Digestive - 3 Flashcards
What is the function of the pancreas?
Manufactures the precursor of the digestive enzymes and produces hormones to regulate body function
Why does the pancreas create precursor, not final, enzymes?
To avoid auto digestion
What are the two systems which enzymes can be released from the pancreas? How what gets released from each system?
Endocrine - Via the blood it release insulin and glucagon
Exocrine - Via a duct into the duodenum it releases digestive pre-cursor enzymes
How do the digestive pre-cursor enzymes released by the pancreas become activated?
By the environment of the duodenum
What comes into the duodenum during digestion?
Acidic chyme, bile and pre-cursor enzymes
What identifies if a particular layer is the serosa layer?
It is the OUTER boundary of an organ
What is the serosa layer made of what and what does it produce?
Mesothelial cells and produces serous fluid
What is the functional unit of the pancreas?
What is the function of the small intestine?
Most digestion and absorption occurs here
What are the three section of the small intestine? What is their relative position and length?
Duodenum - 25cm long
Jejunum - 1m long
Ileum - 2m long
How is the mucosa adapted in the small intestine for its function?
It is specialised to greatly increase its surface area for secretion and absorption
How is the submucosa adapted in the small intestine for its function?
It contain glands of Brunner (types of mucous glands) that secrete HCO3- which neutralise the acidic chyme allowing for optima pH for pancreatic enzymes
Label the vessels and cells in the mucosa of the small intestine and what their function is
Why do the villi need to have smooth muscle in them?
The capillaries and lymph vessels don’t have any smooth muscle on them but need assistance in moving their content
How do you tell when enterocytes turn into undifferentiated cells?
The enterocytes have microvilli on them (i.e. a sheath seen on the lumen side of the gut)
What stimulates the release of the secretin from what kind of cell?
Secretin is released from the enteroendocrine cells due to arrival of acidic chyme
Where does the release of secretin go? What does it do?
It goes into the blood stream where it then stimulates the release of pancreatic juice and bile
What hormone performs a similar function as secretin?
Cholecystokinin (CCK)
What causes coeliac disease?
Oversensitive to gluten
What can condition can occur because of coeliac disease? How does this affect someone?
Villous atrophy causes problems with absorption (villi become smaller therefore less surface area for absorption)
What is the function of the colon?
To turn chyme into faeces and ferment remaining carbohydrates
How much water per day does the colon vs small intestine absorb? Why is the colon important?
SI = 8L
Colon = 1L
The water absorbed by the colon is the difference between faeces and diarrhoea
How can diarrhoea occur?
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
What is the opposite of diarrhoea?
Constipation
What causes constipation? How can it be cured and how does it work?
Decreased increased intestinal mobility
Laxatives loosen the stool increasing mobility
What do bacteria do in the colon?
Ferment cellulose to break it down into sugar and produce vitamin B and K
What is the composition of the faeces?
Bacteria (30%), undigested fibre (30%) and cells (40%)
How does the colon manage the large bacteria population inside the gut?
It has many cluster of lymphocytes
What are the external muscle of the colon? When they contract what structure is created and what is its function?
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
Label the cells in the mucosa of the colon and what their function is
How do the number of goblet cells change through the colon? Why?
There are more goblet cells further down the colon because the faeces become more dehydrated and needs more lubrication to move
When is the urge to defecate felt?
When the rectum fills to about 25% of capacity
What are the control mechanisms of (i.e. what muscle control) defecation?
Internal anal sphincter (involuntary) and external anal sphincter (voluntary)
