Lecture 21 - Alimentary 1

Question 1

what is an example of transient folds and permanent folds of the gut?

Answer 1

transient - rugae of stomach (disappear when full)
permanent - plicae circularis of small intestine

Question 2

describe the enteric nervous system

Answer 2

a branch of the autonomic nervous system which is stimulated by the parasympathetic nervous system and inhibited by the sympathetic nervous system

Question 3

what are the four tunics of the gut tube from the lumen?

Answer 3

mucosa
submucosa
muscularis externa
adventitia/serosa

Question 4

parotid salivary gland contains what type of glands?

Answer 4

serous glands only

Question 5

the submanibular gland contains what type of glands?

Answer 5

mixed glands

Question 6

the sublingual gland contains what type of glands?

Answer 6

mixed, mostly mucous

Question 7

true or false, the salivary glands are made up of lobules, each which contain acini that secrete saliva

Answer 7

true

Question 8

describe the structure of a serous acinus

Answer 8

central, spherical nuclei
zymogen granules containing amylase near lumen
myoepithelial cells to squeeze granules

Question 9

describe the structure of a mucous acinus

Answer 9

flattened nuclei, pushed peripherally due to mucous globules
surrounded by basal lamina

Question 10

describe the structure of a striated duct/intralobular duct

Answer 10

Interlobular ducts are formed by the convergence of multiple striated ducts
contain a lot of mitochondria for active transport of secretions
secrete bicarbonate ions

Question 11

what are the three key functions of saliva?

Answer 11

lubrication
protection
digestion

Question 12

how does the saliva lubricate?

Answer 12

contains carbohydrate-rich glycoproteins and mucopolysaccharides (mucins)
- also has protective feature

Question 13

how does the saliva protect?

Answer 13

bicarbonate ions
lysozyme (breaks down bacteria cell walls)
lactoferrin (counteracts Fe dependent bacteria)
Immunoglobulin A (fight bacteria and viruses)

Question 14

how does the saliva digest?

Answer 14

amylase (carbs and starches)
lipase (fats)
Kallikrein

Question 15

what stimulates saliva secretion

Answer 15

sight and thought of food, nausea

Question 16

what inhibits saliva secretion

Answer 16

fatigue, sleep, fear, dehydration, exercise

Question 17

what is xerostomia and what causes it?

Answer 17

dry mouth
- salivary gland tumors
- salivary duct calculi (blockages)
- some medications

Question 18

what causes hypersalivation

Answer 18

associated with many conditions, medications and some toxins

Question 19

at which end of the oesophagus is the skeletal muscle?

Answer 19

pharyngeal end

Question 20

which layer of the oesophagus contains often dilated blood vessels

Answer 20

submucosa

Question 21

why does the oesophagus epithelia transition from stratified squamous to simple columnar?

Answer 21

The lower oesophagus is exposed to acid from the stomach.
Columnar epithelium secretes mucus and bicarbonate, which protects against acid injury.

Question 22

what is barrett’s oesophagus

Answer 22

when gastric reflux induces the stratified squamous epithelium to undergo metaplasia into columnar epithelium with goblet cells

Question 23

describe the structure of the muscularis externa of the oesophagus

Answer 23

two thick coats:
- inner circular, spiral and oblique bundles
- outer irregularly arranged longitudinal

Question 24

describe peristalsis vs segmentation

Answer 24

peristalis: coordination of inner and outer muscle layers to move food
segmentation: inner circular layers churn and mix food up

Question 25

what are oesophageal varices?

Answer 25

extremely dilated submucosal veins. - increased hypertension due to resistance from liver in cirrhosis (backflow) - can cause haemmorrage, necrosis, ulceration

Question 26

describe the sphincters in the oesophagus vs elsewhere

Answer 26

the sphincters are more physiological rather than anatomical, as there is no obvious muscle thickening, but there is tonal contraction

Question 27

what is chronic oesophagitis?

Answer 27

lamina propria becomes exposed to the lumen of the oesophagus. causes increased recruitment and activity of blood and lymph vessels - inflammation reaction

Question 28

where in the stomach are there more mucous glands?

Answer 28

the cardia and the pylorus - the beginning and the end

Question 29

where in the stomach is there more acid secreting cells?

Answer 29

the fundus and the body

Question 30

name the three muscle layers of the stomach and describe their main action

Answer 30

- outer longitudinal (shortens organ) - inner circular (narrows organ) - innermost oblique (twists)

Question 31

true or false, pepsin can digest transmembrane proteind

Answer 31

true

Question 32

state the functions of simple columnar mucous cells

Answer 32

- lines pits and surface - alkaline mucous coat with HCO3- ions

Question 33

what chemical increases mucous secretion of the simple columnar stomach cells?

Answer 33

immune modulator prostaglandin E2 - inflammation cascade promotes mucous secretion

Question 34

what two things inhibit prostaglandin E2 secretion?

Answer 34

NSAIDs e.g ibuprofen helicobacter pylori

Question 35

what happens if ibuprofen inhibits prostaglandin E2?

Answer 35

less mucous secretion and more prone to stomach ulcers

Question 36

what is the function of parietal cells?

Answer 36

- secrete HCl to sterilise food and provides acidic environment so pepsinogen -> pepsin can happen - produces intrinsic factor, which allows vitamin B12 absorption, vital for haemopoesis

Question 37

what disease can occur when there is a lack of intrinsic factor?

Answer 37

pernicious anemia

Question 38

describe the structure of chief cells

Answer 38

contain zymogen granules containing pepsinogen which is secreted