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What are the undigested residues at the final stage of digestion?

Fatty acids, fibers, cholesterol, bile acids, minerals, additives, contaminants, and water.

What is the role of undigested residue in the colon?

It exercises intestinal muscles.

What is the microbiome in the colon?

It refers to the bacteria present throughout the GI tract.

What happens when bacteria ferment fiber in the colon?

Bacteria produce water, gas, and small fat fragments, which are used by colon cells for energy.

How many microbes are housed in the GI tract?

About 100 trillion microbes, including bacteria, viruses, fungi, and protozoa.

What are the two main bacterial species in the GI tract?

Firmicutes and Bacteriodites.

How does microbial composition vary in the GI tract?

It varies based on pH, peristalsis, diet, and the presence of other microbes.

Why are there fewer microbes in the stomach compared to the intestines?

The stomach has fewer microbes due to its acidic environment.

Why do the intestines support a diverse microbial population?

The intestines have a neutral pH and slower peristalsis, which create a favorable environment for microbial growth.

What do microbes in a healthy GI tract digest?

Microbes digest fibers and complex proteins.

How do microbes in a healthy GI tract affect the immune system?

Microbes modify immune status.

What do microbes in the GI tract secrete?

Microbes secrete neurotransmitters.

How do microbes protect the body?

Microbes protect against infection.

What do microbes in the GI tract do to chemicals?

Microbes detoxify chemicals.

What do microbes in the GI tract produce?

Microbes produce compounds that affect physiological systems elsewhere in the body.

What diseases may microbes in the GI tract play a role in?

Inflammation-related diseases like heart disease, arthritis, autoimmune conditions, and GI problems.

What links have been found between microbiota composition and brain function?

There are links between microbiota composition, brain biochemistry, and behaviors.

How can psychological and physical stress affect the microbiota?

Stressors can affect the composition and metabolic activity of the gut microbiota.

What impact can experimental changes to the gut microbiome have?

They can affect emotional behavior and related brain systems.

What brain diseases may be affected by the gut microbiome?

Autism, anxiety, depression, and chronic pain.

How does the gut microbiome differ in obese vs non-obese people?

Differences exist in the microbiota composition between obese and non-obese individuals.

What vitamins are produced by GI bacteria?

GI bacteria produce biotin, folate, pantothenic acid, riboflavin, thiamin, B12, B6, Vitamin K, and others.

What is homeostasis?

Homeostasis is the maintenance of constant internal conditions in the body.

How does digestion relate to homeostasis?

Digestion is an example of homeostatic regulation, as it helps maintain balance in the body.

Which systems coordinate digestive processes?

The endocrine and nervous systems coordinate all digestive processes.

What is a feedback mechanism in digestion?

A feedback mechanism involves a response that changes the initial condition, such as the stomach's pH, and then turns off once the desired state is reached.

What hormone is secreted when food enters the stomach?

Gastrin is secreted when food enters the stomach.

What is the function of gastrin?

Gastrin stimulates stomach glands to secrete hydrochloric acid, which maintains an acidic pH in the stomach.

What hormone is released when acidic chyme enters the small intestine?

Secretin is released when acidic chyme enters the small intestine.

What is the function of secretin?

Secretin stimulates the pancreas to release bicarbonate-rich juice, which helps maintain a slightly alkaline pH in the small intestine.

What hormone is secreted when fat or protein enters the small intestine?

Cholecystokinin (CCK) is secreted when fat or protein enters the small intestine.

What are the functions of CCK?

CCK stimulates the gallbladder to release bile for emulsifying fat, and the pancreas to release bicarbonate and enzyme-rich juices for digestion. It also slows GI tract motility.

What does CCK target in the digestive system?

CCK targets the gallbladder to release bile.

What hormone is released when there is a lack of food?

Ghrelin is released when there is a lack of food.

What does ghrelin signal?

Ghrelin signals the brain to initiate the next eating episode and stimulates GI motility.

What are the key defense mechanisms of the GI tract?

The GI tract's cells, bacteria, and secretions (saliva, mucus, gastric acid, enzymes) help defend against diseases.

Why is steady blood flow important for the GI tract?

Steady blood flow is essential for the GI tract to function properly; reduced blood supply (intestinal ischemia) can cause pain, urgent bowel movements, and blood in stool.

How does sleep affect digestive health?

Sleep helps tissue repair and waste removal, supporting overall digestive health.

What is the role of physical activity in digestive health?

Physical activity maintains healthy muscle tone, which is important for proper digestion and motility.

How does stress impact the digestive system?

Stress disrupts GI motility, secretions, blood flow, and microbiota, which can impair digestion. Relaxed meals help aid digestion.

How does diet impact digestive health?

A balanced diet in moderation helps avoid excess or insufficient intake of nutrients. A variety of foods is important to avoid inhibition of nutrient absorption, and ensuring adequacy of all essential nutrients, fiber, and energy is crucial for digestive health.