Upper Gi tract structure and function

Question 1

Give 2 reasons why we chew

Answer 1

to prolong taste

defend against respiratory failure

Question 2

In what 2 ways is chewing controlled?

Answer 2

Somatic nerves innervate skeletal muscle voluntarily

Reflex - pressure of food on parts of the mouth initiating mechanoreceptors

Question 3

How many pairs of glands secrete saliva and what are they?

Answer 3

3 - submandibular, parotid and sublingual

Question 4

What is the major component of saliva?

Answer 4

water

Question 5

What 2 substances found in saliva mix to form mucus?

Answer 5

mucins and water

Question 6

What are mucins?

Answer 6

Major protein component in saliva

Question 7

What else is found in saliva?

Answer 7

alpha amylase to form maltose
electrolytes for pH balance
Lysozyme to kill bacteria

Question 8

Are salivary glands endocrine or exocrine?

Answer 8

exocrine

Question 9

What are the 3 types of alveoli found in salivary glands?

Answer 9

mucous, serous and mixed

Question 10

What nervous system is stimulatory for saliva production?

Answer 10

both

Question 11

What nerves control parasympathetic innervation of saliva production and what saliva is produced?

Answer 11

glossopharyngeal (4) and facial (7) cranial nerves

profuse, watery

Question 12

What nerves control sympathetic innervation of saliva production and what saliva is produced?

Answer 12

adrenoreceptors (alpha1 - high mucus and beta 2 - high amylase) - low volume and viscous

Question 13

What reflex is due to food being in the mouth on saliva production?

Answer 13

chemoreceptors and mechanoreceptors

Question 14

What kind of epithelium line the mucosa of the oesophagus?

Answer 14

non keratinising stratified squamous epithelium

Question 15

Explain the muscles in the muscularis externa in the oesophagus (smooth, skeletal)

Answer 15

smooth in the lower 2/3 and skeletal above to help with swallowing

Question 16

What does the upper and lower oesophageal sphincters control?

Answer 16

upper - prevent regurgitation into the airway

lower - control entry into the duodenum

Question 17

What are the 3 stages of getting food to the stomach?

Answer 17

oral, pharyngeal and oesophageal

Question 18

What is the oral phase monitored by?

Answer 18

voluntary as bolus is put to the back of the mouth by the tongue

Question 19

What muscles contract and how to help with swallowing?

Answer 19

pharyngeal muscles coordinated by medulla swallowing centre

Question 20

What closes off the nasopharynx?

Answer 20

soft palette

Question 21

What closes off the larynx?

Answer 21

epiglottis

Question 22

What does the UOS contracting prevent?

Answer 22

reflux

Question 23

How long and by what means does the bolus get from oesophagus to stomach?

Answer 23

10 seconds

peristaltic wave

Question 24

What causes the relaxation of the stomach?

Answer 24

As the LOS relaxes and the food enters

vagal reflex relaxes smooth muscle of fundus and body

Question 25

How does the stomach not change in pressure when going from a volume of 50ml to 1500ml?

Answer 25

Gastric rugae unfold

Question 26

What are some functions of the stomach?

Answer 26

temporary store, dissolve food and digestion, control small intestine delivery, sterilisation and produce intrinsic factor

Question 27

Why is intrinsic factor produced from the stomach important?

Answer 27

Important for vitamin B12 absorption

Question 28

Explain the difference between muscle found at the top and bottom of the stomach

Answer 28

stretchy smooth muscle at the top and thick powerful muscle at the bottom to break down larger molecules

Question 29

What is the additional layer found in the muscularis externa in the stomach? What does this allow?

Answer 29

oblique

like wringing a cloth

Question 30

Where is the cardicac region of the stomach close to?

Answer 30

The heart

Question 31

Where is the antrum of the stomach?

Answer 31

Basically the pyloric region

Question 32

What layers is the rugae present in the stomach?

Answer 32

mucosa and submucosa

Question 33

What are present in the lumen of the stomach?

Answer 33

mucus cells with gastric pit invaginations feeding into gastric glands

Question 34

What are the 3 types of gastric glands?

Answer 34

chief, parietal and mucus neck cells