GI tract & Motility - Week 1 Flashcards
What is the purpose of the mouth & oropharynx?
chops and lubricates food, starts carbohydrate digestion, propels food to oesophagus
What is the purpose of the oesophagus?
muscular tube - propels food to the stomach
What is the purpose of the stomach?
stores/churns food, continues carbohydrate and initiates protein digestion, regulates delivery of chyme to duodenum
What are the 3 components of the small intestine?
duodenum, jejunum and ileum
What is the purpose of the small intestine?
principal site of digestion and absorption of nutrients
What are the components of the large intestine?
caecum, appendix and colon
What is the purpose of the large intestine?
storage andColon reabsorbs fluids and electrolytes, stores faecal matter before delivery to rectum
What is the purpose of the rectum and anus?
storage and regulated expulsion of faeces
What are the structures contained within the hepatobiliary system?
(i) salivary glands, (ii) the pancreas, (iii) the liver and gall bladder
Secretions from which organ enter the stomach?
Pancreas
Where are most absorptive cells found?
Duodeum and ileum
What are the 3 parts of the colon?
Ascending, transverse and descending
What is reabsorbed in the large intestine?
Water and electrolytes
What is meant by motility?
Mechanical activity mostly involving smooth muscle
The alimentary canal is made from smooth muscle apart from…
Mouth, pharynx, upper 1/3rd of oesophagus and external anal sphincter
Secretion is required for…
(i) digestion, (ii) protection and (iii) lubrication
What is meant by digestion?
Chemical breakdown by enzymatic hydrolysis of complex foodstuffs to smaller, absorbable, units
Give examples of secretions.
Liquid & electrolytes
What is meant by absorption?
Transfer of the absorbable products of digestion (with water, electrolytes and vitamins) from the digestive tract to the blood, or lymph
What are the 4 general layers of the alimentary canal?
Mucosa, sub-mucosa, muscularis externa, serosa
Which cells are contained within mucosa?
epithelial cells exocrine cells endocrine gland cells lamina propria (capillaries, enteric neurones, immune cells) muscularis mucosae
Intestinal absorption cells are called…
Enterocytes
What are the components of submucosa?
connective tissue larger blood and lymph vessels glands nerve network submucous plexus
Where is the submucous plexus found?
Submucosa
What is contained within muscularis externa?
circular muscle layer
nerve network
myenteric plexus
longitudinal muscle layer
Where is the myenteric plexus found?
Muscularis externa - between circular muscular layer and longitudinal muscular layer
What is the role of the muscularis mucosae?
can change the shape of the mucosa for mixing contents of the lumen
What is the purpose of the serosa?
squamous cells produce lubricant which helps abdominal organs to move over one another
Which adaptation in structure is made by the stomach?
additional oblique smooth muscle layer in stomach
What is the overall length of the GI system?
7-10m
What is the effect of Circular muscle contraction?
lumen becomes narrower and longer