Lecture 24: The stomach and pancreas

Question 1

What are the functions of the stomach ?

Answer 1

STORAGE
- Expanded lumen, sphincters
- Folded mucosa which allow extension 
MECHANICAL DIGESTION
- motility ---> smooth muscle 
- Sphincters
CHEMICAL DIGESTION
- secretion of strong chemicals = acids & enzymes
- Protective epithelium

Question 2

How does mucosa of the stomach wall aid the stomach in its role of :

• storage
• mechanical and chemical digestion

Answer 2

mucosa is modified for secretion

• extensive infolding to form pits and glands
• modified epithelial cells

Question 3

How does smooth muscle of the stomach wall aid the stomach in its role of:

• storage
• mechanical and chemical digestion

Answer 3

• slow contraction - does not tire
• basal tone
• gap junctions link cell - electrically coupled
• stomach filled —> mechanical digestion

Question 4

How do folds of rugae of the stomach wall aid the stomach in its role of:

• storage
• mechanical and chemical digestion

Answer 4

• allow stomach distension for storage
• allow expansion up to 1.5 litres
• throughout the stomach
• Mucosa and submucosa

Question 5

What are glands?

What do they do?

Answer 5

Extensive infolding of modified epithelial cells which secrete:

• mucous
• enzymes - secreted in inactive form & activated in stomach
• acid
• hormones

Question 6

Summarise the stomach

• Secretion
• Protection
• Movement
• Storage
• Controlled release

Answer 6

Secretion = enzymes, acid, hormones
Protection = mucous secreting cells
Movement = extra muscle layer & modified muscle layer
Storage = regions of the stomach muscle
Controlled release = muscle, nervous, endocrine cells

Question 7

Where is the pancreas located ?

What is its function ?

Answer 7

Location:

• head in C-shaped duodenum
• tail to spleen - 12 - 15 cm long
• behind the stomach
• duct into duodenal lumen

Pancreas = secretory gland - secrete bicarbonate and enzyme

Question 8

What are the two different secretory units found in the pancreas?

How do they differ?

Answer 8

Exocrine = empties secretory products into DUCT
- Acinus —-> produces enzymes
- Duct cell —-> produce bicarbonate
Endocrine == empties secretory products into BLOOD
Islets of Langerhans
- alpha cells = glucagon
- beta cells = insulin

Question 9

What does the submucosal plexus regulate?

Answer 9

Controls regulation of secretion

Question 10

What does the myenteric plexus regulate?

Answer 10

Controls regulation of motility