Digestive System Flashcards
Digestion
Breakdown of large complex molecules into smaller ones that can be absorbed by blood and transported to body cells.
Digestion steps
Step 1 Ingestion: intake of nutrients by eating or drinking
Step 2 Digestion: breakdown of macromolecules into smaller that can be absorbed by the cell. 2 TYPES.
Mechanical - chewing food, grinding of food in stomach
Chemical - using digestive enzymes
Digestion steps
Step 3 Absorption: nutrients such as water, minerals, vitamins are absorbed into blood.
Step 4 Egestion: elimination of undigested materials.
Digestion is complete when _____
When all carbohydrates broken down to monosaccharides, all proteins to amino acids, and fats and oils to fatty acids and glycerol.
Digestive enzymes
Carbohydrase - Amylase
Protease - pepsin
Lipase
Bile
Acts like dishwater detergent. Breaks down fat in the small intestine (but chemical nature remains same).
Bile increase surface are for lipase to work.
Mechanical digestion.
Produced in liver
Structures of Alimentary canal
MOUTH
Physical digestion: teeth + tongue
Chemical digestion: amylase to breakdown starch.
Saliva contains:
Water - moisten food
Amylase - breakdown starch
Mucin - lubricant + binds food
How does food get to the stomach?
Peristalsis - rhythmic waves of contraction + relaxation of muscular walls that moves food.
Controlled by nervous system.
Starts in esophagus ->
Structure of alimentary canal
STOMACH
- Stomach: begins chemical digest of proteins.
Pepsin: begins protein digestion, activated by HCl (low pH) protects stom. cells from self-dig.
Hydrochloric acid: lower pH (1-2) destroys bacteria.
Mucus: prevents acid + protein digesting enzymes from damaging wall.
Stomach ulcers
Mucus secreted by stomach lining cells prevents ulcers by preventing HCl and pepsin from damaging walls.
Small intestine functions
- Lined with villi and microbiology to increase SA and absorption of nutrients.
- Completes physical digestion (bile)
- Receives secretions from the pancreas and liver to aid in digestion
Enzymes: proteases (amino acids chains to amino acids) and carbohydrases (disaccharides into monosaccharides)
Large intestine
- Shorter than small intestine but bigger in diameter
- Joins to small intestine through the ilial-caecal sphincter
- absorbs water, vitamins, and minerals into blood
Cecum and appendix
Cecum: small pouch at beginning of large intestine
Appendix: small projection on caecum (vestigial organ)
Order of events
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Anus (feces stores in rectum and exits through)
Pancreatic juices contain
ALTA
ALKALINE salts - buffer/neutralize HCL from stomach
LIPASE - enzyme digesting lipids (triglycerides) into fatty acids and glycerol
TRYPSIN - enzyme (trypsinogen) activated by alkaline pH (basic)which continues protein digestion.
AMYLASE - digestion of starch, completes digestion started in mouth.
