Upper GIT Structure and function

Question 1

What is the voluntary control of chewing?

Answer 1

Somatic nerves - skeletal muscles of mouth/jaw

Question 2

What is the reflex control of chewing?

Answer 2

Increased pressure of food on gums, hard palate, tongue triggers mechanoreceptors to inhibit jaw muscles

Question 3

From where is saliva secreted?

Answer 3

3 pairs:
Parotid glands
Submandibular glands
Submental glands

Question 4

What is in saliva?

Answer 4

Water
a-amylase
Lysozyme
Mucins
Electrolytes

Question 5

What is the role of water in saliva?

Answer 5

Soften/moisten food
Dilute particles
Act as solvent

Question 6

What is the role of mucins in saliva?

Answer 6

Combine with water to form mucus

Viscous solution acting as lubricant

Question 7

What is the function of a-amylase in saliva?

Answer 7

Hydrolyse a-1,4 glycosidic bonds

Catalyse polysaccharides

Question 8

What is the role of electrolytes in saliva?

Answer 8

Maintain tonicity

Regulate roughly neutral pH

Question 9

What is the role of lysozymes in saliva?

Answer 9

Bacteriocidal

cleaves polysaccharide of bacterial cell wall

Question 10

What types of glands are the salival glands?

Answer 10

Exocrine

Question 11

What types of alveolus are present in the salivary glands?

Answer 11

Mucus alveolus
Serous alveolus
Mixed alveolus

Question 12

What is the function of mucus alveoli?

Answer 12

Produce mucins

Question 13

What is the function of serous alveolus?

Answer 13

Produce proteins

Question 14

What nerves control parasympathetic salivary secretion?

Answer 14

VII (Facial)

IX (Glossopharyngeal)

Question 15

What is the effect of parasympathetic stimulation on the salivary secretion?

Answer 15

Profuse watery salivary secretion

Question 16

What is the effect of sympathetic stimulation on the salivary secretion?

Answer 16

Small volume of highly viscous saliva

Question 17

alpha1 adrenoreceptor stimulation has what effect on saliva?

Answer 17

High mucus content

Question 18

alpha2 adrenoreceptor stimulation has what effect on saliva?

Answer 18

High amylase content

Question 19

What is the reflex control of salivary secretion?

Answer 19

Presense of food in the mouth triggers chemoreceptors and mechanoreceptors

Question 20

How long is the esophagus?

Answer 20

25cm

Question 21

What are the histological layers of the esophagus?

Answer 21

Mucosa
Submucosa
Muscularis externa
Adventitia

Question 22

What type of epithelium lines the esophagus?

Answer 22

non-keratinised stratified squamous epithelium

Question 23

Are there glands present in the submucosa of the esophagus?

Answer 23

Yes

Question 24

What types of muscle is present in the esophagus?

Answer 24

Upper 1/3 - skeletal muscle

Lower 2/3 - smooth muscle

Question 25

What is the function of the upper esophageal sphincter?

Answer 25

Stops regurgitation

Question 26

What is the function of the lower esophageal sphincter?

Answer 26

Stopping reflux

Question 27

Describe the oral phase of swallowing

Answer 27

Voluntary | Bolus pushed to the back of the mouth by the tongue

Question 28

Describe the pharyngeal phase of swallowing

Answer 28

Presence of bolus causes reflex contractions of pharyngeal muscles Soft palate reflects backwards (closing nasopharynx)

Question 29

Where is the pharyngeal phase co-ordinated

Answer 29

Swallowing centre (medulla)

Question 30

How does the esophagus respond as the bolus approaches?

Answer 30

Upper esophageal sphincter relaxes and epiglottis covers laryngeal opening

Question 31

How does the esophagus respond as the bolus enters?

Answer 31

Upper oesophageal sphincter contracts, closing the opening

Question 32

Describe the oesophageal phase of swallowing

Answer 32

Propulsion of bolus via peristaltic wave (10sec)

Question 33

Describe the peristaltic wave

Answer 33

Contraction of muscle behind the bolus and relaxing muscle ahead

Question 34

How is the receptive relaxation of the stomach initiated?

Answer 34

Initiated by relaxation of the lower oesophageal sphincter

Question 35

What is the vagal response of this?

Answer 35

Relaxation of the thin, elastic smooth muscle of the fundus and body

Question 36

What are the volume changes of the stomach

Answer 36

50ml --> 1500ml

Question 37

What are the pressure changes of the stomach upon receiving food?

Answer 37

None

Question 38

What is the non-compensatable factor of the stomach?

Answer 38

Production of Intrinsic Factor

Question 39

Where does adventitia end and serosa begin?

Answer 39

Passing the diaphragm

Question 40

What is the most superior, hollow area of the stomach called?

Answer 40

Fundus

Question 41

How many layers of muscle has the stomach? Name them

Answer 41

3 layers Longitudinal Muscle Circular Muscle Oblique muscle

Question 42

What is the function of the oblique muscle of the stomach?

Answer 42

Contract to wring out the stomach, creating additional torque

Question 43

What is the area where the oesophagus reaches the stomach called?

Answer 43

Cardiac region

Question 44

What is the final part of the stomach called?

Answer 44

Pyloric region

Question 45

What stomach structure controls outflow of the stomach into the duodenum?

Answer 45

Pyloric sphincter

Question 46

What are rugae?

Answer 46

Folds in the submucosa and mucosa which stretch when filled