Lab: Enzymatic Digestion of Foods + Digestive Organ Table

What molecule is the precursor of pepsin and the cell that produces it?

pepsinogen; chief cells

How are chief cells activated into pepsin?

HCl in the stomach

1. What molecule does pepsin hydrolyze (break down)? (What is its substrate?)


2. Products?

1. **Proteins** → albumin in this experiment (protein digestion by pepsin)
2. **Peptides**

Optimal pH for hydrolysis reaction (proteins → peptides)?

Cells that produce the chemical to provide optimal pH?

pH 2; parietal cells

How did the pH of the solution change after pepsin digestion (hydrolysis)?

Why?

1. Should have become more acidic (decrease in pH)
2. Amino acids contribute to greater acidity

What structure in the pancreas produces pancreatic lipase?

serous acini

1. What molecule does pancreatic lipase hydrolyze (break down)?
2. Products?
3. Optimal pH?
4. Glands that produce the chemical to provide this pH?

1. Triglycerides
2. Monoglycerides & fatty acids
3. pH 7.1 - 8.2
4. Pancreas & duodenal glands

**Lipid Digestion by Pancreatic Lipase & Bile Salt:** How did the pH of the solution change after pancreatic lipase digestion (hydrolysis)? Why?

Decreased; fatty acids contribute to pH decrease.

What color does litmus have in an acidic & basic environment?

pink; blue/lavender

What cells produce bile?

hepatocytes

Function of bile salts in digestion?

emulsifies lipids to increase surface area for enzymes

In an experiment, what’s the purpose of the negative control groups, positive control groups, and experimental groups?

Control groups let you compare your experimental group to what a positive and negative result would look like.

What does IKI test for?

Starch

What does Benedict’s test for?

Glucose & reducing sugars

Describe all applicable negative & positive control molecules & expected results.

1. ==Negative:== IKI + water
2. %%Positive:%% IKI + starch
3. ==Negative:== starch+ Benedict’s
4. %%Positive:%% glucose + Benedict’s

What structure in the pancreas produces pancreatic amylase?

serous acini

What molecule does pancreatic amylase hydrolyze (break down)? How did you test for this substrate?

Starch, IKI test

What are the products of the hydrolysis of **pancreatic amylase**, and how did you test for them?

Maltose & reducing sugars; Benedict’s reagent

Mouth and salivary glands secretion?

* salivary amylase
* lingual lipase
* mucus
* lysozyme

Volume/day mouth and salivary glands?

1 L/day

Digestion of mouth and salivary glands?

* **starch:** maltose + small carbs
* mastication

Absorption of mouth and salivary glands?

None; nitroglycerin

Stomach secretion?

* **parietal cells:** HCl, intrinsic factor
* **chief cells:** pepsin, gastric lipase
* **mucous neck cells**: mucous
* **g-cells:** gastrin

Volume/day stomach?

2 L

Motility of mouth and salivary glands?

tongue aids to form bolus; deglutition

Motility of stomach?

Mixing waves, gastric emptying

Digestion in stomach?

* triglycerides → monoglycerides (gastric lipase) or diglycerides (lingual lipase) + FAs
* protein → peptides
* HCl → denature protein; **fundus:** salivary amylase

Absorption in stomach?

alcohol, aspirin

Pharynx and esophagus secretion?

mucus

Volume/day pharynx and esophagus?

none

Motility in pharynx and esophagus?

deglutition, peristalsis

Absorption and digestion in pharynx and esophagus?

None

Pancreas secretion?

* **Serous acini:** NaHCO3-, pancreatic amylase, ribonuclease, trypsin, elastase, chymotrypsin, carboxypeptidase, pancreatic lipase, deoxyribonuclease
* **Pancreatic islets:** alpha - glucagon; beta - insulin

Volume/day pancreas?

2 L/day

Motility, digestion, absorption of pancreas?

None

Liver secretion?

bile

Volume/day liver?

1 L

Motility, digestion, absorption of liver?

None

Small intestine secretion?

* **Intestinal glands:** intestinal juice
* **Brush border enzymes:** lactase, alpha-dextrinase, maltase, sucrase, enterokinase, peptidase
* **CCK-cell:** cholecystokinin
* **S-cell:** secretin

Volume/day small + large intestine?

1 L/day

Motility of small intestine?

* Segmentation
* MMC: migrating motility complex

Digestion in small intestine?

* protein, lipid, carbs
* Bile: emulsify fats
* brush border enzyme digestion
* DNA, RNA → nucleotides
* pancreatic juice digestion

Absorption in small intestine?

* most vitamins
* glucose, fructose, galactose, amino acids, fatty acids + monoglycerides, water, electrolytes

Motility of large intestine?

haustral churning, mass peristalsis

Digestion of large intestine?

bacterial fermentation

Absorption of large intestine?

water, vitamin B + K