Digestive System P1 Flashcards
What are the components of the digestive system?
- Mouth
- Pharynx
- Oesophagus
- Stomach
- Small intestine
- Large intestine
- Accessory organs (salivary glands, pancreas, liver, gall bladder, biliary tract)
Define ingestion in the context of the digestive system.
Oral intake of substances into the mouth.
What substances are secreted during digestion?
- Water
- Acid
- Emulsifiers
- Buffers
- Enzymes (saliva, gastric juices, pancreatic juices)
What is the process of absorption in digestion?
Substances passing through walls in the alimentary canal into blood and lymph.
List the four basic layers of the gastrointestinal tract (GIT).
- Mucosa
- Submucosa
- Muscularis
- Serosa (peritoneum)
What is the function of the mucosa layer?
Innermost layer of the GIT involved in protection and absorption.
What are Goblet cells responsible for?
Secretion of mucus to lubricate food and protect against digestive juice erosion.
What is GALT?
Gut-associated lymphoid tissue, part of the immune system located in the GIT.
What is the role of the muscularis mucosa?
Creates villi to increase surface area for absorption and digestion.
True or False: The peritoneum is the largest serous membrane in the body.
True.
What is ascites?
Accumulation of fluid in the peritoneal cavity.
What is the greater omentum?
The largest fold of the peritoneum that drapes over the transverse colon and small intestine.
Fill in the blank: The enteric nervous system is known as the _______.
brain of the gut.
What are the two layers of the peritoneum?
- Parietal
- Visceral
What is the primary function of saliva?
Chemical breakdown of polysaccharides and lubrication of food.
What is the length of the oesophagus?
25 cm long.
What does the stomach secrete daily?
2–3L of highly acidic gastric juice and mucus.
What are the three types of exocrine cells in the stomach?
- Parietal cells
- Chief cells
- Goblet cells
What hormone stimulates hunger?
Ghrelin.
What is the function of pancreatic amylase?
Breaks down starches into sugars.
What is the role of the lower oesophageal sphincter?
Prevents reflux of stomach contents into the oesophagus.
Explain peristalsis.
Involuntary smooth muscle contractions that aid in propelling food along the digestive tract.
What does the submucosal plexus control?
Digestive secretions and detects sensory information.
What is the role of the liver in the GIT blood supply?
Filters the blood and processes nutrients which then enter systemic circulation.
What is the primary function of pancreatic amylase?
Breaks down starches into sugars
What does pancreatic lipase digest?
Lipid / fat digestion
Name two enzymes involved in protein digestion.
- Trypsin
- Chymotrypsin
What is the function of ribonuclease?
Digest RNA
What is the function of deoxyribonuclease?
Digest DNA
How long is the pancreas?
Approximately 15 cm
What connects the pancreas to the duodenum?
Pancreatic duct
What is the shape and size of the gallbladder?
Pear-shaped sac measuring 7–10 cm in length
What is the role of bile in digestion?
Emulsifies fats
What constitutes bile?
- Bile salts
- Cholesterol
- Bilirubin
What hormone is secreted by enteroendocrine cells in the duodenum?
Cholecystokinin (CCK)
What triggers the release of cholecystokinin?
High fat or protein chyme entering the duodenum
What is the primary function of brush border enzymes?
Facilitate absorption
Fill in the blank: 90% of absorption occurs in the _______.
small intestine
What are the three regions of the small intestine?
- Duodenum
- Jejunum
- Ileum
What is absorbed in the ileum?
Vitamin B12
What are the four regions of the large intestine?
- Caecum
- Colon
- Rectum
- Anal canal
What is the function of Kupffer cells in the liver?
Remove foreign bodies from the blood
How does the liver process blood from the gastrointestinal tract?
Through the portal vein for filtration and metabolism
What type of blood does the hepatic artery bring to the liver?
Oxygenated blood
What is the role of the ileocaecal valve?
Allows one-way flow of materials from the small to large intestine
What is the primary energy storage molecule in animals?
Glycogen
What are the two phases of liver detoxification?
- Phase I: Bio-activation
- Phase II: Conjugation
What is the composition of triglycerides?
Glycerol and three fatty acid chains
What is the primary function of dietary lipids?
Energy, insulation, cell membranes, hormone production, protection of organs
What distinguishes saturated fatty acids from unsaturated fatty acids?
Saturated fatty acids contain the greatest number of hydrogen atoms without double bonds
What is the basic building block of proteins?
Amino acids
What is the role of the gallbladder during fat digestion?
Contracts to eject bile into the duodenum
What are microvilli?
Projections of absorptive cells that increase surface area
What is the role of dipeptidase?
Breaks down proteins into amino acids
True or False: The large intestine produces enzymes for digestion.
False
What percentage of bile is typically reabsorbed and returned to the liver?
90–95%
What is the primary function of the liver?
Over 500 functions including detoxification and bile production
What is the role of dietary cellulose in digestion?
Acts as indigestible fiber
What are trans fats?
Fats associated with heart disease, formed by positioning H atoms on opposite sides
Trans fats are typically found in hydrogenated vegetable oils.
What are the basic building blocks used to make proteins?
Amino acids
What percentage of total body mass do proteins make up?
15%
What is the significance of the 3D structure of proteins?
It is essential for their function
What must happen to proteins before protease enzymes can cleave amino acids?
They must be denatured
What does denature mean?
To destroy properties of a molecule
Where are amino acids absorbed in the body?
In the small intestine
List at least three functions of proteins.
- Immunity (immunoglobulins, antibodies)
- Structures (muscles, collagen)
- Enzymes, hormones, neurotransmitters, energy
What are enzymes?
Proteins that act as biological catalysts
What is the role of enzymes in chemical reactions?
They speed up chemical reactions up to thousands of times
How are enzymes specific in their function?
They are highly specific regarding what substrate they react with (lock and key)
What suffix do enzyme names typically end with?
-ase
What is an example of an enzyme involved in protein digestion?
Pepsin
Are enzymes changed or consumed in a chemical reaction?
No, they can perform the same reaction many times
What factors can easily denature proteins?
pH and temperature changes
Fill in the blank: Proteins must first be _______ before protease enzymes can efficiently cleave the amino acids apart.
denatured
True or False: Enzymes are consumed in a chemical reaction.
False
