BIOS 256 Week 1 Lab A&P IV Digestive System Upper GIT

Part A: Histology of the Digestive Tract

In this lab, you will examine four different slides under a microscope and describe the various cells present in them. The four slides are the sub-mandibular gland, taste bud, esophagus, and stomach.

To complete this lab, you should observe each slide under various magnifications and take two pictures of each slide, identifying important structures in the sections. You can use online resources like real anatomy to help you label the structures you see in the slides.

BIOS 256 Week 1 Lab A&P IV Digestive System Upper GIT

Sub-mandibular gland

This slide shows the sub-mandibular gland, which is a salivary gland located beneath the mandible. The gland is composed of several different types of cells, including serous cells, mucous cells, and my epithelial cells. Serous cells produce a watery secretion that contains enzymes such as amylase, while mucous cells produce a thick, sticky substance that helps to lubricate the mouth and throat during swallowing. My epithelial cells help to squeeze the gland and release its secretions.

Taste bud

This slide shows a cross-section of a taste bud, which is a sensory organ located on the tongue and other parts of the mouth. Taste buds are made up of several different types of cells, including taste receptor cells, supporting cells, and basal cells. Taste receptor cells are responsible for detecting different tastes, such as sweet, sour, bitter, and umami. Supporting cells provide structural support and help to regulate the activity of the taste receptor cells, while basal cells are responsible for replenishing the other types of cells in the taste bud.

Esophagus

This slide shows a cross-section of the esophagus, which is a muscular tube that connects the pharynx to the stomach. The esophagus is composed of several layers of cells, including stratified squamous epithelium, smooth muscle, and connective tissue. Stratified squamous epithelium is the outermost layer of cells and helps to protect the underlying tissue from damage caused by food and other substances. Smooth muscle helps to propel food down the esophagus and into the stomach, while connective tissue provides structural support.

Stomach

This slide shows a cross-section of the stomach, which is a muscular sac that receives food from the esophagus and begins the process of digestion. The stomach is composed of several layers of cells, including simple columnar epithelium, smooth muscle, and gastric glands. Simple columnar epithelium lines the inner surface of the stomach and produces mucus, which helps to protect the stomach from the acidic environment. Smooth muscle helps to mix and churn the food, while gastric glands secrete digestive enzymes and hydrochloric acid to break down the food into smaller molecules.

BIOS 256 Week 1 Lab A&P IV Digestive System Upper GIT

Part B: Upper GI tract identification

Identify all the structures of the upper GI tract on the torso model or in Real Anatomy by going layer by layer. Then, provide three pictures of three different organs from the GI tract. Feel free to also include pictures of organs from the lower GI tract. Submission: Three pictures of three different organs with descriptions.

TONGUE

The tongue is a fleshy muscular structure in the mouth used for tasting via taste buds, swallowing, and speaking. It is attached to the floor of the mouth and has various muscles that allow it to move in different directions. Taste buds on the tongue’s surface detect sweet, salty, sour, and bitter flavors, among others.

ESOPHAGUS

The esophagus is a muscular tube-like structure that connects the pharynx to the stomach. It begins below the trachea and descends behind the heart to connect to the stomach. The esophagus is lined with a protective layer of flattened tissues and has circular and longitudinal muscles that help push the chewed food down to the stomach.

STOMACH

The stomach is a muscular, sac-like organ located in the upper abdomen. It is divided into three regions: the fundus, the body, and the pylorus. The fundus is the uppermost part of the stomach, while the body is the middle section, and the pylorus is the lower part of the stomach that connects to the duodenum. The stomach’s muscular walls contract and mix food with digestive juices, breaking it down into a semi-liquid mixture called chime. The stomach also secretes acid and enzymes to help with digestion.

Description

The picture shows a frontal view of the stomach, with its three regions visible. The stomach’s muscular walls are visible, along with its internal folds, which help mix and break down food. The pyloric sphincter, which regulates the release of food into the duodenum, is also visible.

BIOS 256 Week 1 Lab A&P IV Digestive System Upper GIT

Part C: Starch Digestion in the Mouth

Break two squares of a cracker, each approximately a 1/2-inch square. Place one square on your tongue without chewing or swallowing it. Time how long it takes for you to taste sweetness. (A) – 40 seconds Swallow the cracker and rinse your mouth with water. Place the other square in your mouth and chew it without swallowing. Time how long it takes for you to taste sweetness. (B) – 20 seconds Calculate the difference in time to taste sweetness for the chewed cracker and compare it to the time taken to taste sweetness for the whole cracker. (A-B) = 20 seconds Pool your results with one of your classmates and calculate the following averages:

• Average time to taste sweetness for whole cracker: 39.5 seconds.
• Average time to taste sweetness for chewed cracker: 15 seconds.
• Average difference in time to taste sweetness of chewed cracker compared with whole cracker:

Explain why there is a difference in average time to taste sweetness between the whole cracker and chewed cracker. The chewed cracker undergoes both mechanical and chemical digestion, which breaks down the cracker into smaller particles and increases the surface area for the enzymes to act on. This speeds up the digestion process and shortens the time it takes to taste sweetness. Compare your results with your friend’s results and explain any differences. Think how conditions in your mouth may differ from other students in the class. List all possible differences.

Differences in the time taken to taste sweetness can be due to variations in saliva composition, oral pH levels, oral hygiene, individual taste sensitivities, and chewing techniques. Additionally, factors such as smoking, alcohol consumption, and certain medications can affect the digestion process in the mouth.