Anatomy Digestive System Unit

What is peristalsis, and in which organs does it occur?

Peristalsis is wave-like muscular contractions that push food through the digestive tract. It occurs in the esophagus, stomach, small intestine, and large intestine.

Compare and contrast mechanical and chemical digestion. Give at least 2 examples of each.

Mechanical: physically breaks food down (chewing, stomach churning). Chemical: uses enzymes/acids (salivary amylase breaks starch, pepsin breaks proteins).

Where does absorption of nutrients and water take place?

Nutrients are absorbed in the small intestine. Water is absorbed in the large intestine.

What accessory organs are associated with the digestive system?

Liver, pancreas, and gallbladder.

What are the three main functions of the digestive system?

1) Digestion 2) Absorption 3) Elimination

What valve opens from the esophagus to the stomach?

The cardiac sphincter (lower esophageal sphincter).

What valve opens from the stomach to the small intestine?

The pyloric sphincter.

The blank system refers to the liver, pancreas, and gallbladder.

The hepatic (accessory) system.

What digestive enzyme is produced by the salivary glands?

Salivary amylase — breaks down starches.

The part of the stomach slightly above the esophagus is called the blank region.

The cardiac (cardia) region.

What is lactose intolerance? What enzyme is missing?

The inability to digest lactose due to a deficiency of the enzyme lactase.

What is food called after it has been broken down into a paste?

Chyme.

What are the folds inside the stomach called?

Rugae.

Trace the path of food through the large intestine.

Cecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum, Anus.

What are the functions of the pancreas?

Produces digestive enzymes, bicarbonate to neutralize acid, and hormones insulin and glucagon.

After bile is stored, where does it go?

Released from the gallbladder through the bile duct into the duodenum.

What are the functions of the liver?

Produces bile, detoxifies blood, metabolizes nutrients, stores glycogen, produces blood proteins, regulates cholesterol.

Which section is the longest and how does its length help its function?

The small intestine (~20 feet). Length increases surface area and time for nutrient absorption.

What is the function of the gallbladder?

Stores and concentrates bile, releases it to emulsify fats in the small intestine.

What is the function of bile?

Emulsifies fat globules into smaller droplets so lipase can digest them.

What is the function of the stomach?

Churns food with HCl and pepsin to begin protein digestion and form chyme.

What is the function of the intestinal villi?

Increase surface area of the small intestine to maximize nutrient absorption.

What causes Celiac disease and what is the result?

Triggered by gluten; immune system attacks the villi causing malabsorption of nutrients.

Where is the cecum located? What useless structure is attached to it?

At the junction of the small and large intestine. The appendix is attached to it.

What part of the system stores waste prior to elimination? Is it useless?

The rectum. It is NOT useless — it controls when waste is eliminated.

What is the function of the large intestine? If it fails, what sickness results?

Absorbs water and electrolytes to form feces. Failure causes diarrhea or constipation.

What substance is mainly responsible for breaking down fats?

Bile (emulsification) and pancreatic lipase (chemical digestion).

What substance is created in the stomach and breaks down food?

Hydrochloric acid (HCl) and the enzyme pepsin.

What hormone influences the amount of stomach acid produced?

Gastrin — produced by stomach G-cells, stimulates HCl production.

Label the 13 structures of the digestive system in order of food travel.

Mouth, Esophagus, Stomach, Liver, Gallbladder, Pancreas, Duodenum, Jejunum, Ileum, Ascending colon, Transverse colon, Sigmoid colon, Rectum/Anus.

Explain denaturation. What two things can cause an enzyme to denature?

Denaturation is when an enzyme's shape is permanently altered so it can't function. Causes: extreme heat and extreme pH.

How do enzymes affect chemical reactions? What do they do to activation energy?

Enzymes speed up reactions by lowering the activation energy required. They are biological catalysts.

How do inhibitors affect chemical reactions? What do they do to activation energy?

Inhibitors slow or block reactions by preventing substrate binding, raising the activation energy needed.

What factors affect reaction rate for biological molecules?

Temperature, pH, substrate concentration, enzyme concentration, and presence of inhibitors.

Why are enzymes essential to the human body?

They catalyze nearly every reaction needed for life. Without them reactions would be too slow to sustain life.