Upper GI Tract structure and function

Question 1

Why Chew?

Answer 1

Prolong taste, help stop choking (keep resp system open

Question 2

Control of chewing

Answer 2

Voluntary (somatic - skeletal muscles) and reflex (mecanoreceptors - contraction and relaxation based on pressure of food)

Question 3

What are the 3 pairs of salivary gland?

Answer 3

Parotid, submadibular and sublingual

Question 4

What is in saliva?

Answer 4

Water (99%)
Mucins (make mucus when mixed with water, lubricant)
Alpha amylase - breaks down polysaccharides into maltose and glucose
Electrolytes (Na/Cl/K, Na controls tonicity), pH through bicarbonates (stop teeth disintegrating!
Lysozyme - bacteriocidal - cleaves polysaccharide component of bact cell wall

Question 5

What electrolytes are present in saliva and how is the pH controlled?

Answer 5

Na/Cl/K, Na controls tonicity), pH through bicarbonates (stop teeth disintegrating!

Question 6

Biggest saliva gland, where?

Answer 6

Parotid, below and infront of ear

Question 7

What type of glands are saliva?

Answer 7

Exocrine (secrete to outside of body)

Question 8

exo vs endo crine glands

Answer 8

Exo = secrete to outside of body
Endo = secrete within the bloodstream

Question 9

Serous vs mucous cells produce what?

Answer 9

Serous = watery fluid, lysozyme, alpha amylase etc
Mucus = mucins

Question 10

NS innervation of salivary glands and secretion

Answer 10

Sypmathetic and parasympathetic

Symp = sticky, mucussy, amylasey saliva

Parasymp = watery secretion

Question 11

Which nerves parasympathetic supply of salivary secretion

Answer 11

glossopharyngeal (IX) and facial (VII)

(NOT vagus)

Question 12

Sympathetic vs parasympathetic salivary production

Answer 12

Symoathetic = viscous - mucus and amylase

Parasymp = watery

Question 13

What receptors do we have that contribute to the reflex control of saliva production?

Answer 13

Chaemo/pressure receptors in the walls of the mouth/tongue

Question 14

how long is the oesophagus?

Answer 14

around 25cm

Question 15

What are the layers of the oespohagus?

Answer 15

-Mucosa (Stratified squamous epithelium (non keritizing - needs to be flexiable and move))
-Submucosa (including mucus glands for lubrication)
-Muscularis externa (superior 1/3 lined with skeletal muscle, inferior 2/3 = smooth muscle)
-adventitia

Question 16

What epithelium are in the oesophagus?

Answer 16

stratified squamous - non-keritizing

Question 17

re there glands in th epoesophagus?

Answer 17

Yes! In sub mucosa, produce mucous. Also glands in the stomach.

Question 18

Control of the muscularis externa in hte oesophagus

Answer 18

Superior 1/3 = skeletal muscle
Inferior 2/3 = smooth muscle

Question 19

Where are th esphincters in the oesophgus?

Answer 19

Inferior and superiorly

Inferior = prevents food from coming back up into the oesophagus from the stomach
Superior - prevents food from coming back up from the oesophagus (projectile vomiting

Question 20

Wht cuases projectile vomitting in babies?

Answer 20

Under developed oesophagus sphincters… So nothing to stop the full regurgitation

Question 21

What is the soft palate?

Answer 21

At the back of the mouth, forms a flap over th enose, stops food etc from going out of nose.

Question 22

Where is the hard palate?

Answer 22

Front of mouth above the tongue, push food against it to help break down food and stimulates the salivary glands

Question 23

Wht is the voluntay phase of swllowing?

Answer 23

The first (Oral) stage within the mouth. Controlled by skeletal muscle (tongue) and pushes Bolus to the back of the mouth.

Question 24

What happens n the pharyngeal phse? How is it regul;ated?

Answer 24

Autonomic controlled by reflex contractions controlled by the swallowing center in the medulla (next to brething center)
Presence of food causes contraction of the pharyngeal muscles and the soft palate is pushed up to close off nasopharynx

Question 25

What stops food going down the irwy tube and insted off in th eright direction?

Answer 25

Epiglotis

Question 26

How does food move down the oesophagus, what muscle causes it? How long does it take?

Answer 26

Muscularis externa in the oesophagus causing peristalsis

around 10 seconds

Question 27

What initiates the relaxation of the stomach?

Answer 27

The vagal reflex of parasympathetic response of the relaxation of the Lower Osophageal Shincter and the presence of food being detected in the stomach and

Question 28

What nerve causes the relaxation of the stomach?

Answer 28

It is a vagal reflex

Question 29

What can the stomach volume vary from?

Answer 29

50ml to 1500ml

Question 30

How does the stomach change volume without a chnge in pressure?

Answer 30

Because of the curtain like folds in thin the stomach wall (mucosa)

Question 31

What are the functions of the Stomach?

Answer 31

Storage of food (prevents the shock of all the mini particles in the stomach causing an osmotic effect and shock in the duodenum at once)
Initial breaking down and disolvtion of food (pepsin, HCL)
Sterilisation
Production of intrinsic factor (for B12 absportion)

Question 32

Where is intrinsic factor produced?

Answer 32

In the stomach (crucial for B12 absorption)

Question 33

What is the fundus?

Answer 33

A thin stretchy smooth muscle

Question 34

What are the histological layers of the stomach?

Answer 34

Mucosa - including gastrointestinal pits
Submucosa - glands

Both submucosa and mucisa are folded (rugae)

Musculris externa - 3 layers this time(!) longituinal, circular and oblique (outside to inside)
Serous - (inside peritoneal cavity)

Question 35

Talk throuhg oesophagus to pyloric opening?

Answer 35

Oesophagus
Lowe Oesophogeal sphincter (gastroeosophageal opening)
Cardiac prt
Fundus
Body (greater and lesser curvature)
Pyloric region
Pyloric sphincter

Question 36

WHat are gastric pits?

Answer 36

Parts of the rugae that end up in the glands of the stomach (and allow juices etc to come out)

Question 37

What do mucus neck cells secrete?

Answer 37

mucus

Question 38

Parietal cells secrete what?

Answer 38

HCL and intrinsic factor

Question 39

Chief cells secrete what?

Answer 39

Pepsinogen