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ESA 3 - Gastrointestinal System > Overview of Gastrointestinal Function > Flashcards

Flashcards in Overview of Gastrointestinal Function Deck (99)
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What do metabolic processes need? 

A specific range of small molecule


What does food have? 

A wide range of mostly large molecules


What is the problem with food? 

The large molecules are locked into complex structures

It may be contaminated with pathogens


What does digestion do to food? 

Makes it into a sterile, neutral, and isotonic solution of small sugars, amino acids and small peptides, small particles of lipids, and other small molecules


What can happen once food has been digested? 

It is now ready for absorption and excretion 


Give the processes that occur in the GI tract, from eating food to excreting it

  1. Initial physical disruption 
  2. Ingestion and transport to storage
  3. Initial chemic disruption and creation of suspension (Chyme)
  4. Disinfection
  5. Controlled release of Chyme
  6. Diluration and neutralisation 
  7. Completion of chemical breakdown
  8. Absorption of nutrients and electrolytes
  9. Final absorption of water and electrolytes
  10. Producing faeces for controlled excretion


What are the regions of the GI tract? 

  • Mouth and Oesophagus
  • Stomach
  • Duodenum 
  • Small intestine 
  • Large intestine 
  • Rectum


What are the functions of the mouth and oesophagus? 

  • Mastication
  • Saliva
  • Swallowing


What is the purpose of saliva? 

  • Protects mouth
  • Lubricates food for mastication and swallowing
  • Starts digestion


How does saliva protect the mouth? 

  • Wets
  • Bacteriostatic
  • Alkaline
  • High Ca2+


How does saliva lubricate food? 

  • Wet
  • Mucus


What does the saliva digest?



What is the function of the mouth and oesophagus in swallowing? 

  • Formation of bolus
  • Rapid oesophageal transport


What is the function of the stomach? 

  • Storage
  • Initial disruption 
  • Delivers Chyme slowly into duodenum 


How does the stomach acheive it's storage function? 

It relaxes to accommodate food 


How does the stomach acheive initial disruption? 

  • Contracts rhythmically to mix and disrupt
  • Secretes acid and proteolytic enzymes to break down tissues and disinfect 


What happens once stomach has performed initial disruption of food? 

The food is now called Chyme 


What is the function of the duodenum? 

Dilation and neutralisation of Chyme 


How does the duodenum dilate and neutralise Chyme? 

  • Water drawn in from ECF. The stomach is impermeable, the duodenum is permeable 
  • Alkali (bile) added from liver and pancreas
  • Enzymes added from pancreas and intestine


What is the function of the small intestine? 

  • Absorption of nutrients and electrolytes
  • Absorbs the majority of water 


How does the small intestine absorb nutrients and electrolytes?

  • Fluid passes very slowly through the small intestine
  • Large surface area
  • Epithelial cells absorb molecules 
  • Pass into hepatic portal circulation


How do epithelial cells absorb molecules?

Some actively, some passive

Often coupled to Natransport


How much water does the small intestine absorbed?

Compare to large intestine 


Compared to 0.15L in large intestine


What is the function of the large intestine? 

  • Final absorption of water
  • Faeces form and accumulate 


How fast is transit in the large intestine? 

Very slow


Where does faeces form and accumulate in the large intestine? 

In the descending and sigmoid colon


What happens to faeces after formation and accumulation in the large intestines? 

It is propelled periodically into the rectum


What happens once the faeces has been propelled into the rectum? 

You get the urge to defecate, and there is controlled relaxation of sphincters and expulsion of faeces


Label this diagram of the alimentary canal

  • A - Salivary glands
    • ai - Parotid
    • aii - Submandibular
    • aiii - Sublingual 
  • B - Oral cavity
  • C- Pharynx
  • D - Tounge 
  • E - Oesophagus
  • F - Pancreas 
  • G - Stomach
  • H - Pancreatic duct
  • I - Ileum (small intestine)
  • J - Anus
  • K - Rectum
  • L - Appendix 
  • N - Cecum 
  • N - Colon 
    • ni- Transverse colon
    • nii- Ascending colon 
    • niii- Descending colon
  • O - Common bile duct
  • P - Duodenum 
  • Q- Gallbladder
  • R - Liver


What does the alimentary canal consist of? 

From the oval cavity to the anus

Four layers