2.1 Gut Function

Question 1

What is the purpose of digestion and what does the solution comprise of?

Answer 1

Converts food to a: Sterile, Neutral, Isotonic solution containing:

Small sugars, amino acids, small peptides, lipids, other small molecules

Question 2

Digestion is accomplished by the action of what 3 things?

Answer 2

1) HCl
2) bile
3) enzymes secreted by exocrine glands

Question 3

What is Absorption

Answer 3

Specific active or passive uptake of nutrient molecules, water and electrolytes

Question 4

Purpose of Excretion

Answer 4

To process, store and release: residues from food, gut debris, materials specifically excreted via liver to gut

Question 5

List the accessory digestive organs

Answer 5

teeth, tongue, gallbladder, salivary glands, liver, spleen, pancreas,

Question 6

Histological layers of the Ailmentary canal (4)

Answer 6

Mucosa
Submucosa
Muscular Externa
Adventitia/Serosa

Question 7

Describe the Mucosa

Answer 7

lining epithelium, connective tissue, thin layer of smooth muscle

Question 8

Describe the Submucosa

Answer 8

fibro-elastic tissue, vessels, nerves from Meissner’s plexus, fat and leukocytes

Question 9

Describe the Muscularis externa

Answer 9

Inner circular and outer longitudinal layer of muscle

with Auerbach’s plexus located between layers

Question 10

Describe the Adventitia/ Serosa

Answer 10

thin outer covering of connective tissue

Question 11

Nerve plexuses are made up of post-ganglionic neurones of the _____ NS

Answer 11

Parasympathetic

Question 12

List 4 properties of saliva that provide protection to the mouth

Answer 12

1) Wet
2) Bacteriostatic
3) Alkaline
4) High Calcium

Question 13

Give an example of an enzyme found in saliva?

What does this do?

Answer 13

Amylase ➞ begins digestion of starch

Question 14

What is Barett’s esophagus? (incl the epithelial change)

Answer 14

A pre-malignant shift from stratified squamous epithelia to simple columnar usually due to constant acid reflux (GERD)

Question 15

Barett’s esophagus is often seen in patients who already have ______

Answer 15

GERD

Question 16

What’s achalasia?

Answer 16

Absence of esophageal peristalsis and failure of the LES to relax in response to swallowing ➞ leads to impaired emptying of food from oesophagus into stomach

Question 17

What is Dysphagia

Answer 17

difficulty swallowing

Question 18

List 4 enzymes contained in pancreatic secretions

Answer 18

amylase
lipase
protease
nuclease

Question 19

Where does dilution and neutralisation of chyme take place?

Answer 19

Duodenum and Jejunum

Question 20

Where does storage, initial disruption and disinfection of food take place?

Answer 20

The stomach

Question 21

Where does absorption of nutrients and and electrolytes take place

Answer 21

small intestine

Question 22

List 3 features that provide a large SA for absorption in the small intestine

Answer 22

1) Plicae circulars - folds of mucosa and submucosa
2) villi - extensions of mucosa on plicae circularis
3) microvilli - enterocytes covering villi

Question 23

What is a lacteal?

Answer 23

A lacteal is an enlarged lymphatic contained within the centre of each villus which aids absorption of fats

Question 24

Where does final absorption of water and electrolytes take place

Answer 24

The large intestine ➞ faeces accumulate in the defending and sigmoid colon

Question 25

What is meant by the term “controlled excretion”

Answer 25

The faeces are propelled periodically into the rectum
The urge to defecate occurs leading to controlled relaxation of of sphincters
Results in expulsion of faces

Question 26

Which Nervous systems play a part in controlling the GI tract?

Answer 26

Somatic motor system for ingestion and excretion

Autonomic NS for everything else ➞ PNS is the most significant + Enteric nervous system, responsible for local control of secretion and motility

Question 27

What are paracrine hormones? Give two examples

Answer 27

Chemical messengers diffusing locally:

1) Histamine in stomach
2) Vasoactive substances

Question 28

What two structurally related groups do hormones in the gut come from?

Answer 28

Gastrin group

Secretin group

Question 29

What is a bolus?

Answer 29

A mass of chewed food formed in the mouth from the Initial physical and chemical disruption