Upper GI Tract Structure and Function Flashcards Preview

07. Year 2: Alimentary System > Upper GI Tract Structure and Function > Flashcards

Flashcards in Upper GI Tract Structure and Function Deck (56)
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1

What is the purpose of chewing?

Prolong taste experience

Defence against respiratory failure

2

How is chewing controlled?

Voluntarily - somatic nerves controlling the skeletal muscles of the mouth/jaw

Reflex - contraction of jaw muscles causes pressure of food against gums, hard palate and tongue, activates mechanoreceptors causing inhibition of jaw muscles, reducing pressure causing contractions

3

Explain the process of the reflex that controls chewing?

1) Contraction of jaw muscles causes pressure of food against gums, hard palate and tongue

2) Activates mechanoreceptors causing inhibition of jaw muscles

3) Reduces the pressure causing contractions

4

What are the 3 pairs of glands that secretes saliva?

Parotid

Submandibular

Sublingual

5

What is in saliva?

Water

Mucins

a-Amylase

Electrolytes

Lysozyme

6

What is the function of water in saliva?

Softens, moistens, dilutes particles (controls osmosis)

Solvent

7

What is the function of mucin in saliva?

Combines with water to make mucus, viscous solution to perform lubricant function

8

What is the function of a-Amylase in saliva?

Catalyses breakdown of polysaccharides into disaccharide

9

What is the function of electrolytes in saliva?

Tonicity/pH

10

What is the function of lysozyme in saliva?

Bactericidal - cleaves polysaccharide component of bacterial cell wall

11

Why would teeth enamel dissolve without saliva?

Saliva increases the pH

12

What class are the glands that secrete saliva?

Exocrine

13

What does the serous alveolus of glands release?

a-amylase and other proteins

14

What does the mucous alveolus of glands release?

Mucus which enters the duct where water is secreted

15

What controls salivary secretion?

Parasympathetic nervous system

Sympathetic nervous system

Reflex control

16

What parasympathetic nerves control salivary secretion?

Cranial nerve VII (facial)

Cranial nerve IX (glossopharyngeal)

17

What effect does parasympathetic nerves have on saliva secretion?

Stimulates profuse watery salivary secretion

18

What effect does sympathetic nerves have on salivary secretion?

Stimulates small volume, viscous salivary secretion, high mucus content (a1 adrenoceptors) and high amylase content (B2 adrenoceptors)

19

What receptor does the sympathetic system act on to create high mucus content saliva?

a1 adrenoceptors

20

What receptor does the sympathetic system act on to create high amylase content saliva?

B2 adrenoceptors

21

Explain the reflex control of salivary secretion?

Presence of food in mouth activates chemoreceptors/pressure receptors in the walls of mouth/tongue

22

What is special about the sympathetic and parasympathetic effects on salivary secretion?

They are both stimulatory

23

What is the oesophagus?

25cm conduit (pipe) between the pharynx and stomach

24

What is the length of the oesophagus?

25cm

25

What are the 4 layers of the oesophagus?

Mucosa

Submucosa

Muscularis externa

Adventitia

26

What is the mucosa of the oesophagus lined by?

Stratified squamous epithelium (non-keratinised)

27

Why is it important that musosa of oesophagus is stratified and not simple?

Food would destroy a simple layer

28

Why is it important that the mucosa of the oesophagus is non-keratinised?

So it is flexible

29

What is contained by the submucosa of the oesophagus?

Submucosal mucous glands

30

What do submucosal glands secrete?

Mucous for lubrication