BIOS 256 Week 1 Lab Worksheet

Student Name

Chamberlain University

BIOS-256: Anatomy & Physiology IV with Lab

Prof. Name

Date

Week 1 Lab Worksheet

Lab Manual Exercise 34: Digestive System Structure and Function

This week’s lab focuses on the digestive system, exploring both the anatomical structures and the physiological functions involved in digestion. Students are required to complete Lab Activities 1–9 (pages 561–582) to prepare for the “Reviewing Your Knowledge” and “Using Your Knowledge” sections. Once completed, the form should be downloaded, saved with the filename lastname_iLab1, and submitted to the Week 1 Lab Dropbox.

Part 1: Reviewing Your Knowledge

A. Layers of the Gastrointestinal Tract

The gastrointestinal (GI) tract is made up of several distinct layers, each playing a crucial role in the digestion and absorption of nutrients.

Layer	Description
Muscularis	Responsible for peristaltic movement and mechanical digestion.
Mucosa	Innermost layer that secretes mucus and absorbs nutrients.
Lamina propria	Connective tissue that supports blood vessels, lymphatics, and immune cells.
Serosa	Outermost protective layer that reduces friction with surrounding structures.

B. Gastrointestinal Tract Organs

The organs of the GI tract, also known as the alimentary canal, are specialized for transporting, digesting, and absorbing nutrients.

Organ	Function
Esophagus	Conducts food from pharynx to stomach using peristalsis.
Pharynx	Passageway for food and air; involved in swallowing.
Mouth	Begins mechanical digestion and mixes food with saliva.
Stomach	Stores food, mixes it with gastric juices, and initiates protein digestion.
Small Intestine	Primary site of nutrient digestion and absorption.
Duodenum	First section of the small intestine; receives chyme and digestive enzymes.
Large Intestine	Absorbs water and electrolytes, forms feces.
Anus	Eliminates waste from the body.

C. Digestive Organ Structures

The digestive system is supported by various structural components that aid in digestion.

Structure	Function
Villi & Microvilli	Increase surface area for absorption in the small intestine.
Rugae	Folds in the stomach that allow expansion after eating.
Plica circularis	Circular folds in small intestine enhancing absorption.
Pyloric valve/pylorus	Controls the passage of chyme into the duodenum.
Peritoneum (parietal & visceral)	Protective membrane layers surrounding abdominal organs.
Ileocecal sphincter	Regulates passage of contents from small intestine to large intestine.
Hard & Soft palate	Structures in the oral cavity aiding speech and swallowing.
Vestibule	Space between lips/cheeks and teeth/gums.
Colon & Haustra	Segments in the large intestine that contract to aid in fecal movement.
Cardiac region	Entryway of stomach near esophagus.
Saliva	Secreted fluid that begins chemical digestion and lubricates food.

D. Accessory Digestive Organs and the Peritoneum

Accessory organs support digestion by producing enzymes, bile, and other secretions essential for nutrient breakdown.

BIOS 256 Week 1 Lab Worksheet

Organ/Structure	Function
Teeth	Mechanically break down food.
Tongue	Assists in chewing, swallowing, and taste perception.
Salivary glands (parotid, submandibular, sublingual)	Secrete saliva with enzymes for carbohydrate breakdown.
Liver	Produces bile for fat emulsification.
Gallbladder	Stores and concentrates bile.
Pancreas	Produces digestive enzymes and bicarbonate.
Mesentery	Supports and supplies blood to the intestines.
Greater & Lesser omentum	Fatty layers providing protection and immune defense.
Falciform ligament	Connects liver to the anterior abdominal wall.

Trace of Bile Flow

Question: Trace bile from its secretion to the gallbladder for storage and concentration, and then to the duodenum, listing the structures in order.

Answer:
Bile is secreted by hepatocytes, travels through the bile ducts, and passes into the common hepatic duct. From here, it may flow into the cystic duct for storage in the gallbladder. During digestion, bile is released from the gallbladder into the common bile duct, which delivers it into the duodenum to assist in fat digestion.

Trace of Blood Flow in the Liver

Question: Trace blood from the hepatic portal vein through the liver to the inferior vena cava, listing the structures in order.

Answer:
Blood enters the liver via the hepatic portal vein and moves through the liver sinusoids, where nutrient exchange occurs. From there, it collects in the central vein, drains into the hepatic vein, and finally exits into the inferior vena cava, returning to systemic circulation.

Part 1: Using Your Knowledge

A. Digestive System Structure

The digestive system relies on two essential processes for effective function:

Digestive enzymes – Secreted by organs such as the pancreas, salivary glands, and stomach, enzymes chemically break down macronutrients into absorbable units.
Hormonal regulation – Hormones such as gastrin, secretin, and cholecystokinin coordinate the release of enzymes and bile, regulate motility, and maintain homeostasis within the system.

B. Identification of Digestive System Structures

Key structures within the digestive system include the oral cavity, esophagus, stomach, small intestine, large intestine, accessory organs (liver, gallbladder, pancreas), sphincters, and the mucosal layers that facilitate digestion and absorption.

Part 2: PowerPhys #14: Effect of Dietary Fiber on Transit Time and Bile

For this activity, follow the PowerPhys instructions under Course Home. After completing all required sections, save the results under the filename lastname_iLab1 and submit them in the Week 1 Lab Dropbox. This lab helps students understand how dietary fiber influences digestive transit time and bile circulation, highlighting the importance of fiber in maintaining healthy bowel movements and reducing cholesterol levels.

References

Marieb, E. N., & Hoehn, K. (2019). Human anatomy & physiology (11th ed.). Pearson.
OpenStax. (2022). Anatomy and physiology. OpenStax, Rice University. https://openstax.org/books/anatomy-and-physiology