Digestive lab

Identify the enzyme secreted by the salivary glands that begins the digestion of starch.

-Amylase. Also lubricates the mouth to help soften food.

Explain mastication and its role in the digestion of food

-Mastication is the chewing of food, chewing breaks down food particles into smaller pieces so that they may be better digested.

o Identify the class of carbohydrates absorbed by the small intestine.

-Monosaccharides are absorbed into the blood

What substances from the exocrine pancreas are released into the duodenum? their function?

Bicarbonate is released, helps in neutralizing the stomach acid. This is essential because the small intestine can't withstand the strong acids from the stomach

What is the function of the mucosal cells that line gastrointestinal structures?

Lubricates and protects the organ from abrasive particles (sharp food) and bodily fluids (gastric acid).

What events take place in the small intestine

Most digestion of macromolecules and absorption of nutrients, water, and electrolytes.

How is the stomach protected from acidic gastric juices (HCl)?

Mucous forms a physical barrier against HCL and it contains high volumes of bicarbonate, which helps to neutralize the acid when it comes in contact with your stomach lining. Because of this advanced system, hydrochloric acid can perform its job without hurting you.

PHYSIOLOGY PART

PHYSIOLOGY PART

What nutrients are digested by pepsin and how does acidic gastric juices affect its function?

Pepsin breaks down proteins in the small intestine into smaller subunits, amino acids. Acidic gastric juices essentially turn on pepsin, allowing for the break down of proteins into amino acids.

How does acidic gastric juices affect pepsin?

Pepsinogen (inactive form) is activated by the acidic environment (gastric jucies) which consist of low PH and high amounts of hydrogen ions within the stomach. Acidic gastric juices essentially turn on pepsin, allowing for the break down of proteins into amino acids.

Function of the large intestine

Primarily absorbs water, electrolytes and vitamins. The process is completed when the semifluid mass of partly digested food is converted to feces and then eliminated through the anus (sigmoid colon).

· Describe the ducts that carry bile and pancreatic juices to the duodenum.

The accessory pancreatic duct is a smaller duct where limited amounts of pancreatic juice enter the duodenum. The cystic duct + the common hepatic duct = common bile duct. The common bile duct carries bile from the liver and gallbladder and into the intestines to break down food for digestion.

o Describe the activation of these proteases.

The acidity of the stomach (HCL) activates these enzymes. Pepsinogen -> pepsin. Trypsinogen -> trypsin

·Describe the exocrine pancreas

The exocrine pancreas is a gland that produces digestive enzymes and bicarbonate.

Organs of the GI tract

oral cavity, esophagus, stomach, small intestine, large intestine (all organs that come in contact with food)

Identify circular folds and how they aid in digestion

the biggest, noticeable to the eye. Acting as "speed bumps" to slow down the movement of chyme and to make sure it remains within the small intestine for maximal nutrient absorption.

o Identify the digestion product of lipids that is absorbed by the small intestine

-Monoglycerides and fatty acids

Identify the structures secreting amylase.

Amylase is released from the salivary glands into the oral cavity (salivary amylase) and from the exocrine portion of the pancreas as pancreatic amylase into the duodenum

What is bile? its function?

Bile is a liquid produced by your liver and is stored in the gallbladder. When prompted, bile is released from your gallbladder into your duodenum and intestines. Your body uses bile to break down fats, absorb vitamins, and remove wastes your body does not need. Lipids that are ingested trigger the gallbladder to release bile into the duodenum.

How does mastication help the digestion process?

Chewing increases surface area for additional exposure to chemical digestion. Promotes salivation to soften and moisten food.

What are the enzymes released by chief cells that go into the stomach?

Pepsinogen, active form is pepsin

Function of the oral cavity

Where mastication begins, saliva is secreted from the salivary glands in response to food being present in within the oral cavity. It is mixed with ingested materials to form the wet mass called bolus. Amylase, initiates the chemical digestion of starch.

Identify villi and how they aid in digestion

a small finger-like projection of the simple columnar epithelium. Aids in digestion by increasing the surface area of the epithelial lining through which nutrients are absorbed lined on the inside of the duodenum.

Function of the esophagus

serves to pass foods and liquids from the mouth to the stomach

Function of the stomach

to digest food and send it to the small intestine

· Explain the impact of a reduction in temperature on chemical digestion.

A reduction of temperature will inhibit enzymes from working properly. Maintaining an internal body temperature is important to chemical digestion in order to keep enzymes functioning optimally

What does the small intestine receive from the stomach?

Receives acidic chyme from the stomach that is then mixed with bile released from the gallbladder and pancreatic juices.

o Describe the digestion of carbohydrates by amylase.

Salivary amylase begins the process of starch (polysaccharide) digestion by breaking the bonds between glucose molecules resulting in shorter glucose chains. Salivary amylase begins digestion of starch, no carbohydrate digestion happens in the stomach, HCL breaks down salivary amylase.

What organs are considered accessory digestive organs?

Salivary glands, pancreas, liver, and gallbladder.

Describe the role of bile and lipases in the digestion of triglycerides

-Bile contains bile salts, these bile salts emulsifies fats, into smaller micelles -Lipase break triglyceride into diglycerides into fatty acid, then it breaks diglyceride into monoglyceride

· Identify the three classes of carbohydrates.

-Monosaccharides, disaccharides, and polysaccharides.

· Describe the muscular contraction propelling ingested food along the esophagus.

-Peristalsis, which is a wave contraction to move food downward through the stomach and then the digestive tract.

Describe the action of a protease on a protein

-Protease are enzymes in pancreatic juice that must be activated. Helps break down protein food into amino acids, the body uses amino acids for energy.

o Describe the impact of gastric acidity on amylase function.

-Salivary amylase is deactivated by HCL in the stomach, low PH is produced by gastric acid.

o Identify the digestion product of proteins that is absorbed by the small intestine

-Single amino acids

o Identify the structures secreting inactive proteases (pepsinogen and trypsinogen).

-Stomach and small intestine

Identify the enzymes that digest disaccharides and their location in the small intestines.

-The brush border enzymes digest disaccharides and they are lined all along the small intestine. (S.I. tract)

· Identify the two classes of lipids.

-Triglycerides (a glycerol molecule and 3 fatty acids) and cholesterol (not broken down, absorbed as is).

o Identify the direct impact of HCl on the digestion of a protein (beyond protease activation).

-low ph denatures proteins, denaturing an enzyme breaks down the chemical bonds that hold the structure together.

Function of the small intestine

To churn and mix ingested food passed on from the stomach. Receives acidic chyme from the stomach that is then mixed with accessory digestive organ secretion (bile). Most digestion of macromolecules and absorption of nutrients, water, and electrolytes.

Identify microvilli and how they aid in digestion

To further increase the surface area of the small intestine. They are projections off of villi, the brush border inside the duodenum. Helps to complete the chemical digestion of most nutrients immediately before absorption.