1. 6.1 - Digestion

2. Purpose of digestion
A. Food is made of cells, and therefore macromolecules (carbs, lipids, proteins, nucleic acids) that your body needs to function
B. Macromolecules are too big to cross cell membranes
C. Your digestive system breaks polymers down into monomers so that they can get into your cells
D. Your cells use the monomers to build macromolecules

3. 4 steps Ingestion – eat Digestion – break down into smaller molecules
Absorption – molecules move from digestive tract into blood and lymph
Transport – circulatory system delivers molecules to cells

5. Digestion is an enzyme-driven process
A. Digestive enzymes catalyze hydrolysis reactions – hold macromolecules in place and stress bonds until body heat causes them to break

6. glycerol and fatty acids
Salivary Amylase
Pepsin
Trypsin
Pancreatic Lipase
Pancreatic Amylase
Source
Salivary Glands
Stomach cells
Pancreas
Location of action
Mouth
stomach
Small intestine
Small Intestine
Substrate
Amylose (starch)
proteins
lipids
Product
maltose, glucose
amino acids
glycerol and fatty acids pH 7
pH 3 8

7. Absorption
Villi – finger-like projections that line the small intestine – increase surface area!
1. Contain a capillary network for nutrients to pass into the blood (carbs and proteins) and a lacteal for the lymph system (lipids)
Passive Transport
1. Simple diffusion - fatty acids
2. Facilitated diffusion – glucose, amino acids
Active Transport
Pumps – glucose, amino acids
Endocytosis – not fully digested macromolecules

9. Importance of smooth muscle
A. Longitudinal – moves food through
B. Circular – mechanical digestion