metabolism & digestive system

Metabolism

All chemical reactions happening in the body to keep you alive.

Catabolic Reactions

Break big molecules into small ones; release energy; produce monomers.

Memory Trick for Catabolic

“CATA = catastrophe = things break apart.”

Anabolic Reactions

Build big molecules from small ones; require energy.

Memory Trick for Anabolic

“ANA = anabolic = adding.”

Products of Catabolic Reactions

Monomers (glucose, amino acids, fatty acids) + energy.

Use of Monomers

Used by cells to build new molecules or make ATP.

ATP

Energy currency of the cell; powers all cell activities.

How ATP Is Made

Food is broken down → energy released → ATP produced.

Memory Trick for ATP

“ATP = A Tiny Powerpack.”

Enzymes

Proteins that speed up chemical reactions.

Role of Enzymes in Digestion

Break food into monomers faster.

Amylase

Enzyme that breaks down starch.

Lipase

Enzyme that breaks down fats.

Pepsin

Enzyme that breaks down proteins.

Memory Trick for Enzymes

“Enzymes = scissors for food.”

Main Function of Digestive System

Break down food, absorb nutrients, eliminate waste.

Steps of Digestion

Digest → Absorb → Deliver → Dump.

Memory Trick

“Small intestine does the BIG work.”

Mouth

Starts digestion; amylase breaks starch; chewing increases surface area.

Esophagus

Moves food to stomach using peristalsis.

Peristalsis

Wave‑like muscle contractions that push food forward.

Memory Trick for Peristalsis

“Toothpaste tube squeeze.”

Stomach

Acid + pepsin break proteins; churns food into chyme.

Small Intestine

Main site of digestion AND absorption; receives enzymes + bile.

Large Intestine

Absorbs water; houses gut bacteria; forms feces.

Liver

Makes bile; detoxifies; stores nutrients.

Gallbladder

Stores bile.

Pancreas

Releases digestive enzymes; releases insulin + glucagon.

Where Digestion Begins

Mouth.

Where Protein Digestion Begins

Stomach.

Where Most Digestion Occurs

Small intestine

Where Most Absorption Occurs

Small intestine.

What Gets Absorbed

Glucose, amino acids, fatty acids, vitamins, minerals, water.

Gut Bacteria

Live mostly in large intestine; help digestion and health.

Role of Gut Bacteria

Break down fiber, make vitamins, support immunity.

GERD

Acid reflux; LES doesn’t close properly.

Memory Trick for GERD

“GERD = Gate Doesn’t close.”

Ulcers

Holes in stomach lining; caused by H. pylori or NSAIDs.

Diarrhea

Too little water absorbed; often due to infection or irritation.

Diverticulitis

Inflamed pouches (diverticula) in colon.

Celiac Disease

Autoimmune reaction to gluten; damages villi; reduces absorption.

Memory Trick for Celiac

“Celiac = Cannot Eat Gluten.”

Order of Digestive Tract

Mouth → Esophagus → Stomach → Small intestine → Large intestine → Rectum → Anus.

Chyme

Semi‑liquid food mixture in stomach.

Monomers

Smallest units of nutrients: glucose, amino acids, fatty acids.

Why We Need Food

Energy, growth, repair, and building molecules.

Catabolic

Catabolic = break + energy

Anabolic

Anabolic = build + energy used

What organ makes bile?

Liver

What organ stores bile?

Gallbladder

What organ releases insulin?

Pancreas

Where does most absorption occur?

Small intestine.

What enzyme breaks down proteins?

Pepsin

What causes ulcers?

H. pylori or NSAIDs.

What causes GERD?

Weak LES allowing acid to move upward.

What is ATP used for?

Energy for all cell activities.

What is peristalsis?

Muscle waves that move food through the digestive tract.