Digestive part 2 wk2 flashcards ( 2 days revision)

What three phases regulate gastric secretion?

Cephalic phase, gastric phase, intestinal phase.

What triggers the cephalic phase of digestion?

The thought, sight, or smell of food.

What is the primary substance produced during the cephalic phase?

Gastric juices.

What role do G cells play in gastric secretion?

They produce gastrin, which stimulates gastric juices.

Which cells in the stomach produce hydrochloric acid?

Parietal cells.

What is pepsinogen?

An inactive enzyme that is activated to pepsin by hydrochloric acid.

What occurs during the gastric phase of digestion?

Food enters the stomach, causing distention and increased gastric juice production.

What is the primary neurotransmitter involved in stimulating gastric secretion?

Acetylcholine.

In the intestinal phase, what substance is primarily decreased?

Gastric juices.

What do somatostatin and secretin have in common?

They both function to reduce gastric secretion.

What is the primary environment required for enzyme activity in the small intestine?

Alkaline conditions.

What is the main function of the small intestine?

Digestion and absorption of nutrients.

Which part of the small intestine is primarily responsible for absorption?

Jejunum.

What are the two types of muscle movements seen in the small intestine?

Segmentation and peristalsis.

What is segregation in the small intestine?

A slow contraction to mix chyme with digestive enzymes.

What is peristalsis?

Alternating contractions of longitudinal and circular muscles to move chyme.

How much of the small intestine's length is attributed to its surface area modifications?

300 square meters if flattened.

What are plicae circulares?

Circular folds in the small intestine that increase surface area.

What role do villi play in the small intestine?

They increase surface area for absorption.

What are microvilli?

Tiny projections on enterocytes that further increase surface area.

What are the functions of goblet cells in the small intestine?

Secrete mucus to protect the intestinal lining.

What do paneth cells produce?

Antimicrobial peptides like lysozyme.

What primary secretion does the small intestine produce?

Mucus, water, and bicarbonate.

What are Brunner's glands?

Glands in the duodenum that produce bicarbonate-rich secretions.

What is the primary function of bile?

Emulsifying fats to aid in digestion.

What hormone stimulates the gallbladder to release bile?

Cholecystokinin (CCK).

What is the role of secretin?

Stimulates the pancreas and liver to produce bicarbonate and bile.

What type of blood vessels supply the liver?

Hepatic artery and hepatic portal vein.

What is the liver's primary functional cell type?

Hepatocytes.

How is bilirubin formed?

From the breakdown of hemoglobin in red blood cells.

What do high levels of bilirubin in the blood indicate?

Jaundice.

What is the outcome of the Ornithine cycle?

Formation of urea to excrete ammonia.

What does biotransformation refer to?

The liver's process of modifying xenobiotics for detoxification.

Which two hormones does the pancreas secrete?

Insulin and glucagon.

What enzyme activates trypsinogen?

Enteropeptidase.

What is the bile canaliculus?

A small duct in the liver that collects bile secreted by hepatocytes.

How are bile acids synthesized?

From cholesterol in the liver.

What type of secretion do the pancreatic duct cells produce?

Bicarbonate to neutralize acidity.

What is the primary function of the liver related to nutrients?

Metabolism and storage of carbohydrates, proteins, and fats.

What do hepatocytes secrete?

Bile, proteins, and various enzymes.

What happens to excess cholesterol in the body?

It can form gallstones if not properly disposed.

What is the role of CCK in digestion?

It stimulates the gallbladder to contract and release bile.

What do you call the hormone that inhibits gastric secretion?

Somatostatin.

Why is bilirubin made water-soluble?

To facilitate its excretion through the bile.

What primary adaptation does the ileum have for absorption?

Increased surface area due to length and villi.

Where is the gallbladder located?

Underneath the liver.

What regulates the release of bile into the duodenum?

The sphincter of Oddi.

What components make up bile?

Cholesterol, bile salts, and bilirubin.

What is a consequence of removing the terminal ileum?

Increased synthesis of bile salts by the liver.

What substances are often detoxified by the liver?

Ammonia, alcohol, and drugs.

What condition is caused by excessive destruction of red blood cells?

Hemolytic jaundice.

Where are Peyer’s patches located?

In the ileum, part of the immune defense in the gut.

What is the role of lysozyme in the digestive system?

To manage microbial populations.

How does the liver detoxify drugs?

Through biotransformation, which modifies and excretes them.

What does secretin act on in the digestive system?

It stimulates pancreatic duct cells and bile production in the liver.

How is the gallbladder's bile concentrated?

By absorbing sodium chloride, bicarbonate, and water.

What is the function of the central vein in the liver lobule?

To collect blood from the sinusoids and drain it into the hepatic vein.

What happens to bilirubin after it is formed from hemoglobin breakdown?

Bilirubin is transported in plasma bound to albumin for solubility, then de-conjugated in the liver and re-conjugated with glucuronic acid for bile transport.

What is deamination and what product does it generate from L-glutamate?

Deamination is the process where the amino group is liberated from L-glutamate, resulting in the production of alpha-ketoglutarate and ammonia.

What is the Ornithine cycle responsible for?

The Ornithine cycle is responsible for removing ammonia, a toxic byproduct of deamination, by converting it into urea in the liver.

What role does carbamyl phosphate synthetase play in the urea cycle?

Carbamyl phosphate synthetase binds ammonia with carbon dioxide to produce carbamyl phosphate, which enters the Ornithine cycle.

How is urea produced in the Ornithine cycle?

Carbamyl phosphate, bound to L-ornithine, undergoes several steps in the Ornithine cycle, culminating in the production of urea.

What happens to urea after it is produced?

Urea is excreted by the kidneys, but some may diffuse back into the intestine where it can be converted to ammonia by enteric bacteria.

What are xenobiotics and how does the liver deal with them?

Xenobiotics are substances not normally found in the body, like certain drugs, and the liver detoxifies them through a process called biotransformation.

What are the two main steps of biotransformation in the liver?

The first step reduces the toxicity of a molecule, and the second step increases its solubility for removal from the body.

What occurs during the process of biotransformation?

Biotransformation involves modifying the chemical structure of substances to inactivate and facilitate their excretion.

How does the liver influence hormone metabolism?

The liver inactivates and excretes hormones such as steroids, insulin, and glucagon, through processes like proteolysis and deamination.

What methods can be used in the first step of detoxifying a molecule?

Methods include oxidation, reduction, hydrolysis, or acetylation, which help in reducing the molecule's toxicity.

Where is bilirubin formed in the body?

In the spleen during the breakdown of red blood cells.

What transports bilirubin in the plasma?

Bilirubin is conjugated to albumin for solubility.

What happens to bilirubin once it reaches the liver?

It is de-conjugated from albumin and conjugated to glucuronic acid.

How does bilirubin get its yellow color?

Bilirubin is yellowish, resulting from the reduction of greenish bilirubin.

What is urobilinogen?

A colorless substance formed from bilirubin by intestinal bacteria.

How is urobilinogen excreted?

It can enter circulation and be excreted via the kidneys or return to the liver.

What causes the brown color of feces?

Stercobilin, formed from the reduction of urobilinogen.

What is the consequence of excessive bilirubin in the blood?

It causes jaundice, leading to yellow discoloration of the skin and eyes.

What is hemolytic jaundice?

Jaundice resulting from excessive destruction of red blood cells.

How is neonatal jaundice typically treated?

With UV light to facilitate the isomerization of bilirubin.

What stimulates the production of cholecystokinin?

The presence of fatty acids, amino acids, and chyme in the digestive system.

What effect does secretin have?

It stimulates bile production in the liver.

What is the Ornithine cycle responsible for?

The conversion of toxic ammonia into urea for excretion.

What role do transaminases play in amino acid metabolism?

They catalyze the transfer of amino groups during transamination.

What does deamination produce from L-glutamate?

Alpha-ketoglutarate and ammonia.

What is the fate of ammonia produced from amino acid catabolism?

It is converted into urea in the liver to be excreted.

What is the function of albumin in relation to bilirubin?

It binds to bilirubin to increase its solubility in plasma.

What happens to bilirubin during the breakdown of hemoglobin?

It gets converted to heme and subsequently to bilirubin.