Digestive - 3

Question 1

What is the function of the pancreas?

Answer 1

Manufactures the precursor of the digestive enzymes and produces hormones to regulate body function

Question 2

Why does the pancreas create precursor, not final, enzymes?

Answer 2

To avoid auto digestion

Question 3

What are the two systems which enzymes can be released from the pancreas? How what gets released from each system?

Answer 3

Endocrine - Via the blood it release insulin and glucagon

Exocrine - Via a duct into the duodenum it releases digestive pre-cursor enzymes

Question 4

How do the digestive pre-cursor enzymes released by the pancreas become activated?

Answer 4

By the environment of the duodenum

Question 5

What comes into the duodenum during digestion?

Answer 5

Acidic chyme, bile and pre-cursor enzymes

Question 6

What identifies if a particular layer is the serosa layer?

Answer 6

It is the OUTER boundary of an organ

Question 7

What is the serosa layer made of what and what does it produce?

Answer 7

Mesothelial cells and produces serous fluid

Question 8

What is the functional unit of the pancreas?

Answer 8

Question 9

What is the function of the small intestine?

Answer 9

Most digestion and absorption occurs here

Question 10

What are the three section of the small intestine? What is their relative position and length?

Answer 10

Duodenum - 25cm long

Jejunum - 1m long

Ileum - 2m long

Question 11

How is the mucosa adapted in the small intestine for its function?

Answer 11

It is specialised to greatly increase its surface area for secretion and absorption

Question 12

How is the submucosa adapted in the small intestine for its function?

Answer 12

It contain glands of Brunner (types of mucous glands) that secrete HCO3- which neutralise the acidic chyme allowing for optima pH for pancreatic enzymes

Question 13

Label the vessels and cells in the mucosa of the small intestine and what their function is

Answer 13

Question 14

Why do the villi need to have smooth muscle in them?

Answer 14

The capillaries and lymph vessels don’t have any smooth muscle on them but need assistance in moving their content

Question 15

How do you tell when enterocytes turn into undifferentiated cells?

Answer 15

The enterocytes have microvilli on them (i.e. a sheath seen on the lumen side of the gut)

Question 16

What stimulates the release of the secretin from what kind of cell?

Answer 16

Secretin is released from the enteroendocrine cells due to arrival of acidic chyme

Question 17

Where does the release of secretin go? What does it do?

Answer 17

It goes into the blood stream where it then stimulates the release of pancreatic juice and bile

Question 18

What hormone performs a similar function as secretin?

Answer 18

Cholecystokinin (CCK)

Question 19

What causes coeliac disease?

Answer 19

Oversensitive to gluten

Question 20

What can condition can occur because of coeliac disease? How does this affect someone?

Answer 20

Villous atrophy causes problems with absorption (villi become smaller therefore less surface area for absorption)

Question 21

What is the function of the colon?

Answer 21

To turn chyme into faeces and ferment remaining carbohydrates

Question 22

How much water per day does the colon vs small intestine absorb? Why is the colon important?

Answer 22

SI = 8L

Colon = 1L

The water absorbed by the colon is the difference between faeces and diarrhoea

Question 23

How can diarrhoea occur?

Answer 23

When the intestines move food through too fast reducing the time which water can be absorbed

If part of the colon is removed (i.e. from colon cancer)

From the cholera toxin permanently activating the G protein increase water secretion

Reduced enterocyte function

Question 24

What is the opposite of diarrhoea?

Answer 24

Constipation

Question 25

What causes constipation? How can it be cured and how does it work?

Answer 25

Decreased increased intestinal mobility

Laxatives loosen the stool increasing mobility

Question 26

What do bacteria do in the colon?

Answer 26

Ferment cellulose to break it down into sugar and produce vitamin B and K

Question 27

What is the composition of the faeces?

Answer 27

Bacteria (30%), undigested fibre (30%) and cells (40%)

Question 28

How does the colon manage the large bacteria population inside the gut?

Answer 28

It has many cluster of lymphocytes

Question 29

What are the external muscle of the colon? When they contract what structure is created and what is its function?

Answer 29

Teniae coli (separated into three large strips)

When they contract they pull the intestine tube into sac-like pockets (haustra coli) which help move material through the gut

Question 30

Label the cells in the mucosa of the colon and what their function is

Answer 30

Question 31

How do the number of goblet cells change through the colon? Why?

Answer 31

There are more goblet cells further down the colon because the faeces become more dehydrated and needs more lubrication to move

Question 32

When is the urge to defecate felt?

Answer 32

When the rectum fills to about 25% of capacity

Question 33

What are the control mechanisms of (i.e. what muscle control) defecation?

Answer 33

Internal anal sphincter (involuntary) and external anal sphincter (voluntary)