made of?

Answer 12

Connective tissue made of fibroblasts

made of muscle nerve blood cells

Question 13

What are the two layers of the muscularis externa?

How are they positioned?

Answer 13

Inner Circular muscle- wraps around tube

Outer Longitudinal muscle -along the length of the tube

Question 14

What is serosa made of

Answer 14

Connective tissue made of fibroblasts

made of muscle nerve blood cells

Question 15

What things are found in the wall of the GI tract? Where?

Answer 15

Lymph node(GALT) - mucosa
Glands- Submucosa
Network of neurons

Question 16

What does GALT stand for?

Answer 16

Gut associated lymphoid tissue

Question 17

What is the function of GALT

Answer 17

To recognise food stuffs so body doesn’t initiate immune response against them
So protects GI Tract

Question 18

Where do you find glands in the submucosa? Names?

Answer 18

In two places
Bottom of oesophagus - submucosal gland
Top of small intesstine(Duodeum)- Brunners gland

Question 19

What are the network of neurones found in the GI tract?

Function?

Answer 19

Two
Submucosal plexus
(Meissner’s plexus)

Myenteric plexus
(Auerbach’s plexus)

regulating gastrointestinal tract function

Question 20

Where are the network of neurones found in the GI tract?

Answer 20

Submucosal plexus 
(Meissner's plexus)- Found in between muscularis externa and submucosa- Only found in small and large intestine

Myenteric plexus
(Auerbach’s plexus)- found in between the two layers of muscularis externa
Starts at oesophagus and ends at rectum. Completely throughout

Question 21

What are the levels of amplification of surface area of the GI tract

Answer 21

Circular or spiral folds
Villus
Microvilli

Question 22

What is special about the epithelial cells of the GI tract?

Answer 22

Polarised

Question 23

What is meant by polarised?

Answer 23

Two distinct membranes

Question 24

What are the membranes of the epithelial cells

Answer 24

Apical membrane

Basolateral membrane

Question 25

What is an apical membrane?

Answer 25

Facing the lumen of the gastrointestinal tract

Question 26

What is a basal lateral membrane?

Answer 26

Facing the rest of the gastrointestinal tract that isn't the lumen

Question 27

What membrane makes up most of the epithelial cells?

Answer 27

basolateral membrane

Question 28

What separates the membranes of the epithelial cells

Answer 28

Tight juctions

Question 29

What is the function of tight juctions in the epithelial cells?

Answer 29

Sorting different transport proteins to the two membranes. Preventing proteins entering apical membrane frim travelling to the basolateral membrane

Question 30

What is vectorial transport

Answer 30

Cells can transport in a specific direction

Question 31

What is transcellular transport

Answer 31

Transporting through cells

Question 32

What is paracellular transport/pathway?

Answer 32

Transport between cells

Question 33

What are parietal cells function?

Answer 33

Acid secretion

Question 34

What are the major sites of GI secretion in the GI tract? 4

Answer 34

Salivary glands Gastric glands Exocrine pancreas Liver-biliary system Small Intestine

Question 35

What is the total GI secretion per day

Answer 35

6 ~ 7 l

Question 36

What does GI secretion contain?

Answer 36

enzymes, ions, water and mucus

Question 37

What is the function of secretion

Answer 37

breakdown large compounds regulate pH dilute and protect

Question 38

What is the blood supply to the GI tract

Answer 38

Splanchnic circulation

Question 39

Describe how arteries positioned in the Splanchnic circulation

Answer 39

``` Branching from abdominal aorta Arteries goes to Intestines Pancreas Spleen Stomach Liver ```

Question 40

Describe how veins positioned in the Splanchnic circulation

Answer 40

``` Veins branching from Intestines Pancreas Spleen Stomach join together to form Portal vein and pass through the liver ( where liver absorbs nutrients FIRST) and join the hepatic vein which joins into the inferior vena cava ```

Question 41

Microvasculature of the Villus

Answer 41

Central arteriole goes through middle of villi then goes to top of the villi to form rich capillary network and then through central venule Central lacteals

Question 42

What happens to nutrients absorbed by the villi

Answer 42

Arterioles and Venules take in absorbed amino acids and sugars to take to the liver Lacteals take in reassembled fats that were fatty aids and monoglyceride where they join with intestinal lymph and then into circulation at the thoraxic duct

Question 43

difference in blood supply to the gastrointestinal tract between the fasting state and the fed state after a meal

Answer 43

Eight times increases | sequential blood delivery- doesnt happen all at once

Question 44

What regulates the blood supply of the GI tract?

Answer 44

Vagus nerve increases digestion cholecystokinin CCK vasodilator metabolites

Question 45

What is cholecystokinin

Answer 45

Peptide hormone

Question 46

How does absorbing via vili affect metabolism

Answer 46

Metabolically expensive

Question 47

Example of vasodilator metabolites

Answer 47

CO2

Question 48

Regulatory Mechanisms | Control Gastrointestinal Function

Answer 48

Endocrine: Peptide hormone released by a specialised cell Release of a transmitter (e.g. peptide) into blood for delivery to distant target cell. Paracrine: Release of a transmitter from a sensor cell to affect adjacent target cells without entering blood or activating neurons Neuronal: Electrical signalling via neurons

Question 49

Where do you find endocrine cells

Answer 49

In the mucosa of the stomach. intestine and pancreas

Question 50

What cells produce gastrin?

Answer 50

G cells

Question 51

What cells produce cholocystokinin

Answer 51

I cells

Question 52

What cells produce secretin?

Answer 52

S cells

Question 53

What cells produce Glucose-dependent insulinotropic peptide (GIP)?

Answer 53

K cells

Question 54

What cells produce Somatostatin?

Answer 54

D cells

Question 55

Where are G cells located?

Answer 55

Stomach

Question 56

Where are I cells located?

Answer 56

Small Intestine

Question 57

Where are S cells located?

Answer 57

Small Intestine

Question 58

Where are K cells located?

Answer 58

Small Intestine

Question 59

Where are D cells located?

Answer 59

Stomach, Pancreatic islets, Small Intestine

Question 60

What is Glucose-dependent insulinotropic peptide (GIP) also known as?

Answer 60

Gastric inhibitory peptide

Question 61

What opposes the role of Gastrin?

Answer 61

Somatostatin

Question 62

What is special about the Somatostatin hormone

Answer 62

Dual role | Endocrine and Paracrine factor

Question 63

What is the function of Gastrin

Answer 63

Gastric secretion | Gastric motility

Question 64

What is the function of CCK

Answer 64

Gallbladder contraction Pancreatic secretion Stimulates blood flow

Question 65

What is the function of GIP

Answer 65

Stimulates insulin release

Question 66

What is the vagovagal reflex

Answer 66

Intrinsic mervous system interacting with the autonomic nervous sytem and parasymthetic nerves to make change Long range reflex

Question 67

Explain what happens in the Intrinsic nervous system?

Answer 67

Chemo/ Mechanoreceptors detect change Submucosal/ Myenteric plexus carry signals through to effectors (smooth muscle/ Secretory cell/ blood vessel)

Question 68

Explain what happens in the Vagovagal reflex

Answer 68

Chemo/ Mechanoreceptors detect change Submucosal/ Myenteric plexus carry signals through to parasympathetic which get signals to brain and then signals to effectors (smooth muscle/ Secretory cell/ blood vessel)

Question 69

What are the three phases of gastrointestinal control

Answer 69

Cephalic phase Gastric phase Intestinal phase