Digestive system part 2

What is the main function of the colon?

It absorbs water and electrolytes and forms feces for elimination.

How does the colon help with fluid balance?

It reabsorbs water and electrolytes, turning liquid chyme into semi-solid feces.

Does the colon do a lot of digestion?

No, most digestion is already completed in the small intestine.

What role do gut bacteria (microbiota) play in the colon

They ferment fiber and leftover carbs to produce short-chain fatty acids (SCFAs)

What are short-chain fatty acids (SCFAs)?

They are molecules made by bacteria that can be absorbed and used as energy by colon cells.

What vitamins can be produced in the colon?

Vitamin K and some B vitamins are produced by gut bacteria.

How is the colon structurally different from the small intestine?

It has no villi and instead absorbs through its mucosa surface.

What are goblet cells and their function?

Goblet cells secrete mucus to lubricate feces and help it move easily.

What are intestinal crypts?

Glands in the colon lining that secrete mucus.

What is haustral churning?

Back-and-forth mixing movements within colon pouches.

What are mass movements?

Strong contractions that push feces toward the rectum

What is the colon’s overall role (summary)?

It is mainly a water/electrolyte absorber and a site of bacterial fermentation, with minimal digestion.

What is the primary physiological role of the colon regarding the processing of leftover digestive material?

Absorption of water and electrolytes

A patient is diagnosed with a condition that significantly speeds up the transit time of material through the large intestine, preventing the organ from completing its normal processes

Which of the following symptoms is the patient most likely to experience?

Watery stools and dehydration

What is the liver’s main role in digestion?

The liver produces bile, which helps digest fats in the small intestine.

What is bile?

Bile is a fluid made by the liver that contains bile salts, water, electrolytes, and waste products (like bilirubin).

What are hepatocytes?

Hepatocytes are liver cells that continuously produce bile.

Where is bile stored and released from?

Bile is stored in the gallbladder and released into the duodenum

What triggers bile release into the duodenum?

CCK (cholecystokinin), a hormone from the small intestine, signals the gallbladder to contract and release bile

What is the sphincter of Oddi?

It is a valve that relaxes to allow bile to flow into the duodenum

What does it mean that bile salts emulsify fats?

Emulsification breaks large fat droplets into many small droplets, increasing surface area for digestion

Why is emulsification important?

It allows pancreatic lipase (fat-digesting enzyme) to work more efficiently.

What are micelles?

Micelles are tiny transport particles formed by bile salts that carry fatty acids to the intestinal lining for absorption

What is the overall process of bile in digestion?

The liver makes bile, the gallbladder stores it, and CCK releases it into the duodenum to help digest fats.

Which specific cells in the liver are responsible for the continuous synthesis of bile?

Hepatocytes

A patient has their gallbladder surgically removed. Following the procedure, they consume a meal particularly high in saturated fats

Which process will be most significantly impaired during their digestion?

fat emulsification

What is the main role of the pancreas in digestion?

It releases enzyme-rich pancreatic juice into the duodenum to digest nutrients and neutralize acid.

What is pancreatic juice?

A watery fluid containing digestive enzymes and bicarbonate that is released into the duodenum.

How does the pancreas help digest carbohydrates?

It releases pancreatic amylase, which breaks carbohydrates into simpler sugars

How does the pancreas help digest proteins?

It releases inactive enzymes (trypsinogen, chymotrypsinogen, proelastase) that are activated in the duodenum to break proteins into amino acids.

What is enterokinase?

An enzyme in the duodenum that activates trypsinogen into trypsin, which then activates other protein-digesting enzymes.

How does the pancreas help digest fats?

It releases pancreatic lipase (with colipase) to break fats into fatty acids and monoglycerides

Why is bile important for fat digestion?

Bile emulsifies fats, making it easier for pancreatic lipase to work effectively.

What is the role of bicarbonate in pancreatic juice?

It neutralizes stomach acid in the duodenum, creating the right pH for enzymes to function

What hormone stimulates the pancreas to release enzymes?

CCK(cholecystokinin).

What hormone stimulates the pancreas to release bicarbonate?

Secretin

Where does the pancreas mainly act in digestion?

In the duodenum, where its enzymes mix with chyme.

Which hormone is responsible for stimulating the pancreas to release bicarbonate into the duodenum?

Secretin

A patient has a genetic mutation that prevents the production of enterokinase in the small intestine.

Which process of chemical digestion will be most directly impaired by this deficiency?

Protein breakdown

What are the main salivary glands?

Parotid

submandibular

sublingual

What is saliva?

A watery fluid containing mucus, salivary amylase, buffers, and protective (antibacterial) substances.

How does saliva help with swallowing?

Mucus lubricates food and forms a smooth bolus so it can move easily down the esophagus.

What is a bolus?

A soft, rounded mass of chewed food ready to be swallowed

How does saliva begin chemical digestion?

Salivary amylase breaks down starch into smaller carbohydrates (like maltose).

Why does salivary amylase work in the mouth?

The mouth has a near-neutral pH, which allows the enzyme to function.

What happens to salivary amylase in the stomach?

It stops working because stomach acid inactivates it

How does saliva protect the mouth?

It contains buffers and antibacterial substances that neutralize acids and protect teeth and tissues

How does saliva help trigger swallowing?

Saliva and chewing activate sensory signals that start the swallowing reflex

What is the overall role of saliva?

It lubricates food, begins carbohydrate digestion, protects the mouth, and helps initiate swallowing.