Chapter 2

What are the accessory organs of digestion?

An organ that helps with digestion but is not part of the digestive tract. The accessory digestive organs are the tongue, salivary glands, pancreas, liver, and gallbladder.

What is the role of the large intestine in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Does it have any muscle movements? If so, which ones and what is their purpose?

Any food that is incompletely broken down & the food's indigestible fiber content move from the small intestine to the large intestine (colon) through a connecting valve. Main task is to absorb much of the remaining water. No further chemical or mechanical breakdown of food takes place unless it is accomplished by the bacteria that inhabit this portion of the intestinal tract. # of bacteria residing in large intestine is > 1014

What is the role of the esophagus in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Does it have any muscle movements? If so, which ones and what is their purpose?

As the bolus travels through the pharynx, a small flap called the epiglottis closes to prevent choking by keeping food from going into the trachea. peristalsis in the esophagus propel the food bolus down to the stomach. The sphincter muscle remains closed until food bolus approaches. The pressure of the food bolus stimulates the lower esophageal sphincter to relax and open and food then moves from the esophagus into the stomach.

What is the role of the stomach in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Does it have any muscle movements? If so, which ones and what is their purpose?

Food is accentuated by the muscular contractions of the stomach and small intestine that mash, mix, slosh, and propel food down the alimentary canal. When food enters the stomach, peristaltic contractions help mash, pulverize, and churn food into chyme-is a semi liquid mass of partially digested food that also contains gastric juices secreted by cells in the stomach. These gastric juices contain hydro chloric acid and the enzyme pepsin, that chemically start breakdown of the protein components of food.

Where do water and other nutrients get absorbed?

Liver via the portal vein; and large intestine

How are nutrients broken down in the small intestine? How are they absorbed? What food components are NOT absorbed or digested?

Nutrient absorption takes place mainly in the remaining length of the small intestine, or ileum. The surface area is increased by folds, villi, and microvilli. Digested nutrients are absorbed into either capillaries or lymphatic vessels contained within each microvillus. Amino acids, short fatty acids, and monosaccharides (sugars) are transported from the intestinal cells into capillaries, but the larger fatty acids, fat-soluble vitamins, and other lipids are transported first through lymphatic vessels, which soon meet up with blood vessels.

What is the role of the small intestine in digestion? What are its different segments called? Does it produce digestive fluids? If so, which ones and what do they do? Does it have any muscle movements? If so, which ones and what is their purpose?

Once the Chyme enters the duodenum, the pancreas and gallbladder are stimulated and release juices that aid in digestion. Peristalsis and segmentation, control the movement and mixing of the food in various stages of digestion through the small intestine.

What are the muscle movements associated with digestion including peristalsis and segmentation?

Peristalsis - Smooth muscle tissue surrounds the digestive tract and its contraction produces waves, known as peristalsis, that propel food down the tract. Segmentation - from circular muscle contraction slows movement in the small intestine by forming temporary type of segments that allows chyme to slosh food back and forth in both directions to promote mixing of the chyme and enhance absorption of nutrients.

What is the role of the liver in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Where is it found in the body?

Regulate Metabolic Homeostasis - nutrient energy intake equals energy output. Whereas glucose and amino acids are directly transported from the small intestine to the liver, lipids are transported to the liver by a more circuitous route involving the lymphatic system. The lymphatic system is a one-way system of vessels that transports lymph, a fluid rich in white blood cells, and lipid soluble substances after a meal containing lipids. The lymphatic system slowly moves its contents through the lymphatic vessels and empties into blood vessels in the upper chest area.

What are prebiotics and probiotics? What are their benefits?

The World Health Organization defines probiotics as live bacteria that confer beneficial health effects on their host. They are sometimes called "friendly bacteria." The most common bacteria labeled as probiotic is lactic acid bacteria (lactobacilli). Prebiotics are indigestible foods, primarily soluble fibers, that stimulate the growth of certain strains of bacteria in the large intestine and provide health benefits to the host.

What is the role of the gallbladder in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Where is it found in the body?

The gall bladder secretes a much smaller amount of a fluid called bile that helps to digest fats. Bile passes through a duct that joins the pancreatic ducts and is released into the duodenum. Bile is made in the liver and stored in the gall bladder.

What is the role of microbes in our large intestine?

The many bacteria that inhabit the large intestine can further digest some material, creating gas. Bacteria in the large intestine also make some important substances, such as vitamin K, which plays an important role in blood clotting.

What is the role of the mouth in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Does it have any muscle movements? If so, which ones and what is their purpose?

The mouth is the 2nd part of the digestion process. It starts with mastication (chewing) in the mouth. Teeth crush and grind large food particles, while saliva provides lubrication and enables food movement downward. slippery mass of partially broken-down food is called a bolus, which moves down the digestive tract as you swallow. The bolus is pushed from the mouth through the pharynx and into a muscular tube called the esophagus.

What is the role of the pancreas in digestion? Does it produce digestive fluids? If so, which ones and what do they do? Where is it found in the body?

The pancreas secretes 1.5 liters of pancreatic juice a day, mostly water, also contains bicarbonate ions, which derive enzymes and chyme that break down carbs, fats, proteins.

In your own words describe how the process of digestion takes place. For example, where does it begin? What organs are involved and what does each of them do? How is the food broken apart?

The process of digestion begins with the mouth and ends with the anus. The mouth, pharynx, esophagus, stomach, small intestine, large intestine (colon), rectum, and anus are used. Food is broken down mechanically -to move and mix ingested foods- and chemically -to break down large molecules.