BIOS 256 Week 1 Lab Worksheet

Grace J.
August 6, 2025August 6, 2025
BIOS-256, CU BSN

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 worksheet is based on Lab Manual Exercise 34, which focuses on the structure and function of the digestive system. Students are expected to work through Lab Activities 1–9 (pages 561–582), then complete the “Reviewing Your Knowledge” and “Using Your Knowledge” sections. After completing the worksheet, save the file using the naming convention lastname_iLab1 and submit it to the Week 1 Lab Dropbox.

Part 1: Reviewing Your Knowledge

Layers of the Gastrointestinal Tract

The gastrointestinal (GI) tract consists of four primary layers, each with specialized functions:

Layer	Description
Mucosa	The innermost layer involved in secretion and absorption; contains the lamina propria.
Lamina propria	A connective tissue layer within the mucosa that supports capillaries and lymphatic vessels.
Muscularis	Responsible for peristaltic movement through smooth muscle contractions.
Serosa	The outermost layer that reduces friction between digestive organs and surrounding structures.

Gastrointestinal Tract Organs

The following are the major organs involved in the digestive process:

Organ	Function
Mouth	Mechanical and chemical breakdown of food begins here.
Pharynx	Serves as a pathway for the movement of food from the mouth to the esophagus.
Esophagus	Transports food to the stomach via peristalsis.
Stomach	Breaks down food using enzymes and acids.
Duodenum	The first part of the small intestine where digestion continues.
Small intestine	Main site for digestion and nutrient absorption.
Large intestine	Absorbs water and forms feces.
Anus	Terminal opening of the GI tract for waste excretion.
Alimentary canal	Continuous tube from mouth to anus where digestion and absorption occur.

Digestive Organ Structures

Structure	Function
Villi / Microvilli	Increase surface area for absorption in the small intestine.
Plica circularis	Circular folds that slow food movement to maximize absorption.
Rugae	Folds in the stomach that allow expansion when food enters.
Pyloric valve / Pylorus	Regulates passage of chyme from stomach to duodenum.
Parietal / Visceral peritoneum	Layers of the peritoneum that cover abdominal organs and line the cavity.
Ileocecal sphincter	Controls movement from the small intestine to the large intestine.
Saliva	Contains enzymes that initiate digestion in the mouth.
Hard / Soft palate	Form the roof of the mouth; aid in food manipulation and swallowing.
Vestibule	Space between the lips/cheeks and the teeth.
Cardiac	Refers to the cardiac sphincter that prevents reflux of stomach contents.
Colon (large intestine)	Involved in water absorption and stool formation.
Haustra	Pouches of the colon that help in segmenting and moving waste.

Accessory Digestive Organs and the Peritoneum

Organ / Structure	Function
Teeth / Tongue	Aid in mechanical digestion and taste.
Salivary glands (Parotid, Sublingual, Submandibular)	Produce saliva for digestion and lubrication.
Liver	Produces bile for lipid digestion and detoxifies blood.
Gallbladder	Stores and concentrates bile before releasing it into the duodenum.
Pancreas	Secretes digestive enzymes and hormones such as insulin.
Mesentery / Omentum (Greater and Lesser)	Hold organs in place and contain blood vessels and nerves.
Falciform ligament	Anchors the liver to the anterior abdominal wall.

Trace Bile from Its Secretion to the Duodenum

Question: Trace bile from its secretion to the gallbladder for storage and concentration, and then to the duodenum, listing the structures in order, using Figure 34.9

Answer:
Bile is produced in hepatocytes within the liver and travels through bile ducts to the common hepatic duct. From there, it enters the cystic duct and is stored in the gallbladder. Upon stimulation, bile exits via the cystic duct, joins the common bile duct, and is released into the duodenum for fat emulsification.

Trace Blood Flow Through the Liver

Question: Trace blood from the hepatic portal vein through the liver to the inferior vena cava, listing the structures in order, using Figure 34.11

Answer:
Blood enters the liver through the hepatic portal vein and flows into the liver sinusoids for detoxification and nutrient processing. It then passes into the central vein, continues to the hepatic vein, and finally drains into the inferior vena cava.

Using Your Knowledge

Digestive System Structure

Concept	Description
Digestive enzymes	Catalyze the breakdown of macromolecules into absorbable units.
Hormonal regulation	Involves hormones like gastrin, secretin, and cholecystokinin (CCK) to coordinate digestion by signaling various organs.

Identification of Digestive System Structures

Structure	Role
Oral cavity	Beginning of digestion; mechanical and enzymatic activity occurs.
Esophagus	Propels food via peristalsis from the throat to the stomach.
Stomach	Performs both chemical digestion and mechanical mixing.
Small intestine	Main site for enzymatic digestion and nutrient absorption.
Large intestine	Reabsorbs water and prepares undigested food for elimination.
Accessory organs	Assist digestion (e.g., liver, pancreas, gallbladder, salivary glands).
Sphincters	Control movement of contents between different digestive segments.
Mucosal layers	Composed of epithelial tissue aiding in secretion and absorption.

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

This virtual lab investigates how dietary fiber influences digestive transit time and bile recycling. Students are required to complete the lab activity in PowerPhys under Course Home, record their results, and analyze how fiber impacts digestion. The completed file should be saved under the folder lastname_iLab1 and submitted to the Week 1 Lab Dropbox.

References

Marieb, E. N., & Smith, L. A. (2019). Human Anatomy & Physiology Laboratory Manual (13th ed.). Pearson.

OpenStax. (2023). Anatomy and Physiology. OpenStax, Rice University. https://openstax.org/books/anatomy-and-physiology/pages/preface