Gastrointestinal Systems Flashcards
What are the accessory structures of the duodenum?
The liver (forms bile), gall bladder (stores bile), pancreas
Where is bile formed and stored?
Formed in the liver and stored in the gall bladder
What does bile do?
Emulsify fat
What is acidic chyme?
It’s neutralised by bicarbonate in pancreatic juice
What else is added to chyme?
Intestinal juice
What enzymes do the pancreas secrete and as what?
Proteolytic enzymes are secreted as Zymogens so they don’t digest the cells that produce them
GI tracts functions are controlled by hormones such as?
Gastrin: controls gastric HCL secretion
Secretin: controls pancreatic bicarbonate
Cholecystokinin: pancreatic enzyme secretion, bile release by Gall Bladder, inhibits stomach
Motilin: stimulates gastric motility
Somatostatin: inhibits gastric acid secretion
G inhibitory peptide: potentiates insulin secretion
What is the small intestine sub divided into?
Duodenum (25cm)
Jejunun (1.5m)
Ileum (2.5m)
What’s the main site of enzymatic digestion and absorption?
Duodenum and jejunum
What does the ileum do?
Absorbs nutrients
How is the surface area increased for absorption?
So simple tube, with folds, with villi, and microvilli
Explain the structure of intestinal Villi and how the surface area is increased?
Villi and microvilli on individual absorptive cells (enterocytes)increase surface area for absorption
What is found in the cell membrane of microvilli?
Lactase,Maltase, nuclease, peptidases
What is transported through epethelial cells to the hepatic portal venous system?
Amino acids and sugars
How is fructose absorbed?
By facilitated diffusion
How are glucose and amino acids absorbed?
They are co-transported with sodium involving secondary active transport
What is a chylomicron?
Triglycerides packaged within a lipoprotein coat by the endolasmic reticulum
What is fat absorbed as?
As chylomicrons which entree lymphatic vessels rather than blood capillaries
How does co-transport with sodium involve a secondary active transport?
Use of ATP to pump sodium makes this a secondary active transport
What provides facilitated diffusion?
Glut2 and Glut5
Small peptides and amino acids are co-transported with?
With H+ and Na+
What do chylomicrons enter?
Lymph vessels not blood!
How do lipids diffuse?
Freely
What’s the appendix and where’s it located?
A vestigial cecum found where the small and large intestines meet
What is the function and structure of the colon?
It recovers water and ions, and it only has a few villi
What does the colon mucosa do?
It has intestinal glands with mucous secreting cells
What does the mammalian colon do?
It contains microbes which convert cellulose to fatty acids which are absorbed
What does the rectum do?
Forms faeces
What’s hydrolysis?
The enzyme assisted breakdown of food
After you swallow food where does it go ?
The oesophagus
After the oesophagus where does food go?
To the stomach
What does the stomach do ?
- churning of food
- hydrolysis
- storage
- make chyme
After the stomach where does food go?
The intestine (small intestine)- hydrolysis, absorption of nutrients
Then to the large intestine/colon:
Absorption of water/ions
After the intestine where does food go ?
To the rectum:
Storage until time to expel the food via the anus through expulsion
