Digestive System Flashcards
What are the layers of the alimentary canal?
Mucosa, submucosa, muscularis (inner and outer), serosa
What is the movement of food within the GI tract called?
Peristalsis
What are the accessory organs within the digestive system?
The liver, gallbladder, pancreas.
The mucosa is made up of _______
Epithelial cells
The submucosa is made up of ________
Underlying tissue (containing glands, blood vessels, nerves)
The muscularis is made up of _______
An inner and outer muscle layer (a third internal layer within the stomach)
What 2 layers does the serosa form?
Visceral peritoneum and periental peritoneum (with serous fluid between)
What enzyme does saliva contain?
Salivary amylase
What does salivary amylase do in the mouth?
Assists with the initial digestion of carbohydrates - converts some to disaccharides.
The glands on the mucosa secrete ________
Mucus (lubricant..helps with the movement inside the GI tract) and digestive enzymes (breakdown products from lumen)
The mixture of food and saliva is called ______
Bolus
Name the 3 pairs of salivatory glands
Parotid glands, submandibular glands, sublingual glands
Name and describe the 3 stages of swallowing.
Oral stage - voluntary muscles (tongue and cheeks) push bolus to pharynx)
Pharyngeal stage - involuntary pharynx muscles propel bolus into oesophagus.
Oesophageal stage - bolus moves by peristalsis into the stomach.
What allows food into the stomach?
Lower oesophageal sphincter
_____ are small pores in the lining of the thick stomach mucous membrane.
Gastric Pits
What are the 3 types of secretory glands in the gastric glands and what do they secrete?
Mucous cells - mucus
Chief cells- pepsinogen (inactive digestive enzyme) Parietal cells - hydrochloric acid and intrinsic factor
What is the purpose of hydrochloric acid?
Activates pepsinogen, converting it to pepsin, allowing it to convert proteins into polypeptides.
_____ is the name of the liquid released from the stomach into the small intestine
Chyme
The pyloric canal leads to the ______________ which controls gastric emptying.
Pyloric sphincter
______ and ______ stimulate the secretion of gastric glands
acetylcholine and gastrin
Taste, smell, food entering stomach cause SYMPATHETIC/PARASYMPATHETIC stimulation by the _________, which releases acetylcholine.
parasympathetic , vagus nerve
What is the function of the hormone gastrin? (2)
Stimulates gastric glands and increases mitosis in the mucosa - replaces damaged cells to protect outer layers.
Chyme entering the small intestine causes _____ impulses to _______ gastric secretion.
Sympathetic, inhibit.
Chyme stimulates the intestinal wall to release _______, which …..
Cholecystokinin
decreases gastric motility ( stomach emptying, intestine filling).
What is the exocrine function of the pancreas?
Release pancreatic juice
Which cells release pancreatic juice?
Pancreatic acinar cells
Where does pancreatic juice enter the duodenum?
At the duodenum papilla (surrounded by the sphincter of oddi/hepatopancreatic sphincter)
The entry of pancreatic juice into the duodenum is regulated by ________
The hepatopancreatic sphincter/sphincter of oddi
What are the enzymes within pancreatic juice and what do they breakdown?
Pancreatic amylase - polysaccharides to disaccharides
Pancreatic Lipase - fats to fatty acids and glycerol
Nucleases - digest DNA and RNA
Trypsin, chemotrypsin, carboxypeptidase - proteins, polypeptides, peptides to amino acids.
What is the function of bicarbonate ions within the pancreatic juice?
Provide an alkaline environment - for best enzyme action and to neutralise acid chyme entering the duodenum.
The entry of chyme to the duodenum triggers the _____ to release secretin.
mucosa
Pancreatic juice secretion is regulated by _____ and _____.
Secretin and Cholecystokinin
Bile is secreted in the _____ and stored in the _____
liver , gallbladder
What causes the gallbladder to contract and the secretion of bile and pancreatic juice into the duodenum?
Cholecystokinin
What are the functions of bile? (2)
Emulsifies fats in the small intestine.
Enables absorption of fatty acids and cholesterol.
(also facilitates the excretion of bilirubin)
Name the 3 sections which make up the small intestine.
Duodenum, jejunem, ileum
What controls entry into the large intestine?
Illeocaecal valve (prevents backflow into ileum)
The ______ is a double layer of peritoneal membrane
Mesentry
What are the functions of the mesentry?
Supports the jejunem and ileum
Supports blood vessels, nerves and lymphatics
The ________________ is a double fold of the peritoneum that drapes over the stomach, transverse colon and small intestine.
The greater omentum
_____ are projections from the mucosa within the small intestine
Intestinal villa
what is the function of intestinal villa?
Better absorption - push into lumen contents to increase surface area and carry the nutrients away from the small intestine
Intestinal villa are lined with __________ cells
columnar epithelial
The connective tissue core of the intestinal villa contain ______ and a ________.
Blood capillaries
lacteal (a lymphatic capillary)
______ sit at the base between villi.
Intestinal glands
______ secrete mucus throughout the small intestine.
Goblet cells
What do intestinal glands secrete and what is the purpose?
Watery fluid - brings products for digestion to villi surface,
_____ (smaller than intestinal villi) of the cells carry ________ to complete the final phase before absorption into the villus.
Microvilli, digestive enzymes
What are the digestive enzymes of the microvilli and what do they breakdown?
Peptidase - peptides to amino acids
Sucrase, maltase, lactase - disaccharides to monosaccharides
Intestinal lipase - fats to fatty acids and glycerol
What are the 4 methods of absorption of nutrients through the small intestine?
Diffusion, facilitated diffusion, active transport, osmosis
Monosaccharides are transported into ______ by ______
capillaries
facilitated diffusion or active transport
Amino acids are transported into ______ by _______
active transport
Fatty acids and glycerol are transported into _______ by _______.
epithelial cells , diffusion
What are fatty acids and glycerol converted into within epithelial cells and why?
Chylomicrons (tryglycerides surrounded by water soluble proteins)
Allows them to enter lacteals where they are transported along lymphatic vessels to thoracic duct - water soluble so dont clog them
Electrolytes are transported by ______ and ______
diffusion and active transport
Water is transported by ______
osmosis
Name the sections of the large intestine
Caecum
Colon ( ascending, transverse, descending)
Rectum
Anal canal (internal sphincter-involuntary smooth muscle, external sphincter-voluntary skeletal muscle)
_____ is not regular in the large intestine - only 4-6 times daily
peristalsis
Does the large intestine have villi?
Nooooooooo
____ are pouch like folds within the large intestine
Haustra
The large intestine involves only some reabsorption of _____ and ______
water and electrolytes
Faecal matter is forced from the ______ colon into the ______
sigmoid , rectum
