Stomach 1 & 2

Question 1

What is deglutition?

Answer 1

Swallowing: propulsion of food from oral cavity -> osephogus

Question 2

What is food molded into by the tongue before being moved up and back to the pharynx?

Answer 2

Bolus

Question 3

When pressure sensory cells are stimulated, the swallowing reflex is stimulated. Where is the swallowing centre in the brain?

Answer 3

Medulla

Question 4

What temporarily closes off the trachea whilst swallowing?

Answer 4

Epiglottis

Question 5

What are some deglutition disorders?

Answer 5

Failure of epiglottis
Soft palette
Pharyngeal paralysis
Botulism (clostridial toxins block AcetylCh release)

Question 6

What is myasthenia gravis?

Answer 6

The body produces antibodies against Acetylcholine receptors, so the swallowing reflex does not work

Question 7

Why are animals starved before anaesthesia?

Answer 7

Inhalation pneumonia

Anaesthesia induces vomiting - leads to inhalation

Question 8

What are the 4 layers of the oesophagus?

Answer 8

Mucosal layer
Submucosal layer
Muscular layer
Serosal layer

Question 9

What happens when the bolus reaches the oesophagus?

Answer 9

Upper oesophageal sphincter closes behind food bolus
Epiglottis opens to allow respiration
Peristaltic contractions force bolus down
Lower oesophageal sphincter opens to allow food to pass to stomach

Question 10

What is the lower oesophageal sphincter also known as? What is its function?

Answer 10

Cardiac sphincter

Prevent regurgitation

Question 11

What is the scientific word for vomitting?

Answer 11

Emesis

Question 12

What is an anti-emetic drug?

Answer 12

A drug which prevents vomitting

Question 13

Why is there deep inspiration before emesis?

Answer 13

To increase intrathoracic pressure

Question 14

Whilst taking a deep inspiration, which parts of the digestive system close?

Answer 14

Trachea

Nasal cavity

Question 15

Which muscles contract during emesis

Answer 15

Abdominal muscles

NOT gastric

Question 16

Emesis is controlled by the medulla. What stimulates emesis?

Answer 16

Pharyngeal or gastric distension/irritation

Question 17

Which two species do not vomit? What happens to them if they are unable to vomit?

Answer 17

Horses and rats

Stomach ruptures

Question 18

What is gastric torsion? Which breeds are most prone to it?

Answer 18

The twisting of the stomach around its on axis

Any horses/dogs with a wide chest - more room for stomach to move

Question 19

Why does gastric torsion prevent vomiting?

Answer 19

It seals off the cardiac sphincter

Question 20

Gastric torsion may compromise blood supply. What does this lead to?

Answer 20

Oedema
Hypoxic stomach
Eventually leads to necrosis

Question 21

During gastric torsion, the stomach may dilate. This may lead to emergency surgery. Why?

Answer 21

Stomach impairs venous return to the heart

Causes hypovolaemic shock

Question 22

What are the functions of the stomach?

Answer 22

Digestion (continuation of starch, initiation of protein)
Protect rest of GI tract by killing bacteria
Storage (wild animals)
Mechanical breakdown and mixing

Question 23

What are the 4 regions of the adult stomach? What sphincters are at the start and end of the stomach?

Answer 23

Cardia
Fundus
Corpus
Pylorus
Eosphogeal sphinter, pyloric sphincter

Question 24

Is the oesophageal region of the stomach glandular or non-glandular?

Answer 24

Non - glandular

Question 25

What is the purpose of motility?

Answer 25

To prepare stomach for meal Mix and breakdown chyme Empty stomach Prevent regurgitation

Question 26

What actually is ‘heart burn’?

Answer 26

Regurgitation of chyme into the oesophagus

Question 27

What is receptive relaxation?

Answer 27

The process of the stomach relaxing to accommodate for food as a meal is eaten

Question 28

Where is receptive relaxation regulated, and via which nerve? What is the neurotransmitter?

Answer 28

Swallowing centre (medulla) Vagus nerve VIP

Question 29

Regulation of stomach emptying is hormonal or neural. When may the regulation by neural?

Answer 29

When in pain

Question 30

When might the duodenum inhibit gastric contractions (therefore gastric emptying)?

Answer 30

If too much chyme is present in the duodenum | If pH is too high

Question 31

What is the pH of the stomach?

Answer 31

2 - 2.5

Question 32

What is amylase a polysaccharide of? What is the bond present?

Answer 32

Alpha glucose | 1, 4 glycosidic bond

Question 33

What is amylopectin a polysaccharide of? What is the bond present?

Answer 33

Alpha glucose | 1,6 glycosidic bond

Question 34

Starch is broken down by amylase, which is only active at pH > 6. Protein is broken down by pepsin, which is only active at a lower pH. How does the stomach deal with this?

Answer 34

Acid is released from stomach walls Newly swallowed food goes to the centre Starch is broken down in the centre (lower pH) and protein is broke down by edges of stomach (higher pH)

Question 35

Why do carnivores and ruminants have no amylase in their saliva?

Answer 35

They have a low starch diet

Question 36

Where is amylase produced?

Answer 36

``` The mouth Exocrine pancreas (back up) ```

Question 37

Why do humans have such a high level of salivary amylase in comparison to pigs/horses?

Answer 37

Human stomach cannot digest starch as well as pigs and horses

Question 38

What is gastric juice mainly composed of?

Answer 38

Hydrochloric acid | Pepsinogen (inactive pepsin, activated by stomach acid)

Question 39

Why does pepsinogen need to be inactive?

Answer 39

Organs are made up of protein | Pepsin would digest them

Question 40

Stomach mucosa is resistant to digestion. Failure of this leads to..?

Answer 40

Stomach ulceration

Question 41

Why is HCl needed in gastric juice?

Answer 41

Kill microorganisms Active pepsinogen and provide environment for pepsin to work Degrade large chunks of CT & MT into smaller pieces

Question 42

How does the duodenum cope with the acidic chyme released from the stomach?

Answer 42

The pancreas secretes HCO3- into the duodenum which neutralises the acid

Question 43

What is the alkaline tide?

Answer 43

After eating, pH of blood increases due to stomach parietal cells secreting H+ into the stomach and HCO3- into the blood

Question 44

Where is pepsinogen synthesised and stored?

Answer 44

Chief/peptic cells

Question 45

Pepsin can act as an auto catalyst. What does this mean?

Answer 45

Pepsin can activate more pepsinogen

Question 46

What are the three phases of digestion? And what happens? (In terms of gastric juice secretion and what stimulates it)

Answer 46

Cephalic & gastric phase - stimulates gastric juice secretion directly via acetylcholine and indirectly via gastrin in blood Intestinal phase - inhibits gastric secretion until intestines ready fro more. Stimulated via cholinergic transmitters and gastrin/CCK

Question 47

If stomach pH is less than 2, gastric juice secretion is inhibited to protect mucosa. What is responsible for this?

Answer 47

Hormone gastrin

Question 48

The duodenum inhibits motility and gastric juice secretion by which nerve, and which 3 hormones

Answer 48

Vagus nerve | Secretin, CCK, GIP

Question 49

How often is stomach mucosa epithelium replaced?

Answer 49

Every 2-3 days

Question 50

When there is increased acid in the duodenum, there are decreased protective functions by the stomach. Damaged cells produce what, which leads to more acid production?

Answer 50

Histamine

Question 51

What is the treatment for a too low pH in the stomach?

Answer 51

Increase HCO3 and decrease H+ | Treat with antacids, antihistamines