Salivary glands, oesophagus, and Stomach micro anatomy

Question 1

Parasympathetic and Gut activity?

Answer 1

Activates and enhances gut activity

Question 2

Sympathetic and Gut activity?

Answer 2

inhibits gut activity

Question 3

What are the layers of the GI tract?

Answer 3

1) Mucosa - epithelium, lamina propria and muscularis mucosae
2) Submucosa
3) Muscularis Externa
4) adventitia/Serosa

Question 4

Purpose of epithelium?

Answer 4

Protection (multiple layers)
Secretion
Absorbtion

Question 5

Purpose of lamina propria

Answer 5

Support

1) Mechanical Support - collagen
2) functional support - BV, nerves, lymphatics

Question 6

Purpose of Muscularis Mucosae

Answer 6

Movement independent of peristalsis

Question 7

Purpose of Submucosa?

Answer 7

Same as lamina propria

Question 8

Why is the lamina Propria loosely arranged?

Answer 8

to allow for the expansion of a bolus

Question 9

How is the muscularis externa arranged? What is the exception of this?

Answer 9

Inner circular and outer longitudinal

exception stomach

Question 10

What type of muscle is the muscularis externa? What is the exception of this?

Answer 10

Smooth muscle (involuntary). 
Exception: Upper 1/3 oesophagus
                  internal anal sphincter

Question 11

Whats the difference between adventitia and serosa?

Answer 11

Adventitia: outermost CT covering any organ, vessel or other structure.

Serosa (visceral peritoneum) slippery outer covering for the gut tube; two layered, with the outer mesothelium sitting on a bed of CT

Question 12

Intra peritoneal

Answer 12

Organs totally suspended. These are covered in serosa (simple squamous mesothelium)

Question 13

Retroperitoneal

Answer 13

lined with serosa on anterior surface only (‘outside peritoneal cavity’)
Posterior surface is adventitia

Question 14

how much Serous Fluid do we produce daily?

Answer 14

7L

Question 15

Submucosal plexus is also called?

Answer 15

Meissner’s plexus

Question 16

Sphincters. What layer are they formed by

Answer 16

gate keepers that control the volume/timing/flow if substances from one region to another.
Thickening of the IC

Question 17

Ascites

Answer 17

Caused by cirrhosis/liver damage, heart failure

• accumulation of fluid in the peritoneum, abdominal swelling, distortion of visceral organs
• can be drained

Question 18

Peritonitis

Answer 18

-inflammation of the peritoneum > impaired function

Question 19

What determines the composition of the secretions

Answer 19

The proportion of Serous acinar (dark) and mucus acinar (light) whether it is serous/watery or mucous/sticky

Question 20

% of contribution and types of acini in the salivary glands

Answer 20

Parotid (~25%) - serous acini (dark cells) > watery

Submandibular (~70%) - mixed (dark and light) > serous + mucus

Sublingual (~5%) - mixed (dark and light) > serous + mucus

Question 21

Draw and describe a serous acinus

Answer 21

• central, darkly staining nuclei
• Mitochondria perpindicular to the basal surface
• Zymogen granules in the apical cytoplasm (predominate AMYLASE)
• myoepithelial cells surround the base of acini

Question 22

Myoepithelial cell

Answer 22

modified contractile epithelia. Squeeze acital secretion into lumen.
-in BOTH serous and mucus acinus

Question 23

Draw and describe a mucus acinus

Answer 23

• flattened, peripheral nucleus
• mucus granules in the apical cytoplasm (flatten nuclei)
• myoepithelial cells around base of acinus

Question 24

Striated ducts are… How are they striated and whats this for?

Answer 24

Intralobular ducts.

• aligned mitochondria in the basal infoldings of the cell give striated appearance
• this is because they have increased METABOLIC ACTIVITY and ACTIVE TRANSPORT

Function is to exchange Na+ and Cl- for K+ and HCO3-

Question 25

Composition of saliva

Answer 25

99% water | 1% ions, buffers, enzymes etc

Question 26

Lubrication function of saliva

Answer 26

Carb-rich glycoproteins (mucins): slippery molecules of mucus also has a protective function as they prevent bacterial adhesions (hard to attach)

Question 27

Protection Function of the saliva

Answer 27

PREVENT: - Bacterial adhesions & secretions (usually acidic) - vomit (acidic) -Bicarbonate ions (counteract acid (gastric to an extent)) - Lysozyme (breakdown bacteria cell walls) - Lactoferrin (fight iron dependent bacteria) - Immunoglobulin A (fight genetic infection/virus)

Question 28

Why do we get a huge saliva influx before vomiting?

Answer 28

Protective reflux reaction to ensure the alkaline saliva buffers the acidic vomit

Question 29

Digestion Function of Saliva

Answer 29

AMYLASE: (pH 4-11), starts sugar/carb BD into monomers. (as sugars are good site of bacterial growth this decreases potential growing sites!) LIPASE (pH 4): breakdown fats, more active in stomach as pH lower Kallikrein: protease, cleaves another proenzyme > increased blood flow and bloody supply to sustain demand for metabolism whilst eating

Question 30

PSNS

Answer 30

accelerates secretion > lots of watery saliva myoepithelial cells contract -increased blood flow

Question 31

SNS

Answer 31

small amount of viscous saliva containing high enzyme concs -less volume = dry mouth feeling BVs constricted

Question 32

Why do meth users have such bad teeth

Answer 32

destroy salivary gland > destroy protective function!

Question 33

Function of Oesophagus

Answer 33

rapid transport (PS) of the food bolus. straight ~25cm tube, thick muscular wall, protective lining. Collapsed outline with folds of submucosa when empty (loosely packed)

Question 34

Epithelium of oesophagus

Answer 34

thick sacrificial stratified squamous epithelium (6-8 layers). non-keritinised as it approaches stomach >> cuboidal/columnar

Question 35

Muscularis mucosae of oesophagus

Answer 35

absent/rare upper but developed near stomach, not defined, discontinuous in places. Allows for mucosa movement independent of peristalsis

Question 36

Are glands present in the oesophagus

Answer 36

yes

Question 37

Muscularis externa

Answer 37

2 coats, not always circular and longitudinal, irregular areas. upper 1/3: skeletal (striated) middle 1/3: skeletal & smooth lower 1/3: smooth (poorly preserved)

Question 38

Covering of oesophagus

Answer 38

adventitia (except 1-2cm)

Question 39

Chronic Oesophagitis

Answer 39

Often caused by GORD > inflammation - stratified squamous only protective of mechanical abrasion - chronic exposure can cause Barretts syndrome (precursor to oesophageal cancer)

Question 40

In the body/Fundus

Answer 40

Parietal Glands - HCl - Intrinsic factor - pepsinogen - somatostatin

Question 41

Rugae are

Answer 41

transient folds that come and go (less when full)

Question 42

Four anatomical regions

Answer 42

cardia: mucus (bufferzone) fundus body: parietal glands pylorus: mucus (bufferzone

Question 43

Pyloric Glands

Answer 43

- Mucus** - pepsinogen - gastrin - somatostatin

Question 44

Muscularis externa layers of the stomach

Answer 44

Inner oblique middle circular outer longitudinal